THE

CARBOHYDRATES

AND ALCOHOL

BY

SAMUEL RIDEAL, D.Sc., F.I.C.

AND ASSOCIATES

LONDON

BAILLIERE, TINDALL AND COX

8, HENRIETTA STREET, COVENT GARDEN

PRINTED IN GREAT BRITAIN

GENERAL PREFACE

THE rapid development of Applied Chemistry in recent yearshas brought about a revolution in all branches of technology.This growth has been accelerated during the war, and theBritish Empire has now an opportunity of increasing itsindustrial output by the application of this knowledge to theraw materials available in the different parts of the world.The subject in this series of handbooks will be treated fromthe chemical rather than the engineering standpoint. Theindustrial aspect will also be more prominent than that ofthe laboratory. Each volume will be complete in itself, andwill give a general survey of the industry, showing howchemical principles have been applied and have affectedmanufacture. The influence 'of new inventions on thedevelopment of the industry will be shown, as also theeffect of industrial requirements in stimulating invention.Historical notes will be a feature in dealing with thedifferent branches of the subject, but they will be keptwithin moderate limits. Present tendencies and possiblefuture developments will have attention, and some spacewill be devoted to a comparison of industrial methods andprogress in the chief producing countries. There will be ageneral bibliography, and also a select bibliography to followeach section. Statistical information will only be introducedin so far as it serves to illustrate the line of argument.

Each book will be divided into sections instead ofchapters, and the sections will deal with separate branchesof the subject in the manner of a special article or mono-graph. An attempt will, in fact, be made to get away from

vi GENERAL PREFACE

the orthodox textbook manner, not only to make the treat-ment original, but also to appeal to the very large class ofreaders already possessing good textbooks, of which "thereare quite sufficient. The books should also be found usefulby men of affairs having no special technical knowledge, butwho may require from time to time to refer to technicalmatters in a book of moderate compass, with references tothe large standard works for fuller details on special pointsif required.

To the advanced student the books should be especiallyvaluable. His mind is often crammed with the hard factsand details of his subject which crowd out the power ofrealizing the industry as a whole. These books are intendedto remedy such a state of affairs. While recapitulating theessential basic facts, they will aim at presenting the realityof the living industry. It has long been a drawback of ourtechnical education that the college graduate, on commencinghis industrial career, is positively handicapped by hisacademic knowledge because of his lack of information oncurrent industrial conditions. A book giving a compre-hensive survey of the industry can be of very materialassistance to the student as an adjunct to his ordinary text-books, and this is one of the chief objects of the presentseries. Those actually engaged in the industry who havespecialized in rather narrow limits will probably find thesebooks more readable than the larger textbooks when theywish to refresh their memories in regard to branches of thesubject with which they are not immediately concerned.

The volume will also serve as a guide to the standardliterature of the subject, and prove of value to the con-sultant, so that, having obtained a comprehensive view ofthe whole industry, he can go at once to the properauthorities for more elaborate information on special points,and thus save a couple of days spent in hunting through thelibraries of scientific societies.

As far as this country is concerned, it is believed thatthe general scheme of this series of handbooks is unique,and it is confidently hoped that it will supply mental

GENERAL PREFACE vii

munitions for the coming industrial war. I have beenfortunate in securing writers for the different volumes whoare specially connected with the several departments ofIndustrial Chemistry, and trust that the whole series willcontribute to the further development of applied chemistrythroughout the Empire.

SAMUEL RIDEAI,.

AUTHOR'S PREFACE

THIS industries briefly summarized in the present volume intheir modern applications have reached a considerablemagnitude and involve considerations of an economiccharacter which must be bused upon accurate chemical datafor future development. A student making a choice ofindustrial chemical work is apt to think that the industriesdealing with starch, sugar, and alcohol, do not afford muchscope for the application of chemical principles; but thisbook may serve to dispel such an erroneous view, and showthat; not only is a fairly wide knowledge of the chemicalconsti tution of these sugars and their synthesis, formationin the plant and in the laboratory important, but that theirdecomposition products involve biochemical changes of greatinterest which cannot fail to be of value in establishing newworld conditions of exchange.

Many of the problems specially appeal to the Britishpublic, and afford considerations of tropical agriculture andchemical manufacture under economic conditions of powerand labour which may modify future progress. It isimpossible within the scope of a single volume more than toglance at. these varied developments, but it is hoped that theoutline here presented may be of interest to many readers,and stimulate greater interest in this country in some of theindustries which hitherto as a nation we have not takeninto sufficient account. It has been difficult to avoid

x AUTHOR'S PREFACE

references to companion volumes in the series seeing thatwood and cellulose supply methyl alcohol and sugars, thatfuel production and utilization includes the problem ofindustrial alcohol, and that the Carbohydrates are stillindustrially plant products.

SAMUEI/ RIDEAX.

July, 1920.

CONTENTS

INTRODUCTION.

Cellulose as a natural product, an industrial material, and a chemicalsubstance. General properties of cellulose. Its growth and decay.The production of cotton. Starch. Origin and natural characters.General and chemical properties. Starch paste and gelatinization,soluble starch. Proximate constituents of starch, hydrolysis byacids and enzymes. Dextrins. Sugars. General constitution ofsugars. Properties of glucose, fructose, invert sugar, galactose,sucrose, maltose, lactose, raffinose, dextrin . . . . 1-15

References . . . . . . . . . . . I S

PART I.

STARCH AND ITS PRODUCTS.

SECTION L—STARCH.

Raw materials for the preparation of starch . . . . . . 1 6YieMs of starch from various sources . . . . . . . 16(a) Wheat starch. Structure of the wheat grain. Preparation by the

fermentation process. The sweet process. Gluten . . . . 1 7(l>) Maize or corn starch. Preparation. Utilization of residues. Corn oil,

Germ cake, Chemicalled and unchemicalled starch. Thin boilinga n d thick boiling starch . . . . . . . . . 2 0

(<:) Rice starch. Composition of raw material. Softening, grinding,sieving, moulding, drying. Uses of rice starch . . . . 2 2

(d] Potato starch. Composition of potatoes. Determination of starch con-tent of potatoes. Washing, rasping, sieving, drying. Treatment ofresidues 24

(e) Arrowroot, sago, tapioca . . . . . . . . . 2 9Preparation o f soluble starch. Uses . . . . . . . 2 9Uses o f starch . . . . . . . . . . . 3 0References 43

xi

xu CONTENTS

SECTION II.—DEXTRIN.PAGE

Properties. Preparation of solid dextrin or British gum. Roasting orTorrefaction process. The acid process . . . . . 31

References 43

SECTION III—GLUCOSE.

Manufacture of glucose syrup and grape sugar . . . . . . 34Conversion of starch. Neutralization. Filtration. Evaporation . . 36Filtration through animal charcoal . . . . . . . 3 8Concentration in the vacuum pan. Uses . . 39Chemical Synthesis o f sugars . . . . . . . . 41References 43

SECTION IV.—MALTOSE.

Industrial preparation o f maltose syrup . . . . . . . 4 2References . . . . . . . . . 4 3

PART II.

SUGAR.

SECTION I.—CANE SUGAR.

The -Sugar Cane. Origin a n d distribution . . . . . - 4 5The Plant. Cultivation. Soil and water requirements. Composition of

t h e cane. Varieties. Pests a n d diseases . . . . . . 4 8Extraction of the Juice. Cane mills. Maceration and Imbibition. Megass:

Multiple crushing. The diffusion process. Yields. Character of the juice 53Clarification. Defecation agents. Defecators. Sulphuring. Eliminators.

Carbonation. Treatment of scums. Filtering media . . . 64Evaporation. Earlier methods. The copper-wall battery. Panela train

and concretor. Film evaporators. Vacuum pan, triple effect. Lillieand Kestner evaporators. . . . . . . . • 71

Boiling. Crystallization. Muscovado tanks. Vacuum pan . . - 77Curing. Crystallizers. Centrifugals . 78Molasses. Composition. Utilization . . . . . . . 8 0References . 8 2

SECTION II.—BEET SUGAR.

The Beetroot. Cultivation. Improvement by selection. Composition . 83Manufacture. Brief history of the foundation of the beetroot sugar manu-

facture. Early methods of the [extraction of the juice. Pressing the

CONTENTS X1U

rasped pulp. Cold and hot maceration processes. The diffusionprocess. Theory of the diffusion process . . . . • . 8 7

Extraction of the Juice. Washing the roots. Beet slicing machines. Dif-fusers. Working of theibattery. Exhausted pulp. Pressing and dryingthe pulp. Molasses fodder • 94

Purification of the Juice. Defecation. Single and double carbonation.Sulphiting. Filtration. Treatment of scums. Lime kilns, carbondioxide. Sulphur burner . . . . . . • • Io°

Evaporation. Multiple effect evaporators . . . . • . 1 0 9Boiling. The vacuum pan. Boiling to grain. Control of the boiling . 1*3Treatment of the Massecuite. Centrifugal treatment of the first massecuite.

Crystallization in motion of the second massecuite. Molasses • . 118Recovery of Sugar from Molasses. Osmose process. Elution process. The

substitution and separation processes. The strontia process . . 122References 125

SECTION III—SUGAR REFINING.Raw sugars. Preliminary treatment or affination. Melting. Filtration.

Filtration through animal charcoal. Revivication of char. Boiling tograin. Drying the massecuite. Granulated sugar. Cube sugar. Prepara-tion of invert sugar and sacchamm. Table syrups. Refinery molasses 127

References I32

SECTION IV.—MINOR SOURCES OF SUGAR.Sorghum sugar and syrup . . . . . . . - . 1 3 4Maple sugar and syrup . - *35Palm sugar . . . . . . . . . . - . 1 3 6References *37

SECTION V.—CARAMEL.Properties. Manufacture. Uses . . . . . . . . 1 3 8References 139

PART III.

ALCOHOLIC FERMENTATION.—BEER.

SECTION L—MALTING.Barley, malt, diastase. Supplementary materials. Preparation of grist . 140

SECTION II—MASHING.Nature of the changes during mashing. Influence of water used for brewing

xiv CONTENTS

SECTION III.—BOILING AND IIOITINT, .t'A

The chemical constituents of Imps. Cooling and u-iuj' .mitiutf . . .

SECTION IV,—KKKMKNTATU ) N .Yeasts. The chemical chants during fermentat ion. H i c h a m ! Imv ye.u-i- , .

Tare cultures. Aeration, temperature, durat ion. I V u . i t y <>t \ v » u t ; iu>!attenuation. Maker's yoast. Yeast food product. Ui.r;i-.r-; < • ( l irrt.Zymase . . • . « • • • • • , i J ,

References , . . . . • • • • • • » ^

PART IV.

W I N E .

SECTION I.—GRAPHS AND T H I C V I N I C .Pressing and must. Constiluents of the must. M.uc , j o j

SECTION II .—FKRMKNTATIOM.Fermentation and slow feruu:nlatu)n. Stonier and t rc . i t tucut . Svvrr t , < U y ,

and eflervcscinp; wines, modicatol wines uud nthrr ulcoholif hrvrta^r-4 . KJIJ

SECTION I I I . TARTAR.Lees, ar^ol, tartaric acid . . . . . . . . . t<»SReferences . . . . . . . . . , id\)

PART V.

DISTILLATION.

SECTION I.—GRAIN SPIRIT.Malting and mashing. Fermentation. Distillation. Rectifying. Al»- .oJut r

alcohol. Proof spirit . . . . . . . * I70

SECTION IL^rOTABLK S P I R I T .Brandy, rum, whiskey, gin, potato spirit, liqueurs and cordial,-*, rhysinli^iuil

action of alcohol, alcohol as a food, mental cflrets, j i r t i tm on th<'di|T-.Uun,action on respiration and circulation of the Mood, alo.hol iitul theperformance of muscular acts, effect on the body Irmpmttuv, | i i>r.nnaction, longevity ' wi

CONTENTS xv

SECTION III.—INDUSTRIAL ALCOHOL.PAG re

MoLisses, potatoes, beetroots, clenaturants. Alcohol as a fuel . . . 1 9 0

SECTION IV.—SYNTHETIC ALCOHOL.

From wood, starch, peat, carbon . . . . . . . . 194.References . . . . 1 9 8

PART VI.

VINEGAR.

SECTION L—PREPARATION OF THE WORT.

Fermentation. Acetification. Acetic acid bacteria. Quick vinegar process.Acetates . . . . . . . . . . . 2 0 0

SECTION II.—ACETIFICATION.

Malt vinegar. Wine vinegar. Vinegar from alcohol . . . . 2 0 3

SECTION III.—ACETIC ACID.

Acetic acid. Formation, synthetic acetic acid, glacial acetic acid. Aromaticvinegar . . . . . . . . . . . 2 0 6

SECTION IV.—ACETONE AND GLYCERINE.

Industrial preparation of acetone, glycerine from molasses . . . 211References . . . . . . . . . . . . 2 1 6

INDEX 217

CARBOHYDRATES

INTRODUCTION

THE great group of the carbohydrates, including cellulose,starch, the sugars and gums, forms a class of compoundsof extreme interest, both from their wide distribution,especially in the vegetable kingdom, fed for their utilityto mankind, furnishing food, clothing, building materials,fuel, paper and explosives, and the source from which wine,spirits, beer and other beverages are prepared.

They are classified on the basis of molecular complexityinto—

Monoses or Monosaccharides, as dextrose and levulose ;Saccharobioses or Disaccharides, as cane sugar and

maltose;Saccharotrioses or Trisaccharides, as raffiiiose ; andPolysaccharides, including starch and cellulose.

Cellulose.—Cellulose in its many forms constitutes thebasis of the skeletal framework of all plants, supportingand containing the living protoplasm of the vegetable cell.The cell-walls in the early stages of development consistentirely of cellulose, but as the plant grows they becomeencrusted with other products of growth either mechanicallyas colouring matters, resins, and other foreign substances,or chemically, as bodies closely allied to cellulose formingthe compound celluloses. The latter are considerably lessresistant than cellulose proper to the action of alkalis,oxidizing agents, and the halogens.

Cellulose to form the cell-wall is probably deposited asa hydrated colloid formed indirectly from starch. At this

2 CARBOHYDRATES

early stage it is much more susceptible to chemical reagentsthan in its later less hyclratcd form. The purest form inwhich it occurs in nature is in cotton and similar seed hairs,and in pith, but even these contain a small proportion ofinorganic constituents in such close combination with thetissue that after ignition they retain the form of the originalstructure.

As prepared from raw fibrous materials such as cotton,flax, and hemp, cellulose is a white, lustrous, more or lesstranslucent substance of organized structure and possessedof a certain hygroscopic character, so that: when air-dried,it usually contains from 7 to <j per cent, of moisture. Thequestion of moisture is of great importance in the text i leindustry, since the pliability and tensile strength of thethreads are greatly affected by their hygroscopic condition.

The elementary composition of pure, dry, ash-free cellu-lose is: carbon 44*2, hydrogen 6*3, oxygen 40/5 per cent.,corresponding to the empirical formula CYnJOO6, and thusaccords with the constitution characteristic of the carbo-hydrates in which the hydrogen and oxygen are presentin the same ratio as in water.

Cellulose is insoluble in water and all simple solvents,but is dissolved in cupnunmonium hydrate (Sehwei/ei'sreagent) from which it is precipitated by acids, some alkalisalts, and by sugar, but in a hydnited and modified form.Its general inertness to chemical reagents renders it usefulfor filtering purposes. Attention may here be directed toits power of retaining considerable quantities of some saltsby absorption. For further details we refer the reader tothe volume in this series on Wood and Cellulose.

The immense accumulation of vegetable matter in theworld as leaves and wood, consisting mainly of cellulose, isremoved to re-enter the cycle of life after being brokendown by the action of bacteria and enzymes.

Without attempting to make any estimate of the totalproduction of cellulose in the world by vegetable growth,some idea of its magnitude may be formed by consideringthe case of one particular plant, cotton, the seed hairs of

INTRODUCTION 3

wliicli form the product in question. vSir Charles W. Macarastates that the world's average cotton crop may now beestimated at 20,000,000 bales of 500 Ibs. each, or three timesthe quantity that was produced ten years ago. There arc,moreover, 2 Ibs. of seed to every i Ib. of cotton. The hullsform hay for feeding, and oil is obtained from the seedand the residual cake is used for feeding stock.

Starch.—The earliest preparation of starch was nodoubt made from wheat, and was called amylinn by theGreeks, since it was not obtained by grinding in a mill asHour is. Dioscorides states that the best kind of starchHour is obtained from Cretan or Egyptian wheat. Thegrain was steeped in water to soften it, and then kneadedand washed with water. The husks were next sieved out,and the deposited starch dried on bricks in the sun, sinceif left moist it soon became sour. Pliny (lib. xviii. c. 7)gives a similar account, and states that starch was discoveredat Chios.

Starch is, next to cellulose, the most abundant materialfound in the vegetable world, and is present in all greenplants, in which it occurs as microscopic granules of appa-rently organized structure. It is absent from the top of thebud and the extremity of rootlets, otherwise it is foundin all parts of the plant in varying amounts ; in seeds,with the exception of certain oleaginous seeds, and mostabundantly in those of the cereals and leguminosai, inroots, tubers, stems, and leaves. It acts as a reserve materialfor the needs of the plant, and forms and disappears by theaction of diastases secreted by the protoplasm according asthe cell juice is rich or poor in sugars. In the green parts ofplants it is associated with chlorophyll, which determines itsformation by the action of light from carbon dioxide andwater. Although it is the first visible product of thisphotosynthesis, it is probably a polymerized form of simplerbodies. It gradually disappears from the leaves during thedark, but is formed in darkness when a living leaf is floatedon a solution of glucose, galactose, fructose, sucrose, maltose,or even glycerine, but not when lactose or raffinose is used.

4 CARBOHYDRATES

Pure starch is a white glistening powder, free from tasfror smell, not volatile, infusible, uncrystallizable, and insolubl-in water and all neutral solvents. It differs from cellulos<in being insoluble in cuprammonium oxide. Under th<microscope it is seen to consist of minute granules of '<concentrically stratified structure, the size and form of th<granules being characteristic of the plant from which th<starch is derived. The outer layers are denser than thosenearer the nucleus or hilum, which appears as a dark spo*and generally occupies an excentric position. The granuleswhen intact, are quite unacted upon by water, owing tcthe protective action of the outer layer. When this layeiis broken, however, water is readily absorbed, the contentsof the granule swell considerably, and a small quantitypasses into solution. By appropriate treatment the whokof the contents of the granule may be removed, whilst theouter coating is left in the form of extremely thin layers,Treated with a solution of iodine this outer coating gives adirty yellow colour, whilst the cell contents are coloured anintense blue. This reaction is characteristic of all starches,and is not produced by any other known substance. Theinterior contents of the granules have been named granulose,and the substance forming the outer layer, starch cellulose.Another view of the matter is that this granulose, or amylo-cellulose, constitutes from 80 to 85 per cent, of the granules,the rest being a mucilaginous substance, amylopectin, towhich the viscosity of starch paste is due. But amylo-pectin is probably derived from amylo-cellulose by condensa-tion just as amylo-cellulose is derived from stigars. Solidstarch may be regarded as a coagulated substance which innature has passed from the state of colloidal solution to thesolid form, the passage of solid starch to starch-paste andsoluble starch being a reverse process to this. Moreover, inthe transference of starch by the action of translocationdiastase, whereby it is removed in a soluble form for theneeds of the plant, instead of being converted into solublesugar for this end, it may possibly be merely converted toa soluble starch.

INTRODUCTION 5

When heated with water to a temperature varyingaccording to the origin of the starch, it swells up and formsa paste, which on cooling forms a jelly. The viscosity ofstarch paste varies widely, depending not only on the varietyof starch used, but also on the treatment during preparationin purifying and drying.

When starch is heated with water under pressure to150° C. it is converted into a modification known as solublestarch. In this form it is soluble in hot water, but separatesout on cooling, or on the addition of alcohol, as a white,flocculent amorphous precipitate. Soluble starch may alsobe prepared by treating starch with hydrochloric acid, withextract of malt, hot glycerol, or a weak solution of causticsoda. Its specific rotation is [«]I)~|-202 at 15° C. in a 2*5 to4'5 per cent, solution.

The action of dilute acids on starch varies with theconcentration, temperature, and pressure, resulting in itsgradual hydrolysis or saccharilication. The same result isobtained on starch paste by various enzymes, the mostactive of which are the diastase of malted barley, the ptyalinof saliva, and the pancreatic juice ferment (trypsin). Thestarch is first converted into soluble starch, then mto dextrinand maltose, and finally, on prolonged action, into glucose.

Dextrin.— vStarch gum or dextrin is a gum-like substancesoluble in cold water, and precipitated from its solution inan amorphous form by alcohol or by barium hydroxide.The name dextrin was given to it to indicate its dextro-rotatory power. It was first obtained by heating starch,and was found along with glucose when starch was actedupon by diastase or by boiling with dilute acid. It ispresent in all starchy seeds during germination and inmalted grain. During the progressive hydrolysis of starchby diastase a number of dextrines are formed intermediatebetween starch on the one hand and the final products,maltose and glucose, on the other. These are of graduallydiminishing dextro-rotation and of increasing cupric-reducing power, and certain of them give characteristiccolour reactions with iodine. vSoluble starch or ainylo-

6 CARBOHYDRATES

dextrine is first formed and is coloured blue by iodine,next erythrodextrine, coloured red by iodine, and subse-quently achroo-dextrines, which give 110 colour.

The starch molecule may be regarded as consisting offour complex dextrin groups connected with a fifth groupof similar character, but which is far less readily resolvedthan the others by diastase and remains as the so-calledstable dextrin on hydrolysis. The first action is the break-ing up of the complex molecule of starch [(C12H2oOi0)2o]5 intothe stable dextrin (C12H20O10)20 and four groups of readilyhydrolyzable dextrins or amylin groups. Each amylin groupgradually hydrolyzes to a series of complex amyloin ormalto-dextrin groups containing one or more molecules ofmaltose, C12H22On, thus : (C12H2o010)20+H2O=C12H22O11.(C12H20010)i9, and so on to (C12H20O10)20 + I9H2O=(C12H22Ou)i9.Ci2H20O10. These complex amyloin groupsbreak up into smaller molecular aggregations, which, how-ever, retain all the characteristics of the amyloiiis, andthis goes on until the maltose stage is reached.

An alternative view of the process is that the stabledextrin stage is reached when the whole of the amylose ofstarch is converted into maltose, and the amylo-pectin,which forms one-fifth of the starch, is left, and this is onlyslowly converted into maltose by another ferment, dextri-nase, also present in diastase.

Commercial dextrin is a light powdei or semi-transparentmasses generally of yellowish colour with a smell somewhatlike new bread. It dissolves completely in water and givesa red colour with iodine. The specific rotation is [a] D =+195.

Sugars.—Sugar in the popular sense always meanscane sugar or sucrose, whether derived from the sugar cane,beetroot, or other plant, and to the manufacturer is knownas crystallizable sugar because the glucose and fructosepresent along with it, especially in cane products, remainbehind in the mother syrup or molasses. Unlike starch,which is present as a solid, sugar is found in the plant insolution in the juice of the cells where it is stored as areserve food material.

INTRODUCTION ^

The sweet taste characteristic of sugar is possessed bya number of other substances in no way related to it inchemical constitution, but the reason why these sub-stances taste sweet is not known. It is a curious fact thatdextrorotatory asparagine has a sweet taste, while that of1-asparagine is disagreeable and cooling. Pasteur suggeststhat the substance of the nerves dealing with taste behavesas an optically active substance and reacts differently witheach acid. Acetate or sugar of lead, the salts of beryllium(glucinum) and glycerine, all have a sweet taste. Of thecoal-tar sweetening agents saccharine, o-anhydrosulphaminebenzoic acid, or benzoic sulphimide, is five hundred times assweet as cane sugar. It is often used in the form of itsmore easily soluble sodium salt. Dulcine or sucrol, mono-p-phenetol carbamide, glucine, amido-triazine sulphonicacid or its sodium salt, and sucramine or methyl saccharineare also intensely swee+, but none of these chemical sub-stances have any nourishing value, while sugar is valuableas a food.

By preparation from natural products or by chemicalsynthesis monosaccharide sugars have been obtained contain-ing from three to nine atoms of carbon in the molecule, but thesugars dealt with industrially have six atoms of carbon or amultiple of this, namely, twelve atoms in the disaccharidessucrose, maltose, and lactose, and eighteen in the trisaccharideraffinose. The hexoses are usually spoken of industrially asreducing sugars from their action on salts of copper.

Glucose. — Dextrose, or dextroglucose, is also calledgrape sugar from its occurrence in the juice of grapes andother fruits associated with fructose (laevulose) ; these twohexoses are probably derived from cane sugar, as all threeare usually present, and cane sugar is easily resolved intoglucose and fructose by hydrolysis whereby a molecule ofwater is taken up thus —

Cane sugar. Glucose. Fructose.

From the more complex; sugars or other carbohydratesit may also be prepared when these are hydrolyzed by

8 CARBOHYDRATES

suitable enzymes or by acids, as from maltose or malt sugarlactose or milk sugar, starch and cellulose.

It crystallizes in cauliflower-like masses of needles froiian aqueous solution with one moleciile of water of crystalliza*tion, but the anhydrous substance may be obtained as needle-shaped crystals from a solution in alcohol. Anhydrousglucose melts at 146° to 147° C. to a colourless glass, butthe hydrate has no proper melting-point. When glucoseis heated above its melting-point it becomes brown at once :at 170° it loses water and the residue contains glucosan.At higher temperatures it is converted into caramel. Diluteaqueous solutions may be boiled without change, but moreconcentrated solutions decompose. Ammonia turns asolution of glucose yellow at ordinary temperatures andalkalis generally darken the solutions on heating and theaction of oxidizing agents is accelerated in presence ofalkalis. The action of acids upon glucose is greatly affectedby the concentration. Glucose may be dissolved in coldconcentrated sulphuric acid without charring. From thesulphonic acids thus formed dextrins may be separatedsimilar to those obtained from starch. Hydrochloric acidof 7 to 10 per cent, concentration produces more hiunicacid than sulphuric acid of the same strength. Sodiumamalgam reduces glucose to the corresponding hexahydricalcohol, sorbitol, no mannitol being formed if the solutionis maintained slightly acid. The reducing action of glucosesolutions on metallic salts varies according to the conditions,thus a neutral solution of copper sulphate gives metalliccopper, but an alkaline one, as Fehling solution, gives redcuprous oxide. Ammoniacal solutions of gold, silver, andplatinum are reduced to metal, giving beautiful mirrors.

Dextroglucose exhibits the phenomenon of mutarota-tion, formerly called birotation from the fact that a freshlyprepared solution has a rotatory power on polarized lightabout twice as great as that which it eventually assumeson standing for some time. The change may be broughtabout immediately by adding a few drops of ammonia toits solution. Mutarotation is explained by the existence

INTRODUCTION 9

of two isomeric closed-chain forms, a glucose with arotatory power [a]l)~|-no and j3 glucose, [a]I)-fi9, thestationary rotation of [a]D+52'5 of the solution being dueto an equilibrium mixture of the two forms, the proportionspresent depending on the concentration of the solution andon the solvent.

vSince the aldohexose C0H1200 or CH2OH.(CHOH)4COHcontains four asymmetric carbon atoms, there are in allsixteen possible stereoisomers, and there is, correspondingto ordinary glucose (d-glucose), a lorvorotatory isomeride ofequal and opposite rotatory power, 1-glucose. Moreover,as two closed-chain forms (a and j3) should exist for each ofthese, the total number of isomeric aldohexoses is 48, butonly three of these occur naturally, namely, d-glucose,d-mannose, and d-galactose.

Five of the six atoms of oxygen in the molecule of glucoseare thus to be regarded as present in the alcoholic form ashydroxyl (OH), while the remaining one under certainconditions shows aldehydic functions. Glucose accordinglyforms with metallic hydroxides compounds called glucosates,similar to the alcoholates, and also yields esters with acids.Calcium glucosate is more soluble than the correspondingcompound with levulose, and this fact is utilized in thepreparation of levulose from invert sugar.

The taste of glucose is only about half as sweet as canesugar.

Fructose.—Fructose, formerly called levulose or fruitsugar, is a keto-hexose, and is now termed d-fructose toindicate its configuration, and without reference to its kevo-rotation. When found free in nature it is almost alwaysassociated with glucose as a constituent of plant juices, suchas in fruits, the sap, and in the nectar of flowers. In honeythe percentage of fructose is slightly greater than that ofglucose.

It is formed also by the hydrolysis of inulin, a polysac-charide which takes the place of starch as a reserve materialin the roots and tubers of many plants. Among thesemay be mentioned elecampane (Inula Hclenium), dahlia,

io CARBOHYDRATES

dandelion, chicory, and the Jerusalem artichoke, the amountpresent being greatest in autumn. Imiliu may be detectedin plant tissues by treating a thin section with strong alcoholor glycerol and examining under the microscope when theinulin is observed as spluero-erystals in the cells.

Fructose may be prepared from invert sugar by treatinga 6 to 8 per cent, solution with slaked lime at 30" 35" C\,filtering quickly and cooling to o". Calcium hevulosatecrystallizes out on standing. The crystals are washed withice-cold water and decomposed with oxalic acid, and thefiltrate evaporated in vacuo at a low temperature. Thesyrup crystallizes much less readily than glucose. Fructoseis very soluble in water, but only very slightly in coldalcohol. In hot alcohol it is easily soluble and crystal-lizes from this solution in very line needles \vhieh areanhydrous.

A solution of fructose is strongly hcvorotutory, [ajD- <)£>and the polarization changes considerably with tempera-ture and concentration. Jt shows mntarot.ai.ion, a freshlyprepared solution shows | a ) l ) — i o O . The syrup readilydarkens on heating. Alkalis act upon it similarly toglucose. Sodium amalgam gives equal amounts of mamiitoland sorbitol. Fructose as a pharmaceutical preparation isrecommended for diabetic patients ; its taste is far sweeterthan that of cane sugar.

Invert Sugar.—Invert sugar is a mixture of equal partsof glucose and fructose, and is found hi many plant juices.In unripe canes it is present in considerable amount. It;may be prepared from cane sugar by the hydrolyzinj^ actionof acids, enzymes, and salts. The rate of inversion by variousacids runs closely parallel to their electrical conductivity,and thus appears to be dependent on the ionization of theacids, but the rate is increased by rise of temperature farmore than can be accounted for by the increase in ioni/.atiouor the increased speed of the H ions to which the catalyticaction is attributed.

The most important inverting enzyme is invertasc, whichis present in the leaves, buds, fruit, and reserve organs of

INTRODUCTION u

many plants. It may be prepared from yeast by allowingthis to undergo autolysis.

Invert is readily fermented. It forms salts with bases.In assessing the value of raw sugars for refining purposes itis assumed that invert sugar renders its own weight of canesugar uncrystallizable. On heating invert sugar with alkalisdark-coloured products and soluble salts are formed. Itreduces alkaline solutions of copper salts. When concen-trated it forms a syrup the colour of which is dependent onthe purity. When pure the syrup readily becomes pastyfrom the deposition of crystals of glucose.

Both as a syrup and in the form of a cheese-like pasteit is largely used by brewers and termed " saccharum."

Galactose.—Galactose is a reducing sugar formed alongwith glucose on the hydrolysis of lactose or milk sugar. Asan anhydride product or galactan it is a constituent of manygums, hemicelluloses, mucilages, and pectins. Agar-agar onhydrolysis by boiling with 2 per cent, sulphuric acid is largelyhydrolyzed to d-galactose. It is of interest industriallyfrom its occurrence as a constituent of raffinose which isfound in beet sugar. On oxidation it yields mucic acid.It is fermented much more slowly than glucose. d-Galactoseis strongly dextrorotatory and shows mutarotation. Theinitial [a]D is about +140, the constant value +81. It isless sweet than glucose. It crystallizes in the form of largeprismatic needles which contain one molecule of water ofcrystallization. It is not found free in nature, but the wideprevalence of galactans in fodder plants may provide thesource of lactose in the milk of the herbivora.

Sucrose.—Sucrose or cane sugar is the best known ofthe sugars, and is found widely distributed, being found innearly every part of the plants. Its manufacture, however,is mainly restricted to the sugar cane in the tropics, thebeetroot in temperate climates, sorghum, and sugar maplein North America, and a smaller proportion from the datepalm in the East.

It crystallizes in anhydrous tables belonging to themonoclinic system, with hemihedral faces. The shape of

12 CARBOHYDRA TES

the crystals is modified by impurities ; the presence ofraffinose causes the formation of pointed needles. Its

i^°specific gravity at -^ C. is 1*591. There is contraction

on solution in water, and on dilution, the maximum beingreached at 55-56 per cent. At 20° C. 100 grammes of waterdissolve 203*9 grammes °^ sucrose,and at ioo°,487*2 grammes.Sucrose is soluble in 80 parts of boiling absolute alcohol,more easily soluble in dilute alcohol, but insoluble in ether.The solubility in water is increased by the presence of manysalts and organic substances. Such impurities play animportant part in the sugar industry in preventing thecrystallization of sugar and its recovery from molasses.The sugar is supposed to form compounds with the salts,which have then a greater solubility than sucrose alone ;such salts are called melassigenic.

The boiling-point of aqueous solutions of sucrose are—

Per cent sucrose 10 20 30 40 50 60 70 80 90*8Boiling-point °C. 100*4 100*6 101*0 101*5 102-0 103*0 106*5 112*0 130*0

The specific rotation is [a]D20°+66*5, an(i *s slightlyaffected by concentration and temperature. Sucrose is notdirectly fermentible by yeast, being first hydrotyzed (in-verted) by the invertase secreted by the majority of yeasts.Although, finally, the same amount of alcohol and carbonicacid is produced as from glucose and fructose, the processis retarded by the effect of the inversion which must precedefermentation. Saccharomyces octosporus and 5. apiculatus,which do not secrete invertose, do not ferment sucrose. Ithas been suggested to use such organisms to ferment awaythe invert sugar present in molasses so as to obtain thesucrose by subsequent crystallization, but the process hasnot proved a success. Sucrose also undergoes lactic andbutyric fermentations. In the viscous fermentation fre-quently met with in sugar factories the sucrose is convertedinto the gum, dextran. This result is produced by theorganism Leuconostoc mesenterioides as well as by otherorganisms. The masses of gum are spoken of as frog's

INTRODUCTION 13

spawn. Various Citromyces ferment aerated solutions ofsucrose with the production of citric acid.

When sugar is heated above its melting-point it beginsto lose water and decompose. At 170° to 190° C. caramelis formed. Solutions of sucrose also deteriorate on pro-longed heating ; in the presence of acids inversion takesplace. Sucrose forms compounds with metallic bases, andof these the sucrates of the alkaline earths are of technicalimportance.

Calcium monosucrate is formed by dissolving finelypowdered quicklime in sucrose solutions maintained at alow temperature and precipitating the compound withalcohol, C12H22On.CaO+2H2O. It is easily soluble inwater, and the solution on heating becomes turbid, themonosucrate decomposing into trisucrate and sucrose.

Calcium bisucrate separates in white crystals on coolingwith ice a sucrose solution to which two equivalents of quick-lime have been added.

Strontium bisucrate begins to separate from a boilingsucrose solution as soon as two equivalents of strontiumhydroxide have been added, and the separation is almost'complete with three equivalents. The bisucrate is decom-posed in cold water into monosucrate and strontiumhydroxide. Barium monosucrate is separated in crystallineform on cooling a solution of sucrose containing an excessof barium hydroxide.

Maltose. — Maltose, or maltobiose, is obtained by theaction of malt diastase on starch paste. The hydrolysis at50° to 60° C. gives a mixture containing 80*9 per cent, ofmaltose and 19'! of dextrine. I/ower temperatures give agreater yield, but the action is slower. The hydrolysis withacids converts the maltose into two equivalents of d-glucose.Maltose crystallizes in groups of very fine needles, con-taining one molecule of water of crystallization. It is verysoluble in water, and also soluble in alcohol. It exhibitsmutarotation, for ordinary anhydrous maltose [a]D = +i40.Although a biose, one of the two hexose residues exhibits

I4 CARBOHYDRATES

aldehydic functions, and consequently it reduces Fehling'ssolution, but about one-third less than glucose. It does notreduce acetate of copper. Its hydrolysis by acids is onlyabout one-fifth of the rate at which sucrose is hydrolyzed.It is hydrolyzed by the enzyme maltase, but not by invertase.Alkalis act upon it in much the same way as on glucose.

Lactose.—Lactose, lactobiose, or milk sugar, is presentin the milk of mammals to the extent of 3 to 6 per cent.,and may be prepared from whey by boiling to coagulatealbuminoids and concentrating the filtrate, using animalcharcoal for decolorizing the syrup.

It contains a glucose and galactose residue, and thesesugars are formed on hydrolysis. It forms large ortho-rhombic crystals containing one molecule of water. Itexhibits mutarotation, the stable form has [a]D20°+52'5.It reduces Fehling a little less than glucose, but not theacetate, and is thus distinguished from reducing sugars.Sodium amalgam yields dulcite and mannite. Alkalis acton it as on glucose. Yeast ferments it only with difficulty,but the kefir organism ferments it readily owing to thepresence of the ferment lactase which it secretes. The tasteof lactose is only faintly sweet.

Raffinose.—Raffinose is a trisaccharide, being a con-densed product of glucose, fructose, and galactose. It ispresent in beetroots to the extent of 0*02 per cent., and incotton seed, 3 per cent.; beetroot molasses may containas much as 16 per cent. It crystallizes in warty crusts oflong monoclinic needles, with 5 molecules of water, and itspresence in commercial sugars frequently causes sucrose toform elongated crystals, or spiky crystals as they are termed.It is less soluble in cold water, but more soluble in hot waterthan sucrose. On heating slowly at 80° to 105° C. it becomesanhydrous, but decomposes if heated quickly. Sugarscontaining raffinose become brown when heated. It hasno action on Fehling's solution, and is only slowly attackedby alkalis. Bottom yeast ferments it completely, but topyeast, which does not contain the ferment melibiase, onlyferments the levulose portion, leaving the glucose and

INTRODUCTION 15

galactose combination, melibiose, unattacked. The rota-tory power of raffinose hydrate is [a]D20° +104*5 withoutmutarotation. The presence of raffinose in raw beet sugarshas therefore a disturbing effect on the polarization for thevaluation of these products, and its amount must be deter-mined as far as possible. This is effected by moderatewarming with dilute acid, whereby fructose is split off andresulting polarization reduced to [a]D20°+53'5 for themixture of fructose and melibiose. Prolonged heating withhydrochloric or sulphuric acid resolves melibiose intod-glucose and d-galactose, the same products of hydrolysis asare obtained from lactose. This hydrolysis is not effectedby acetic, tartaric, citric, or lactic acids. Raffinose formscompounds with soda, lime, strontk, and lead oxide.

REFERENCES.

Cross, Bevan and Beadle, " Cellulose." Longmans. London. 1918.Cross, Bevan and Beadle, " Researches on Cellulose." 1895-1900,

1905, 1910.Schwalbe, " Chemie der Cellulose." Berlin. 1910.Tollens, " Handbuch der Kohlenhydrate." Brcslau, i. 1888; ii. 1895.Von Lippmann, " Chemie der Zuckerarten." Braunsweig. 1904.Maquenne, " Les Sucres et Principaux derives." Paris. 1900.E. F. Armstrong, " The Simple Carbohydrates and the Glucosides."

London. 1910.E. F. Armstrong, " Starch and its Isomerides." (Vol. I. of Allen's

"Commercial Organic Analysis.") London. 1909.Mackenzie, " The Sugars and their Simple Derivatives." London.

Gait, " The Microscopy of the more commonly occurring Starches/1900,

PART I.—STARCH AND ITS PRODUCTS

SECTION I.—STARCH

STARCH is prepared on the industrial scale from the partsof those plants in which it occurs in greatest abundance.The seeds of the cereals contain starch as their principalingredient. Wheat contains 55 to 65 per cent. ; barley,38 to 46 per cent. ; oats, 28 to 38 per cent. ; rye, 44 to 47per cent.; maize, 54 to 67 per cent.; rice 70 to 76 per cent.;potatoes, 16 to 23 per cent.

Wheat, the original material from which starch wasmanufactured, is not used so much as formerly. There areseveral reasons for this, not the least being the desire toretain the expensive wheat for food purposes. The largeamount of gluten present, 12 to 16 per cent., renders theprocess difficult, and the starch being made by souring awaythe gluten, the vicinity of a wheat starch factory was un-pleasant, and became a nuisance to the workmen and theinhabitants of the neighbourhood, so that frequent enact-ments were necessary to regulate the manufacture. Maizeand rice are now mostly employed. The seeds of theleguminosae also afford about 38 per cent, of starch.

Early in the eighteenth century the potato began to beused as a cheaper source of starch than that of wheat, andpotato starch is now made in far greater quantity thanother kinds, especially in Germany.

Tous les mois is a variety of starch made from the tubersof Canna edulis. Portland sago or Portland arrowroot isobtained from the tubers of Arum maculatum. Salep, oncelargely consumed, and still used in Turkey and the East asa food, is a starch derived from the tubers of various kinds

STARCH 17

of Orchis. The roots, about 30 pounds in weight, of thebitter cassava, Manihot utilissima, a native of SouthAmerica, contains prussic acid as well as starch, but thispoisonous ingredient is removed by washing the gratedroots and recovering the tapioca starch after settling. Ina similar manner prussic acid contained in haricot beansis removed by soaking the beans in water, which is thenpoured away, leaving the beans free from it and fit for food.Arrowroot is obtained chiefly from the rhizome or root-stock of Maranta amndinacca, a native of the West Indiesand Brazil. Sago is likewise a starch mainly produced fromthe stems of the sago palms, Sagus rumphii and S. levis,and a coarser kind is obtained from the nuts of Cycas rcvolutain Ceylon and the East Indies. Banana starch is preparedfrom the unripe fruits of Musa sapientium.

Structure of the Wheat Grain.—A grain of wheatconsists of three parts, the germ or embryo situated near thebase, the endosperm, which forms the bulk of the grain andis formed of a number of thin-walled polygonal cells filledwith starch granules embedded in proteins (Fig. i), includinggluten, and the various coverings which constitute the bran.One of these coverings, the aleurone layer, is conspicuousas a single layer of cells, rect-angular in section, filled withminute grains of undissolvedprotein, the aleurone grainsor " crystals."

Gluten does not exist assuch in the grain, but is formed

.i r u i F I G i.—Transverse section o fiu the presence of water by iL" Whoat Grain.the interaction of gliadin andghitcnin. Of these proteins glutenin is not dissolved byneutral aqueous solutions, by saline solutions, or by alcohol.Gliadin is soluble in 70 per cent, alcohol, is nearly or quiteinsoluble in water or salt solutions, but readily forms saltswith acids or especially with alkalis, and these salts aresoluble in water. The aim of the manufacturer of starchis to set free the granules from the cells in which they are

I8 CARBOHYDRATES

enclosed and to separate the starch from the other con-

stituents.The average composition of wheat is : starch ( > « S - < > , sugar

3-2, cellulose 2% fat 17, proteins iro, mineral ma t te r r < > ,

water 12*0 per cent.The Fermentation Process,-—Although the sour or

fermentation process of preparing wheat starch is w n M r f u lowing to the loss of the valuable constituent gluten, and isnow superseded by the sweet or Martin's process. vet ashort description may not be out of place considering thechemical changes which occur.

The wheat grains, after a preliminary cleaning, arc soaUnlin water until sufficiently soft to be crushed between t h efingers. This is best done in a metal cistern w i t h a conicalbottom and provided with a wide perforated pipe* in thecentre into which water is passed from below. When .softthe wheat is either placed in hempen bags and the starehvmatter pressed out by treading the bags in water, or t hegrains are crushed in a mortar mill. The impure s tarchyliquid is run into tanks where it is allowed to remain fortwo or three weeks, some liquor from a previous fermenta-tion or sour dough being added, and the mass is stirredoccasionally; the liquid is now covered wi th mould andshould have a pleasant vinous odour, but it is d i f l ieu l t toprevent the production of stinking gases. 'During thefermentation the sugar and some starch acetifies wi th t h eproduction of acetic, propionic, butyric, and lactic acids,and the gluten is thereby acted upon and softened, losingits stickiness, and is partly dissolved, setting free the starchgranules. The acid liquor is decanted and run to waste,and the mass washed repeatedly with water so long as tin:;becomes coloured, and then allowed to settle. The variouslayers are removed and the starch washed through fairsieves to separate particles of bran and fibre. The deposit edstarch is then placed in shallow boxes lined with canvas,and when compact is turned out, cut into blocks and driedon porous bricks, then stoved, scraped, and packed.

The starch may be more quickly recovered in a

STARCH 19

centrifugal separator with a solid drum. The purer starchforms a compact layer at the periphery; the less pure starchmilk is run off to form a second quality and fresh liquid runin until a thick layer is obtained. The impure yellow super-ficial layer is taken off with a sponge. The starch is removed,stirred with water, blued if necessary, and put into suctionmoulds. In order to avoid the development of mouldinessthe starch is dried at once either in the open or in stoves at30° to 70° C. At a certain stage the cakes shrivel at thesurface. This impure starch is scraped off, and the cakesbroken into blocks, wrapped in paper and dried. It thenacquires the radiating columnar structure which is regardedas a criterion of its good quality. The addition of gluten topotato starch does not enable it to assume a similar structure.Wheat starch is regarded as the best starch for dressing andfinishing linen, and the only two wheat starch factories inthe United Kingdom are situated in the north of Ireland inthe vicinity of the flax industry there.

The Sweet Process.—In the preparation of wheat starchby the sweet or non-fermentation process flour is preferablyused. This is kneaded with water to a stiff dough andleft for a time for the water to permeate thoroughly. Itis then washed on a fine sieve under a jet of water until allthe starch forms a milk and the gluten is left. This is doneon a reciprocating frame with a number of holes in the bottomcovered with gauze. The frame bears a number of rollersto assist the operation and is supported in a trough under-neath which is an inclined shoot and tanks to collect thestarch. When the masses of gluten are removed from thesieve they are placed at the ends of the frame againstbuffers, and there beaten to remove the last portions ofstarch. The usual washings and settlings as describedabove are then proceeded with, but a better result and anincreased yield of first quality starch is obtained by treatingthe impure starch with a weak solution of caustic sodasufficient to give a blue reaction to litmus. After standingsome time part of the gluten is dissolved, and the remainderaltered so as to be more readily removed on the sieves*

20 CARBOHYDRATES

Gluten.—Gluten is a valuable digestible protein con-taining 18 per cent, of nitrogen, and when recovered freshis used to mix with dough for baking bread, and in otherfood stuffs. Inferior starches rich in gluten are used inthe same way and also as fodder. Gluten does not dryeasily, and when wet readily undergoes putrefaction.When allowed to ferment at 50° C. it liquefies, and maythen be dried on metal plates to form transparent sheetsused as a kind of glue for leather in boot manufacture.Mixed with salt and fashioned into strips and dried, it canbe reduced to powder and used as flour.

Maize or Corn Starch.—The structure of a grain ofmaize is similar to that of a grain of wheat already described.The average analysis of maize is : starch 55, other carbo-hydrates 15, proteins 10*5, fat 5, ash 2*5, water 12 per cent.Of the proteins present one is soluble in water, and the glutenis soluble in dilute caustic alkali.

The maize, after being cleaned from dust, dirt, and otherchance impurities, is steeped in water at about 60° C. for30 hours or less to swell and soften the grain, and a littleweak sulphurous acid is added to prevent fermentation orputrefaction, the water being kept in circulation by meansof steam siphons. The steep waters are concentrated to beused for feeding cattle. The softened grain is then passedthrough a mill to crack or split the corn and partially grindit. The mass is then diluted with water and passed througha long V-shaped tank with a screw conveyer along the bottomand skimming paddles at the top. The germ, or embryo,being now loosened, and since it contains oil is specificallylighter than the bran, gluten, starch, and fibre, rises to thesurface and is skimmed off by paddles, while the othersolid matters are carried away by the water. The germsare collected, and after again being washed to removeadhering starch, are put through revolving cylindricaldriers. The dried germs are ground, steamed, and subjectedto hydraulic pressure to extract the oil. The oil obtainsa higher price than any of the other ingredients of thecorn, and is exported to Europe in bulk for use in soap

STARCH 21

manufacture. It is also used in tanning, for paints and formaking artificial rubber. The fatty acids derived from itmay be saponified with soda ash, which is cheaper to usethan caustic soda. A medium-sized factory working25,000 bushels of corn per day would turn out 100 barrelsof oil. This represents 2000 millions of germs used. Theresidue from the oil-press is considered superior as an oilcake to cotton seed or linseed cake ; it contains 20 per cent,of proteins.

The bran, gluten, and starch in suspension are now passedover the shakers, vibrating screens of wire gauze, or coarsemesh silk, the coarser portion being first ground and thenreturned to be likewise passed on the sieve. The starchpasses through the sieve while the bran separated is re-moved, pressed to squeeze out the water, and sold as pressfeed or dried to form corn bran containing 14 per cent, ofprotein.

The starch milk is collected in tanks, whence it is pumpedto flow over the settling tables or runs which are about120 feet long, a foot or two wide, and 6 or 8 inches deep,and with a fall of a few inches only in the whole length.On these tables the starch gradually settles, and forms acompact layer, while the gluten and other residues withsome starch pass off to settling tanks. From the latter thewater is run off to waste ; the sloppy mass of solids, afterbeing pressed and dried, is sold as gluten feed, containinglip to 40 per cent, of protein. The starch deposited on theruns, called green starch, which contains about 50 per cent,of water and a half per cent, of protein, is removed withwooden shovels, and may be used for conversion intoglucose or is stirred up with water and again passed overthe settling runs to secure further purification by sievingand draining. It then contains about 50 per cent, of water,and is dried in stoves at a temperature of 30° to 50° C.,until the water content is reduced to 10 per cent. It isground fine, passed through revolving silk screens, andpacked, for use as edible starch and baking powder, forlaundry purposes, for giving a stiffening and finish to

22 CARBOHYDRATES

cotton and other textiles, for paper, and for adhesivepastes and gums.

Where no caustic soda has been used the starch is de-scribed as unchemicalled. This gives a viscous paste,although less so than wheat starch, and is characterizedas thick-boiling starch suitable for baking powder and foruse as size with textiles. Alkaline treatment has theeffect of causing a flocculation of the colloidal gluten anda saponification of the oil so that the starch obtained iswhiter and purer. The deposit of this chemicalled starchis diluted in tanks, technically called breakers, to a creamof 22° Be., and then placed in cloth-lined boxes of 7 to 8inches cube. When drained to 45 per cent, of water contentit is removed and placed on porous biicks to set, then stoved.A brownish crust forms about J inch in thickness which isscraped off. When the water content is reduced to about30 per cent, it is wrapped in paper and dried for use asdomestic laundry starch. This quality is slightly thinboiling ; special thin boiling starches are made by treatingthe wet starch with- hydrochloric acid and drying at atemperature not exceeding 65° to 75° C., that is, below thegelatinizing point. By this means some of the starch isconverted into dextrine. This quality of starch is in demandfor steam laundries and in confectionery works.

Rice Starch.—The raw material for making rice starchis the broken rice from the mills in which it is cleaned andpolished, and since the removal of the proteins is difficultit is always necessary to use caustic soda. The averageanalysis of the broken rice as used is : starch 76, othercarbohydrates 1*5, proteins 8, fat 0*5, ash 1*5, water 12*5per cent.

The rice is steeped in caustic soda lye of 0*5 to I'O degreeBaume, for 18 hours, and the liquid then drained off. Afteranother like treatment for 12 hours the grains are soft.They are ground between millstones, and the creamy massof crushed grain is usually passed through a second mill toensure the absence of lumps that would entail loss of3tarch. Soda lye is added during the grinding in quantity

STARCH 23

such that the resulting cream contains 20 to 28 per cent.of solids. From this cream the starch is separated by sievesor centrifugals. The sieves are rotating drums consistingof a framework covered with the finest silk gauze. Theseare about 12 feet long, and with a fall of about 6 inches.The axle is hollow and perforated so that jets of water maybe played on the inside of the drum to keep the gauze clean.The starch milk passes through into the casing to collectiiit.o the settling tanks, while the waste passes out at theprojecting end of the drum and is used as cattle food. Inthe settling tanks the starch is deposited and the proteinand fibre remain in suspension and are run off. Centri-fugals are to be preferred to settling tanks ; they are usuallyabout three feet in diameter, and are run at 1400 revolu-tions per minute. The basket is not perforated. When asufficient layer of starch has been formed the surface isscraped and the deposited starch ground up and againcentrifugalled. The yield of starch is about 85 to go percent, of that in the rice used.

The recovered starch is mixed with water and weak sodalye and run into a row of wooden boxes, the bottoms ofwhich are perforated and covered with cloth. These boxesarc lifted and dropped again to assist the draining. After24 hours the blocks of compact starch which have formed,and still contain 42 to 44 per cent, of water, are cut intorectangular blocks ready for drying. It is now more usualto employ filter moulds where pressure is used, but it isnecessary in this case not to use a milk of more than 1*2 to1*25 specific gravity, otherwise the finished product has anundesirable rough fracture.

When the above blocks dry a yellow crust is formedabout half an inch thick. This is removed at a certainstage and the rest dries white. It has not been foundpossible to devise means to prevent the formation of thiscrust. The amount cut away represents about 25 per cent,of the total starch and the whole of this material has to bereworked in the next batch. The starch is generally bluedwith ultramarine. The blocks remain in the drying chamber

24 CARBOHYDRATES

at 30° to 50° C. for two or three weeks. When dry thestarch still contains 12 per cent, of moisture, and takes upfrom the atmosphere another three per cent.

Rice starch has largely replaced wheat starch for manypurposes. Owing to the smallness of the granules, it maybe used in powdered form with cold water for stiffeninglinen in laundry work ; also for cosmetics. The smallnessof the granules led to the selection of rice starch for usein the Lumiere process of colour photography. Threeportions of starch are dyed, each a different selected colour,and the mixed granules spread over the photographic plate.On viewing the negative by transmitted light objects areseen in their natural colours.

Potato Starch. — The manufacture of potato starchreaches its highest development in Germany, where itsproduction far exceeds that of other kinds ; a considerableamount is also made in the United States, but our owncountry has abandoned this source of starch in spite of themanifest advantages to be derived from the association ofthe industry in small factories attached to farms and workedduring the winter months, as is the case to a great extentin Germany, where small factories are the rule, and the wastepulp is utilized on the spot for feeding cattle and the wash,of considerable manurial value, for irrigating the fields. Aresuscitation of this industry would tend to .reduce theimports of starch at present necessary. The imports ofstarch, farina, dextrine, and potato flour into the UnitedKingdom are given below : —

1912. 1913. 1914*Cwts. 1,721,977 2,135,598 1,729,010 1,861,207Value £1,119,143 £1,311,044 £1,069,470 £1,348,317

The average analysis of the potato is : starch 16 to 23,other carbohydrates and fibre 2-5, proteins 2, fat 0'2, ash i,water 76 per cent. The potato yields more starch per acrethan grain, notwithstanding the fact that it only containsabout 20 per cent., while wheat contains 60 and rice 83per cent. ; the low percentage of starch is more than

STARCH 25

counterbalanced by the great weight of the crop per acre.Thus from grain with a yield of 12*5 cwts. per acre, 8*2 cwts.of starch are produced, potatoes with 125 cwts. to the acregive 22 cwts. of starch, or nearly three times as much.For the decade 1904-1913 the annual production of potatoesin Germany amounted to 50,000,000 tons or 1815 Ibs. perhead of the population, an average of 5*5 tons per acre,although crops of 9 to 14 tons per acre are recorded. Theyfurnish fresh food, starch, glucose, grape sugar, dextrine,and spirit. In Ireland the crop during the same period wasabout 5 tons per acre, 591,000 acres under cultivationyielding 3,132,000 tons. The average crop in the UnitedKingdom averages 5*63 tons per acre.

The value of the potato to the starch manufacturer isdependent on its content of starch, and the value increasesin greater proportion than the richness owing to the greaterfacility in recovering the starch and the smaller loss inthat carried away with the diminished quantity of wastepulp. A rough approximation of the value may be obtainedby a determination of the specific gravity of the tubers,since this increases with the total dry solids and is moreor less proportional to the starch contained. The deter-mination is made by weighing about 10 Ibs. of potatoesfirst in air and then in water and calculating the specificgravity therefrom. Two wire baskets are suspended fromone arm of a steelyard or other balance, one immersed inwater and the other above. The potatoes are first weighedin the upper basket and then transferred to the lowerone and again weighed. More accurate results may beobtained, if necessary, by chemical methods, the starchbeing hydrolyzed with hydrochloric or lactic acid in anautoclave, and the dextrose produced determined bytitration with Fehling's solution. The specific gravity method,however, is usually a sufficient guide, with the assistance ofthe table.

Specific gravity ro8o 1*090 noo i-uo 1*120 1*130 1*140Dry solids .. 197 21*8 24-0 26*1 28*3 30*4 32-5Percent. Starch 13-9 16*0 18*2 20*3 22*5 24*6 267

26 CARBOHYDRATES

The potatoes are first passed through a washing machinefor thorough cleansing. This is a trough filled with waterin which the potatoes are moved along by rotating armsdxed on a horizontal axis, the potatoes rising and fallingand rubbing against one another, thus helping to free themfrom adhering earth. The washed potatoes are nowrasped as finely as possible in order to open the cells andrelease the starch granules contained therein. The raspor grater is a drum revolving on a horizontal axis at aboutloco revolutions pet minute, the periphery of the drumbeing provided with a number of radially fixed saw blades(Fig. 2), and covered with a casing. The potatoes are torn

FIG. 2.—Section of Rasping Drum.

by the teeth of the blades into a coarse, frothy, reddishpaste, and further comminution is ensured by the massbeing compelled to pass between the drum and an adjustablewooden block, and the finer portion is collected in a pitbelow the machine (Fig. 3). A perforated metal sheetbelow the drum prevents the passage of coarse particlesuntil the latter are sufficiently reduced in size. Water isadded during the operation in quantity equal to the weightof potatoes worked. The rasped mass consists of free starchgranules, starch-bearing cells that have escaped disruption,fibre, and dilute juice. The starch is washed out of thismaterial on a sieve by a powerful stream of water, the starchmilk passing through, and the fibre and unopened cells thatare retained being, in small factories, removed to be used

STARCH 27

as cattle food, but in most cases is further comminuted bybeing ground with millstones and again sieved. The sievesare either flat with an oscillatory motion or formed of asemi-cylindrical trough provided with a series of brushes

FIG. 3.—Potato Rasper.

arranged radially in a spiral on a horizontal axis (Fig. 4).The starch and juice with the added water pass throughthe wire gauze to the trough below, and then on to a finersieve.

The starch milk from the fine sieve is run into settlingtanks or through gutters wherethe specifically heavier starch withany sand present settles out, andthe juice and the bulk of the fibrepass away through outlets or by afloating siphon after the starch hasbecome a firm mud. The time re-quired for settlement in the tanksis from 8 to 10 hours. The rawstarch thus obtained is yellowish,brownish, reddish, or grey in colour,and so firm that a man may standupon it to shovel out the mass. It is purified by makingit into a cream of 18 degrees Baume with water and mostlyagain settled for 6 to 10 hours. It then forms a layerwhite below with a discoloured scum of inferior starchabove. The tipper layer is sprayed or scraped away andthe operation repeated. The wet starch may be sold as

FIG. 4.—Sieve.

28 CARBOHYDRATES

such for the jnanufacture of glucose and dextrin or themoist or " green " starch may be further treated and driedfor first quality starch.

The scum is worked to a milk and passed over silk gauzesieves to obtain white starch, or in addition it may be passedalong gutters to settle, and thus yield a further quantityof first qualit}^. The water run off into pits forms a depositwhich is worked up at the end of the season for inferiorgrades of starch.

For drying the starch centrifugal machines are used,provided with a filter cloth inside the basket. The starchmud contains 50 per cent, of water, and this is reduced inthe centrifugal to 35 per cent. The brownish layer on thesurface is scraped off, and the rest is broken up and driedon frames covered with cloth in stoves heated not higherthan 35° C., that is, below the gelatinizing point of the starch,until the percentage of water is reduced to 20 per cent.This gives a coarse-grained starch which is the form preferred.It may, when dry, be powdered in mills and sieved to formstarch flour, a soft, pure white, glistening powder.

The pulp from the fine washing sieves cannot be profitablyworked further for starch. It contains 97 to 98 per cent, ofwater and contains fibre, insoluble protein, unbroken cells,and potato skin. It is used as cattle food. It is sometimespressed to reduce the water content to 20 to 30 per cent.,and dried to form pulp bran.

The washings, containing nitrogen, potash, and phosphoricacid, are prone to undergo putrid fermentation, and whenthey cannot be used to irrigate the fields must be purifiedbefore they are run into neighbouring water, otherwisedisputes may arise owing to disturbance of fishing rights.Besides methods of irrigation for this purification, aluminiumhydroxide is used for clarifying them.

In order to prevent the development of bacteria in thestarch milk during settling, a weak solution of sulphurousacid is frequently employed, and may be added immediatelyto the raspings. The use of this reagent is more particularlynecessary during warm weather. When diseased, frozen

STARCH f'^7 _, ,29:-O La^>^* : :-

or unripe potatoes are used the starch is-^enr slow in settlingand frequently has an acid reaction. . Tl^j^%ult may bovercome by the addition of caustic sbdalatter is safer, as there is less likelihood of an excess ofalkalinity when lime water is used. The amount addedshould be just sufficient to give a blue reaction to litmus.

Arrowroot Starch.—In the West Indies the roots ofMaranta arundinacea are utilized for the preparation ofarrowroot. The long, jointed, tap-shaped roots are firstsoaked in water and washed, then peeled with knives toremove the skin which contains a resin that would com-municate an unpleasant taste to the starch, and also dis-colour it. The roots are then pulped by crushing them,and the pulp is washed through perforations in a cylinderwith water to separate the fibre. The milk is filtered throughmuslin, settled and washed repeatedly, and finally dried inshallow copper pans covered with muslin to keep out dust.The roots yield about 19 per cent, of starch and give 22 cwts.of air-dried starch, containing 14 per cent, of moisture,per acre.

Sago.—Sago is extracted from the pithy interior ofSagus Rumphii and other palms. The trunks are cut intopieces about two feet long, which are split in half and thepith taken out and kneaded in water. The starch is thenwashed, and the moist sago formed into pearl sago byforcing it through sieves or rolling in a cloth, and thenheating in pans with a little vegetable fat. A single treeyields six or seven cwts. of sago. It is chiefly exported fromSingapore. Artificial sago is made from potato starch bypressing the moist starch through coarse sieves, dusting thepellets with dry starch and heating until partly gelatinized.

Tapioca.—The tubers, about 30 pounds in weight, ofManihot utilissima or Cassava in Brazil are washed, peeled,and pounded to pulp and pressed in baskets to wash outthe starch. This is then heated on iron plates at a gentleheat to volatilize the hydrocyanic acid. The grains swell,burst, and agglutinate.

Soluble Starch.—When starch is allowed to remain

30 CARBOHYDRATES

for twenty-four hours in contact with 12 per cent, hydro-chloric acid and freed from acid by washing, it dissolves inhot water without forming a viscid paste. The solutiondeposits the soluble starch on cooling as a pasty mass. Ithas no action on Fehling's solution. Many reagents havebeen employed at various temperatures to produce solublestarch. Most of these preparations, however, containdextrose, dextrin, or maltose, as well as modified starch,and possibly starch esters. Starch is heated with i per cent,formic or acetic acid at 115° C. for 5 to 6 hours, the excessof acid distils off so that it is not necessary to neutralize.Starch, when heated with caustic soda solution, becomespasty, and when the alkali is neutralized with sulphuricacid the paste is miscible with water. Chlorine gas, bleach-ing powder, persulphates, and ozone have all been proposedfor rendering starch soluble.

Uses of Starch.—Besides the use of starch and materialscontaining starch for food, and the production of beer andalcohol, and for the manufacture of glucose, dextrin, andcaramel, it is used in laundry work for stiffening linen. Thestarch is gelatinized, and the hot iron converts the starchinto a shining layer of dextrine. Potato starch, the cheapestform, when mixed with borax forms a starch glaze. It isalso used mixed with powdered stearic acid or paraffin. Ricestarch may be used mixed with cold water. Wheat starchis used as a paste for bill-posting, paper-hanging, and book-binding, owing to its superior adhesive power. Starch isused for applying mordants in calico printing, and starchand rosin for sizing paper. Thin starch paste is used forfinishing and weighting calico and cloths. Rice starch isused as a face powder, and for dusting moulds in the metalfoundry, and for moulds in making fondants in confec-tionery. Starch is used in chemical titrations to indicatethe presence of free iodine. For this purpose it is preferableto use a form of starch soluble in cold water. This may bemade by running starch paste in a fine stream into absolutealcohol or acetone. The precipitate is dried at a moderatetemperature.

SECTION II.—DEXTRIN

COMMERCIAL dextrin, or British gum, is usually met withas a yellow or brownish powder which has a mealy odourslightly reminiscent of newly baked bread but at the sametime somewhat repulsive. It is also produced in thegranulated form as brittle, semi-transparent lumps re-sembling gum arabic, for which dextrine forms a cheapsubstitute. This is sometimes described as " crystal-lized" gum. Occasionally it is sold as a fluid dextrin,an opaque, milky syrup. The different qualities are madeto suit the various purposes for which it is used. It dis-solves in cold water, forming a viscous solution withadhesive properties, and is used for gumming labels, en-velopes, and postage stamps, for finishing cloth, and asa thickening for mordants in calico printing. Thea finerqualities are also used in confectionery and in variousfoods.

Dextrins are manufactured by heating starch, eitheralone or after treatment with acid, until the desired degreeof dextrinification is reached. The preliminary changeis indicated by the reaction with iodine, but for the con-trol of the more highly dextrinized products the onlymethods yet available are the feel, colour, and appearancewhen moistened on a glass plate. It is consequentlyextremely difficult to imitate exactly a given sample ofdextrin, and for the production of the few constant qualitiesmade by a given firm reliance is placed on the control ofpreliminary drying, the percentage of acid used, and regu-lation of the temperature and rate of heating.

The Roasting or Torrefaction Process.—The pre-viously dried starch is heated in trays in a stove to a

32 CARBOHYDRATES

tv::.* c:..t::rc c<: i ^ j to 2^uz C., until the transformation:, ./r.i-lcvj cr tl:e starch is fed into rotating iron drumsI: . .tu: bv oil or bv direct fire and passes out as dextrine,ta.« r rxv^r being thus continuous. The higher tempera-r.:: -~:ve u darker product, but this is more completelyr-.a:!l'-- tLan the paler qualities. A better product is;/: t^ir.L-d bv heating the starch in a closed vessel providedwith 5t:rr:::g gear and heated below with superheatedftji:::. After roasting, the product is ground or crushedbv racing benveen rollers and then sifted.

The Acid Process.—Starch is treated with 0-2 to; ^5 T cr cent, of hydrochloric or nitric acid and then driedand v-v.vdered to secure uniform acidification, after whichi: ir -u>5ed to the heating apparatus, consisting of coveredpa::? or drams heated by oil, steam, or direct fire to atc:;:- urifare of IGCT to 150" C. In these it is stirred duringth-j 'mating until the change is completed, which mayrv faire frora i to z hours. The dextrin, after roasting^c :::;an5 about 3 per cent, of moisture; this is raised tot*;e ::.-u,.l 10 cr 12 per cent, present in commercial samples,I..}- i:x*:u-fr^ it to a moist atmosphere. It is then sifteda::a v»dl raixed. The colour, flavour, and odour are saidt * be improved by passing ozonized air over the starch.

So-called "crystal" gurn is made by decolorizing ahot relation of slightly dark dextrin with animal charcoaland evaporating either to dryness, and grinding the flakescotaised to powder, or to such a density that the solutionen cooling forms a pale transparent solid mass.

S i:l stances which are applicable for many purposes\vh^re dextrin is used may be formed by esterifying starch\vith dcetic acid.

According to Traquair acetic acid in solution has littleaction cr. starch, but when an excess of glacial acetic acidi> heated vrith starch, dried to a content of only 3 or 4 percent, of moisture, a product is obtained insoluble in coldwater, so tint the excess of acid can be removed by washingby Ccc^nt^tion. To prevent formation of products soluble

DEXTRIN 33

in cold water (dextrins), limited heating, 8 hours at 90° C.,or 2 to 3 hours at 120° C., is necessary, thus allowing theexcess of acid to be removed by washing. When swelledby boiling with 5 or 6 times its weight of water, feculose,as the acetylated starch is called, gives a clear solutionwhich is permanent and does not set or revert on standingfor a few hours. A portion of the solution poured on aglass plate dries to a clear, continuous film equal to thatobtained from the finest gelatin, and, in fact, technically,feculose may be described as non-nitrogenous gelatin.

The Uses of Dextrin.—In addition to the commercialuses of dextrin already mentioned, it is largely employed asan adhesive in paperhanging and bookbinding. " Gloy " issaid to be a mixture of dextrin with magnesium chloride.When it is employed as a thickening agent for colours andmordants in calico printing, it is usually mixed with starch.Shoemakers' paste is also a mixture of dextrin with starch.The glaze produced on linen, and the gloss on the crust ofbread, are due to the dextrinization of the starch by heat.The corn syrups used in making confectionery, preserves,and sweetmeats are preferred to sugar or cane syrup owingto the absence of grain.

SECTION III.—GLUCOSE

IN 1803 Proust established the fact that a sugarysubstance, grape sugar, could be extracted from the juiceof the grape. In the following year Bouillon Lagrangeobserved the change which starch undergoes when sub-mitted to high temperatures, and used the resulting productas a substitute for gum arabic for fixing dyes and for makinginks. In 1811 Vaucquelin incidentally described the for-mation of dextrin when starch was torrefied, gave an accountof its properties, and pointed out the commercial possibilitiesof the substance. Kirchhoff, the same year, requiring gumarabic for some experiments he was making on the manu-facture of porcelain, and being unable to procure it, madeuse of the substitute prepared from starch. Then, probablywith the intention of obtaining clearer and less highlycoloured solutions, he tried boiling the starch with dilutesulphuric acid, and found that the solution contained sugarinstead of the adhesive gum which he required. Braconnotfound that the same sugar was formed by treating linenrags in a similar manner. At the time of Kirchhoffsdiscovery colonial or cane sugar was almost unobtainableon the continent except at fabulous prices, owing to theembargo then existing against the entrance of all productsfrom England and its colonies, and the method was put topractical use almost immediately after its first publication.

Kirchhoff's method as described by Nasse was to use100 parts of starch, 400 parts of water, and i part of sul-phuric acid. It was recommended to dilute the acid withhalf the above quantity of water and bring to a boil. Thestarch was made into a milk with the rest of the waterand poured gradually into the boiling acid mixture which

GLUCOSE 35

was kept stirred and at boiling temperature for 36 hoursin succession in open vessels, the water lost by evaporationbeing renewed. Neutralization with calcium carbonate,followed by filtration over bone-black and evaporationof the sugary liquid to a syrupy consistency, completedthe operations. The syrup left for a certain time beganto crystallize, usually about the third day, and wasseparated from the mother liquor through filter bags andpressing. From 100 parts of starch Kirchhofi obtained90 parts of solid sugar or 120 parts of very sweet syrup.The sugar, evidently supposed to be sucrose, is describedas less sweet than cane sugar, with a peculiar after-tastewhich, however, can be removed by refining. The dimin-ished sweetness was accounted for by the higher percentageof water of crystallization which could not be removed athigher temperatures. The sugar resembled more thatobtained from grapes, but was considered superior to thelatter. The sulphuric acid was found to act on starch inthis wray in all proportions, provided it was properlydiluted, and it was also observed that at first a gummysubstance was formed, and sugar was only obtained oncontinuing the boiling. Vogel, of Paris, repeated the ex-periments in 1812 and concluded that sugar and gum areformed in variable proportions, the gummy matter beingprecipitable from the syrup by 85 per cent, alcohol; thatlieat alone is not sufficient to transform starch into sugar,and that the sugar formed is a true sugar since it is capableof undergoing alcoholic fermentation; also that the syrupwhen properly purified contains no sulphuric acid. Theidentity of starch sugar with grape sugar was establishedby Saussure in 1814; and by combustion he also found"that starch differed from sugar only by the elements ofwater.

When the continental blockade could no longer bemaintained against the gigantic system of smuggling tov^hich it had given rise and was removed in 1814, theoolonial products flooded the market and brought down-tlae price of sugar to extremely low levels, especially as this

CARBOHYDRATES

Yk...- JJ.d l»v competition of beet sugar, the manufactureof ;\!::cli had now considerably advanced, and moreovert r i e :••reduction of starch sugar was still beset with diffi-*.::l::^ 5o that this manufacture was practically abandoned.I: \Y:.S o::Iv with tlie gradual introduction of tlie use of.;',:_,-;re m the fermentation industries through the labours: Lam:, -.idius in Germany and Dubrunfaut and Pay en in

r rar^e that the manufacture took on a new development.Starch sugar finds no application which common crystal-

lized sugar could not fulfil, and it must always be con--idered as merely a substitute; it is, however, directlyi'L-rmentible, while cane sugar is not. Its sweetness is onlytuo-tliirds that of cane sugar ; in nutritive value the twoJ.Tc trOjltm.

Manufacture.—In the manufacture of glucose syrup.•;nu .starch sugar by means of sulphuric acid the followingc' ciutions are necessary : the conversion or saccliarifi-c . t l :: which consists in boiling the starch with diluter:.l:•::::rie acid, generally under pressure; removal of the..id ly neutralization and elimination of the sulphate of

I::::c produced from it; concentration of the filtered liquoru.nd reining and concentration to syrup with subsequent>cp;iration of the crystallized sugar.

In the earlier processes the boiling was conducted in>tror.^ wooden vats, either open or constructed, so thatt ' icy could be heated under pressure, and provided with.. ^tearn coil. The required quantity of water with, the[Tcvionsiy diluted sulphuric acid is placed in the vat andheated to boiling. The starch milk is then run in gradu-ally at such a rate that boiling does not cease. The starchmilk is prepared in a separate stirring vat; since starchdeposits quickly from the starch rnilk it must be keptconstantly stirred. It is necessary to avoid formationa a. paste while the starch milk is run into the boilingvuidulatcd water. Por each 2 cwt. of air-dry starch 40t r > > 50 Dillons of water and about 4!- Ibs. of sulphuric acidarc required if syrup is to be produced and about double

:oiii:t of acid if solid sugar is to be made. Half of

GLUCOSE 37

the water is used to make the starch milk. Where the" green " or wet starch is used a larger quantity is takento allow for the moisture present.

When the whole of the starch-milk is in, the boiling iscontinued until transformation is attained. A shorterduration of boiling is needed for the production of s}~ruptlian for solid sugar. During the boiling a very disagree-able and penetrating odour is developed, especially whenpotato starch is used.

During the boiling the liquid is tested with solution ofiodine, and afterwards with alcohol. When a few drops ofthe liquid in cold water no longer give a violet or reddishcolour with iodine the conversion of the starch into dextrinand glucose is finished. The alcohol test is now appliedby adding one or two volumes of alcohol to one of theliquor, and from the quantity of precipitate formed theamount of dextrine still unconverted may be judged. Aconvenient and ready means for determining the completeconversion into sugar is still a desideratum. The liquid isnow neutralized by the addition of chalk ; lime cannot beused as it would destroy the glucose. When litmus papershows a perceptible decrease of acidity the liquid is boiledfor a short time before more chalk is added. The liquidwhen neutral is allowed to deposit the sulphate of lime,and the liquor is then drawn off from the depositing vats,otherwise it is passed through a filter press. The clearliquor is evaporated either over a direct fire or by steamuntil it reaches a concentration of 30° Baume, or until aseparation of sulphate of lime renders it necessary, whenit is either allowed to settle or is passed through a filterpress. It is then evaporated to a dense syrup of 40° to 45°Baume in vacuum pans. In order to improve the colourand flavour it may be filtered through animal charcoalbefore the final concentration; this treatment is indis-pensable for producing a solid, white sugar. If the conver-sion of the starch into sugar has been very- complete theresulting syrup will soon begin to crystallize.

The manufacture of glucose from maize in the United

:* CARBOHYDRATES

States L,s attained enormous proportions, rendered possible:•" tc-.hnL.il improvements in the process of manufacturea::.; the cretin;; demand for the various products of themil-try. The starch is heated with hydrochloric acid-.;:: .k-r : re-ure in the converters, strong vessels of hammeredc:;: V.T. which may be 20 feet high and 6 feet in diameter.V.V.vr a::i the acid are introduced and raised to the con-v-^kt: temperature, and the starch suspended in coldv. .ter is pumped into the boiling acid. As conversion^ .v- MI during the pumping there is no formation of clotso,\:n5 to accumulation of starch paste. The extent to\\ hich conversion is carried depends on the purpose for;u.Lh the product is designed, and is regulated by thet;^:::: erature and duration of the conversion. For grape.:c:.r.. the solid crystalline form of glucose, the conversion

:- carried to completion; for liquid glucose or syrup, thec:::.n^-e is not allowed to proceed so far, and a certain- ..--vrit^e c: dextrin is left unconverted. The products,.re ^hivXse dextrose , maltose, and dextrin. It takes 12 to:> minutes to pump a charge of 1000 gallons into theconverter, and a little longer to complete at a maximumtemperature of 132" C. As soon as a sample shows asatisfactory test the operation is stopped by releasing thepressure, which at once causes a fall in temperature. Theproduct is run into vats, and neutralized with soda ash.The small quantity of hydrochloric acid present is therebycr.nvcrted into common salt which has no effect on thetaste of the glucose in these proportions. The neutralized!:-,::o: is passed through filter presses to take out fibre,protein matters etc., and then through evaporators in^h:;h it is concentrated to a density of 30° Baume. It isthen run in succession through three filters filled with animalcharcoal, each cistern being 10 feet in diameter and 24 feetc.ep and containing about 35 tons of char, the total depthtr.L-.-cr-ed is thus 72 feet. The proportion of char is morethan is used in refning cane or beet sugar, and the liquori^sue- practically colourless and brilliant. When the desiredquantity 01 h^uor has passed through the char, and its

GLUCOSE 39

decolorizing power begins to fail, the sweet is washed offand the char revivified during its passage by gravity throughthe pipes of a kiln heated by oil or coke. The revivifiedchar is sieved to remove dust and the loss made up by theaddition of new char. The filtered liquor is now concen-trated in a vacuum pan or Lillie apparatus until it reachesa density of 42° to 45° Baume. It then forms a clear,viscous syrup. In this form the less highly convertedproduct, containing about 40 per cent, of dextrine, is soldas glucose or corn syrup, for use in confectionery and fortable syrups. The more completely saccharified liquors,after concentration, crystallize on cooling to a tough, solidmass of white or yellow sugar called solid glucose or grapesugar. This is ground up or chopped into fragments andused in brewing as an adjunct to malt, and for the manu-facture of caramel. It is also employed for petiotizing winesthat are deficient in sugar. Pure anhydrous grape sugaris obtained in oystalline form by the process introducedby Behr. Into the warm glucose syrup a small quantityof anhydrous glucose is quickly and thoroughly incorporatedto act as seed to induce crystallization, and the mass allowedto stand in crystallizing troughs. After the crystals areformed the whole is stirred up to a magma and the mothersyrup separated by centrifugal treatment. The driedcrystals contain less than i per cent, of ash and of dextrinand 4 per cent, of water.

A process for making glucose which possesses specialfeatures is one due to S. H. Johnson. Whole, crushed,bruised, or broken grain or other granular amylaceousmaterial is used in a condition such that steam may be ableto permeate a mass of it. Rice or other grain in the formof flour is unsuitable, as the gelatinous paste which wouldbe formed by it would be impermeable to steam. The grainis first macerated in 2 per cent, hydrochloric acid, whichdissolves proteids and carries off essential oil. The acid isdrawn off below and water then percolated until neutral tolitmus, when the mass is drained and again macerated withI or 2 per cent, hydrochloric or other acid until the grain has

40 CARBOHYDRATES

taken up enough acid to effect conversion into glucose, theproportion varying with the nature of the grain. Riceusually requires about 0*25 per cent, of actual HC1. Thedrained material is then introduced into the converter, astrong vessel of wrought iron lined with lead or with asilicate enamel capable of resisting the action of the acid,and provided near the bottom with a perforated diaphragm.The prepared grain introduced into the converter retainsits form, and being porous is readily permeated by the steamentering below the diaphragm, so that the whole mass israised to the conversion temperature before the porosityof the grain is destroyed by the water condensed from thesteam, without the necessity of any stirring arrangement.The contents of the vessel become liquid, and at pressuresof 50 to 100 Ibs. rice is converted in from 5 to 15 minutesas indicated by the iodine test on samples withdrawn duringthe operation. The liquid is then run off into coolers,stirred to assist the cooling, and neutralized with dry sodiumcarbonate. The mass will become more or less solid afterstanding, provided the material did not contain an undueamount of water when introduced. The glucose thusprepared is very pure and free from any bitter or empyreu-matic flavour, and is used for brewing and distilling. Sagoand tapioca which have already undergone purificationduring their manufacture may be used without the pre-liminary treatment, and are much used for making glucose.

The Board of Trade bulletin gives the value of starchof all kinds exported from Germany in 1912 at £555,200 ;from Austria-Hungary (1913), £46,010 ; and from the UnitedKingdom (1913), £88,200. The value of the exports to theprincipal colonial and neutral markets was: Germany(1912), £288,350 ; Austria-Hungary (1913), £27,580 ; UnitedKingdom (1913), £72,610. Of the total German exports,potato starch, green fecula (wet starch), and dry potatostarch powder (potato meal) accounted for £220,350 ; dex-trine, roasted starch, adhesive and surface dressing sub-stances containing starch, gluten and gluten powder,£187,100 ; rice starch, £117,750 ; and starches of maize,

GLUCOSE 41

wheat, etc., £30,000. More than half of the total Austrianexports consisted of paste, size, and similar starch-containingsticking and dressing substances, and rice starch and ricestarch meal.

The corn (maize) manufactured into corn products inthe United States amounts to 50 million bushels per annum.From this are produced 400,000 tons of glucose, 300,000 tonsof starch, 115,000 tons of grape sugar, 300,000 tons of glutenfeed, 37,000 tons of oil, and 45,000 tons of oil cake; 300,000bushels of potatoes are used in the starch factories.

Chemical Synthesis of Sugars.—The manner in whichcarbohydrates are formed by the vital activity of plantsfrom carbon dioxide and water oilers a difficult problem forsynthetic chemistry. Moreover, it is not the simplercarbohydrates which appear, but starch is the first visibleproduct, and sucrose the first sugar which can be detected.The first step towards a solution was afforded by the observa-tion that on treating formaldehyde with lime water a sweetsyrup was obtained, having the properties of a sugar dueto the aldol condensation, whereby the carbon atoms ofseparate molecules of the aldehyde link together in a chain.In a similar manner glyceraldehyde and dioxyacetone gavea syrup containing a-acrose, which was shown to be inactivefructose. This was converted into the correspondingracemic mannonic acid, and the dextro and laevo formsseparated by fractional crystallization of the alkaloid salts.From dextro-mannonic acid both ^-fructose (ordinarylevulose) and ^-glucose were prepared. There is considerableevidence in favour of the view that carbohydrates as formedin the plant may originate from formaldehyde through thecatalytic decomposition of carbon dioxide by chlorophyllunder the iiifluence of sunlight, the formaldehyde being atonce polymerized into carbohydrates by the protoplasm ofthe cells.

SECTION IV.—MALTOSE

THE main product of the action of malt diastase on starchpaste is maltose, which was first observed in 1819 by DeSaussure, who isolated the unknown sugar from the hydrationproducts of starch and described its crystalline character.It was further examined in 1849 by Dubrunfaut, who gaveit thename "maltose." Hefoundits opticity was three timesthat of glucose, and that it was the sugar first formed whenacids act upon starch. No further notice was taken of thesefacts until C. O'Sullivan in 1872 rediscovered the sugar andbrought the matter into prominence. The process of thesaccharification of starch by acids had by this time becomefirmly established, and no industrial application of the useof diastase for the preparation of the sugar or syrup appearsto have been made until Cuisinier in association withDubrunfaut in 1883 patented a process for preparingmaltose either as syrup or crystallized. His procedure wasto liquefy starch at a temperature of 70° to 80° C. with 5to 10 per cent, of an infusion of green malt, and then tocarry out the saccharification at 50° C. with from 5 to 20per cent, of the diastase, after making the solution faintlyacid with hydrochloric acid. The solution was filteredthrough paper supported on linen cloth. After standingfrom 12 to 15 hours it was concentrated to 28° Baume,filtered and further concentrated to 38° Baume, filteredthrough animal charcoal and allowed to crystallize. Asample of syrup made by the Maltose Company of Brusselswas found on analysis by Marcker to contain, water 19-8,maltose 787, non-sugar 1-5, and no dextrin. The process,however, did not prove a commercial success. Morerecently the subject has been investigated by Duryea, who

MALTOSE 43

attributes the failure to the use of crude raw materials,ground maize, or impure starch flour, and in such a statethat, owing to the thick boiling condition and consequentformation of viscous paste, concentrations equal to thoseof the light liquors of the glucose industry could not berealized, and the quantity of malt required was excessive.The presence of a large percentage of undesirable nitrogenousand other extraneous matters increased the cost of refining.Duryea uses a thin boiling starch made to 16° Baume,neutralized, boiled, cooled to 59° C., and saccharified with5 per cent, of malt, calculated on the dry highly modifiedstarch. He finds that the product has a more luscioustaste when made into hard candy than the similar sweetsmade with glucose, and maltose candies have less tendencyto attract moisture and run. High-grade industrial maltosesyrups produce an impression of superiority upon the palateas compared with glucose syrup, which is never used alone,but only for mixing with cane or sorghum syrups to maketable syrup.

The intention of Cuisinier was that th maltose productsshould be used for brewing purposes, for making liqueurs,sweetening wines, and in the distillery. It may be notedthat the proportion of maltose in commercial glucosegenerally exceeds that of glucose (dextrose), the contentof the latter may be as low as 12 per cent.

REFERENCES.

Wagner, Frankel, and Huttcr, " Manufacture of Starch, Glucose, andDextrine." Philadelphia. 1881.

L. von Wagner, " Die Starke-fabrikation, Dextrin and Traubenzuckcr."Braunschweig. 1886.

1?. Guillaume, " Fabrication de 1'Armdon." Paris. 1886.O. Birnbaum, " Die Fabrikation dcr Starkc, des Dcxtrins, dcs Starke-

zuckers, dcr Zuckercoulcur, etc." Braunschweig. 1887.J. Berger, " The Manufacture of Rice Starch/' Jour. Soc. Chem. 2nd.,

1891, 152.G. Archbold, " The Maize Starch Industry," Jour. Soc. Chem. Ind.,

1887, 80 ; 1902, 4.J. W. Macdonald, " Manufacture of Arrowroot Starch in St. Vincent,"

four. Soc. Chem. Ind., 1887, 334.

44 CARBOHYDRATES

O. Saare, " Die Fabrikation der Kartoffelstarke." Berlin. 1897.O. Saare, " Die Industrie der Starke in der Vereinigten Staaten."

Berlin. 1896.W. Griffith, " The Principal Starches used as Food." Cirenccstcr. 1892.J. Borsch, " Die Fabrikation von Starkezucker, Dextrin, &c." Wien.

1901.R. van der Borght, " Geschichte der deutschen Rcisstarkc Industrie."

Berlin. 1899.Pro'. Chandler, " Indian Corn, Starch, and Grape Sugar," Jour. Soc.

Chan. Ind., 1900, 616.Parow, " Lehrbuch der Starkefabrikation." Berlin. 1908.J. Schmidt, " Die Starkefabrikation." Hanover. 1909.T. B. Wagner, " The American Industry oi Corn Products," Jour. Soc-

Chem. Ind., 1909, 343.F. F. Armstrong, " Starch and its Isomerides." (Allen's " Commercial

Organic Analysis." Vol. i. London. 1909.)J. Traquair, " The Manufacture and Properties of some Starch Esters,"

Jour. Soc. Chem. Ind., 1909, 288.W. P. Kaufmann, " Maize Products, and Maize Starch and its Products,"

Jour. Soc. Chem. Ind., 1910, 527.'* Potato Starch in Germany," Jour. Ind. Eng. Chem., 1910, ^43.T. B. Wagner, " Disposal of Starch Factory Wastes," Jouy. Ind. Eng.

Chem., 1911, 99.O. A. Sjostrom, " Treatment of Waste Water from a Starch and Glucose

Factory," Jour. Ind. Eng. Chem., 1911, 100.B. Herstein, " The Centenary of Glucose and the Early History of

Starch, "Jour. Ind. Eng. Chew., 1911, 158.W. Rosenkranz, " Starke, Dextrin, &c." (Dammcr's " Chem. Techn. der

Neuzeit." Vol. iii.) Ferd. Enke. Stuttgart. 1911.F. Rehwald, " Starkefabrikation." Hartleben. Wien. 1911.W. and W. C. Jago, " Technology of Bread Making." London. 1911.J. Traquair, " The Starch Industry of Great Britain," Jour. Soc.

Chem. Ind., 1912, 1016.H. Wichelhaus, " Der Starkezucker chemisch and technologisch

behandelt." Leipzig. 1913.A. P. Bryant, " Factory Control in the Manufacture of Corn Starch

and Corn Syrup," Jottr. Ind. Eng. Chem., 1916, 930.C. O'Sullivan, " Maltose," Jouy. Chem. Sec., 1872, 579.L. Cuisinier, " Maltose," La Sucrcrie Indig. et Colon., 1884, 23, 279 ;

1887,20,81.C. B. Duryea, " Industrial Maltose," Jour. Ind. Eng. Chew., 1914, 419.

PART II.—SUGAR

SECTION I.—CANE SUGAR

THE universal sweetening substance in use at the presenttime is cane sugar, whether derived from the sugar cane,which formerly furnished the whole supply of sugar, thebeetroot, sugar maple, sorghum or sugar palm, for thepurified product from any of these sources is the chemicalcompound sucrose, C12H22On. The oldest sweeteningmaterial used by mankind, however, either for flavouringfood or as a medicament, was without doubt the honey ofwild bees. The sugar cane became known at a much laterperiod, and at first it was merely chewed or eaten for thesake of the sweet juice ; there was no actual preparation ofthe sugar contained in it.

The original home of the sugar cane was probably eitherthe East Indies or the Pacific Islands, and the art of extract-ing sugar from it was certainly discovered in India, since theword " sugar " is common to all languages, and is derived fromche Sanscrit "sharkara" (Pracrit sakkara), which meant apebble, and was used to denote .sugar. The first Europeansto become acquainted with the cane were the followers ofAlexander the Great on his expedition to India B.C. 327, forthe early writers in describing this undertaking speak of ahoney which did not come from bees. Later it was knownto the Greeks and Romans as Indian salt. The sugar canewas already known in China in 200 B.C., but it did not comeinto general use until after the Persians had becomeacquainted with it in the fifth century. Persia was longthe principal seat of the suga- industry, and, where now onits arid plains only the ruins of old sugar mills and sluices

46 CARBOHYDRA TES

remain, there were formerly extensive cane fields. It wasused chiefly for medicinal purposes, and the first successfulattempts at refining it were made at Gondisapur. TheArabs who conquered Persia in 640 developed there con-siderably the culture of the cane and the industry of sugar,and then transplanted it to Arabia and the countriessuccessively conquered by them—Egypt, Morocco, Sicily,and Spain. From the chemical knowledge of the Egyptiansthe manufacture of sugar received important improvements.They had known for centuries the manipulations andapparatus for filtration, distillation, crystallization, etc.They knew how to clarify plant juices by the addition ofalbumin, boiling and filtration, or by treatment withalum ; how to precipitate albumin by tannin and the use ofhydrometers. As they were aware of alkaline working,their sugar bore transport by water, and for centuries wasa highly esteemed commodity. The Egyptians were thereal founders and inventors of refining. Even the Chinesewere only able to prepare sugar as a pasty mass by dryingcane juice in the sun, and first learnt the manufacture about650, and refining from their conquerors, the Mongols, in thethirteenth century. The Arabs having carried the cultiva-tion of the cane westwards along the shores of the Mediter-ranean, from 1095 the Crusaders made sugar widely knownand extended its use everywhere. The Venetians tradingwith the Arabs were actively engaged in the supply of sugarto Central Europe. A sudden change occurred in the sugarindustry with the capture of Constantinople by the Turksin 1453, and their subsequent conquests in the Black Sea,the uSJgean, and Egypt closed access to Asia for the Venetians ;wherever they entered as conquerors the Turks arrived asdevastators of the conquered countries and of all ancientcivilization. The sugar cane disappeared from all theseparts or became of no importance. Its cultivation has notreappeared in any of the'se /countries except in Egypt, whereMehemet Ali, in i8'20, reintroduced it. Meanwhile thePortuguese had brought cane from Cyprus to Madeira andthe other islands off the coast of Africa, and the sugar

CANE SUGAR 47

industry flourished there, aided by cheap labour due tonegro slaves. This sugar by its cheapness competed withthe Mediterranean for 300 years in provisioning Europe.They also discovered round the Cape the route to India, andthe costly route through Asia being no longer necessary,the great market for sugar was transferred to Lisbon, sothat in 1515 Venice had to buy its sugar there. Duringthis time America had entered the producing countries forsugar. Columbus, in 1492, on his second voyage took canefrom the Canary Islands to San Domingo ; thence it spreadto Cuba, Mexico, and Peru. By 1553 Mexico exported sugarto Spain. In 1532 the sugar cane was taken to Brazil fromMadeira. In 1600 there were 120 sugar factories in Brazil,and its production ruined that of Sicily and threatened thatof Madeira to such a point that Portugal had to establish animport duty to protect its old colony. Important Dutchhouses founded branches at Lisbon to import direct theircolonial commodities. Sugar was sent from Lisbon toAntwerp and thence up the Rhine; numerous refinerieswere established at Antwerp, but the war of independenceof the Low Countries (1566-1609) decided many Dutchto leave, and the industry was transferred to Amsterdam,where sugar refining prospered greatly. In 1580 Philip II.of Spain, having taken possession of Portugal, endeavouredto prevent the Dutch, with whom he was at war, fromcommerce with Lisbon; the result was different from whathe sought. The Dutch colonies entered into direct relationswith the Indies and Java, founded a company, and soonconquered all the Asiatic colonies of Portugal. They alsoattacked Brazil, devastated the plantations, and soon beganto make sugar themselves in the conquered country. WhenBrazil was restored to Portugal by treaty (La Hague, 1661),the Dutch still remained. On their expulsion they went tothe West India islands, where the manufacture was so badthat it did not pay to send the sugar to Europe; they improvedit and became prosperous. In 1791 the revolt of the slavesof San Domingo stopped all industry there, but was of benefitto Brazil, Guiana, Jamaica, and Cuba; Louisiana also

48 CARBOHYDRA TES

profited, although its production was backward on accountof the unfavourable climate. In Mexico and Cuba theSpanish maladministration had at the end of the sixteenthcentury completely ruined the sugar industry. The manu-facture was introduced into the Far East, principally Manilla,towards 1750 ; in 1800 Manilla already exported sugar.In 1319 this country obtained about fifty tons of sugarfrom Venice, and sugar refining was introduced in thesixteenth century, for in 1544 there were twro refineries inLondon.

British India is estimated to produce about 2,600,000tons annually of cane sugar and gur (crude sugar), andnearly 500,000 tons of palm sugar, and consumes over3,750,000 tons, so that the deficit has to be imported, chieflyfrom Mauritius, Java, and Europe. About 25 per cent, islost in the canes through bad cultivation, and another 25 percent, in manufacture through overheating and in the megassburnt. Efforts are, however, being made by the Agricul-tural Departments to improve the cultivation and theprocesses of extracting cane juice and of sugar manufacture.Java produces an average of 4*3 tons of sugar per acre, andat this rate India could produce 10 millions of tons of whitesugar per annum. Java is an example of the successfulapplication of energy and intelligence aided by science andorganization. They not only make the finest raw sugar,but a considerable amount of white sugar, the total pro-duction amounting to 1,300,000 tons. The yield per acreis still surpassed by Hawaii, where 5*6 tons of sugar isreached, and the total output approaches 500,000 tons.Cuba produces about 2,500,000 tons, some of its hugefactories dealing with 300,000 tons of cane per annum. Thetotal cane sugar crop of the world for 1913-1914 is estimatedby Willett and Gray at 9,773,348 tons.

The Plant.—The sugar cane, Saccharum officinamm,which belongs to the natural order Graminese, is a giganticgrass reaching about 15 or 16 feet in height, and grows in alltropical and sub-tropical countries. It is most favoured bya hot moist climate with a dry ripening season, and any

CANE SUGAR 49

lowering of the temperature is prejudicial to its growth.The plant consists of root, stem, leaves, and flowering shootcalled the arrow. As in all grasses the roots are fibrous andwide-spreading, never branching or growing to any greatsize, although they extend to distances up to three feet,dependent on the condition of the soil. The larger roots fixthe plant in the soil and act as channels for the transferenceof water and food absorbed by the root hairs. These finerootlets take up food in solution only and possess a selectivepower so that only suitable matters are absorbed for thenourishment of the plant. The root stock is made up of anumber of underground shoots giving rise by tillering tonumerous stems and producing the tufted habit and formingthe stools characteristic of the sugar cane as of other grasses.The stalk consists of joints averaging about six inches inlength, and separated by the knotty parts or nodes. Thenode extends transversally right through the cane, forming atangled felt of fibres; the internodes are composed of pith,soft parenchymatous tissue, the cells of which are filled withthe sugar juice, and traversed by numerous fibres, the fibro-vascular bundles. The rind of the stem is hard and polished,contains silica, and is impervious to water. Just below eachnode is a narrow, whitish band formed of white powder,really rods of wax. Above this is the scar of the fallen leaf,and next the bud, or eye, and again another band encirclingthe stem with rows of semi-transparent dots indicating thepresence of sleeping roots. The latter arise from within thestem, and when the cane is exposed to excessive moisture,or the node is planted in ftioist earth, they force their waythrough and form the roots. The buds are arranged underthe base of each leaf on alternate sides of the stem, and arecapable of growing into a stem of the future cane plant.The leaves, alternate as in other grasses, consist of a sheathencircling the stem, and the blade often coloured along themidrib. The leaf sheath is often provided with stinginghairs. The fibro-vascular bundles of the stem are thechannels through which water and food pass from the rootsto the leaves, there to be elaborated, under the action of

50 CA RBOHYDRA TES

sunlight, by combination with carbonic acid absorbed fromthe air, into sugar and albuminoids, and then pass downinto the stem where the sugar is stored in solution in thejuice of the cells. The leaf is thus the workshop of the plant,where the materials for its life-functions are elaborated, andby the transpiration from those cells in contact with theair a considerable evaporation of water occurs, determiningthe upward current of water and dissolved food materialsfrom the roots. At the time of maturity the elongation ofthe stem bears at its apex a sheath, from which bursts forththe arrow or inflorescence, a grey or white cluster composedof countless minute silky flowers. The ovary, after fertiliza-tion, becomes the fruit or seed. Previous to 1887 thegeneral opinion prevailed that the sugar cane had lost thepower of producing fertile seed through the long-continuedpractice of propagating by cuttings, but about that timeHarrison and Bo veil in the West Indies, and Soltwedel, inJava, found that seedling canes could be raised. A numberof such canes are now being experimented with, the objectin view being to rear varieties capable of yielding larger cropsof sugar and of greater resistance to the attacks of disease.In order to secure this end it is necessary to avoid chancepollination, so that the source of the pollen must be controlledas well as the seed-bearing cane, and this presents somedifficulty, owing to the extremely minute size of the flowersand the fact that they are borne on the summit of a slenderstalk some fifteen feet high.

For planting cane it is mostly the tops or upper jointsof the cane, after removal of the" head, that are used, butfrequently the whole cane is cut into short lengths of twoor three joints each for this purpose. These pieces areplanted in furrows, or in holes, in rows several feet apartat intervals of one or two feet. The land requires to bewell drained, although a considerable supply of water isrequired for the growth of the cane, and where rain isdeficient irrigation is necessary. When the canes are fromone to three months old they are manured ; they are mouldedup as they grow to keep the root under the surface, and the

CANE SUGAR 51

necessary weeding and tillage is done. At six to sevenmonths the cane stool is sufficiently developed to be leftwithout further operations except that, as maturity ap-proaches, the dead leaves or trash are removed. The canebeing thus more open to air and sunshine maturity ishastened, and the dead leaves help to retain the moisturein the soil and prevent the growth of weeds. The usualperiod to reach maturity is sixteen months for plant canes andtwelve months for ratoons; but in countries with a cold seasonthe period is reduced to eight or nine months, as in Louisiana.When the cane is cut and the stool is allowed to remain,shoots arise from it and form a new growth called ratooncanes. This may be repeated for several years in successionon suitable soil. In Java the Government allows only thegrowing of plant canes, and these are alternated with cropsof rice and beans for native use. The most suitable soilfor the cane is clay and loam, which allows of suitableaeration and drainage, yet retains sufficient moisture forthe plant growth. The mineral constituents removed fromthe soil by the cane are small in amount and less than0*5 per cent. Lime is important, and the principal fertilizersnecessary are those containing potash, phosphoric acid, andnitrogen. Since the residual fibre or bagasse is used forfuel, and therefore lost to the soil, as much of the trash aspossible is returned to it, and the humus or vegetable debrisis supplemented by the growth of catch crops betweencutting and replanting. These are usually leguminousplants, and by ploughing in the fully grown plants, green-soiling as it is called, the nitrogen content of the soil is alsoincreased. The time of harvest of the cane crop variesfor the different tropical regions, and thus the sugar marketsof the world receive a succession of supplies as the variouscrops mature. The average composition of the cane variesfrom 7 to 16 per cent, of sucrose; reducing sugars up to 1*5,fibre 10 to 15, ash 0-4 to 2, water 69 to 75 per cent., andthe yield being from twenty to forty tons per acre, the sugarobtained may amount to about four tons per acre or morethan double what is recovered from the growth of beetroot.

52 CARBOHYDRATES

Varieties.—There is a large number of varieties of canesunder cultivation chosen for their special suitability for aparticular soil or climate, or for their high content of juice.The names of these various kinds of cane, however, showgreat confusion, since different names have been applied towhat is the same variety; hut grown in localities wide apartand the lack of communication between these regions hasled to the perpetuation of the name given. The distinctivecharacters of the varieties are the colour of the stern andleaves of the mature cane, the size, form, and position of thebuds, and the length of the internodes, with other differences.Of the white, yellow, and greenish canes the more noted arethe Otaheite, Louzier, Salangore, and Bamboo ; the WhiteTransparent, White Java, and Rose Bamboo. The stripedcanes include the Striped Tanna, Otaheite Ribbon, Cheribon,and Java Yellow. Of the dark-coloured canes there are theBlack Tanna, the I/ouisiana Purple, and Java Cheribon.

Seedlings.—The object in view in growing seedlings isto get varieties with new characters, and then continue theselection by cuttings until they are found stable and fitfor industrial cultivation. In reproduction from seed theplants from the same mother show greater variability, whilethose from cuttings are remarkably fixed in hereditarycharacters. It takes about five years to settle the value of aseedling variety. The first plants from seed are small andseem inferior, they are likewise poor in sugar, but the plantcanes grown from these soon begin to reach a normalcharacter, and it is here that real selection is made, basedon the form, height, and colour of the stem, the length of theinternodes, the content of sugar, quantity and purity of thejuice, and resistance to the attacks of disease and capabilityof furnishing successive ratoon crops.

Pests and Diseases.—When the cane plant is weakenedby drought or by defective soil conditions it becomes moiesusceptible to the attacks of fungi and microbes, particularlyif the hard outer rind is broken or injured, as by excessivetrashing or when gnawed by rats, and a great deal of thetime and attention of the experiment stations is devoted to

CANE SUGAR 53

the study of the diseases to which cane is subject, and todevising means to prevent or counteract the damage. Theends of cuttings used for planting are particularly open toinfection, and when these are sent from distant parts theyare first soaked for 24 hours in Bordeaux solution, dried,and then packed in animal charcoal with a little coppercarbonate; this enables them to keep sound for a long period.

The rftoth borer lays its eggs on the leaf, and the cater-pillars make their way through the soft parts of the rindnear the joint or at the eye, or the terminal point and tunnelalong the stalk. Fungus pests then enter and spread. Thebeetle known as the shot borer makes small holes in the rindof weak or diseased canes. The rind fungus causes darkdiscolorations on the stem. The root fungus, Marasmiussacchari, produces dark red spots on the root and lowerparts of the stem, and the canes gradually die. The serehdisease in Java has caused enormous damage. It is markedby a general dwarfing of the growth and a reddening of thestalk and tissues. Although hereditary, and apparentlynot infectious, the disease appears to be due to special soiland cultural conditions rather than to micro-organisms.In the gumming disease drops of a gummy substance exudefrom the fibro-vascular bundles when the cane is cut across ;growth ceases, and the leaves turn yellow. It has beenshown to be due to the bacillus Pseudomonas vascularumagainst which certain varieties of cane are immune. Thepine-apple disease is due to the fungus Thielaviopsis etha-ceticus, a wound parasite, often introduced in the ends ofplant cuttings. The inside of the stalk becomes red, thenblack, and gives off a pleasant odour of pine apples. Thecontrol of the various diseases is secured by the use ofimmune varieties, the use of only sound, healthy canes forplanting, the isolation of diseased areas and their treatmentwith lime, the use of fungicide washes, as Bordeaux mixture,and attention to drainage and healthy soil conditions.

Extraction of the Juice.—When the cane reachesmaturity it loses all its leaves except a wide-spreadingbunch at the top, and the stem becomes shiny and of a

54 CARBOHYDRA TES

lighter colour; the sugar content is then at its maximum.The canes are cut by hand close to the ground and thesoft top joints removed with the cluster of leaves, and thestem is cut into pieces about three or four feet long. Theseare then transported to the factory to be worked tip im-mediately lest deterioration of the juice should occur. Inlarge central factories where canes from outlying plantationsare brought, or in cases where a breakdown happens, thiscannot always be done, and the canes may remain severaldays after being cut before they can be crushed. In suchcase they should be covered with trashed leaves kept moistto prevent desiccation. It has been found that an enzymepresent in the tops and capable of diffusing downwards inthe stem is liable to cause rapid deterioration of the sugarin the juice, and this supplies a reason for cutting off thetops at once.

Cane Mills.—Earlier forms of mills for extracting thejuice consisted of two or three rollers of wood, stone, oriron, supported vertically in a strong wooden frame. Toone roller a long horizontal lever was fixed, turned byhand or by animal power, and the canes were fed in byhand, the pressure causing the other roller to revolve. Inthis way only about half of the juice present was extracted.The first step in improvement was to arrange the rollershorizontally, the advantage obtained being that the feedcould then be utilized over the whole length of the roller,bevel gearing being used to change the motion. In back-ward or primitive countries such mills arc still in use,driven by wind or water power, but in all more modernfactories steam is universally employed as motive power,and several are now using electrically operated mills. Theunit mill consists of three rollers placed horizontally one aboveand two below with a space between, the most effectiveposition being such that the centres of the axles form atriangle with a vertical angle about 80°. The first of thewo lower rolls is the feed roll, the other is the megass roll.

Between these is placed the dumb turner or megass turnerto carry on the crushed cane to the megass roll and prevent

CANE SUGAR 55

it from becoming buckled in the passage. The adjustmentof this turner is a matter of great importance in the efficientworking of the mill, ensuring that the crushed cane ispassed to the space between the back roll and the upperone in a state that the juice is not reabsorbed and yetwithout overmuch resistance. The second pair of rolls areplaced closer together than the first pair, since the felt ofcane passing between them is thinner, owing to the crushingit has undergone in passing through the first pair, and hasalso lost juice. In a mill of this kind about 60 per cent,of juice is expressed in the double crushing to which thecane has been subjected, or in the most powerful mills65 per cent, may be expressed. Thus in cane containing10 per cent, of fibre 25 per cent, of juice still remains inthe crushed bagasse. However, as the fibre in its naturalundried state contains colloidal water the remaining juicewill not have the same density as that already extracted.By passing the bagasse through a second and third milla further quantity of juice may be extracted, and this isstill further increased by the addition of water in restrictedamount so as not unnecessarily to dilute the juice.

Maceration and Imbibition.—In the addition of waterto the bagasse between the first and second mills or betweenthe second and third, it may be done by spraying over thelayer of bagasse, when the operation is properly calledimbibition, or by passing the bagasse through a bath ofwater, when it is called maceration. To secure the bestresults with imbibition the pressure of the mills must beregular and constant, the bagasse well subdivided as it

56 CA RBO HYDRA TES

as to enable it to absorb the juice. If we suppose an ex-traction of 72 per cent, by the time the bagasse leaves thesecond mill, it will still contain 18 per cent, of juice, as-suming the fibre to be 10 per cent. Now, on the additionof 15 per cent, of water calculated on the original cane,the bagasse will then contain 18+15=33 Per cent, ofdiluted juice. If this 15 is squeezed out in the third millthere is recovered 15x^1=8*2 per cent, of juice. As themixing is incomplete the actual recovery is less than this.There are limits to the amount of water that may be usedfor imbibition, since it is necessary to balance the economyof extra sugar gained as juice against the increased costof fuel required to evaporate the more dilute juice. Further,with repeated imbibition and crushing, impurities are ex-tracted from the fibre, especially where the water added,is rendered alkaline with lime to avoid fermentation. Thejuice is also more difficult to clarify. The increased yieldof juice, moreover, is not proportioned to the water added,and must be kept within limits. The gain, however, ismore marked with cane of a higher content of fibre.

In order to render the bagasse more capable of absorb-ing the water of imbibition and to facilitate crushing, itis now usual to subject the cane to a preliminary cuttingor shredding before it is passed through the mill. Thecane cutter or shredder is particularly useful when dealingwith canes that are bent and do not lie evenly. It con-sists of a series of slightly curved knives arranged helicallyon a horizontal axis near the feed-plate of the mill. Theknives tear or slit open the canes. The Krajewsky crusherconsists of two steel rolls with zigzag corrugations whichmesh into each other and break the cane before it is passedthrough the mill. These arrangements materially increasethe amount of cane dealt with and give increased extraction.

Multiple Crushing.—Although various forms of millhave at times been tried, the modern form of mill consistsof a number of units of the three-roller type preceded ornot by a two-roll crusher, thus giving mills with eleven,fourteen, or seventeen rolls. The higher pressing thus

CANE SUGAR 57

obtained give more of the juice from the bark and nodesof a lower quality than that from the pulp, thus the higherthe extraction the lower the quality of the juice. If thepurity of the juice is 90*6 with an extraction of 87 per cent.,it would be only 89*3 purity when the extraction reached92 per cent. The sugar obtained from a given juice doesnot increase proportionally with the extraction; the result

FIG. 5.—Cane Mill.

of the higher extraction, however, is found to be economical,the present mills with multiple units yielding a greaterquantity of sugar of slightly lower quality.

The Diffusion Process.—Since the cells of plants areable to take tip their nutritive materials from outside toinside by purely osmotic processes, it should be possibleunder suitable conditions to make them yield these upagain from inside to outside. Each cell is formed of thecellulose wall, a layer of protoplasm, the cell juice, and thenucleus. The juice cannot leave the living cell because

58 CARBOHYDRATES

the protoplasmic envelope is impermeable to the cell juice -It is necessary for the process of extraction of the juiceto kill the protoplasmic layer, or at least to modify it byheat, so that it no longer offers an obstacle to the diffusionof the contents, but allows of an osmotic exchange, throughthe cell-wall, of the dissolved substances—sugar, salts,albumen, colouring matters, etc.—just as through anyother membrane. This is the basis of the process ofdiffusion for extracting the sugar juice from the beetroot,which was successfully applied by Jules Robert at Scelowitfcin Moravia in 1864.

At this period double milling of the cane was the rule,and only 83 per cent, of the total sugar present in tlic canewas extracted, or 86 per cent, when maceration was alsoused, and attempts were soon made to apply the diffusionmethod to the cane with the object of increasing the ex-traction yield. Although the process necessarily entailsincreased dilution of the juice up to 25 per cent, on theoriginal cane juice and consequent increased expenditureof fuel for evaporation of the extra water, an extraction of95 to 96 per cent, of the total sugar was obtained. Theeffect of this increased extraction was to stimulate im-proved crushing by the use of multiple mills, the adoptionof cane breakers or crushers and carefully controlledmaceration, whereby the yields by milling were so in-creased that, all points considered, diffusion no longeroffered any advantage. On the other liand, combinationsof the two processes have been put forward ; cane bagasse,from which part of the juice has been extracted by milling,is put through the diffusion process for the more completeexhaustion of its sugar content. In the diffusion processthe cane is cut into thin slices or chips one millimetre ormore in thickness, and the chips then filled into a seriesof 12 or 14 vessels, the diffusers, and treated until suffi-ciently exhausted. Two of the diffusers are always outof the circuit, one being emptied and the other being filledwith fresh chips. Of the remaining twelve, the one thatcontains the most nearly exhausted chips is supplied with

CANE SUGAR 59

water to remove the last traces of juice. The dilute juicefrom this passes through the next, and so on in turn througheach cell of the battery, finally passing through the diffuserlast filled with fresh chips from which the juice is drawnoil for treatment in the factory. The usual course of thecirculation in the diffusers is from above downwards, butin the freshly filled diffuser (A, Fig. 6) this direction isreversed, the juice entering from below so as to drive outthe air from the chips through the air-cock in the lid cover.As soon as juice issues from this vent, the cock is closedand the direction of flow reversed to the normal and thejuice drawn off below. Even by this means it is not

WATER

FIG. 6.—Diffusion Battery.

possible to get rid of all the air, and circulation in thebattery is thereby considerably impeded. It is also usualto introduce water below in the diffuser containing nearlyexhausted chips so as to loosen these and facilitate theirremoval when the diffuser is opened, because there is atendency for them to become tightly packed owing to thepressure under which the battery is worked. To eachdiffuser there is attached a juice heater by which the juicepassing from one diffuser to the next is heated during itspassage through a series of tubes heated by exhaust steam.By this means the diffusers are maintained at the tempera-ture most favourable for diffusion, usually 85° to 95° C.The diffusers containing the more recently filled chips arequickly raised to 90° C., and this is kept up through the

62 CARBOHYDRATES

heating surface is to be avoided, otherwise the reduction oftemperature causes loss due to incomplete combustion,distillation products escaping unburnt. Heated air supplyensures better combustion and increased efficiency. Wherelabour is cheap the megass is partly dried by spreading itin the sun, or in other cases it is passed through a dryingchamber, where it is heated by the waste furnace gasesduring its passage on travelling bands. By this means halfof the water may be removed and the water content reducedfrom 50 to 35 per cent., with a corresponding increase in itsvalue as fuel. If the supply of megass proves insufficientfor steam requirements it is supplemented by burning trash,wood, molasses or coal. From 4 to 5 tons of megass areequal in thermal value to a ton of coal. The ash of themegass is used as fertilizer on the cane fields, the large amountof potash and phosphoric acid in it being thus restored to thesoil. The soft portion or pith of the megass sifted out andmixed with molasses forms the cattle food molascuit.Owing to its length of fibre megass affords a suitable materialfor the manufacture of strong wrapping paper in localitieswhere it can be replaced at reasonable cost by coal or otherfuel. It has also been used as a filtering medium for canej uice, but there is a tendency for it to render the j uice gummy,especially when exposed for long to alkaline (limed) juiceat a high temperature.

Yields.—The highest yields of sugar per acre are obtainedin Java and Hawaii, and the lowest in the primitive partsof India and other tropical countries where the canes arenot only poor in sugar, but the methods of manufacture aredestructive and wasteful. In Java the sugar cane is analternative crop with rice and other food crops, and thewater of the rivers used for irrigation leaves a fertilizingslime rich in potash and phosphoric acid, giving for thewhole island an average yield of 42 tons of canes to the acre.In the Hawaiian Islands a still heavier crop is obtained, asmuch as 100 tons of canes have been obtained from therich volcanic loam assisted by irrigation, and with the aidof up-to-date machinery the sugar obtained has reached

CANE SUGAR 63

5-6 tons to the acre in some of the islands. In Cuba a singlefactory may crush as much as 600,000 tons of cane in theseason, and produce 70,000 tons of sugar. In the WestIndies about 20 or 30 tons of canes to the acre is the usualcrop.

The results obtained in the Bareilly district of theUnited Provinces of India given recently by Hulme andSanghi, show the great need for improvement. Java, usingmodern methods, obtains no maunds (the maund is 82} Ibs.)of sugar per acre; Bareilly, with modern methods, 64maunds ; and by native methods only 7| maunds per acre.From these figures it is not surprising that, in spite of a10 per cent, import duty and the payment of freight, railway,handling, warehousing, and other charges, Java can sellsugar in the interior of India against that produced locally.

Character of the Juice.—Cane juice direct from the millis an opaque liquid, frothy from entangled air, and in colourfrom grey to yellowish or dark green, according to the canefrom which it is derived. It contains in solution all thesoluble constituents of the cane; sucrose, reducing sugars,pectin, gums, salts of potash, soda, lime and iron as sulphates,chlorides, phosphates, silicates and salts of organic acids;and in suspension, sand and earth from the soil adheringto the cane, fragments of fibre, wax, and colouring matters.The fresh juice has a faintly acid reaction to litmus, morepronounced when burnt or damaged canes are worked, andis viscous from the presence of albuminoids, pectin, andgums so that it cannot easily be filtered cold.

The colouring matters of the cane are chlorophyll,saccharetin, and, in dark-coloured canes, anthocyan. Neitherchlorophyll nor saccharetin dissolves in the juice, but entersit with the cush-cush, as the finely divided megass fragmentsare called, and is thus present only as suspended particles;but by the action of lime or alkalies the saccharetin turnsyellow and passes into solution. The colour of Demeraracrystals as originally made was due to this substance.Anthocyan, the pigment of dark-coloured canes, is freelysoluble and adds its quota to the colour of the juice. As

64 CARBOHYDRA TES

Zerban has shown, the darkening of expressed juice, whichis colourless while in the cane, is due to the action of oxidaseand peroxidase ferments on the polyphenols or tannins,and a green colour is caused by a trace of iron dissolved fromthe mill rolls by the organic acids present in the juice. Acloser study of these reactions will doubtless lead to methodsfor the removal of the colour or the avoidance of its formation.

Clarification.—The turbid juice as it flows from the millpasses through a coarse strainer of wire gauze to removecush-cush before it is pumped to the measuring tanks. Itis then defecated by treatment with milk of lime, usuallyat 20 degrees Baume, and passed through a juice heater toenter the defecator or clarifier where the separation of ascum and a sediment takes place, leaving a more or lessclarified juice ready to be sent to the evaporators. Thistempering with lime is an operation requiring considerableexperience; the amount added must be sufficient toneutralize the free natural acidity of the juice and such as isfound by trial to give a ready separation of the sediment.By the action of the lime and heat albumen is coagulated,much of the pectin also becomes insoluble, and calciumphosphate forms as a flocculent precipitate. If too littlelime is added the precipitate does not settle readily ; and iftoo much, the clarified juice is left alkaline, and on beingheated, dark-coloured compounds are formed from thereducing sugars present. Since each separate lot of canesdiffers in the amount of lime needed, constant adjustmentsare necessary to keep pace with the varying composition ofthe juice. Some juices will not clarify without an excess oflime, and the alkaline juice in this case must be neutralisedby passing through the sulphuring box, in which it is sub-jected to a stream of sulphur dioxide, or by the addition ofphosphoric acid when a slight excess only of lime has beenused. As it is impossible to filter the juice the clarifiedportion of juice between the scum and the sediment is drawnoff as soon as the separation is sufficiently complete, theoperation being thus merely a decantation.

Defecation Agents.—Besides lime and sulphurous and

CANE SUGAR 65

phosphoric acids many other agents, either alone or incombination, have been proposed and used for clarification,the object in view being to cause a separation of mechanicaland dissolved impurities by the formation of a more or lessbulky precipitate, and at the same time to effect a decolora-tion of the juice. Among these may be mentioned salts ofaluminium, zinc, tin, and even lead. Barium hydroxideand salts of barium, tannic acid, ozone, and other oxidisingagents and oxalic acid. Many of these are effective enoughbut from the expense involved, or from their poisonousnature, are either not economical or obviously inadvisable,and in practice only the three agents first mentioned are ingeneral use. Manoury used 075 grm. of BaO and I grm.of magnesium sulphate per litre of juice after defecationwith lime. The filtrate from this treatment was free fromthe defects of decanted juice. Processes which do notpermit of filtration of the turbid juice lead to ready foulingof the evaporators and boiling apparatus, causing loss fromthe frequent cleanings necessary. The transmission ofheat is also retarded by the deposits formed. A dilutesolution of formaldehyde was used by Simpson at theCavadonga central factory in 1906-1907. At a concentra-tion of i in 20,000 formaldehyde was found to retard thedecomposition of cane juice for several hours. It hardensthe tissues and cells of the fragments of cane in suspensionin the juice and precipitates them with the scums so thatthey are eliminated from the juice. It coagulates thealbumen which is taken up by the lime and removed, andalso precipitates pectic matters and ferments, and thuslessens the tendency to acidification, and it does not combinewith sucrose or alter it. The vapours pass off on evaporationand are harmless to the workmen. An increase of purity ofthe juice thus treated was found of 1*0 to 17.

Hydrosulphites are used to bleach the juice, particularlywhen the object is to manufacture sugars for direct con-sumption. The sodium salt is known under the name ofBlaiikit and the calcium salt as Redos. These salts act aspowerful reducing agents on the colouring matters of the

Q- 5

66 CARBOHYDRATES

juice, much more so than sulphurous acid, but as with theuse of sulphurous acid and sulphites the flavour of theproducts is adversely affected, notwithstanding the smallproportion required. The reaction proceeds according tothe equation: Na2S2O4+O+H2O==2NaHSO4. The darkproducts formed by overheating the juice are far less readilybleached.

Defecators.—Instead of completing the operation ofdefecation in one vessel where the juice is limed and heatedby steam, the scums removed, the sediment allowed tosubside, and the clarified juice run off for concentration, it

is now the almost universal practiceto heat the juice in a j uice-heater toremove air-bubbles and then trans-fer it to special vessels, the defeca-tors or clarifiers, where lime isadded and, after settling, the clearjuice is decanted. In Mauritius aform of continuous settling tankcalled the Bac Portal consists of ashallow tank about 15 feet square,divided by parallel partitions intoa series of troughs a foot wide. Aportion of the partition is removedat alternate ends of the troughs

so that the juice entering ut one corner of the tank over-flows from one trough to another, and takes a zigzagcourse of about 200 feet, depositing in its passage thebulk of the suspended impurities. In Hatton's continuousdefecator the cold limed juice enters in a regular andsteady stream at the bottom, and as the level rises over-flows into the smaller suspended vessel from which theclear juice flows off as the vessel fills. The juice is heatedby steam admitted to the double bottom, to a temperaturenot exceeding 100° C., the temperature being maintainedconstant by an automatic regulating device. The scumsrise and form a layer on the surface several inches thick.These are removed in a fairly dry state, and need no further

FIG. 8.—Hatton's Con-tinuous Defecator.

CANE SUGAR 67

treatment as their sugar content is very small. Anysediment which may fall and adhere to the bottom, thuslessening the transmission of heat, is removed by means of ascraper which is gently rotated to loosen the incrustation,and then suddenly opening the bottom discharge cock for amoment, which allows the rush of juice to carry out thedeposit. In the Deming system of superheat clarificationthe impurities are precipitated and removed automaticallyand continuously. The limed juice is forced by a pumpfirst through the absorber, andthen through the superheater,where it is heated to Iio°-I20°C., and, finally, through theabsorber, where it is cooled downto 94° C., by giving up its heatto the incoming cold juice. Thequantity of juice required tofill this heating arrangement issmall, and during the operationit is under heat but 45 seconds,being discharged at a tempera-ture below that possible in theopen clarifier system. It thenenters the continuous settlingtank from which the juice is con-stantly decanted to the evapo- FlG

rators. There are no surfacescums to require skimming orbrushing, everything being precipitated with the mud to thebottom of the tank, where they are drawn off. This systemuses but one-half to two-thirds of the amount of limerequired by the open process, because lime more readilycombines with cold juice, and the instantaneous applica-tion of high heat increases the action of the lime duringthe process of clarification. The muddy juice drawn offbelow is sent to filter presses for filtration, the plantrequired being only one-tenth of that which would bereqtiired to filter the whole.

9.—Continuous SettlingTank of Deming's Clarifica-tion System.

68 CARBOHYDRATES

Sulphuring.—In the ordinary defecation process onlyenough lime is used to neutralize the natural acidity of thejuice, but with a greater tempering there will be a moreenergetic action of the lime on the impurities in the juice.The latter would in this case be left alkaline, and to preventthe alkalinity from affecting the juice adversely, the lime isremoved with sulphur dioxide. To each 1000 litres of juiceabout 10 litres of milk of lime at 15° Baume are added, andthe limed juice is treated with sulphur dioxide either bypumping the gas through a perforated pipe lying in the tankor, more usually, by means of a sulphur box. In this thejuice enters at the top and falls in a shower on a series oftrays, while the sulphurous acid gas, generated in a sulphuroven, is injected below by a jet of steam, the supply of gasbeing so regulated that the issuing juice is neutral tophenolphthalein. The turbid juice is then passed through aheater so as to raise its temperature to 90° C., and then intoa defecation tank where it is brought to the boiling-point—I02°-i04° C., and the precipitated calcium sulphite and otherimpurities allowed to settle, and the clear juice drawn offto be concentrated. In the West Indies the juice is " sul-phured " first while hot until the colour becomes lighter,due to acidification rather than to bleaching, and a decidedseparation of flocculent matter takes place, and then milkof lime is added until the juice is neutral. The slightlyopalescent subsided juice is then sent to the eliminators.The action of sulphurous acid prevents fermentation,decolorizes and effects a coagulation of those albuminousmatters which are not affected by heat alone.

Eliminators.—In well-appointed sugar factories theclarified juice is subjected to a further purification beforebeing admitted to the multiple effect for evaporation. Thetank used for this purpose is called an eliminator, and isprovided with heating coils or pipes, and a gutter into whichthe frothy scum overflows. The contents of the tank arebrought to violent ebullition, phosphoric acid added, and theboiling continued for some minutes ; meanwhile the im-purities are brushed away with the scum or overflow by

CANE SUGAR 69

the circulation of the juice until the contents are leftclean.

Carbonatation.—For the manufacture of a superiorquality of refining crystals, or of plantation white sugar, theprocess of carbonatation is employed in Java and in Queens-land. By this means all the beneficial effects of heavyliming are secured in removing gums and other organicimpnrities without the injurious effects on the reducingsugars which otherwise ensues from the application of hightemperature in presence of strong alkalinity, and the wholeof tite juice is filtered, thus yielding a perfectly clear juice.From, i to i-5 per cent, of lime is used as milk of lime, thetemperature while alkaline being maintained at not over50° C. At this temperature the effect of the lime on the" glncose " is to produce lactic acid, the salts of which arecolourless ; at higher temperatures other compounds of adark colour would be produced. Carbonic acid is thenpumped through the juice until the alkalinity is reduced tothe desired point, and the whole is then filtered throughfilter presses. During the saturation with carbonic acidthe temperature is raised to 90° C. The saturation may becompleted in one operation called single saturation, when thegas is passed in until neutrality is reached, or in two stages,double saturation, in the first of which the alkalinity isredticed until equal to 0*04 per cent, of CaO, when the juiceis filtered and then again saturated until neutrality is reached.AlttLongh in double saturation the juice remains muchlonger in an alkaline condition than with single saturation,and suffers somewhat in consequence, the reason for itsadoption is that it is less liable to result in the impuritiesbeing redissolved, since these are only insoluble while thejuice remains alkaline. The lime added to cane juice in thefirst place combines with and neutralizes the free organicacids and forms corresponding calcium salts. Next, anyalkali salts of acids which are capable of forming insolublecompounds with the lime will be decomposed and the alkaliwill "be set free as hydroxide. Part of the alkalinity, there-fore,, produced on adding lime is due to potassium or sodium

70 CARBOHYDRATES

hydroxide. Further, the lime combines with the albumi-noids, gums, and pectins, as well as with the colouringmatters, and forms a precipitate with these various bodieswhich remains insoluble so long as the liquid remains alkaline.Moreover, lime also combines with sucrose to form solublesucrate of lime so that the reaction which takes place duringneutralization is not nearly so simple as that which occurson passing carbon dioxide into lime water or milk of lime,the simple precipitation of calcium carbonate followed by theformation of some soluble calcium bicarbonate when excessof the gas is used. The saturation gas from the kiln, cooledwith the water used for washing it, and containing about30 per cent, of carbon dioxide, when pumped into the limedjuice is rapidly absorbed at the commencement, the escapinggas containing only about 3 or 4 per cent, of CO2. As soon,however, as a certain stage of carbonatation is reached theliquid is observed to become thick and viscous, the rate ofabsorption of the gas falls off, and the whole contents beginto froth up. This is due to the formation of calcium hydro-sucrocarbonate, C12H22O112Ca(OH) 2.3CaCO3. The supplyof gas is now decreased by connecting up to the next satura-tion tank and the froth beaten down by a jet of steam, andas the liquid becomes heated the insoluble hydrosucro-carbonate gradually decomposes into CaC03, and sugar.andthe carbonic acid is again more readily absorbed and theoperation is continued until the desired alkalinity orneutrality is reached. In order to avoid the formation ofsoluble calcium bicarbonate the saturation is stopped whenthe reaction to phenolphthalein paper is only a faint pink.At this point all the lime has been precipitated as carbonate ;the faint alkalinity is due to potassium (and sodium)carbonate.

Treatment of Scums.—The skimmings and muddyresidual juice from the various defecation operations areusually run into a tank, mixed with lime, heated and allowedto settle. The clear liquor is decanted and mixed with thebulk of the clarified juice, while the residue is passed throughTaylor filters (bag filters) or put through filter presses.

CANE SUGAR 71

These turbid juices should be worked up as quickly and ashot as possible, owing to their increased liability to fermenta-tion. In filtering, the pressure should be maintained steady.When great difficulty is found in getting a firm cake, asoccurs when unripe canes are worked, the remedy is to adda solution of I per cent, oxalic acid, and then lime, untildistinctly alkaline before filtering ; or kieselguhr may beused. The defecation juice gives, as a rule, 90 per cent,of clear liquid and 10 per cent, of muddy liquid from depositand scums. As an alternative to treatment the scums mayalso be used to feed cattle, and in those countries where adistillery is run in connection with the factory they arefermented to make rum.

Filtering Media.—Filter cloths soon become coated witha thin, slimy film of the suspended matters, which completelystops filtration, so that various substances have been triedwith the object of obtaining a dry, firm cake in the filterpress. Bagasse has been used, but has a tendency to givethe juice a gummy consistency. Peat, lignite, kaolin, orChina clay and diatomite, have all found more or less applica-tion for this purpose. Sand filters of various forms are alsoused. In Hawaii wood fibre called " Excelsior " has provedsatisfactory.

Evaporation.—The clear yellowish juice after defecationis usually about 10° Baume, requires now to be concentratedto a liquor of 27° to 30° Baume, suitable for boiling to grainin the crystallizing process.

Earlier Methods.—In the tropics where the growercrushes his own canes, the vessel in which the juice is heatedserves both as defecating tank and evaporator. It is heatedover the fire and the concentration is carried through to forma syrup which when cooled forms a mass of syrup and crystalsof sugar. Working on a larger scale the single pot wasreplaced by several cauldrons of copper built on brickworkand set so that the fire under the first copper supplied heatfor the following vessels :—

Copper Wall or Battery.—Thus we reach the stage whichis still in use in some of the West India Islands. The juice

^ CARBOHYDRATES

as it becomes concentrated by boiling is ladled from onecopper to the next until the required density is reached,according as it is to be boiled to a high-class sugar in avacuum pan, when it is withdrawn at about 20° Be, or toa dense syrup when muscovado sugar is to be made. Thehigh temperature to which the juice is exposed and contactwith the air results in a considerable loss of sugar. Variousmodifications have been made in the arrangement with aview to avoiding the losses. Instead of placing the firstor large copper directly over the fire, the last, containing themost concentrated juice, is given this position. The vesselshave also been arranged in cascade form to obviate thenecessity of ladling the contents which in this case are runfrom one vessel by a cock to the one next below.

Panela Train and Fryer's Generator.—In order toincrease the surface of contact the pans are replaced in thePanela concretor by a long shallow tank divided by numeroustransverse partitions, with openings at alternate oppositesides so that the juice traverses in a tortuous course thewhole length of the tank in passing towards the end wherethe fire is placed, and from which the syrup is drawn off ina state sufficiently concentrated to fill into moulds to set.In 1865 Alfred Fryer, a Manchester sugar refiner, intro-duced his concretor by which he sought to thicken the juiceas quickly as possible and at minimum cost to a solidcondition—concrete—suitable for transport. The clarifiedjuice runs in a thin layer over a long sloping platform formedof iron trays placed over a flue, and the juice is caused topass from side to side in its descent by partitions so as totravel a long distance, and the bulk of the evaporation isthus effected. The evaporation is completed in a rotatinghollow cylindrical vessel provided with scroll-shaped plateswhich lift the partially concentrated juice from the lowerpart in which a supply is maintained, and expose it to acurrent of heated air passed through the cylinder by a fan.After a short time the syrup is drawn off, cooled, and thenforms a solid mass ready to be shipped for refining.

The next improvement was the use of steam as heating

CANE SUGAR 73

agent, thus avoiding excessive overheating. This was appliedto the various forms of evaporators already enumerated.

Another method of applying the advantages of filmevaporation is exhibited in Wetzel's evaporator, one form ofwhich was a horizontal helical coil of copper steam piping,revolving so that the lower part dipped into the juice con-tained in a trough, and in its revolution carried up a thinlayer which rapidly evaporated.

Bour's pan consisted of a series of hollow lenticulardrums to the interior of which steam was admitted. Theedges of these likewise dipped into a trough of juice, and onrevolving evaporated the adherent film of juice. AspinalTspan is a cylindrical vessel in which is a calandria or drumprovided with a number of brass tubes through which thejuice in the pan can circulate. High-pressure steam isadmitted to the drum around the tubes and the juice is thusconcentrated. All these forms of evaporator expose thejuice to the atmosphere and to high temperature with thedanger of injuring the juice.

The Vacuum Pan.—The introduction of the vacuumpan in which the boiling temperature is reduced and wherethe juice is concentrated out of contact with the air, was thefirst advance towards remedying the disadvantages of openevaporation. The early form of vacuum pan invented byHoward in 1830 was a globular vessel furnished with acoil of piping for heating the contents of the pan by steam.The vapour from the syrup passed by a wide neck at thetop of the pan to the " save-all/' where any spray carriedover strikes against a pipe and trickles down to be returnedto the pan, while the vapour passes over and enters the pipeto meet a jet of water whereby it is condensed. This pipeis connected to the air-pump which creates the vacuum bypumping away air and any incondensible vapours. Owingto the costly operation of the vacuum pan as regards fuelconsumption the bulk of the evaporation is carried out by thecopper wall or other evaporators and the vacuum pan used tocomplete the boiling of the thickened juice to sugar.

Triple Effect.—The preliminary evaporation, however,

74 CARBOHYDRATES

is now done in all modern factories by multiple vacuumevaporators usually three in number, although quadrupleeffects are common, and even quintuple effects are in use.The first vessel is heated by steam, and the vapour from theboiling juice in this heats the second, and so on. The principleof multiple evaporation with a vacuum was first appliedby Norbert Rillieux, a French engineer in Louisiana, in1834. The triple effect consists of three cylindrical vesselswith dome-shaped heads with a wide neck which carries thevapour from the juice from one vessel to heat the next.

FIG. io.—Triple Effect.

In the lower part of each vessel is the calandria or steamdrum formed by two plates fitted with vertical copper tubes,through which the juice can circulate from the lower partof the vessel to rise just above the top of the calandria, and asit boils and thickens the vapour passes into the calandriaof the next vessel. The juice in this makes it act as a surfacecondenser and assist the boiling in the first vessel, while thevapour of the second vessel enters the calandria of the thirdvessel, which is connected to the vacuum pump. Thesteam supplied to the first vessel thus brings about anevaporation nearly three times what it would do in a singlevessel, and secures the economy in fuel which has made the

CANE SUGAR 75

use of the triple effect practicable. There is a pipe to leadincondensible gases from the calandria to the vapour pipeso as to prevent the steam space becoming air locked, andanother pipe below to lead away condensed steam or vapourto steam traps. There are also (not shown in the Fig.)pipes leading the juice from one effect to the next. Bymeans of multiple effects one pound of steam could evaporatean unlimited quantity of juice, but for practical reasons thelimit is admittedly generally reached with quadruple effects.The evaporation is due partly to the direct steam used andpartly to the heat from the juice itself which enters hot andleaves the last vessel at a lower temperature. At the sametime the latent heat of vapour is higher as the temperatureof vaporization is lowered and the losses from radiation haveto be allowed for.

It is generally stated that one pound of steam evaporatesi-8 Ibs. of water in a double effect, 27 Ibs. in a triple effect,and 3'5 Ibs. in a quadruple effect, but these figures willnecessarily vary with the conditions of the evaporation,besides which the steam used in working the vacuum andother pumps must be taken into account.

Lillie and Kestner Evaporators.—There are variousforms of evaporator with horizontal heating tubes in someof which the steam is inside, in others outside, the tubes ;one arrangement of this kind which differs materially inmechanical detail is the lyillie evaporator. The character-istic feature of this system is that it is a film evaporator.The tubes are expanded into the tube plate at one endwhere the steam enters, the other end being free and closedexcept for a small orifice to allow of the escape of air whichfinds its way into the vacuum space. The juice is circulatedby a rotatory pump and overflows from a series of distributingtroughs in a shower over the tubes which are staggered invertical rows to ensure a perfect film over all. Thisapparatus offers special facilities for cleaning both theinside and outside of the tubes, and there is no thick layerof juice through which the vapours have to force their wayso that evaporation is greatly facilitated. A portion of the

76 CARBOHYDRATES

circulating juice is withdrawn continuously while freshjuice is supplied to make up for what passes off as vapourand in the discharge.

The Kestner evaporator is another essentially differentform of apparatus by which a more uniform film of juice

over the entire tube surface is obtainedthan in the preceding horizontal effect.In this apparatus the calandria isplaced in a vertical position, and steamis admitted to the outside of the tubes.Juice from the supply tank (Fig. n)enters the tubes through the valve V,while steam is admitted at A; B isconnected to the vacuum pump, andthe concentrated juice is drawn off by

2 1 a pump a t if.H I A climbing action ensues a s soon

as the liquid begins to boil, the vapourgenerated filling the centre of the tubeand carrying up with it a film of theliquor which climbs up the whole lengthof the tube. At D is a centrifugalseparator to prevent the concentratedjuice being carried away by entrain-ment. The juice is a minimum oftime under heat, and the coefficient oftransmission of heat is high. Boththe I/illie and Kestner evaporators areusually worked as multiple effects.

Boiling.—The juice from the tripleeffect is usually a syrup of 30° Be, and

contains about 54 per cent, of solids in solution, but hasbecome turbid owing to some of the lime salts and otherimpurities having become insoluble in the more concen-trated solution, and before being passed to the vacuum panto be boiled to grain is frequently further treated eitherby simply allowing the syrup to stand while the suspendedmatter subsides, or it is sulphured or phosphoric acid added,

FIG. ii.—KestnerEvaporator.

CANE SUGAR 77

and then mechanically filtered. In the vacuum pan thecharge of syrup is boiled until the solution of sugar becomessaturated at the temperature prevailing in the pan, andthen the temperature is caused to fall either by shutting offthe supply of steam or by increasing the flow of water tothe condenser and thus increasing the vacuum.

Crystallization.—The sugar then separates in minute,scarcely visible crystals. Instead of graining the pan, asthis is called, the addition of small grained sugar is sometimesmade as seed to the saturated syrup in the pan. The nextstep is to grow the crystals by drawing in a further supplyof syrup and continuing the boiling. The points to beattended to are that the production of a second crop ofcrystals, called false grain, is to be avoided so that theremust be no sudden lowering of temperature allowed, but thefresh charges of syrup are to be drawn in from time to timeas the crystals grow. Should false grain appear, the smallcrystals are washed out, that is, dissolved, by drawing in alarger charge of syrup or by lowering the vacuum and thusraising the temperature. When the pan is sufficiently fullthe charge is closed or brought up to strike by graduallyraising the temperature until the magma of syrup and crystals,called the massecuite, is ready to be dropped. When largercrystals are required it is sometimes done by cutting thepan, as it is called—that is, by dropping half the charge andthen continuing the boiling until the pan is full again.

Muscovado Tanks.—The concentrated syrup from thelast pan of the copper wall or other open evaporator, owingto the high temperature, does not contain crystals. Inorder to start crystallization it is drawn off into crystallizingtanks where, on cooling, a crust of crystalline sugar forms.This is broken from time to time to help the cooling until,finally, a magma of fine crystals and molasses is obtained.Better crystals are obtained by the use of muscovado tanks.These are hemispherical troughs over which is an axisbearing several wooden arms which are oscillated in themass during the cooling of the syrup assisted by the stirring,so that the sugar, instead of forming a larger number of small

78 CARBOHYDRA TES

grains, gradually deposits on the crystals already formed.This quality of sugar, although of low grade, has a richflavour for which it is esteemed.

Vacuum. Pan.—Instead of the small and more or lessglobular vessel formerly used, vacuum pans are now made ofenormous size to cope with the large amounts of juice dealtwith in modern factories. The form adopted as mostsuitable is a cylinder, the lower end is conical and fitted withan outlet valve of large aperture. There are many coilsso arranged that steam may be admitted to the lowest onefirst, and to the others as they become covered with syrup.This arrangement is to prevent splashes of syrup beingcaramelized, as they would be if projected on to a hot, drycoil. The dome of the pan is provided with baffle platesto prevent spray from being carried over with the vapourand consequent loss of sugar by entrainment. There arealso light and sight glasses to enable the panman to observethe boiling mass, and a proof-stick to enable him to withdrawsamples without breaking the vacuum. In these samples,which he spreads on a glass plate, he can watch the progressof the crystallization and note whether false grain is beginningto form and if the crystals are otherwise satisfactory. Hisaim is to obtain crystals all of uniform size, since these partmore readily with the mother liquor when spun in thecentrifugal, and any small grain present may be dissolvedand pass into the syrup and thus be lost to the first product.

Curing.—The earlier method of treating the mass ofsugar and syrup obtained by boiling in open pans, so as toproduce a sugar more or less free from adhering molasses,was by the process of claying. The hot mass was pouredinto conical earthenware moulds, the opening at the tipbeing closed with a wooden plug. The moulds were arrangedpoint downwards until the mass set; at the end of 18 to 20hours the plug was'removed and the mouJd placed over apot to drain. The pots were replaced after another 20 hoursby fresh empty pots, and a puddle of wet clay was placedon the sugar at the base of each mould. The water in theclay slowly filtered out, and spreading in the mass of sugar

CANE SUGAR 79

carried with it the viscous layer of molasses adhering to thecrystals, for the syrup is more readily soluble than the sugarcrystals. When the first portion of clay was dry it wasreplaced by another, and often by a third, until the sugar wassufficiently white and purified. It was then dried in a stove,broken into coarse powder, and packed for shipment abroad.The whole operation took some weeks and required veryconsiderable space, and the method is now almost com-pletely replaced by the process of treatment in centrifugalmachines which, moreover, has rendered possible the boilingof sugar in the vacuum pan. Massecuite from the pan isdropped into a receiver called a mixer, where it is stirred tokeep the magma uniform, and portions drawn off while stillhot into centrifugals. There the molasses is spun off, thenwater, steam, or purer syrup, called clairce, sprayed on thesurface until the sugar is purged sufficiently. The molassesand washed-off syrup are kept separate, since the latter is ofricher quality, and these are submitted to further treatment.

Crystallizers.—Instead of drying the massecuite hot asdescribed above it is, especially if of a low-quality product,run into a. crystallizer, where it is kept stirred, the tempera-ture meanwhile being allowed to fall gradually under controlby the circulation of water or steam in the jacket. This iscontinued until the mass has cooled sufficiently for thecrystals to take up all the sugar possible and the mothersyrup is exhausted, but the mass is still warm enough to betreated in the centrifugal machine. During this cooling,as crystallization proceeds, and the mass becomes colder, itis necessary from time to time to add a portion of exhaustedmolasses from a previous operation to keep the mass suffi-ciently fluid, otherwise it would become too thick to workin the centrifugal. The crystallizers are usually large vessels,one or two of which are capable of holding the wholecontents of a pan. They are either semi-cylindrical troughsor cylinders provided with powerful stirring arms whichmake one revolution in about two minutes. After thiscrystallization in motion the molasses is obtained in a morecompletely exhausted condition, owing to the sugar having

8o CARBOHYDRATES

crystallized in a separable form by deposition on the crystalsalready present during the fall in temperature.

Centrifugals.—The centrifugal machine consists essen-tially of a drum called the basket with perforated walls, whichis rotated at a great speed. Inside the drum is placed thelining or cloth, a sheet of perforated metal which fits againstthe inner surface of the wall. When the massecuite isallowed to flow into the drum, while the latter is rotatingslowly, getting up speed, it is thrown against the side untila sufficient charge is in, and the speed having now increasedthe syrup is thrown off and passes through the perforationsagainst the wall of the casing surrounding the drum, fromwhich it drains down into a gutter around the inside of thebase of the casing and flows away. The syrup is boiledagain for a second quality product, while the richer syrupproduced by washing the charge in the machine is usuallyreturned to be boiled in the next batch of first product.When the machine is stopped the sugar is removed throughan opening in the bottom of the drum.

Molasses.—The syrups obtained from a massecuite inthe centrifugal are spoken of as first or second molasses, andso on, according as they are derived from first or secondproduct, but when the term "molasses" is used withoutqualification it is exhausted molasses that is meant—that is,a syrup from which no more sugar can be obtained by boilingand otherwise dealing with it in the usual way. Canemolasses, however, still contains from 25 to 40 per cent, ofsucrose, and from 5 to 30 per cent, of glucose or reducingsugars. The reason why all this sugar remains immobilizedin this exhausted syrup is to be traced to the combinationformed by the sugars with the various salts present in itinto an uncrystallizable compound. After molasses hasbeen boiled as thick as possible it cools to a blank, vitreousmass. Further details on molasses will be found in thesection on beet molasses.

Composition.—Exhausted molasses considered as themother syrup from a final massecuite varies greatly incomposition dependent on the methods of treatment during

CANE SUGAR 81

manufacture and on the purity of the original juice. Theamount of sucrose held in solution in the water present is lessthan that in a saturated solution of pure sucrose at the sametemperature, but the sum of sucrose and reducing sugarsis greater than that of pure sugar. It is not practicableto boil cane syrups as close as those from beetroot, owingto their greater viscosity, for otherwise they would not workin the centrifugals. The moisture of the undiluted molassesis usually about 15 per cent., but this is raised to 20 per cent,due to the water used in purging the sugar. The sucrosemay be from 30 to 40 per cent., glucose 15 to 25, ash 7 to10, water 16 to 20, organic matter 12 to 15 per cent.

Utilization-—The economical disposal of molasses offersan important problem for solution. The immense outputof the product represents a loss of 8 per cent, of the sugarin the cane, yet the low price it commands and the cost ofcarriage, notwithstanding its large content of sugars, donot secure a sufficient outlet for its complete utilization,so that in some cases it is run into the nearest stream to getrid of it. The small quantity used directly as food is in-significant, but cattle consume it readily owing to its attrac-tive flavour, and from its richness in nutritive material theyfatten upon it and improve in condition. Carbohydratesfavour muscular work, but the poverty of molasses in nitro-genous foodstuff makes it necessary to use it mixed with oilcake. Its fluid condition, however, presents difficulties intransport and in doling out the quantities as required.This objection is removed by the use of absorbent materialto soak it up in the same way that peat is used with beetrootmolasses. At the cane factory a suitable material is foundin the softer part of the bagasse—the pith—the cellulartissue of which originally held seven or eight times its weightof juice, and will absorb four times its weight of molassesand give a material which does not stain the bags in which itis packed, and the cellulose is also in great part digestible.In some cases enough of the pith may be collected below thebagasse carriers, where it has worked through the slats, orthe bagasse is ground and sifted. It is then dried and mixed

Q- 6

82 CARBOHYDRATES

with the hot molasses to form the cattle food called Molascuit.Another food is made with the millings of rice (paddy),but this material is not so good an absorbent as the pith.Molasses is also used as fuel. When sprinkled on bagasseand burnt it tends to form a compact coke and choke thefire, and at a higher temperature the alkali present combineswith the silica of the cane to form a glassy slag difficult toremove from the fire bars. It may also be burnt by sprayingin the same way as oil, but this requires a special form offurnace. The ash contains a large proportion of potash,and is, therefore, useful as a fertilizer, indeed, dilutedmolasses may be spread on the fields as a manure when theacidity it produces is beneficial in destroying the nematodeswhich injure the canes.

REFERENCES.

N. Basset, " Guide du Planteur de Cannes." Challamel et Cic. Paris.1889.

Evangelista, "Fabrication del Azucar de Cana." Madrid. 1895.W. Kruger, " Das Zuckerrohr und seine Kultur." Magdeburg and

Wien. 1899.W. Tiemann, "The Sugar Cane in Egypt." Norman Rodger. Altrin-

cham. 1903.'Sedgwick, " The Sugar Industry in Peru." Trujillo. 1904.H. C. Prinsen Geerlings, " Cane Sugar and its Manufacture/' Altrincliam.

1909.Jones and Scard, " The Manufacture of Cane Sugar." Stanford.

London. 1909.Newlands Bros., "Sugar." Spon and Co. London. 1909.Noel Deerr, "Cane Sugar." Norman Rodger. Altrincliam. 1911.G. Martineau, " Sugar." Pitman and Sons. London, n.d." Lectures to Sugar Planters." Imperial Department of Agriculture

for the West Indies. 1906.A. Rumpler, " Handbuch der Zuckerfabrikation." Vieweg. Braun-

schweig. 1906.de Grobert, Labbe, Manoury et de Vreese, " Fabrication du Sucre do

Betfceraves et de Cannes " J. Fritsch. Paris. 1913.H. Paasche, " Die Zuckerproduction der Welt.' Teubner. Leipzig and

Berlin. 1905.Harlofi and Schmidt, translated by J. P. Ogilvie, " Plantation White

Sugar Manufacture." Norman Rodger. London. 1913.H. C. Prinsen Geerlings, "Practical White Sugar Manufacture."

Norman Rodger. London. 1915.The International Sugar Journal.La Sucrerie Indigene et Coloniale.Journal of the Society of Chemical Iwdustty.

SECTION II.—BEET SUGAR

The Beetroot.—The raw material for the manufacture ofsugar in Europe and other lands with temperate climates isfurnished by the white sugar beet derived from the wildBeta vulgaris or B. maritima found growing in salt marshesand belonging to the order Chenopodiacese which includesthe goose-foot, spinach, and saltwort. Various sports whencultivated become fixed in character and differ in size, form,colour, foliage, and richness in sugar, as the Vilmorin, Quedlin-bourg, Wanzlebener, Imperial, etc. Originally an annual,it has by cultivation become a biennial; grown in the firstyear from seed it forms only root and leaves, and, on re-planting, or after remaining in the ground throughout thewinter, in the next season it bears a stalk with flowers andseed. Occasionally, however, beets run to seed during thefirst year, but the roots are then woody and small, andalthough still rich in sugar, are difficult to cut for use. Thecharacters of a good sugar beet are a conical, somewhat pear-shaped, tap-root, almost completely buried in the soil, themore so the richer it is in sugar, for the green portion or neckwhich rests above the ground contains a lower percentage ofsugar. The skin is rough to the touch and has a longi-tudinal groove on each side, with .well-developed hairyrootlets which penetrate deeply into the soil. When thesoil is stony or too compact and the rootlets cannot thuspenetrate, the root becomes forked, and there is loss inharvesting and the beets are smaller and less rich. Experi-mental trials have proved that beets rich in sugar can begrown in this country equal to those on the continent, butfor various reasons, mainly due to political obsessions, thebeet sugar industry has not been established here. Largesums are required to equip a factory for the manufacture of

84 CARBOHYDRATES

sugar, and guarantees are necessary to ensure delivery of asufficient supply of beets to keep a factory working economic-ally, since this can only be done when the work is on a fairlylarge scale; on the other hand, the deep ploughing andthorough weeding needed for growing sugar beets successfullyleaves the soil in a condition that is highly beneficial for othercrops to follow.

Cultivation.—By proper treatment and manuring anysoil may be made fit for growing beetroot, but the bestresults are obtained with calcareous loams or siliceous clayswith calcareous subsoil. A proportion of humus is needed toregulate humidity, as it only gives up moisture slowly in dry-weather, but an excessive amount renders the soil too acid.The land should be ploughed in autumn to a depth of teninches or more, and farmyard manure used at that time willresult in a good yield and quality of beet while its use inspring is injurious to the crop. As soon as the soil is dry inspring it is ploughed, harrowed, rolled, and spread withnitrogenous and phosphatic fertilizers. The seed is sown bydrills in rows about 16 inches apart on the level, and not overhalf an inch deep ; about 25 to 35 Ibs. per acre is required.The most favourable time for sowing is usually about themiddle of April. The plants will be well above ground abouta fortnight after, when the ground is hoed by hand and thehoeing is repeated several times until the leaves cover theground. The rows are then cut through, leaving a space of8 to 12 inches between the clusters left standing. Whenthese plants have roots as thick as a straw they are thinnedby hand, leaving only the strongest plant in each standing.As soon as the leaves quite cover the ground, about the endof July, no further work is done on the field until the harvest.During the months of August to October the sugar is formedand accumulates in the root. The beet is richer in sugar inproportion as the autumn is drier and sunnier. From themiddle of August onwards tests are made to determine thesugar content of the roots, and to fix the time for taking themup. This should not be later than the end of October inorder to avoid frost. After the roots are taken up and well

BEET SUGAR 85

cleaned from adhering soil, the leaves and top of each beetare cut off to prevent the stored beets from forcing newshoots, as these would use up the sugar. The harvestedbeets are either sent direct to the factory or thrown in heapson the field. If these are to remain some time before beingremoved they are covered with the leaves to protect themagainst drying and the night frosts. The roots not im-mediately used at the factory are stored in silos. The attacksof nematodes, caterpillars, and other injurious pests are keptin check by not planting the same field too frequently withbeetroot, a rotation of crops being usual, the beet followingevery fourth year after wheat or barley. The yield of goodsugar beets, freed from soil and trimmed, varies from10 to 20 tons per acre, and the sugar content from 14 to 16 percent. Forage beets and those grown for producing alcoholgive a greater weight of roots per acre, but the total sugar isno greater and the impurities (non-sugars) present in thejuice while they interfere with the extraction of sugar, areno detriment in the production of spirit, and are of alimentaryvalue, the choice of the kind of beet grown being dependenton whether the tax is levied on the weight of roots or not.

Improvement by Selection.—Perhaps no other agri-cultural crop has shown so markedly the importance of seedselection as the sugar beet. By the careful choice of thosevarieties which seemed most favourable to the productionof sugar and the selection of roots for the production of seedduring the succeeding year, and by judicious and scientificfertilizing for the purpose of increasing the sugar contentwithout unduly increasing its size, the beet has been placedat the head of the sugar-producing plants of the world.The beets to be used for producing seed (mother beets)should be of regular form, high content of sugar, and purityof juice with other characters. Under similar conditionsa beet rich in sugar is mostly smaller than one poor in sugar.The likely roots are sorted into small heaps in autumn.In spring any beets that are damaged are put aside and theothers sorted according to weight and sugar content. Acylindrical piece is bored out from each root and tested fo£

86 CARBOHYDRATES

sugar. The beets which are approved are planted to produceseed, which is gathered when ripe in August and September.This seed is not sold, but a small part is used to grow motherbeets for further selection tests. The bulk is sown close, andnext year produces the seed used for sale. Thus it takesfive years to obtain a select crop of beets from the originalmother beet; 20,000 best mother beets are sufficient toplant a hectare (2-47 acres), and from them are obtained40 to 60 hundredweight of the best seed, and this gives thefollowing year 150 to 250 acres of the best (Elite) beets, orfrom 5 to 7 millions of plants. From these there are finallychosen the i£ million seed-bearers, which furnish the plantingof 250 acres and the seed for sale and for the perpetuation ofthe breed. The seed is cleaned as usual, and regulationsare made for the trade as to moisture, foreign matters, andgerminating quality which it must satisfy. The seed is notpurchased indiscriminately, but each factory has its ownfancy for the particular variety supposed to suit the soil,climate, and other conditions.

Composition.—The cellular tissue of the beetroot ispermeated by vascular bundles, the zones of which areallied to the production of the leaves. In the cells is thejuice containing sugar, salts, and other organic matters.The insoluble tissue forms 4 to 6 per cent., and the juice94 to 96 per cent., 75 to 80 of which is water. The sugarcontent is 14 to 16 per cent., but in some cases, in carefullynursed beets, has been found as high as 22 per cent. Thenon-sugars, including salts and organic matter, amount toabout 2*5 per cent. The inorganic constituents are princi-pally potassium, next sodium, calcium, phosphoric, andsulphuric acids, chlorine and silica. The organic mattersinclude oxalic and other organic acids, invert sugar, raffinose,albumen, pectic substances, gums, ammo-acids, betain,colouring and aromatic substances. The qualities of agood beetroot are thus summarized by Saillard : " A richbeet offers the, following advantages : it bears more leavesper acre, it contains in its root less mineral matter perioo of sugar, and its juice is purer. This makes it less

BEET SUGAR 87

exhausting to the soil and gives less molasses. It needs lessmineral matter for the entire plant (root and leaves) toelaborate 100 kilogrammes of sugar, and the mineral matterswhich it draws from the soil pass in great part to the leaves;it has a firmer flesh, it keeps better in silo, it requires lessexpense for transport per 100 of sugar, it resists dry weatherbetter, and all this does not prevent it from producing asmuch, or more, sugar per acre than the semi-sugar beetroot.It must be added, however, that it leaves less factory pulpper acre/' In addition, the purer juice is less troublesome todeal with in the factory.

Manufacture.—The roots,having been properly harvestedand delivered to the factory, are first conveyed to washingtanks provided with suitable stirring gear for keeping themin motion and conducting them towards the end wherefresh water enters so that any adhering soil, sand, and stonesmay be completely removed. The beets are next raised by asuitable elevator to the slicing apparatus into which theyare allowed to fall. Here the beets are sliced into thinpieces of greater or less length, of such form that when placedin the vessels of the diffusion battery they will not pack soclosely together as to prevent the circulation of the diffusionjuice. These slices, called cossettes or chips, are filled intothe vessels of the diffusion battery, and there submitted tosystematic exhaustion, the diffusion. The exhausted chipsare passed through a press to remove a portion of the water,and are then used either fresh, or, after being dried, as cattlefood. The diffusion juice is led to the carbonatation orsaturation tanks, where it is treated with from 2 to 3 percent, of its weight of lime, and afterwards with carbonic acid,until nearly all the lime is precipitated (the first saturation).The still alkaline juice is now passed through filter pressesby which the precipitated carbonate of lime is removed.The juice next passes to a second set of carbonatation tanksto undergo a similar treatment with lime and carbonic acid,only that a smaller quantity of lime is now used as comparedwith the first (second saturation). The scums are againremoved by filter presses, and the clear yellow juice may be

88 CARBOHYDRATES

treated with sulphurous acid (sulphuring) and once attainfiltered. The purified juice is then concentrated in a mull ij >Ieeffect vacuum apparatus to a syrup. The syrup is soinct imcsagain submitted to saturation with carbonic or sulphurousacid, filtered, and then passed to the vacuum pan to be boiledto grain. The mixture of sugar crystals and syrup, railedmassecuite, thus obtained, and containing 6 to 10 per cent.of water, is run out into large vessels provided with stirringgear, and kept stirred to continue the crystallization on thesugar grains already present—crystallization in motion,as this is called. The cooled mass is spun in centrifugalmachines. The raw sugar crystals remain in the centrifugal,from which they are taken out, sieved, and put into sacks,while the syrup which flows off is treated for second productsugar by boiling to string proof, that is, to a dense syrupwhich only slowly crystallizes when allowed to cool in tanks ;or it is boiled to grain and crystallized in motion to give lowsugar and molasses. The molasses is either used for makingcattle food, treated chemically to extract the sugar by adesugarizing process, or sent to the distillery to be fermentedfor the production of spirit.

Brief History of the Foundation of the BeetrootSugar Manufacture.—The beetroot was not considered ashaving an industrial value, and was cultivated only for tableuse or for cattle food until 1747, when Marggraf, a Berlindruggist, examined a number of plants other than sugar caneand found the beet to be richest in sugar amongst t hesc. I >> ycutting the root into thin slices, drying these carefully, andreducing them to powder, lie was able to extract 5 per cent.of sugar by means of highly rectified spirit from the Silesianbeet. He fully realized the wide-reaching importance ofhis discovery, and advised fanners to extract beetroot, pulpwith water, clarify the solution with albumen or blood, andevaporate the filtered solution to crystallize out the sugar.His proposal was unheeded until his former pupil, Aeharcl,in 1786, repeated the research on roots lie had speciallycultivated, and finally succeeded in extracting sugar from thebeet on a comparatively large scale. In i7w he presented a

BEET SUGAR 89

sample of his sugar with a description of the method ofoperation to the Institute of France, by whom a commissionwas appointed to examine the question. The report was notfavourable at that time; but when the continental blockadeordered by Napoleon closed the harbours of Europe to allIvn^lish commodities, it caused an immense rise in the price<>l sugar and led to the establishment of beet-sugar manu-tacture in France. Under the influence of Chaptal 80,000acres (32,000 hectares) of land were by Royal decree setaside for beet cultivation and substantial premiums awardedfor the promoters of the industry. Figuicr at this perioddiscovered the decolorizing power of bone charcoal, whichwas used at first in the form of powder. On the fall ofNapoleon, in 1814, and the cease of the blockade, the priceof sugar fell so that almost all of the factories closed due tothe crisis. Those remaining at work were under Chaptal'sdirection, and their aim was to continually perfect themethods of working : the introduction of char in granularform, boiling in vacuum, the general use of steam and use ofmany factories as model institutes for instruction, so that ini<S<>8, 103 factories were at work with an output of about5000 tons. This development and its favourable resultswith the experience obtained was not without effect onOeruuuty and Austria, where the industry awoke to new life,assisted in no small degree by the fact that it was notshackled by any duty, a measure which soon paid hand-somely, when the improved technique and increasing yieldenabled the young industry to become strong enough towithstand competition.

Early Methods of Juice Extraction. Pressing.—Thevarious methods of extracting the juice from the beetrootwhich have been successively employed are, briefly, raspingaucl pressing, centrifugal treatment of the rasped pulp,continuous presses, cold and hot maceration and diffusion.In the earliest of these methods used in France the beetswere reduced to a line pulp by special rasping machines, andthis was pressed ; originally wooden presses were used, thenscrew presses, finally succeeded by hydraulic presses. The

9o CARBOHYDRATES

pulp was wrapped in strong but coarse woollen cloths, andplaced in layers in the press with a metal sheet between, andexposed to high pressure. The expenditure of manuallabour in filling and emptying the presses and washing thecloths soon led to the use of roller presses.

Cold and Hot Maceration Processes.™-The method ofpressing extracted only 70 to 80 out of the <j(> to <# percent, of juice present in the beet. The process of rasps andpresses was the one chiefly used in Germany until 1870, andin France until 1876. The introduction of the macerationprocess or soaking out of the juice from the rasped pulp,marks an important improvement. The levigator con-structed by Pelletan in 1836, adopted in several Kivnehfactories, consisted of an inclined, semi-cylindrical troughin which the pulp was raised by a worm against a descendingcurrent of cold water. The water became gradually enrichedwith sugar, and issued as juice, only slightly more dilute thanthat obtained by pressing, while the pulp, on arriving at thetop, had given up its sugar. The fault of the process lay inthe difficulty of obtaining juice free from fibre', which causedtrouble in defecation. The cold maceration process ofSchutzenbach overcame this difficulty. A number of vessels(usually twelve) arranged in line, mostly in cascade form,are filled with pulp resting on the false bottom. Water isrun on the pulp in the highest vessel until full, and the di lu tejuice obtained is drawn from below the sieve on to the next,and so on, until the pulp in the iirst vessel is exhausted.Water is then started on the second vessel, and the* Iirst(the highest) is emptied. As each in turn becomes thestarting-point in the series, the partial juice is pumped fromthe lowest vessel to the highest, and the dense juice from theone most recently filled is sent to the defecators. Kachvessel is provided with stirring gear to mix the water andpulp while maceration proceeds. This process also requiredthe most scrupulous cleanliness to secure juice that couldbe easily worked. After each vessel was emptied it wasthoroughly washed, especially the part below the false bottomwhich afforded a suitable lurking-place for genus ol the

BEET SUGAR gi

dreaded " frog-spawn" (Leuconostoc mesenterioides). Thisorganism develops at a rapid rate, producing the dextran

^fermentation. The earlier filter presses, too, were oftencovered with a growth of this undesirable bacterium.

From time to time various combinations of methodswere used : pressing the raspings followed by macerationof the partially exhausted pulp, as also removing the greaterpart of the juice with a centrifugal machine, and the re-mainder in the same way after macerating in water. In spiteof some advantages the latter method was abandonedbecause of the danger of bursting the centrifugal owing toirregular running from the uneven way the pulp loaded intothe machine.

As early as 1830 maceration with hot water was intro-duced by de Dombasle, who held that the life of the cell must

ibe destroyed by a sufficiently high temperature (60° to100° C.) to enable the juice to pass out, and also that themaceration must be prolonged for a sufficient time for theextraction to be complete. The process was capable ofextracting 90 per cent, of the juice. The beetroots were cutby a machine into slices about 6 millimetres in thicknessand filled into a battery of six vessels, provided with falsebottom and heating coil. The duration of contact in eachvessel was half an hour, and the juice drawn off from eachvessel was run into the next following. De Beaujeu, in 1833,installed a similar plant in which the juice passed by gravityfrom one vessel to the next, and the communicating pipewas utilized for heating the juice. It was further suggestedto heat the fresh slices by steam before treating them withjuice. The process of de Dombasle was adopted in 1847 byF. Robert, at Seelowitz, in Moravia, but owing to the diffi-culty of defecating the maceration juice it was mixed withjuice obtained by pressing, the two processes being workedsimultaneously.

In 1837 Schutzenbach, instead of using fresh raspingsfrom which to extract the juice, proposed to dry slices ofbeetroot to preserve them. These could afterwards besoftened in water to which milk of lime was added, and

92 CARBOHYDRATES

extracted in closed vessels with water at «*T C. In thisway he expected to make the factory independent of theseason and able to work continuously throughout the year.The principal obstacle lay in the difficulty of drying theslices uniformly and without: destruction of sugar by over-heating, and the hope of securing ^ more concentrated juieewas not realized. This process was worked at Seelowit/.along with other methods. At this period J. Kobert enteredhis father's factory, after having made a study of the mor-phology and physiology of plants as well as of the phenomenaof osmosis, diffusion, and dialysis investigated by Dufroehet ,Dubrunfaut, and Graham, and had come to the conclusionthat since the beetroot cells were able to obtain their nu t r i -ment from outside by a purely osmotic process, it should bepossible, under suitable conditions, for them to yield t he i rsoluble contents, principally sugar, in a, s imilar wannerwithout the necessity of tearing or bursting the eells, as isdone when the roots are rasped or when overheated inmaceration.

The Diffusion Process.-- For diffusion the beetroots arecut into thin strips, one millimetre in thiekness, and syste-matically extracted in live or six closed vessels s imilar tomacerators. When the first: vessel is being filled w i t h thefresh chips, water heated to 87" C. in an open heater is run in.The diffusion in each vessel lasts half an hour, and theaverage temperature of the battery is jo" to fjo" C.

Robert worked his patented diffusion process for a weekat the end of the campaign, r<S(>, | i<S(>5 , and the followingseason the factory at tfeelowitz used this method exelusivelv.The results were so satisfactory that in i Mj the diffusion pro-cess was used in 27 factories, and in 1885, out of .fo.S faetoiiesin Germany no less than 402 worked it. Diffusion made*quick process also in Austria and Russia, but. in Framv wasnot introduced owing to the opinion that it was unsuitablefor the poorer quality of beets grown there. Resides thisthe sugar factories had neither chemist nor laboratory,and ^there was some hesitation in introducing a processrequiring some knowledge of science. Otuirez, however.

BEET SUGAR 93

started diffusion in 1876, and obtained a better quality ofjuice and i per cent, more sugar in this way than bypressing. It was then objected that the exhausted pulpwas injurious to stock, and only in 1884, when the dutywas charged on beetroots, the process was definitelyadopted.

Theory of the Diffusion Process.—The rapidity withwhich the diffusion process replaced the older methods wasa proof of its superiority due to the purer juice it furnished.The torn cells of rasped pulp yielded the whole of thecontents of the cells by pressing and maceration of the pulpwas simply a lixiviation of this impure juice. The sameresult followed when the cells were burst by too high atemperature in hot maceration, and prolonged contact withhot water also brought into solution pectous substances andincreased the viscosity of the juice. The aim of diffusionis to obtain as much sugar as possible from the beet withoutat the same time allowing too much non-sugars to enter thejuice. As diffusion is a slow process, it is requisite that theroots be cut into suitably thin slices, and these should beexposed to the action of diffusion as long as necessary forequilibrium to be attained between the juice left in the celland the extract, this diffused juice is then to be replaced byweaker juice, and the operation repeated until the slicesare sufficiently exhausted of sugar. There is a limit to thethinness of the slices since the cut surface lays open cells,the contents of which mingling with the diffused juice lowerits purity, and the cleaner the cut the less will be the numberof cells thus opened ; it is thus advisable to work with well-sharpened knives ; when these become blunt the cells aretorn. Further, diffusion only occurs when the protoplasmis killed or modified so that it can no longer offer an obstacleto the passage of the juice, hence the necessity for the highertemperature in the first diffusion vessel. Apart from thisa rise in temperature accelerates osmosis, but the heatingmust be kept within limits, so as not to injure the qualityof the juice. A microscopical examination of an exhaustedslice after diffusion shows the cells to be intact and the

94 CARBOHYDRATES

intercellular pectose, which only swells in boiling water, isseen to be still compact.

Extraction of the Juice.—To prepare the beetroots forthe extraction of the juice they are first conveyed to thewashing-machines to be freed from adhering earth andstones, then drained, weighed, and cut into chips ready forfilling into the diffusers. The beets are now usually con-veyed from the store sheds by flumes which are cementgutters about 2 feet deep, 15 inches wide, and roundedat the bottom. These gutters run the length of the shedsand are covered with boards. Water is turned on, and theboard at one end is lifted and the beets allowed to fall inand be carried along by the current. As the work proceedsone board after another is lifted until the store is emptied.At the end of the run the beets fall into a drum of perforatedmetal, of large diameter and open at one side ; by this wheelthey are lifted and dropped into a shoot leading to thewashing-machine. Sometimes an Archimedean screw isused to raise the beets from a well into the washer.

Washing the Beets.—The washing-machine consists of awrought-iron trough with a rounded false bottom perforatedby slits through which dirty water may pass into the collect-ing space below. The beets are tossed about and movedalong by a number of arms arranged spirally on a revolvinghorizontal axis, while a constant stream of water is runthrough and kept up to the level of the axis. The beetsthen reach a second compartment of the washer in whichstones, etc., fall to the bottom, while the floating beets arelifted by scoop-like arms and thrown out to the elevator,which raises them to an upper story. Here they are drainedand weighed.

Beet Slicing Machines.—The cutting machine consistsof a horizontal disc 4 to 6 feet in diameter on a vertical axis,and making 80 to 100 revolutions per minute. In the discare a series of 8 to 14 apertures, into which fit the knife-holders on which the knives are screwed. These travel in anannular path to which the beets are confined by baffles inthe hopper, surmounting the casing around the disc. A bell

BETW SUGAR 95

covers the central part of the disc which does not work.Cross-pieces a few millimetres above the disc prevent thebeets from rolling and being carried round with the revolvingdisc so as to ensure their being cut. The hopper is about(> feet high and wide enough so that the beets may fallfreely and exert sufficient pressure, otherwise good chipswould not be obtained.

In another form of machine the knives are arrangedinside a horizontal cylindrical drum with the cutting edgepointing inwards. The chips pass through the aperturesiu the knife-holders. The beets are kept in position by acurved prolongation of the side of the feed hopper.

Kach knife-holder contains a knife with a set of bladessimilar to the blade of a carpenter's plane, but formed so asto cut chips of the sectional form desired. One of the mostApproved forms gives chips the section of which, beingsimilar to the tiles on the ridge of a roof, is called the ridgetile. This form of chip presents a large surface, and thechips lie loosely packed in the diffuser so that the circulationof the juice proceeds freely. Opposite the cutting edge ofthe knife is the counter blade, which can be raised or loweredand fixed in position by a screw. Its set determines thethickness of the cut chips. The far side of this plate has anumber of apertures to allow of the passage of any smallstones which have not been removed in the washing. Thesefrequently blunt or break the knives and cause a stoppageof the work. The apex of one knife follows the other in thesame circle, and the width of the strip—or from apex to apex—varies from 4*5 to 7 millimetres. The size of knife usedis chosen to suit the flesh of the beets being worked, thelarger ones are used when the beets cut badly. A disc5 feet in diameter with twelve sets of knives will cut 300tons of roots per day. The chips are conveyed to thedill users by a travelling belt or otherwise.

Working of the Diffusion Battery.—The ten or twelvediffusion vessels worked in connection constitute a diffusionbattery. Formerly these were sometimes preferred arrangediu a circle, but they are now placed in a single or double row.

96 CARBOHYDRATES

Each diffuser is a wrought-iron cylindrical vessel, about5 feet in diameter, and of a capacity of 1750 to 2500 gallons.They taper conically above and below to where the covercloses the manhole for filling, and the door below closes thatfor emptying the exhausted chips. Each diffuser is con-nected with a heater and with valves in communication withwater and juice conduits. The conical parts are furnishedwith perforated sheet to act as a sieve, and prevent the chipsfrom passing away and blocking the pipes and valves.The last diffuser (No. I suppose) containing the chips mostnearly exhausted of juice is supplied with water underpressure from a tank 30 feet above. The dilute juiceflowing from the bottom of this diffuser passes through theheater and enters the next diffuser at the top, and followsa similar course through the whole of the diffusers at work,becoming enriched on its passage until it issues, still underpressure, from the first diffusion vessel (No. 10) containingthe freshest chips, to enter the measuring tanks as rawdiffusion juice through the juice pipe. The amount drawnoff is thus known precisely and is varied from 160 to nolitres, or even more, per 100 kilos of beetroot to suit theconditions. When the chips lie loosely packed there is agreater proportion of juice present to the chips and moremust be drawn off to get the same exhaustion. When adiffuser (No. n) has been filled with fresh chips the courseof the circulation is altered to mix them with the juice—mashing as this is called. If the juice entered at the topthe air between the chips would become entangled andprevent proper circulation. The valve to the measuringtank is closed and the valve to the heater following No. 10is opened so that the juice from No. 10 passes along thejuice pipe down through the heater and enters diffuserNo. ii below, chasing the air before it. As soon as juiceissues from the air cock in the cover these valves are closedand the normal course of the circulation proceeds, No. nforming now a working part of the battery. Meanwhile No. iis cut out of the circuit and emptied and water is run onNo. 2. In order that the juice in all the vessels should

BEET SUGAR 97

have the temperature considered most favourable, the steamon the heaters is kept full on, but as the chips are filled atabout 20° C. the temperature of 75°-8o° C. is only reachedin the second to the fourth diffuser from the head of thebattery; from this point the temperature falls to the lastvessel, where cold water enters. In some cases the batteryis worked hotter throughout with a quicker exhaustion anda smaller number of diffusers, the chips are heated by a jetof steam underneath the knife plate in the cutting machineand are then hotter when filled, and warm water (40° C.)is used instead of cold. The exhausted chips then, however,require to be cooled before they can be pressed and stored,otherwise they would rapidly deteriorate. Too high atemperature, 85°-90° C., leads to a disturbance of thecirculation, the chips are said to be scalded; they becomesoft and lie close together and against the sieve. Theordinary methods of working differ widely in differentfactories, as regards the temperature, duration and densityof juice and according to the character of the beetroots andof the chips. Diffusion includes lixiviation of broken cells,dialysis and solution of otherwise insoluble matters. Thelatter is injurious, but is favoured by the same circumstancesthat help diffusion. Complete exhaustion of the chips isfavoured by heat, by thin juice and fine chips, and is morecomplete if slow, but the juice is purer when diffusionproceeds quickly. When the chips are irregular in thicknessa solution of insoluble matters proceeds from the thinnerones while the thicker are exhausting. When frozen ordecayed beets are worked, more sugar must be left, otherwisethe circulation is stopped if the temperature is raised tohelp the exhaustion.

Modifications of the ordinary diffusion have been made.The process of Naudet, by bringing the freshly masheddiffuser to the maximum temperature the chips can bear,obtains a quicker extraction and more concentrated juicewhile the chips are kept quite a short time in contact withhot juice. The juice from the second diffuser enters thefirst, which is just filled, below and leaves at the top, and

98 CARBOHYDRATES

then passes through a heater and is again pumped in below,and this is continued until the juice issues at 75° 0. Thenthe first vessel is put into the usual circuit and the cxt motionproceeds more quickly, so that only 4 to 6 clilTusers arerequired instead of 8 or 10, and the exhausted chips can stillbe pressed easily. Perhaps the most successful of theprocesses of continuous diffusion is that of Ilyross Rak.Each battery consists of six upright diffusion vessels about18 feet in height in which diffusion takes place under apressure of i to 2 atmospheres of water ; the chips, however,do not remain in the same cliff user during the whole processbut pass from one vessel to the next. This uninterruptedprogression of the chips is brought about by a spiral blade1

in each diffuser and pallets in the transition connectingchambers. Each of the diffuscrs is somewhat conical in formand fitted with a sheet of perforated metal in the diffusionspace, forming a double wall with the exterior. Beyond thesieving zone of each diffuser is a construction in which thechips become compressed and form a wad and prevent t h ejuice of one diffuser from mixing with that of the nex t .Condense water at about 60° C. from the triple effect ispumped at i or 2 atmospheres' pressure into the almostexhausted chips entering the last diffuser. It permeatesthese and drives the juice separated in the sieving zonethrough the ascension pipe into the previous diffuser, andso on to the third vessel. The juice from this diffuser isdrawn off continuously to serve as mashing juice without,heating for the mashing zone of the first diffuser. Aftermashing, the juice enters the circulating tank, from whichit is drawn by a pump and forced through a heater to raiseits temperature to 85° or 90° C. The heated juice is suppliedto the first diffuser at three different levels in order to allowthe juice to mix more readily with the fresh chips and torender the heating more regular. The lirst: diffuser is of550 gallons capacity, the others 400 gallons, and the batteryis capable of dealing with 400 tons of beets per day. Thelast diffuser acts as a press to the exhausted chips, whichleave the vessel in a more or less pressed condition. There

BEET SUGAR

is no residual press water to be dealt witb^.-aaf*matically returned, and the loss of dryis thus avoided. The scalding process of Steffen extracts'75 to 80 per cent, of the sugar contained in the beetroot, theremainder is left in the pressed pulp, which is dried to givea dry sugary pulp.

Exhausted Pulp.—The spent chips emptied from thediffusers fall into an inclined gutter, and are then raisedeither by an Archimedean screw or by an elevator withperforated buckets for pressing, to free them, as far aspossible, from adhering water. As dropped from thebattery they contain 94 to 95 per cent, of water, and whenraised represent 80 to 100 per cent, of the original beets.They are pressed so as to contain 10 to 15 per cent, of drysolids before delivery to the farmers, who generally requirean agreement to receive 10 cwt. of pulp, at a stipulatedprice, for each ton of beets delivered. The pulp and sweetwater are acid and contain lactic and butyric ferments in afavourable medium and at a suitable temperature fordevelopment, so that the gutters require to be washedfrequently with milk of lime, and when empty, with solutionof bleaching powder.

Pressing and Drying the Pulp.—It is more difficult toremove the water from the spent chips by pressing whenthey have been exposed to too high a temperature duringdiffusion, or the exhaustion carried too far, or if they aretoo acid, and the character of the beets also is of influence.The chips are passed through one of the forms of Klusemanor Berggren mechanical press. This consists of a cylinderof perforated metal, in which a revolving hollow cone isarranged, also perforated and fitted with a series of pro-jecting arms arranged in a spiral. The wet chips fed inabove are moved downwards by the arms to the narrowingspace below and pressed, the water is thus pressed out, andflows through the sieve walls, and is collected, while thepressed pulp falls out by a narrow annular exit. Themoisture is thus reduced from 94 to about 90 per cent,,or in some of the more effective forms to 85 per cent. The

CARBOHYDRATES

disposal of the water offers a troublesome problem owing ioits containing suspended matters and ferments. The pressedpulp forms a useful fodder and is used either fresh or af terbeing stored in silo, where it alters by souring, and losesweight and nutrient matter amounting to ijo or ,|o per cent .of the fresh residue. This loss has led to methods of dryingthe pulp either by the waste furnace gases or by steam.In drying ovens the chips are moved forward by s t i r r ing-arms over several stages in the same direction as the Huegases, or they arc passed through a revolving drum heatedin the same way* Steam drying is effected in heated t raysover which the chips are moved by scoops attached to heatingpipes. The latter method, although more expensive, givesa better fodder. The moisture by drying is reduced toabout io per cent., and the dried chips then represent;about 6 per cent, of tl^c weight of the original beets. Thelighter coloured chips produced by steam drying- sell at, ahigher price than those of a darker hue, which often conta incharred portions and are less digestible. The dried chipskeep well and, not being burdened with unnecessary water ,are suitable for transport.

Molasses Fodder. — The whole of the molasses made inthe factory may be turned into fodder by running it in athin stream on to the pressed chips before they are dried,and then passing the mixture through the oxren. The feedingvalue of the carbohydrates, as well as the nitrogenousconstituents, is thus utilized.

PURIMCATION OK THIS

The various constituents of Hie beet juice do not dif fuseequally, hence the proportion of solids in diffusion juicediffers from that originally existing in the cells, and alsofrom that in the sweet waters or retained in the spent chips.It is found that in a juice containing 12 to i.\ per cent, ofsugar about 97 per cent, of sugar, 65 of the salts, 25 of thealbuminoids, and go per cent, of other nitrogenous mattershave been extracted, so that the diffusion juice is purer.Besides the soluble matters diffusion juice always contains a

BEET SUGAR 101

considerable amount of fibre and cell fragments. In orderto free it as far as possible from this pulp the juice, on itsway from the battery to the measuring tanks, is passedthrough one or more sieves in a closed vessel, the depulper.The raw juice thus obtained still contains line particles of.fibre and cells which have passed through the pulp catcher,and micro-organisms and ferments as well as matters pre-cipitable by heat. These if left in would give rise to acidi-iication and inversion of sugar, and the raw juice is a turbid,grey, opaque, unfiltcrable liquid which, if boiled to sugar,would give a product of very unattractive appearance andproduce much molasses. By the defecating action of limeand heat a considerable part of the impurities is precipitatedand the juice is converted into a bright pale yellow filterableliquid, but alkaline from the action of the lime used. Theexcess of lime is removed by carbonic acid in the processof carbonatation.

Defecation.—The purification of beet juice by treatmentwith lime was adopted from the method long previously inuse for cane juice. As early as the seventeenth centurywood ashes, lime, or alum had been used for this purpose inAmerica. When the cane juice was heated to coagulatethe albuminoids its natural acidity would cause inversionof the sugar unless it was previously neutralized, and limewas found to be better than wood ashes for this purpose,since it produced precipitates with oxalic, malic, and citricacids present which were insoluble, especially in hot juice.Aeliard, however, in his early attempts to manufacturesugar from beet juice used dilute sulphuric acicl to effectdefecation. The risk of inversion from excess of aciditysoon led to the use of lime as a safer reagent. The quantityused then was very small, being only about 0*5 per cent,instead of the 3*5 per cent, used at prcse nt. This was addedin the form of milk of lime to the juice at 70° C., and thetemperature was slowly raised until the impurities separatedas a scum and formed a head on the surface, fro in which theclear juice below was drawn off. Frequently this amountof lime was found to be insufficient to clarify the juice,

102 CARBOHYDRATES

especially if spoilt beets were used, and more lime Lad tobe added to cause the precipitate to separate, so that thejuice when drawn off was alkaline, containing sucrate oflime and therefore difficult to boil and crystallize. Toremove the excess of alkalinity dilute sulphuric acid wasadded, until the juice was only faintly alkaline to litmus.Kiihlmann of I/ille, in 1833, proposed the use of carbonicacid to neutralize and remove lime, and Rousseau, in 1848,adopted the method, preparing the gas by passing air overa coke fire, and passing it through the clear defecated juiceuntil it was nearly completely saturated. The correctpoint was determined by taking a sample in a spoon andobserving if the precipitate of calcium carbonate separatedreadily; subsequently turmeric was used to decide theproper degree of neutralization. The slight residual alkali-nity was removed by passing the juice over animal charcoal.The defecating action of lime on the juice is partly chemicaland partly mechanical. The solubility of lime in water isO'i2 gramme per 100 c.c., while a 10 per cent, sugar solutiondissolves 1-5 grammes, so that the whole of the reagentused would be present as monosucrate or bisucrate of lime.This begins to form insoluble trisucrate of lime at 80° C.,and the precipitation is complete at 100° C. The formationof this insoluble sucrate must be avoided, otherwise therewould be a considerable loss of sugar in the precipitatewhich would form along with the other impurities. Thelime neutralizes the acidity of the juice, forms insolubleprecipitates with some of the organic and inorganic saltspresent, and also with albuminoid and pectin substances;these precipitates carry down with them the mechanicallysuspended impurities; altogether about one-third of thenon-sugars are removed. The lime also acts on invertsugar and amino- compounds, converting them into othersoluble compounds less harmful in the succeeding operations.

Single and Double Carbonatation.—While occasionallythe juice that has been merely defecated with lime is decantedor filtered and carbonated almost to neutrality before beingused in the factory (single carbonatation), it is now the

BEET SUGAR 103

general practice to carbonate the turbid juice withoutprevious separation of the precipitate, as was done byPossoz in 1859, and by Jelinek in 1864.

By this means it is possible to use a larger quantity oflime for defecation and obtain a better purification. From2 to 3*5 per cent, of lime is used. Too small a quantitydoes not give scums that filter easily after carbonatation ;larger amounts arc required when decayed or frost-bittenbeets are used. Excessive amounts are not only unnecessarilyexpensive, but the clearer juices obtained are not in pro-portion to the extra work entailed, and the larger bulk ofscums leads to loss of sugar.

If the lime is added in lumps a separate defecating panis required, provided with stirring gear, heating coils, and agrid on which the lime rests while it slakes. When thepan is sufficiently full the juice is heated to abotit 80° C.,a weighed quantity of lime is added, and the stirring gearstarted. The lime slakes in a few minutes, and is distributedthroughout the juice, which is then run off into the saturator.If milk of lime is used, it is usually made to 20° Be. forconvenience of measuring, and the defecation docs notneed a separate vessel, but is carried out in,the carbonata-tion tank. Defecation may be made continuous by runningin raw juice below, adding milk of lime at a regular rate,and having the tank large enough to allow of the overflowjuice being sufficiently limed.

The first carbonatation is then commenced. At thestart the major portion of the lime is in suspension, thefiltered juice shows an alkalinity of 0-3 of CaO per 100 c.c.,but as the carbonic acid gas is passed in, and the dissolvedlime is precipitated as carbonate, fresh lime dissolves, andthe alkalinity is quickly reduced to a certain point whereit remains almost stationary. This point corresponds to theformation of the viscous hydro-sucro-earbonate of lime ofBoivin and L,oiseau, called " cheese " by the workmen. Thisgelatinous compound, C^H^On . 3CaO.Ca(OH)2 containssugar in the insoluble condition, but is gradually decomposedby heat and carbonic acid, and the alkalinity again falls to

io4 CARBOHYDRATES

about o'i gramme of CaO per 100 c.c. when earbonaUition isstopped. A sample withdrawn from the tank ought; thento show a granular precipitate, which separates and settlesrapidly and indicates that filtration will proceed easily.Any of the gelatinous compound left undeeomposed wouldresult both in a loss of sugar and diflicult filtration. Carbona-tation may be made continuous by numing in the juice atthe bottom of one tank along with carbonic acid ; these mixas the liquid rises, and then overflow to the bottom of asecond tank where the partly carbonated juice meetsa secondsupply of gas. lyess of the gelatinous precipitate is formed,and with good lime for defecation the method works well,but in other cases it often gives rise to irregularities. A f t e rcarbonatation the juice is run into a collecting and mixingtank, and is then passed to the filter presses, sometimes heatedon its way by heaters to facilitate filtration. The point atwhich the first carbonatation is interrupted, indicated bythe rapid settling of the precipitate and the consequenteasy filtration of the juice, is readily determined by anexperienced workman, but to avoid any chance of error,and to keep the operation under strict chemical control , i(is preferable to supplement the test by t i t r a t i n g a f i l teredsample of the juice to determine its a lka l in i ty to phenol-phthalein. The actual percentage of CaO allowed in thecarbonated juice depends on the character of the beetsworked during the season, and is usually fixed at. about.0*10 per cent. The juice therefore still contains a consider-able amount of lime in solution. Had the gas been passedthrough to complete neutrality before removing the precipi-tate, a portion of the precipitated impurities, which onlyremain insoluble in presence of lime, would have been re--dissolved and the juice have acquired a darker colour.Such juice is said to be over-saturated.

The clear filtered juice from the first carbonatation isheated to about 95° C., and again saturated wi th carbonicacid. In many factories <ri to 0-2 per cent, of lime is addedas milk of lime to the hot juice before this secondcarbonatation in order to obtain a further purification.

BEET SUGAR 105

Saturation is continued until the juice on titration showsan alkalinity of 0-04 to 0*05. There is then no free limeor sucrate left in solution, the residual alkalinity being dueto alkalis, ammonia, and. organic bases. The saturationpans are round or rectangular closed vessels of wrought iron,made as high as possible to allow for frothing. The heightis from 16 to 18 feet, and the other dimensions are arrangedto suit the volume of juice treated, which occupies a littleover a third of the height. The juice is admitted below.There is also a wide pipe for introducing the carbonic acid,which is distributed below by a perforated pipe or coil, theperforations being directed downwards to avoid obstructiondue to incrustation by the lime. The more completely thegas is sub-divided, and the smaller the bubbles, the betterIs the carbonic acid absorbed and the quicker the saturation.The unused gases escape into the open air through a pipeat the top, passing through the roof. A smaller pipe intro-duces steam used both for heating, by a coil below, and forbreaking the froth, by jets in the upper part of the tank.

Sulphiting.—Sulphurous acid combines with lime toform calcium sulphite which, like the carbonate, is insolublein alkaline solutions. It likewise decolorizes the juice,while carbonic acid always leaves the fully saturated juicedarker. The second carbonatation juice, after being filter-pressed, is in many factories treated with sulphurous acidgas or a mixture of this and carbonic acid, but this treatmentis generally considered to be superfluous, since the decolori-zation produced by sulphurous acid only occurs whenneutralization is carried very far and there is then a risk ofthe faintly alkaline juice becoming acid during concentration,when inversion would take place and loss of sugar ensue.It is preferable to apply the sulphurous acid to the partiallyevaporated or thick juice. The only advantage it seems tooffer is that it may decompose calcium salts of organicacids that are not attacked by carbonic acid, and it is heldby some that sulphited juices boil more freely.

Filtration,—The earliest methods of filtering off carbona-tation scums was by means of cloths stretched on frames,

io6 CARBOHYDRATES

but the process was slow, and there was a great loss of sugarfrom the large quantity of juice retained in the scums. Bagfilters were then used, from which a part of the juice couldbe pressed out. A great improvement was made by theintroduction of the filter press originally devised by Needham,in 1828, for removing water from clay puddle in the porcelainmanufacture. A press of this kind, shown at the Inter-national Exhibition in 1862, led to its adoption at theSeelowitz factory of J. Robert, where in the form modifiedto suit the purpose it contributed towards the success ofthe diffusion process. The first and second carbonatation•juices are pumped through filter presses at a pressure whichis allowed to rise gradually to 40 or 45 Ibs. per square inch.By this means firm spongy cakes are obtained, which fillthe chambers of the press, and which are easily washed,and separate from the cloths when the press is opened.Too sudden a pressure at the start is liable to choke thepores of the cloth and impede filtration. The presses of thesecond carbonatation naturally filter more easily and run alonger time than those of the first carbonatation which givea much more impure deposit. The juice is always submittedto a third and final filtration before it is sent to the evapo-rators. Filter presses may be used for this purpose, butthe juice is then not pumped but run in by gravity from atank, giving only a few feet head of pressure. In the tankthe juice is kept boiling hot to ensure the complete depositionof carbonate of lime, the last portions of which separateslowly. Instead of filter presses for the third filtration someform of mechanical filter is used with a large filtering surface.These are formed of bags stretched over open frames orgauze and suspended in the filter tank. Filtration proceedsfrom the outside to the inside of the bag, the filtered juiceissuing through a pipe over which the mouth of the bag istightly secured and which is open below to the inside ofbag. These filters are worked under a slight pressure only,as too great a force would drive the fine particles of precipi-tate through the pores of the cloth. Various forms of sandfilter are also used as mechanical filters and prove effective.

BEET SUGAR 107

Treatment of Scums.—The press cakes contain about50 per cent, or more of juice and therefore 6 or 7 per cent,of sugar, most of which must be recovered. By washing thecakes with water at 30 to 40 Ibs. pressure the sugar may becompletely removed, but to avoid excessive dilution of thejuice the sweetening off is stopped earlier, leaving I to 2 percent, of sugar in the washed cake. I per cent, of lime will,therefore, give 3'5 to 4 per cent, of washed cake containing50 per cent, of water. The solids consist, besides the smallamount of sugar, of calcium carbonate with the impuritiesremoved from the beet juice and those in the lime used. Theorganic matters in the cake form about 6 or 7 per cent., thegreater part of the albuminoids being removed. Phosphoricand sulphuric acid originally present in the juice are removedas insoluble calcium salts. The washed cake is of value foragricultural purposes since it contains all the phosphoricacid and part of the nitrogen of the beets. When 2*5 percent, of lime has been used for defecation, 100 of beetrootsyield about 12 of washed press cake from the two carbonata-tions, or 84 of cake to 100 of sugar from beetroots containing14 per cent, of sugar. vSometimes the cakes obtained aresoft and smeary, and do not fill the chambers of the press, inwhich, case filtration and washing are slow and difficult.Attention should then be directed to see that saturation isproperly conducted and that the temperature in the diffusionbattety is not too high. When the trouble is due to unripebeetroots the only remedy is to change the cloths frequently.

Lime Kilns.—The large quantity of lime required fordefecation makes it economical for each factory to preparethe lime it requires by calcining limestone in kilns and usingthe gases produced for carbonatation. The usual kiln is ashaft of wrought iron lined with fire-bricks and taperingslightly above and below, and at least 30 feet in height. Itis supported on columns so as to leave a space below wherethe burnt lime collects and is withdrawn. The opening atthe top is fitted with a funnel or bell through which suppliesof limestone and fuel (coke or anthracite) are introduced.During work the opening is closed by a cover so that the gases

io8 CARBOHYDRATES

may be drawn off by a pump through a side pipe ; when thepump is not working the gases ascend by an exhaust pipeand escape into the atmosphere. The limestone is com-pletely burnt to lime in the hottest zone, which is just abovethe widest part of the kiln where the limestone, heated in itsdescent by the ascending hot gases, arrives partly ealeiuedin its passage, and as it descends below the hottest /-onethe glowing lime is cooled by the incoming eold air before it:drops underneath the kiln. The lime to be effective indefecation should be used as fresh as possible, and in burning-care should be taken that the temperature of the kiln is notallowed to rise too high, otherwise the lime is dead burnt,has the appearance of porcelain and slakes very slowly, andleads to difficulties in carbonatation. This tewleney isincreased by the presence of silica, alumina and iron, so Unitlimestone selected should be as free as possible from theseimpurities as well as from magnesia. A good limestoneought to contain at least 97 per cent, of ealeiiuu carbonate.

Carbon Dioxide.—The gas used for carbonatim;' shouldbe free from noxious constituents and contain at least 20to 25 per cent, of carbon dioxide, consequently boiler linegases which contain only 10 to 15 per cent, are unsuitablefor the purpose. The carbonic acid produced in the kiln isderived partly from the combustion of the coke* fiu*l amipartly from the decomposition of the linu'Stone. Purelimestone burnt with 10 per cent, of pure carbon wi th airshould give theoretically a gas mixture containing .47 percent, of C02 by volume. This result is never reached inpractice; because, to avoid the production of carbonmonoxide, an excess of air is always used ; it is satisfactoryto reach 30 per cent. The quantity of coke fuel should beproportionate to the needs of the kiln; too little does notgive a sufficiently high temperature and unburnt lime results,while the percentage of carbon dioxide is low. Too muchcoke raises the heat unduly and likewise gives a gas poor incarbon dioxide and possibility of over-burnt lime. Thegases leaving the kiln at about 450° C. are too hot to be useddirectly; they are, therefore, passed through a washer to

BEET SUGAR 109

cool them and to free them from flue dust, smoke, soot andtar which have been carried forward owing to the velocitywith which they have been drawn off. These impuritieswould otherwise injure the pump and also contaminate thejuice. In the washer the gases entering below meet acascade of cold water flowing over a series of trays or overa mass of coke, and issue cooled at the top to the pump.The amount of water used must not be excessive, sincecarbonic acid is fairly soluble in water.

Sulphur Burner.—The sulphurous acid used for sul-phiting juices and syrups is generally obtained by burningsulphur in an iron vessel supplied with air either by com-pression or by suction, and fitted with exit pipe lined withhard lead and cooled by a current of cold water in a jacketleading to a washer. liquefied sulphur dioxide is employedonly where the factory is situated so that the question offreight renders this possible. When a compressor is used theair is dried by passing it over a layer of lime or calciumchloride before it reaches the oven. The supply must beunder strict control, for if the volume is too great there isdanger of extinguishing the flame. Another method ofsupplying the air is by drawing off the acid gas by means ofa Kjorting's jet with steam ; this is under easy control, butthe air drawn in is direct from the atmosphere and is moist.

EVAPORATION

With the final mechanical filtration the purification ofthe juice is completed, and it should then be quite bright andof a pale yellow colour or, when inferior beets are worked, ofa brownish tint. Its sugar content is 10 to 12 per cent, andthe total solids as indicated by the Brix hydrometer onedegree higher. Its further treatment for the purpose ofobtaining the sugar in crystals is carried out in two stages,in the first of which, evaporation, the juice is concentratedto a syrup or thick juice of 50 to 60° Brix, in whichno crystals are formed, and in the second, boiling, it isfurther concentrated to a crystalline mass containing 90 to95 per cent, of dry solids. The quantity of purified thin

no CARBOHYDRATES

juice is greater than that of tlic raw diffusion juice owingto dilution, by tlie addition of the sweet water from presswashings and the water condensed from open steam usedfor heating. If 100 kilos of beets give no litres of rawdiffusion juice the amount of thin juice obtained will reach125 litres. In order to concentrate this juice at 12° I J r ix to60° Brix, 80 per cent, of the water must be evaporated, or anamount equal to the weight of the original beetroots. Ina medium-sized factory working 700 tons of beets per dayit is, therefore, necessary to evaporate over 150,000 gallonsof water, and the importance of efficient plant for dealingeconomically with this large quantity is so obvious andpressing that efforts at improvement in evaporation have nowattained a perfection reached in no other industry. Heatingthe juice in open pans over a direct lire in the primitive claysbesides consuming an immense amount of fuel was destruc-tive of sugar owing to contact witli excessively hot wallsof the vessel. The gases produced by combustion gave uponly a small part of their heat and escaped at a wry Jii^htemperature, and the whole of the latent heat of the vapourformed was lost. The use of steam for heating invented byWatt in 1780, boiling under reduced pressure on the principleof the vacuum pan invented by Howard in i8u, multipleevaporation with vacuum apparatus conceived by Rillieux:in 1830, and the various types of film evaporators mark theprincipal steps in the economical utilization of heat, foreffecting evaporation. The boiling-point of water or of anaqueous solution is lowered by reducing the pressure, or inother words, increasing the vacuum, under which it boils.Water at atmospheric pressure boils at 100" 0. and gives oilvapour at the same temperature ; under a vacuum corre-sponding to a pressure of 600 millimetres of mercury waterboils at 6r6° C., so that steam at atmospheric pressure,because it is hotter, may serve to boil water tn ider this vacu u in.Thus if there are several vessels each under a higher vacuumthan the preceding one, direct steam above the atmosphericpressure in the first may boil water iu this, and the vapourgenerated from it boil water in the next and so on. This

BEET SUGAR in

applies to sugar solutions with the difference that the boiling-point of the juice is higher the denser the juice. Thus, theboiling-point of juice at 10° Brix is 0*1° higher thantliat of water, at 20°, 0*3 higher, at 50°, i'8 higher, and^-t 60° C., 3*5 degrees higher than that of water, whateverthe pressure. Not only must a greater difference in tempera-ture be maintained to ensure boiling, but the greater viscosityof the denser juice retards the transmission of heat andrenders the boiling slower; the result, however, is that i kiloof direct steam used in the first vessel has been made toevaporate 2, 3 or 4 kilos of water from the juice accordingto the number of vessels used in the series. This is theprinciple of multiple evaporation in which the juice partiallyconcentrated in the first vessel of the multiple effect is ledinto the second where, although denser, it is under a highervacuum, and the boiling-point is so far lowered as to leavesufficient difference of temperature between it and thevapour from the first vessel for boiling to go on. Similarrelations hold between the second and third.

The thick juice pumped from the last body of themultiple effect is no longer clear owing to the presence of afine, flocculent precipitate formed during concentration,and the colour is now dark yellow or brown. The darkercolour as compared with thin juice is partly a consequenceof concentration, but also due to the formation of browncolouring matters owing to the action of the high temperatureon sugar. The alkalinity has not increased in proportionto tlie concentration, the decrease being due both to volatili-zation of ammonia and to the decomposition of nitrogenouslion-sugars of alkaline reaction and combination with acidsderived from the sugar. The residual alkalinity is still toolii^li for boiling, and the thick juice is therefore sulphited.It leaves the last body at 70° C., and is heated to 100° C.,satvirated and filtered. Filtration of the thick juice issometimes difficult, especially if higlily concentrated, and fortliis reason it is often preceded by sulphitation and filtrationof tlie intermediate juice at 30° Brix, and again filtered onleaving the last body of the multiple effect.

H2 CARBOHYDRATES

Multiple Effect Evaporators.—Two forms of multipleeffect evaporator are in use, vertical and horizontal, eachconsisting of 3, 4 or more vessels, and forming a triple,quadruple or quintuple effect. Each body of the verticalform is a tall upright iron cylinder fitted with a heatingarrangement, the calandria, consisting of a number of brassor steel tubes, expanded above and below into the tubeplates. The juice circulates upwards inside the tubes anddescends by a wide pipe in the centre. The space above thetubes is made as high as possible to allow for the spray tosettle before the vapour passes on to heat the next body,otherwise a juice collector is placed in the connecting pipein which by means of baffles the vapour is made to depositthe drops of juice. In the first bodies of the effect the dangerof entrainment is slight because the vapour formed is onlyunder a slight vacuum and occupies but a small volume, whilethe liquid is very fluid, and the velocity of the issuing vapouris not great. But in the next bodies the syrup is moreviscous and the vapour occupies four or five times thevolume, owing to the higher vacuum, so that when thebubbles burst there is a far greater tendency to entrainment,and a juice collector is indispensable for the last body of theeffect. The calandria is provided with a pipe for carryingoff the water of condensation from the steam or vapour,and another entering flush with the upper tube plate tocarry off incondensible gases and particularly ammoniafrom the intertubular space of the calandria. This is moreparticularly necessary in the later bodies of the effect, wherethe ammonia from the vapour would otherwise corrode thebrass tubes. The separate bodies are each provided withthermometer and vacuum gauges, with light glasses andgrease cock for introducing oil or grease to keep down froth,and with the necessary valves and connections. The vapourfrom the last body of the effect after passing through thejuice catcher and traversing a surface condenser reachesthe air pump which removes the air and incondensible gasesand maintains a vacuum of 600 mm. of mercury inthe last effect. This vessel acts as a condenser to the

BEET SUGAR 113

previous vessel, and this to the next, so that a difference ofi*-l>otit 20° C. is maintained between each vessel, sufficientto keep up the boiling and concentration of the juice.

'JClie horizontal form of multiple effect consists of elongatedl><uas of somewhat rectangular section, the upper part beingseixiicyliiidrical and with the heating tubes placed as lowclown as possible ; the steam circulates through the tubesaucl tlxe juice is outside. The fittings are the same as in theoilier form, but as there is no great height of vapour spacefor spray to settle in, each vessel is surmounted by a juicecateliejr. As the juice becomes more concentrated, more orless precipitate forms, and a portion of this adheres to thetubes as an incrustration, hindering the transmission ofheal, so that the tubes require to be frequently cleaned.Tlie incrustation is much more easily removed from theinside of the tubes in the vertical apparatus than from theoutside of the tubes in the horizontal form, the tubes beingless accessible. For this reason horizontal evaporators aresometimes used for the thin juice and vertical ones for thethicker juice where the deposit is greater. The incrustationconsists of carbonate and oxalate of lime with a portion ofsulphite when the juice has been sulphited. There is also aecrta.iii amount of lime soap derived from the grease used toprevent foaming. The deposit is removed by boiling with asolution of i per cent, carbonate of soda and then withI per cent, hydrochloric acid.

BOIUNG

Xlie filtered thick juice is collected in supply tanks usuallyprovided with floats to indicate the level of the juice, and isdrawn off as reqtiired into the vacuum boiling pan. Boilingmay "be regarded as a continuation of evaporation, but differsin both, method and aim ; while in evaporation the operationis continuous and produces a syrup free from grain ; in boiling,OH tlic otker hand, the operation is intermittent, each chargebeing worked up independently, and the object is to causethe sugar to separate in crystals and to form these as uniformia size as possible, so that they may be easily separated from

u. «

II4 CARBOHYDRATES

the mother syrup. It is not possible, however, in oneoperation to bring the whole of the sugar contained insolution in the juice to crystallization ; this can only be donegradually in several steps until there is finally obtained asyrup, molasses, with still a high proportion of sugar, but.from which, owing to the quantity of non-sugar present, nofurther crystallization of sugar is possible.

There are two methods adopted for producing crystalsfrom sugar solutions : (a) boiling to grain, in which the juieeis so far concentrated in the pan that crystals appear, andthese are then made to grow by suitably conducting theboiling, and (6) boiling to string proof, when a small sampleof the thickened syrup is placed between the thumb andforefinger and these drawn apart forms a thread, adaptedfor syrups of low quality or for juices arising from a badquality of beets; in this case the syrup is merely concen-trated at a high temperature in the pan, and then run out andbrought to crystallization by cooling. The presence of non-sugars influences the crystallization, and when the proportionexceeds 20 parts in 100 of dry solids, boiling to string proofis the only method generally available.

Both methods of boiling depend on the proper regulationof the conditions of saturation and super-saturation. Asolution of pure sugar at a given temperature is saturatedwhen it is in equilibrium with crystals of solid sugar, andneither dissolves sugar from the crystals nor deposits sugarupon them in the crystalline form. The solubility of puresugar in water as determined by Ilencfeld is given in thefollowing table, which shows the number of grammes ofsugar dissolved by 100 grammes of water at the correspondingtemperatures :

0° 10° 20° 30° 40° 50° 00" 70" ,S<i" « , < , " (\179 191 204 220 238 2()0 2X7 : jvsc> jhifc 4 l ( >

Thus, 462 grammes of a saturated solution at tfo'J C. whencooled to 40 degrees will deposit 362 — 238 -..* 124 grammes ofsugar. When a saturated solution is cooled, howeverslightly, it becomes super-saturated, so also if some of thewater is evaporated while the temperature remains constant,

BEET SUGAR 115

and the super-saturated solution crystallizes more or lessrapidly dependent on the degree of the super-saturationand on the purity of the solution. For the speedy depositionof sugar on crystals already formed only a slight super-saturation is required ; if it becomes too great the increasedviscosity of the solution impedes circulation, and there is atendency to the formation of a crop of small crystals, falsegrain, as they are called.

The Vacuum Pan.—Boiling under reduced pressure and,therefore, at a lower temperature, becomes of greaterimportance with the more concentrated syrup required forcrystallization, because the high temperature at which itboils can more readily cause destruction of sugar by caranieli-zation, and especially in the presence of free alkali. Pro-longed subjection to heat in the pan is also injurious, and anendeavour is made to complete the boiling in as short a timeas possible by increasing the difference in temperaturebetween the juice and the heating steam both by increasingthe vacuum and by raising the pressure of steam in the coils.This period, however, is limited by the rate at whichcrystallization can go on increasing the size of the crystalsalready formed without the production of a fresh crop.

Small spherical copper vacuum pans are now used onlyin smaller factories, and are superseded by larger cylindricalpans of cast iron which are more easily constructed and lendthemselves more readily to lagging with non-conductingmaterial to prevent loss of heat. These have generally thesame form and construction as the bodies of the multipleeffect with the modifications essential to allow of the freecirculation of the viscous and pasty final product, the masse-cuite. The outlet valve is large, and there is a cock forsteaming out any masses of sugar left behind when thepan is emptied. There are three or more large copperheating coils which can be worked separately or in combina-tion according as the contents of the pan increase in heightduring the boiling. If the calandria form of heating arrange-ment is adopted the tubes are made wider and shorter toallow for circulation of the massecuite, and with a much

wider tube in Uie centre'. In the horizontal form of pan thetubes are arranged in rows vertically over one another \ \ i t hwide space's between.

Boiling to Grain. It is only juice of high p u r i t y tha tcan be readily boiled to grain ; juices of lower q u a l i t y aresometimes enriched by mel t ing w i t h them the unsaleableline-grained dark sugars from low products. A q u a n t i t y ofjuice is drawn in to the pan suff ic ient to eover the lower coiland concentrated to str ing proof. Hy the l eng th of thethread formed when a drop of the syrup is drawn out betweenthe finger and. t h u m b it is described as weak or strong, proof.For graining thick juice the proof should be rather l igh t .vSinall quantit ies of ju ice are then drawn in suddenly, andowing to the cooling and agi ta t ion which ensue crystals areformed in the syrup. Samples are drawn by the proof stickand spread on a glass p la te , and from the appearance it isjudged whether a stiilieient number of crystals have been.formed. If so, a larger q u a n t i t y of juice is drawn in tolower the super-saturation, and t h i s procedure is repeatedas often as the proof shows the need for f u r t h e r supplies.As tlie grain increases in si/e the panmai i watches t l u * samplesto see that the surrounding syrup is clear and free from smallfalse grain. The indications of the thermometer and vacuumgauge are also noted for guidance, as also the splashes onthe sight glasses. The volume of the juice in the panincrease's, and as each coil becomes cove red, steam is admit tedto it, and boiling is continued unt i l grain of the desired si/eis readied. Kor raw sugar a coarse, sharp gra in is desirable,but for sugar that is to go in to consumption direct the grainshould be line. I,arge grain is obtained by boiling, q u i e t l yand drawing in large drinks of juice at long intervals du r ingwhich the crystals grow ; l iner grain is produced by morevigorous boiling and frequent small supplies of fresh juice.The end of the boiling is indicated by the condition of t i n *maS'Beeuite, which should show a large quan t i ty of crystalsand only a small quantity of syrup from which the crystalsseparate distinctly. The masseeuite as dropped from thepan should be quite s t i f f , but crumbly. The t ime of boiling

BEET SUGAR 117

a charge is from 6 to 8 hours, and when syrups from a previousoperation are drawn into the pan at the end, the boiling mayproceed for another hour or two. Boiling does not alwaysproceed normally. Occasionally a quantity of thick frothforms as soon as the juice begins to boil, and there is dangerof the whole mass boiling over. This is to some extentovercome by boiling at a lower vacuum and higher tempera-ture, and by the introduction of grease into the pan. Thecause is often to be traced to imperfect filtration, or the useof an insufficient amount of lime and faulty defecation.When bad or decayed beetroots have been worked the juiceoften boils badly and almost ceases as soon, as a certainconcentration is reached, the contents of the pan remainingmotionless like melted fat. The grain forms only withdifficulty and grows slowly, and the transmission of .heat intothe thick mass is so small that earamelization ensues, and thejuice becomes dark brown. Slow and dilUcult boiling hasalso been attributed lo presence' of alkali and to calcium saltsof arabic acid. The remedy is either to boil merely to stringproof or to neutralize with sulphurous or phosphoric acid.

Control of the Boiling.—The conduct of the boilingoperation is in the hands of an experienced panman who hasserved an apprenticeship and has learnt from the appearanceof the mass how to regulate the super-saturation and theconsequent: course of formation and growth of the crystals.Boiling to grain was for long considered an art and beyondthe control of science. In recent years, however, severalforms of apparatus have been introduced to secure tinscontrol, among which may be mentioned the brasmoseopeof Curin and the apparatus of Claassen. These arc1 slide rulearrangements by which the temperature of the1- boiling massin the pan and the vacuum give the percentage of sugar ordegrees Bnx of the syrup, and this, in conjunction with thedegree Brix. of a saturated solution of sugar at the sametemperature, shows whether the syrup in the pan is or is notsaturated or super-saturated. Moreover, it is possible toexpress the degree of super-saturation as shown by Claassen.If the ratio of sugar to water in a saturated solution be

n8 CARKOHYDRATRS

denoted by S, and the ratio for the syrup in the pan at thesame temperature be S1, then S1/^ represents the degree oisuper-saturation if S1 is greater thanS. Kor graining thickjuiee the concentration is carried out, unt i l this ratio is r^ tor*3, and after the grain is formed, the super-saturation isreduced to 1*05. With lower-class products the ratiorequires to be somewhat higher, and in any ease, if iveouls arckept of the course of a well-boiled pan, the operation can besafely repeated with the aid of the indicators, preserving thesame? ratios at the different stages of boiling, and thusavoiding errors of personal judgment. The apparatus,however, only affords reliable indications provided t i n *contents of the pan actually boil.

TKKATMKNT OF Tin-: MASSKCUITK

When the massecuite is discharged from the pan it is at atemperature of about Ho" C., and the syrup is somewhatstrongly super-saturated, so that if the crystals were separatedat once the syrup would carry off an undue amount of sugarinto the lower product. If the mass is allowed to coolquickly the super-saturation increases so much tha t a cropof very small crystals is formed which pass off w i th thesyrup from the centrifugal machine, being too line to beretained. To secure this sugar in the fust, product it is,therefore, necessary to moderate the rate of cooling and tolessen the super-saturation by the periodical a d d i t i o n ofsomewhat diluted syrup from a previous operation, or evenwater, as the temperature falls. By th i s means the viscosityand super-saturation are kept low enough for the sugar todeposit on the crystals already present, and th is result isassisted by keeping the whole mass in slow movement u n t i lthe temperature lias fallen to about 50" C, 11 is not advisable*to cool below this tempetature, otherwise* the mass wouldbecome too still and not possess the necessary mobi l i ty toenable it to rise in the centrifugal machine and form auniform layer. The whole contents of the pan are let downinto a crystallizer which is either a closed horizontal cylinderor a large open trough provided with stirring arms with a

BEET SUGAR no

revolution in one or two minutes. The crystallizers areoften jacketed so that they may be heated with steam orhot water, or cooled with water during the 12 to 24 hoursof crystallizing and cooling. The cooled massecuite may bedrawn off in bogies running on an overhead rail, and eachcarrying 2 to 5 cwt., sufficient for one centrifugal machine,or it is passed along a gutter with a screw conveyor. Fromthe latter each machine draws its charge.

Centrifugal Treatment of the First Massecuite.—Assoon as the drum of the centrifugal is set in motion, andwhile it is getting up speed, the massecuite is run in. The*whole mass as it falls is gradually thrown against the wallof the basket and rises to form a uniform layer. The sugarcrystals are retained, while as the speed increase's the liquidsyrup passes off through the holes or slits in the metalliccloth of the basket and strikes against the wall of the outercasing, from which it trickles down to the gutter, and is runoff as first product drainings. The centrifugal is run aslong as syrup comes away, but it is not possible to remove thewhole of the syrup in this way, a thin, strongly adherentlayer remaining on the crystals. This may amount to somelo per cent., dependent on the character of the grain. Theraw sugar obtained has a net rendement of 88 to <)2 per cent.When sugar is required for direct consumption it: is necessaryto remove the greater part of the remaining adherent: syrupwhich gives to beetroot sugar its unpleasant taste. This ispossible when juice of a high degree of purity has been workedand when the defecation has been carefully carried out.After the first drainings syrup has been removed as*far aspossible in the centrifugal, the sugar is washed with water,steam or with a saturated solution of pure sugar, which areintroduced while the drum of the centrifugal is still in motion.The washing removes most of the remaining syrup and yieldsa white sugar, but it cannot be regarded as a relined sugarwhich must have undergone solution and purification. Thesyrup from this operation is, of course, richer than the green,mother syrup first spun off, and is returned to be boiled wi ththe thick juice.

T2o -

Crystallization in Motion of the Second Massecuite. -The green syrup runnings from t i n - raw sugar were formerlyboiled to string proof and the concentrated syrup left at restin shallow iron tanks holding several tons each. A f t e rremaining for some days the whole became a mass of l inecrystals and syrup, or a deposit of fair-sued crystals w i t ha layer of svrnp above. The fold mass was dug ou t , passedthrough a pug mill to make it un i fo rm and mobile, anddried in the centrifugal The syrup drainings were t rea tedin a similar manner to give a third-product, sugar andmolasses, but required a few months for crystalli/.ation to I n -complete, and the tank rooms had to be kept warm dur ingall this period to render the rate of cooling slow. Tlu* t h i r d -product sugar was f requent ly so dark and sticky as to beunsaleable, and had to I K - re-melted and worked w i t h theraw juice. More recently the cen t r i fuga l syrups f r o n t thefirst product are boiled to grain and the masseeuite i n t r o -duced into crystalli/ers and kept in motion as alreadymentioned under first-product t r ea tmen t . (Kv ing to theaccumulation of non-sugars in the syrup the grain is moredillicult to form in this ease and slow in appealing, but it isalways possible tograin the syrups unless they an- too impure.A f t e r grain is formed it is buil t up gradual ly i n t o crystalsduring a boiling lasting; i<S to 'j.| hours, when the pan is t h e nful l . It is an advantage if the pan is provided w i t h s t i n inggear, the rotat ing, arms of which an* arranged above andbelow tin* ealandria. The massceuite is then let down in tothe crystallixer and kept st irred for .j or 5; days, while thetemperature is allowed to fal l f rom <)o" to about . } < > " C.Syrup or water is added from t ime to t ime as may be requiredto keep the mother syrup from becoming too highly super-saturated, lest; false grain should be formed. At the end ofthis time the mass may be eentrifugali/ .ed direct. Thesyrup runnings const i tute molasses. Ano the r and earl iermethod of maintaining the proper degree of super-saturationwas to raise the temperature a few degrees as soon as t h a t ,of the masseeuite had fallen about io", and to repeatthe warming for each similar fall, by passing steam or hot

BEET SUGAR 121

water through the jacket of the crystallizcr. Crystalliza-tion in motion not only gives sugars of bettor quality andhigher yield than were obtained by the older method, butthe second product is obtained within a few days after theend of the campaign instead of the months required bycrystallization in tanks and the expense of keeping the roomswarm all this time.

Molasses.—Factory beetroot molasses has an unpleasantsaline taste and disagreeable odour, and for this reason isunfit for human consumption, and the attempts made toconvert it into a table syrup have not met with success.Molasses represents the last syrup runnings of the sugarmanufacture from which no further crystallization of sugarcan be effected, although it still contains about 50 per cent,of sucrose. The unerystallizability of this large amount ofsugar is partly accounted for by the excessive viscosity of theconcentrated syrup, but; mainly by the mutual solubility ofthe sugar and non-sugar. The average composition of beetmolasses is: sugar 50, ash 10, organic matters 20, water 20per cent. Owing to the large1 proportion of ash present,chiefly salts of potash, when used for feeding cattle, it must:be given in strictly limited rations, otherwise, by its laxativeproperties, it is liable to cause scouring, but: within theselimits it proves to be a highly beneficial fodder, shown bythe glossy coat of the animals an, indication of health. Inorder to avoid the inconvenience attending the measuringout and diluting of this viscous material on the farm, molassesis now made up into molasses fodders by absorbing it withpeat, bran, chopped straw, etc., which are in a suitable1

condition for transport and for distribution. I/arge quant i -ties of molasses are also utilized in distilleries for fermenta-tion to alcohol for the production of silent; spirit. Thefermentation processes for the production of acetone describedand patented by Kernbaeh and others led to experimentsin the United States to develop a process for fe rment ingmolasses to produce acetone which yielded largely ethylalcohol as a by-product and smaller quantities of propyland butyl alcohols. By this means the IVniU'nta i ion in

122 CAKHOIIYJWATKS

50 to 60 hours gave a yield of »S to S-;j per cent , of the sugaras acetone and 20 to 21 per cent , of alcohol.

Another interesting development, of the f e r m e n t a t i o n ofmolasses is the production of glycerine, an account of \\hiehis given by Ar thur R. I,ing. Inedible Porto Rico " blackstrap" molasses is fermented by a special yeast at jo ' to'{2" C.f wi th the addition of sodium eaibonate in poit ions upto a total of 5 per cent. When sufficient caibonate ha:; beenadded the evolution of gas ceases, a copious precipitateforms, and. the yeast lies dormant for a xvhilc. The pre-cipitate eventually disappears and fermenta t ion againproceeds. It. is essential for the precipi tate to form and forthe yeast to lie dormant . The alcohol produced eoveis the*cost of the process, so that , the g lvcei ine is obtained fornothing. ()nec\vt. of black strap gives ;;\:j toMbs. ofidycerine.Prom 25 to jo per cent, of sugar in the mash is conveiird i n t oglycerine and J ])er cent, left unfennen ted , The piesenee ofammonium chloride favours product ion of glycer ine. IMVCdays are required for fe rmenta t ion to be completed. InGermany sodium sulphite war* used as alkaline- substance,

Rl-X'OVIvKV ( > K SfOAU FROM Moj.ASSKS

When for fiscal or other reasons, it is not profi table tosend molasses to the distillery for the production of sp i i i i ,it is treated by one or other of the processes for the e x t t a e t i o nof sugar.

Osmose Process. By the process invented by Ih tb run-faut, in iS(>j , the wore readily diffusible salts of molasses areseparated by osmosis th rough parchment paper f rom theless readily diffusible suj.',ar. A series of sheets of parchmentpaper are arranged as in a f i l t e r press, and water andmolasses are passed through alternate chambers of theosmose apparatus. The relative rates of How of water andof molasses are so regulated that the osmose water does notcontain more than I per cent, of sugar, while the p u r i t y ofthe molasses is increased from about 60 to 70 per cent., sothat a crop of sugar may be obtained from it by boiling in the

BEET SUGAR 123

vacuum pan. The osmose water may be used as a fertiliser,but is often sent to the distillery.

Elution Process.—The elution process introduced bySchcibler, in 1865, and subsequently modified by others,consisted in forming tri-culciuni sucrate and washing theprecipitate with 35 per cent, alcohol. The alcohol in the

"sucrate and washings was recovered by distillation. Theloss of sugar was small and the purity of the saturated sucratehigh, but the cost of the outlay and the danger of workingthe large quantities of alcohol required led to the abandon-ment of the process.

Substitution Process.—In this process, due to 8teflon,a very dilute molasses is saturated in the cold with lime toform mono-calcium sucrate, which is soluble in water. Thesolution is heated to boiling, when tri-calcium sucrate pre-cipitates and two-thirds of the sugar is set free in the liquor.The tri-calcium sucrate is llltered off and washed with boilingwater, which does not decompose it. The filtrate is made upto 10'per cent, by the addition of fresh molasses and theprocess repeated on this substituted mother lye, a fractionof the filtrate being put aside at each operation to preventthe excessive accumulation of non-sugars in it. This partis treated with lime, heated and filtered, and the filtrateutilized as fertilizer.

Separation Process.-8tolTenfs separation process hasdisplaced his substitution process. 1C a dilute solution ofthe mono-calcium sucrate is cooled below 15° C. and finelypowdered quicklime added gradually with agitation, thewhole of the sugar present is separated as a precipitate oftri-calcium sucrate. The precipitate is separated in filterpresses and washed with very cold water saturated withlime. The purity of the sucrate is over 96 and is used in thefactory for defecation in place of lime.

Strontia Process.—The use of strontium compounds forthe desugari/ation of molasses was patented in 3849 byDubrunfaut and Leplay, but the process was not thenadopted. Seheibler worked out the conditions under whichthe separation of sugar by strontia is possible and patented

the processes. In the older method crys ta ls of s t i o u t i u mhydroxide, Sr(OII).,, SILO, are added to a hot d i lu t esolution of molasses u n t i l t l u * so lu t ion is sa tu ra ted , and ifis then heated to boiluu1,. The prec ip i ta te of d i - s t rou t iumsuerate is only stable whils t hot ; on cooling, i t decomposeswith separation of sue.ar. I t m u s t , therefore , be f i l t e r e dhot and washed w i t h boilmj; water . The washed suerateis stirred to a erea.ni in cold wa te r and crys ta l s of thehydroxide separate, leaving, a nea i l v pun* solution of sth'.arcontaining onltf a small q u a n t i t y of s t r o n t i u m hydroxide.This is precipitated as carbonate* by passim*, in a stream ofcarbon dioxide. In the newer process the sur (nr is precipi-tated as the mono-stront ium suciate. Tlu* molasses is runinto a hot (75° C.) solution of s t r o n t i u m hydroxide . I f thesolution of mono-s t ron t ium suerate t h u s formed were l e f t1o cool at rest, s t r o n t i u m hydrox ide would e r y s t a l l i / e out ;but if it. is kept stirred and crystal: ' , of the mono suera teadded, the whole* of the sur.ar separates out as a c r y s t a l l i n emeal of mono-s t ront ium suerate . This is separa ted f i o n i thelye by suction f i l te rs , f i l t e r presses, or in eentu l iu ' . a l s , andwashed w i t h cold wa te r . To obtain t h e pnie stu-.ar .solution.from it, the mono-suernte is dissolved in hot \ \ a t e i ; oncooling, most of the s t r o n t i u m h v d i o \ i d < - e rys ta l l i / e s o u t , thesolution can then In* treated w i t h carbon dioxide, f i l t e redand worked up into sui'.ar.

The strontia process is perhaps the most eomplete. butalso t l u * most expensive of the desue.ai i / i i u 1 , pun-esses,About. ^00,000 tons of sui'.ur were recovered by t h i s pnuvssi n Ocrmany i n i < j i . ; i « j i . ) .

The Preliminary Report of the Umpire Siusu Supply(Technical) Commit tee was presented before a Conferenceat the annual meeting of the Society of Chemieal I n d u s t i von July i f ) , U ) i < ) . The Repoi t rjves numerous s t a t i s t i c a ltables of the production and consumption of siu',ar t lnoni ' .h-out the world w i t h | )ar t icular reference to the supply andneeds of the Bri t i sh Umpire. Tlu* su^ar produced w i t h i nthe Umpire is chieily derived f ront the cane, and whi le theconsumption amounts to (>,.550,000 tons, the t o t a l p rodue l ion

BEET SUGAR 125

within it falls short of this by about 2,500,000 tons. It wasa matter of debate how this deficiency could be suppliedso as to make the production of sugar within the Kinpire self-supporting. Many speakers favoured India as the countrywhich could fuliil this want most readily and suitably. Thesubject of the establishment of a beet sugar industry in theUnited Kingdom was also considered. Beets of sugar contentand purity equal to those produced on the continent can begrown here, but there is still much to be learnt about thecultivation, and co-operation between the fanners andmanufacturers will be necessary to ensure the supply ofroots needed for success in working a factory. There islittle fear that growing beets will lessen the acreage underwheat and other cereals, and the residues will form usefulfood for cattle. The world's production of beetroot sugarin 1913 was 8,758,goo tons, or *j6-<j6 per cent, of the totalproduction of cane and beet together. The cane productionat the same time was 9,894,200 tons.

RICl.aCRKNCl.CS.11. Claassen, " Hect. Sugar Manufacture " (ICug. trans.). London and

New York, T O O I > .G. Dejonghe, " Technologic sucricre." Paris. 1007.Ne.wlands, " Sugar." Spon. London and Now York. 10,00,.A. Kinnpler, " Ausi'uhrlichcs llandbueh der ZnckerJabrikation."

J i runs wick. 1907.1C. Vranckcn, " Manuel do la Fabr. du Sucre, do .Botterave." .Brussels.

IO.O.J.L. S. Ware, "Cattle Feeding with Sugar .Hoots, Sugar, Molasses and

Sugar JBcet .Kcsiduum." Philadelphia. i < ) ( > 2 .L. S. Ware, " .Beet Sugar Manufacture and Refining." New York,

11. VV. Wiley, " The Sugar Beet." Washington, i # < ) < ; ..1C. Saillard, " .Betterave et Sucrerie dtt Betterave." Paris. K > I J .] ' )< t Grobert , Labbe, Manoury ot <le Vreese, " Fabrication du Sucre de

JJetteraves < ^ t de C'aunes." J. Fritsch. Paris. JOJ.3-G. Marlineau, C..B., " Sugar, Cano and .Beet, An Object Lesson." Sir

Isaac Pitman & Sons. London.The International Su^ar Journal (originally I ho S-ittfar Cane}. Lou<lon.

La Sucrerie Jndigfoic ct Coluniale. J.Viris.Zcits. dcs Vcrcins dc.r De-ulscht'-n Zuc-ke-rinduxlric. J iorliu. i M f i i .Sugar (ICnglish and Sj)auish ICdiliou). ('hicago.Journal of the* Society of Chemical Industry. London.Journal oj Industrial and EnKiniwrinft Chemistyy. Now York." llorn< i-gro\vn Sugar" (British Sugar Beet Growers' Society). N J K J .

/nn> '/"// '.4th>/ f r ' i ' » t { o > j y I A I { ) - , { pur . n i « > ) - > >y j » > U O I ) . > I I J M H < j , > i | j ,io| ! . ' ; ; . > . > < >t i < » t |v pi n u i . ) , { y ,, ' U V ' , H < > { \ ; \ j ' \ j pur '.nj'.y 'H "I f < I < > t i | J . n » . \ ! ' I I 'I '

' l ' - 1 . i ' f » t o i ' / ' » / / '/«,'// ) • ' • •* ; *.<«!»/ ' ,/ '•'"> » < u t | p! ,>iVlojoj . i . ) ) .n» > j v p}Tt - , [ ptn* .mo).>.»\ .- p) u o i j mpoi . j >t 'ui:unp!.xls 'H " I I

M/;; ," ' < > i ' ' i "/'"/ 'm.'tf) '.;c)v; *.w/',,'.n!,\\ - >v tm. i*) HI • > • . » > > n j * ) t tni |T)ti.mt.i.» t .i p > .nuj .n 'putr^ ., ' i l u r j ' > j 'V

•>p>Vr. Vnor *7; 'VM.'/ ' , , ' '• »!-'-Vp>l^ I I I O J } . ) U U . > > A p ) J ' ) TIOT J lUpO.IJ ,, ".fui'l '\\ *V

• \ j f , 7 . r ' ( > ! < ) i ";;; V// | i»/ ,/' >' f.Vin{^ UJ01J . M l ! I . » ) A p ) JO UOt J . ) t l j »>1 ( J M ' i l U f ' f '>J 'V

SUCTION 111.—SUGAR REFINING

SUGAR refining is restricted to the preparation from rawsugar of a clean, generally white sugar lit for consumption informs required to suit the convenience and taste of theconsumers. The more usual forms are loaf-sugar, cubes,crystals, granulated, and moist sugars of line grain as whiteand yellow pieces.

The residual molasses is either made into treacle or othertable syrup as golden syrup, or sold to the distillery or usedfor making molasses fodder.

Raw Sugars,—Raw beet sugars are unsuitable for directconsumption owing to their nauseous taste, due to thepresence of salts and organic non-sugars. Raw cane sugars,although often very impure, have a pleasant aromatic taste.They frequently contain numbers of living and dead acari(the sugar-itch "insect") as well as crowds of bacteria,moulds and yeasts and vegetable debris, and need to berefined to obtain a wholesome product.

The whole of the sugar present in raw sugars is notrecoverable as such in the ordinary process of refining, thesalts and organic matters rendering a portion of the sugaruncrystallizable, so that this remains in a final syrup product,refinery molasses.

The raw sugars are valued on the net rendemeiit, livetimes the ash (salts) being subtracted from the polarizationon th<d assumption that so much sugar is rendered un-crystallizable thereby. A deduction is also made forreducing sugars present. The price of raw beet sugars islixed on a basis of 88 per cent, net, with a valuation for

128 r , | / \ ' / > V ) / / V / > A M 1'1'S

variations above ami below th is . Second q u a l i t y beelsugars are classed as 75 per eent , ne t .

Affination. Rawsugars were formerly melted direct , andpreference was given to sugars of good gra in and oi a clear,pale colour. The l iquor t hen con ta ined all the mm-sngar ofthe raw. It is now usual to wash the l a w sugars wherebythe greater part of the molasses adherim1 , to t i n - c i y s t a l s isremoved and t h e * non-sugais conta ined in i t also pass oil i n tothis affi l iat ion syrup. The str ' .ar is mixed to a mash w i t hhot. syrup from a previous opera t ion , and t he mass is spuniu the* centr i fugal machine . The washed sngai is mel ted ,while the. syrup is l)oiled to o b t a i n a crop < > i sugar andmolasses. Raw beet sugars of good sharp gra in an- sonic-tinies subjected to a systematic washing in t a n k s b\ a sciiesof syrups of graduated p u i i t y so as to o b t a i n l i n u l h a moreor less w h i t e sugar. This process, due to SteiYci i , a l thoughknown previously, is used abroad. S o f t - D r a i n e d , sn ieu iysugars unsuitable for washing in t h i s \ \ a \ a i e , accoulin;1, toIv;inj;vn, ]ieaUkd in a vacuum pan to melt t h e l ine i M a i n a i u lthe mass then subjected to ci \ s t a l l i / . a t i on in mot ion in aHock apparatus, a f t e r which the su;,',ar is in a condi t ion toithe Steffen washing' process.

Melting, The washed siu-.ar horn the c e n t i i l ' t u « , a l . s isdissolved or melted in a pan (b low~np) ]uov ided w i t hstirring" gear and heated by steam to « j o ' C. u n t i l the l i ( ( i t o rattains a cl(*nsity of 5;')" Oo" H r i x .

WluMi raw unwashed sugars were melted deiec . in ts wereoften employed at th is stage to aid in the Sepaiation of thecolouring matters and other impur i t ies , ami especially tofaci l i tate filtration, and w i t h washed sugars a l i t t l e milk oflime is f requent ly added to secure a f a i n t a l k a l i n i t y of theliquor so that there may be no danger of inversion of sugarduring subsequent operations. Cane sugars are much moredtllicult to filter than beet, and the addition of porous andgranular substances such as diatomite greatly assistsfiltration.

Filtration,-- When the l iquor leaves the blow-up it runsover a strainer of perforated metal or wire to remove e

SUGAR REFINING 129

coarser suspended impurities, and is then either pumpeddirect to filter presses or to a tank from which it flows at afew feet head of pressure through one of the various forms ofpocket or bag filters, or in some cases through a sand filter.It is essential that a clear, brigl.it liquor is obtained for passingto the char cisterns to be decolorized.

Filtration through Animal Charcoal.—The char cisternsare cast- or wrought-iron cylinders 5 to 10 feet in diameterand 15 to 20 feet in height. The bottom is slightly conicaland has a perforated wooden false bottom covered with asheet called the blanket to prevent the grains of char passingthrough with the liquor. The cisterns each hold 10 to 40 tonsof char. The liquor which has passed through the columnof char of suitable grist issues practically colourless at first,but gradually becomes more coloured after running sometime. The char absorbs a certain small amount of inorganicand organic non-sugars, but the decolorization is of mostimportance. Decolonisation by char is evidently a surfaceaction, and not chemical, for the absorbed colour can beremoved from the char by treatment with alkali. Thedecolonisation is greater when the solutions are kept slightlyacid, but there is always the danger of inversion of stigar ifthe liquor is allowed to become acid. The more solid anddense bones give the best char, which has a closeness andlasting quality, and does not easily wear to dust by thecontinual handling to which it is subjected. The cartilageof bones is rich in nitrogen, and permeating the wholestructure there is nitrogen throughout the char, and thehigh decolorizing power is often attributed to the nitrogenpresent, so that attempts to manufacture artificial charshave been frequently made by soaking porous materialswith gelatine or glue before carbonizing. Good char is of adee]>, dull black colour and is highly porous. When dryit contains 78 per cent, of calcium phosphate, ro of calciumcarbonate, 8 to 10 of carbon, and small quantities of solublesalts as well as calcium sulphate and sulphide, magnesiumphosphate and silica. It is hygroscopic, and is usually soldon a basis of 8 per cent, of moisture'. When the char no

130 CARBOHYDRA TES

longer decolorizes sufficiently it is washed with hot water,drained, and removed to be passed through a series of pipesheated to incipient redness in a kiln. It is then said to berevivified. Char may be revivified a great many timesbefore its decolorizing power deteriorates so far that it isconsidered to be useless. During the reburning absorbedorganic matters are carbonized, and the carbon thus pro-duced, which has little or no decolorizing power, in course oftime blocks up the pores. Weinrich has introduced a methodof burning off this added, useless carbon by passing thechar through an open rotating cylinder heated to a tempera-ture sufficient to burn off the added carbon without attackingthe original carbon of the char. The decoloring power ofthe char is considerably improved by this treatment.Bussy found that when char or char carbon was ignited withpotassium carbonate and the salt washed away, the de-colorizing power was increased about ten times. Recently anumber of vegetable decolorizing carbons have been pro-duced by heating sawdust or other cellulose material withlime, or with calcium, magnesium, or zinc chloride, anddissolving away the lime or salts. These have a muchgreater decolorizing power than char or char carbon, butowing to their high price, and the difficulty of manipulation ascompared with the way in which char is worked, have notyet become established in practice.

Boiling to Grain.—The decolorized fine liquor collectedfrom the char cisterns is boiled in the vacuum pan, much ashas been described under the boiling of raw sugars, onlythat the greatest care and attention is directed to secure agrain of uniform size without the presence of small grainor masses of coherent grains called rolled grain. When alarger-sized crystal is desired, part of the contents of a panis dropped and boiling resumed until the crystals presenthave attained the desired size. When the whole contentsof the pan is discharged into a heater it is kept stirred whileportions are drawn off to separate the sugar from the mothersyrup in the centrifugal machine.

Drying the Massecuite,—The magma of crystals and

SUGAR REFINING 131

syrup is spun in the centrifugal machine, and as soon as thebulk of the syrup has run off, water is sprayed on the sugarin the machine, a small quantity of ultramarine or othersuitable blue being added to the water to correct any slighttinge of yellow in the sugar. The syrup formed by this waterby dissolving a little of the sugar is often collected separately.The sugar is removed while still warm, and has a moisturecontent of I per cent, or less. It is then passed over sievesto remove any unavoidable lumps which arc sometimesformed through sugar adhering to the steam coils.

Granulated Sugar.—For granulated sugar the sievedsugar is passed through a slightly inclined revolving cylinderheated by an inner cylinder through which steam passes,and provided with blades at its inner periphery which liftthe sugar and allow it to fall over the heated drum so that itleaves the granulator with a moisture content of 0-05 percent, or less, after which, when cooled, it is weighed intobags.

Cube Sugar.—The old-fashioned loaf sugar has now beenalmost entirely displaced by the production of cube sugar.The massecuite is filled into moulds consisting of a series ofmetal plates separated by a distance equal to a side of thecube to be produced. As soon as the mass has set a numberof these moulds arc arranged inside the centrifugal machineand held in place by blocks of triangular section, and thewhole is then spun together. As soon as the mother syruphas run off, a quantity of a pure syrup—do arc—is pouredin to displace the last portion of mother syrup. The mouldsare then removed and the plates or slabs of sugar are placediu a hot room to dry and harden, the syrup left between thecrystals solidifying and cementing the crystalline grainsfirmly together. The dried slabs are then placed on a cutting-machine, when a scries of cuts arc made which crack or cutthe plates into the form of cubes which roll over a screento allow any small broken pieces to fall through.

The syrups from the boiling of granulated cubes andcrystals are boiled again to give other crops of sugar, untilfinally the syrup remains which constitutes refinery molasses

132 CARBOHYDRATES

and may be made either into a low quality table syrup ortreacle.

Preparation of Invert Sugar and Saccharum,—Anyof the intermediate syrups from the sugar may be takenaccording to quality for the preparation of invert sugar.For this purpose the diluted syrup is heated in a wooden orlead-lined tank with a quantity of dilute sulphuric acid untilsamples withdrawn show by the polariscope test that thesugar is completely inverted. The syrup is then run outinto the neutralizing tank and made neutral by the additionof powdered chalk. The syrup is then pumped through afilter press to remove the sulphate of lime, and the clearliquor passed through char to improve the colour, after whichit is concentrated in the vacuum pan to the required density.If the resulting syrup when cooled is stirred it forms a honey-like paste, and when filled into pails will gradually set to afirm mass of saccharum. The operation is aided by additionof a portion of solid saccharum from a previous operation.

Table Syrups,—An intermediate syrup is added to aportion of invert syrup, or, in the case of low cane sugars, evenwithout any addition of invert is carefully filtered anddecolorized by passing through char and then concentratedto the required density in the vacuum pan. It is necessarythat the proportions of cane sugar and invert be properlyadjusted that the syrup may remain bright and clear, andnot grain out.

Refinery Molasses,—The lowest syrups from the boilingof washed sugar is more correctly a comestible treacle. Theaffination syrup, after yielding one or more crops of sugar,forms a true molasses, and is sent either to the distillery orto be made into cattle food.

REFERENCES.Lewis S. Ware, " Beet Sugar Manufacture and Refining." New York.

1907.Newlands, " Sugar." London. 1909.W. Gredinger, "Die Raffination des Zuckers/' Wien and Leipzig. 1909.Claassen and Bartz, " Die Zuckerfabrikation und die Raffination des

Zuckers." Leipzig and Berlin. 1905.

SUGAR REFINING 133

G. Martineau, C.B., " Sugar, Cane and Beet. An Object Lesson."London.

F. A. Buhler and J. J. Eastick, " Filters and Filter Presses." London.1904.

" Animal Charcoal," Thorpe's " Dictionary of Applied Chemistry."M. A. Schneller, " Vegetable Decolorizing Carbons." Int. Sugar Jour.,

1918, 191.International Sugar Journal.Journal of the Society of Chemical Industry.

SKCTJON IV.- - M I N O R SOUUdUS OK SIKJA.K

Sorghum Sugar and Syrup. The value of Sorghum cane,Antlrv/wtftni, as a sourer of sugar lias Ions'. been recognized iuAfrica and China, and at tent ion having been directed to thisplant, the United States Department of Agr icu l tu re cult i-vated about thirty varieties of sorghum \v i l h a view to theprofitable extraction of sugar the re f rom. ( M' these the KarlyAmber was the variety mostly in favour u i t h planters inMinnesota and the north-west. It derives its name from itsearly ripening and the bright umber eolonr of the syrupmade from it. It is very rieh in saccharine m a t t e r , the juicecontaining i . ( ' f > per cent, of sucrose, other varieties arethe Honduras, Whi te Siberian and Chinese or Sumach cane.Although State aid in the shape of boun ty was granted tofavour the industry the use of sorghum as an economicalsource4 for the production of cane sugar had to be given upbecause the invert sugar, starch, and gums present in thejuice prevented crystallisation of the sucrose. On the otherluuid, the concentrated juice forms a useful syrup, and theseed of the cane a food for pigs and cattle of feeding valueequal to Indian corn. The juice expressed from the cane bymills, horse-power, or steam, is defecated with a little lime,and after clarifying is evaporated to the required density.One hundred gallons of juice should be obtained from i tonof stripped cane. This, when concentrated to 38° to42° Baume, produced a syrup of good keeping quality,wholesome, highly nutritious, and palatable to those whohave become accustomed to its peculiar sorghum flavour.It forms a staple dietary food in the northern and centralportion of the States. The estimated production in theUnited States was 17 million gallons in lyoo, with a yearly

MINOR SOURCES OP SUGAR 135

increase of about 15,000 gallons at 19 cents per gallon.An analysis of a syrup showed 367 per cent, sucrose,26-6 per cent, reducing sugars, 4 per cent, ash, and totalsolids, 76 per cent.

In a recent report to the Academy of Agriculture, Paris,Andre Piedalia, a French chemist, drew attention to themarvellous utility of the sorghum grass, which is capable ofsupplying sugar, fodder, paper, flour, and dyes for textiles.The plant is indigenous to equatorial Africa, and was carriedthence to Kgypt, India, and China. In the fifteenth centuryit was growing in Italy, in Genoese and Venetian territory.In 1850 it was recommended to agriculturists in France,but did not arouse sufficient interest. In suitable climates itgives a good yield of sugar, in China 0*7 ton per acre. Thefibres yield 2 tons of paper pulp per acre, and furnish apaper of dazzling whiteness. The leaves serve admirablyfor fodder and the roots for the production of alcohol; theseeds supply starch, nitrates, and fatty matter constitutinga flour of good taste easily mixed with bread stuffs, and areenveloped in gluten from which colouring matters may beprepared.

Maple Sugar and Syrup.—Maple sugar is manufacturedfrom the sap of the Acer saccharinum or sugar maple. Whenthe sap begins to flow at the end of winter, before the buds ofnew leaves have developed far, the trees are tapped 3 or4 feet from the ground with a half-inch auger, the hole madeis about an inch deep, and a perforated plug is inserted tocollect the sap in a light tin can. Two or three holes ornotches are made in each tree, and fresh places made thefollowing year. The trees are not tapped until 25 yearsold, but can then go on yielding sap for several yeq.rs withoutharm. The average yield is 10 to 25 gallons each seasonof 4 to 6 weeks ; I Ib. of sugar is obtained from 4-5 to 5 gallonsof sap. The sap is extremely bright and clear and needslittle or no clarifying. It is generally evaporated in ironboilers 6 by 2-5 feet, and 6 inches deep, but copper pans arebetter. It is usually strained during evaporation, and alittle lime added to correct acidity, and milk or white of egg

136 CARBOHYDRA TES

added to clear it. After straining and skimming the con-centrated syrup is poured into moulds to crystallize oncooling. The skimmings formed during concentration aredue to coagulation of the albuminoids present in the sap.Often a deposit of calcium malate and silica is formed on thebottom of the pan. Genuine maple sugar products aredistinguished from cane products by the large amount ofprecipitate formed on adding lead acetate, due chiefly to themalic acid present. Both the sugar and syrup have a mostattractive characteristic flavour and honey-like odour. Itis stated that a docoction of hickory bark will communicatethis flavour to cane syrup and sugar, but there are strictregulations against admixture with cane sugar. The massof concrete sugar from the moulds is never refined, as thiswould remove the flavour and odour which give the chiefvalue to this product. The syrup is evaporated to a watercontent of 25 to 30 per cent., and usually contains 63 to 64 ofsucrose, 1*5 of reducing sugars, 0*5 of ash, and 4 per cent, oforganic matters. The output of maple syrup in the UnitedStates in 1900 was about 2 million gallons. lyittle is madeexcept in the New England States of Vermont, New York,Ohio, and Indiana. In Canada it is made chiefly in Quebec,Ontario, New Brunswick, and Nova Scotia; the amount in1901 was 17,804,825 Ibs. of a value of 1,780,482 dollars.Canada produces three-sevenths of the world's consumptionof maple sugar, but is capable of producing 5 or 6 times thisquantity. The Canada Food Board, in conference with theleaders in the maple sugar industry, recently made effortsto increase the production of both syrup and sugar. Thetotal exports of maple sugar increased from 2,800,000 Ibs.in 1917 to 3,550,000 Ibs. in 1918.

Palm Sugar,—Many kinds of palm yield a saccharinejuice which is utilized in the East for the production ofcrude sugar. The date palm (Phoenix Sylvestris), thepalmyra (Borassus flabelliformis), the coconut (Cocos nuci-fera), the gomuti palm (Arenga saccharifera), the nipa (Nipafrutioans) and the kittool (Caryota urens). Out of 3,000,000tons of crude sugar of India's annual output it is estimated

MINOR SOURCES OF SUGAR 137

that 10 per cent, is derived from palms and about 4 per cent,from the date palm cultivated for the purpose in Bengal.Palm sugar is made by an incision in the soft upper part ofthe stem and collecting the juice in earthenware pots. Itis then concentrated so that it sets on cooling to form guror jaggery, a dark-brown sugar in considerable demand inIndia. Gur is sometimes treated in native refineries bycovering it with a layer 4 or 5 inches thick of the water weedVattisneria spiralis. The molasses drains through the basketto a pot below. Fuel for concentrating the juice is a diffi-culty. The pots are smoked inside to prevent fermentation,but lime-washing would be better. Although the juice iswater white as it exudes, it darkens rapidly on boiling; tolessen this, lime juice is added. The natives obtain 31 percent., but centrifugal machines would yield 59 per cent.The chance of establishing small central factories is nullifiedby the cultivators refusing to sell at a reasonable price.2'3 tons of gur can be obtained from an acre of palms, and thiscan be increased.

REFERENCES.Newlands, " Sugar." Spon. London and New York. 1909.A. Rumplcr, " Zuckcrfabrikation." Braunschweig. 1906.H. E. Annctt, " Date Palm." Memoirs of Dept. of Agric., India. 1919.

SECTION V.—CARAMEL

WHEN* sucrose is heated above its point of fusion it becomescoloured and ends by becoming transformed into a brownmass, caramel. Glucose also yields a like product. Caramelis evidently a carbohydrate of high molecular weight and acondensation product of sucrose or glucose. From cryoscopicdeterminations and analysis of its barium compound itsformula has been given as Ci25H188O80.

Properties.—Caramel is found in commerce as a concen-trated solution or in solid masses or in powder as coffeeessence. The solid forms an amorphous, reddish brown,brittle mass which is porous and highly deliquescent. It iscompletely soluble in water and partly soluble in alcohol.It has a bitter taste due to the presence of assamar, and isnot fermented by yeast. Its melting-point is about 135° C.It reduces the salts of the heavy metals and is precipitatedfrom aqueous solutions by baryta and by neutral leadacetate, as well as by paraldehyde in alcoholic solution.

Manufacture.—Caramel was originally made by heatingcane sugar, and that used for colouring spirits is still generallyproduced in this way. The sugar is heated in an open metalpan over a gas fire with constant stirring, till the whole massmelts, turns brown, and then suddenly froths up, when theheating must be stopped at once. If heated too far it isinclined to char. Water is cautiously added, and whendiluted to the right point the caramal is filtered through wiregauze to remove the carbon and insoluble products. Glucosehas now in great measure replaced cane sugar in the manu-facture, but unless the glucose is comparatively free fromdextrin the product is not so readily soluble in spirit.Potassium or sodium hydroxide or carbonate is heated with

CARAMEL 139

glucose over a fire until irritating vapours commence toappear, the heat is then moderated and the mass stirredcontinuously until samples show the required tint, whenwater is immediately added to stop the further change.Ammonia or ammonium carbonate is also used.

Uses,—The use of caramel for colouring beer is of com-paratively recent application, due to the replacement of partof the malt by sugar or raw grain or less highly kilned malts..The colour is more easily adjusted with caramel to a constantstandard. Caramel is also used to colour spirits, liqueurs,vinegar, gravies, and as a coffee surrogate when mixed withsuitable aromatics and fillings.

REFERENCES.

Article " Caramel." Thorpe's " Dictionary of Applied Chemistry."L. Briant, " Caramel." Jour. Inst. Brewing, 1912, 673.Maqucnnc, " Les Sucrcs ct Principaux Deriv6s." Paris. 1900 GCo

P.\ICT I I I . -ALCOHOLIC K

B K K R

1'uurr juices on keepim; leadi lv undergo a changewhich the liquid seethes or f e rment s and acquires a palatableflavour and an exh i la ra t ing ' , physiological p j o p e i t y \ \ i t h lossof sweetness, and th i s process doubtless led !<> the l irst useof fermented beverages. Saeehaiine juicer. f l ow other partsof ] > l a n t s or honey would in eoiuse of t i m e also be uti l imlin a similar manner, ( . eun tna t in ; , 1 , seeds ot eeteals beeomesweet from the eouveisiou < > f s t a i eh in to sur.ar, and Iheextract therefrom would al;.o f t u n i . ' . l i n i a tn ia l for a like use ;iu fact, there is evidi ' iuv t h a t mal ted ejain was u:-.ed in pve-historic times even in t i n - Stone Ai-.e, \\1ien- .saeeharinejuices from plants were not available the milk of animals wasfermented to produce Koumiss bv the T a i t a i . % and Kephirin the Caucasus, In the wann pa i t s of southein Ivuiope thejuice expressed from j;iaprs is fennented to juoduee wine ,in the colder northern part : ; apples are euished and thefermented juice j;5\vs cidei, but. the bulk of fermentedbeverage in these parts is made from malted bailey to produce*beer.

Barley. Although the seeds of vai iuus ceieals haveb(keu used at times for m a l t i n g , eentui ies of expeiienee ha\*eshown that bailey is the most suitable j'.ruin tor the pro-duction of };ood IHVI\ owine, to the q u a n t i t y of starch itcontains, the act ivi ty of the diastase fonned when malted,and the strong husk which allow the w o r t s to be readilydrained. Malts from wheat and oats are still made to someextent, have special qualities, and are j'.enerally used onlywith a large proportion of baric-}- malt.

ALCOHOLIC FERMENTATION—BEER 141

When each of the flower-bearing spikelets which growalternately on each side of the ear are fertile six-rowedbarley is the result, but most of the malting barley grown inthis country is the narrow-eared two-rowed barley, Hordeumdistichum, the two principal varieties of which are known asthe Chevallier and the Goldthorpe. Long experience isrequired to decide from samples which barley is mostsuitable for malting purposes. The grains chosen should beof large and uniform size, plump, of pale colour and of sweetsmell without the objectionable odour due to mouldiness.The number of cracked and broken grains should be few, andthe barley should not feel cold and damp to the hand, butshould flow easily through the fingers. When a grain isbitten through it should appear white and floury, not glassyor steely. The vitality of the grains is improved on storingfor a time due to gradual drying, and the skin is then some-what crinkled. The vegetative energy is tested by findingthe percentage of grains which germinate when kept forthree days or longer in a moist chamber.

Malting.—The operation of malting consists in allowingthe grains of barley, which have been reduced to uniformsize by screening or sifting, to undergo a restricted germina-tion whereby the insoluble starch of the grain is convertedinto soluble fermentable sugar and then checking furthergermination by the application of heat. The sifted barley isrun gradually and stirred into the requisite quantity of waternot below 50° F. and steeped for fifty hours or longer until asufficient amount of water has been taken up, and the wholecontents of the grain are wetted without being sodden. Thewater is drained to waste and the steeping may be repeated.The action is not merely mechanical, for dust, bacteria andthe spores of moulds are washed away and a certain amountof organic matter and soluble salts are also removed. Thesteeped and drained grains are then run out into a couch orframe and left for a day. One side of the frame is thenremoved and the grains spread over the floor so as to covera greater or less area according to the weather to keep thetemperature not over 60° F. and avoid the accumulation of

r,|2 CARHOllYDKATKS

carbonic acid given off by respiration. The M floor " isturned twice* daily w i t h broad f l a t shovels, and the operationrepeated during live to eight days or more. The grain soonbegins to sprout or " chit ," forming a whi t e protrusion ofseveral curly whi te ' bushy rootlets, and the 1)1111111111', or" acrospire," is visible as a swelling beneath the skin, I Hiringthis ])criod it is f requent ly necessary to sprinkle f h < * grainwith water lo main ta in the requisite* degree of moisture.As soon as the plumule has grown about three-quarters ofthe length of the grain f u r t h e r g rowth is stopped by d iv ingthe grain, or withering, when it is lea t ly to be diied on thekiln. At this stage* t l ie corns .should be crumbly and notpasty and the rootlets dry and shrivelled. In pneumat icmalting the grains are not spread on the f loor , but rotated indrums supplied w i t h moistened air. Con.Mderable floorspace is saved by this method.

The malt is dried on the kiln for three* or four days, amoderate heat only being applied u n t i l t i n * mal t is drv. \\\dry int.'; on the ki ln the malt acquires a pleasant empyreuniatieflavour. The floor of the kiln is of tiles or woven wire, andthe source of heat is the combustion gases i'lom an thrac i t e*coal or coke, which should be low in sulphur and arsenic.Pule malt:, intended for pale and stock ales, is cured at a louertemperature than high-dried malt", which is suited for theproduction of beers oi' a sweeter character and fuller na ture ,tlu i so-called quick-running ales, for which the tempera tureis raised to ;>jo" P. On the continent malt is kilned by hotair alone, the products of combustion not being allowed tocome into contact w i t h the material.

Diastase. The larger portion of a grain of badev isformed by the endosperm in which the starch which consti-tutes the reserve food material for the voting plant is storedup ; the smaller part at the end of the ^rain is the embryo,and separating these* is a cellular layer, the seutellum, fromwhich under the influence of the living e<mbiyo du r inggermination, un enzyme, diastase, is secreted which convertsthe starch of the endosperm into soluble sugar capable ofbeing absorbed and utilized in the* growth. The starch,

ALCOHOLIC FERMENTATION—BEER 143

however, is enclosed as granules in the cells of the endosperm,and the diastase as a proteid cannot pass through the wallsof the cells; another enzyme, cytase, is secreted which dis-solves or changes the cell walls so that they become perme-able, and the starch is thus exposed to the action of thediastase. The endosperm is surrounded by a layer of cells,the aleurone layer, containing proteins, which also con-tributes to this action. Moreover, there are other enzymeswhich convert the protein contents of the cells into diffusibleand soluble substances to help in the nutrition of the growingplant and supply material at a later stage for the nutritionof yeast during fermentation. These various zymases arecatalysts of an albumenoid nature, and minimal quantitiesserve for converting comparatively large quantities of thespecial substances on which they act. They are only secretedby the living plant; dead corns produce no diastase. Theyare all sensitive to the destructive action of heat, but notequally so; but are able to withstand higher temperatureswhen dry. Diastase is contained in air-dried malt, less inkiln-dried, but even this contains more than sufficient toconvert all the starch of the grain. Cytase is also presentin air-dried green malt, but not in kiln-dried, since it isdestroyed at 60° C., at which temperature the activity, ofdiastase remains.

Supplementary Materials.—Other materials containingstarch used along with malt are maize, oats and rice. Themaize and rice are usually torrefied, or more or less gelatinizedand crushed between rollers to form flakes, and in thismaterial there is over 75 per cent, of starch with only smallquantities of soluble nitrogenous products. Cane sugar,invert sugar and glucose also supply fermentable materialwithout unduly increasing the nitrogenous constituents.Highly coloured malts are made by kilning the malted barleyat a high temperature or roasting barley or malt as coffeeis roasted. These brown or black malts are used for stoutand porter. Caramel is also often used.

Preparation of Grist.—The malt from the kiln is groundor, rather, crushed by passing between a pair of steel rollers

r.|4 CARKOIIYDRATKS

so as to form 1lie jurist. The disintegration of the husk isavoided, as far as possible so that Hie soluble mat ters may bereadily drained off after mashing, while the i n t e r io r of thegrain is set free so that the stareh may be readily aeted uponby the diastase when water is added in the mash tun .

The methods of grinding t h e malt, between stones, or ofcutting and tearing it w i t h si eel c u t t i n g mil ls in t h e way I hat.coffee is ground, do not yield, so sa t is factory a product .Malt, when linely ground, is liable to set dur ing mashing andform a mucilaginous magma f rom which much of t h e l iquorcannot, be removed except, by prolonged, washing;, t h u srendering the wort d i lu te , and therefore more liable to sufferfrom acetification. When t he grain is to rn or sliced, water wi l lnot penetrate thoroughly during the t ime usual in washing,and some of the material is unacted on and wasted. It isonly by the use4 of rollers tha t the malt can be properlyprepared, so that the crushed material allows of the mashbeing easily racked off , leaving but l i t t l e extract in thegrains. The grist, mill usually consists of two smooth steelor, better, iron rollers, one of double the diameter of the other,the larger one driven, and the smaller roll revolving by thefrict ion of the malt passing between the two. The distanceapart of the rolls is adjusted by a screw to suit the si/,e ofthe malt, being crushed. The grist formed is raised by anelevator consisting of an endless belt provided w i t h buckets,termed a " Jacob's ladder," and delivered to the grist hopperready for mushing.

SUCTION 1L—MASHING

THIS crushed malt or grist and " liquor/' as water is termedin the brewery, are mixed either in the mash tun or in apreliminary mash mixer. The water is previously'heatedso as to get the necessary temperature limits for the changeswhich occur. The mash tun is a cylindrical covered vessel,provided with a perforated false bottom and with revolvingrakes, and a vSeries of pipes for drawing off the clear wort.There is also a sparger, consisting of a pipe perforatedthroughout half its length on one side, and along the otherhalf on its other side ; this pipe is made to revolve so thatwhen water is supplied to it the whole surface of the " goods "are thoroughly wetted. I/iyuor at a high temperature is runin and allowed to remain until the vessel is sufficientlywarmed, when the water is run off. The grist and waterare then run in, the proportions being so regulated that themash will possess the proper consistency, the rakes mean-while being kept in motion until the whole is thoroughlymixed. The contents are then left at rest for about twohours until tests show that all the starch has been converted,when the clear, bright wort is drawn off into the under-backor copper. While the wort is running off sparging is con-tinued so as to avoid any tendency to set and obstruct freedrainage. This will form a second mash. After this is runoff the material should be sufficiently exhausted, and isremoved as brewers' grains to be sold to farmers for fatteningcattle.

Nature of the Changes during Mashing.—During themashing process the starch of the grist is acted upon by thediastase and the starch molecule broken down (page 6) intomaltose, dextrin and intermediate malto-dextrins, one of the

• I0

146 CA RBOH YDRA TES

latter being practically unfermentable and henee termedstable dextrin. The relative' proportions of the malto-dcxtrins which contain relatively lew anvyl in Croups and alarge number of maltose groups, and therefore more1 readi lyfermentable, and those in which the reverse is t h e - case isdetermined by the temperature at: which the malt, has beenkilned and mashed, and on this wil l also depend the class ofbeer produced therefrom, the i lavonr and character of thebeer being due as much to these extract ives as to the alcoholpresent. A pale ale, free from excessive sweetness, must,contain more of the less readily fermentable bodies in orderto provide for cask fermentat ion and the constant: slow pro-duction of carbonic acid to keep it in condit ion, while a mi ld ,quick-running ale must be sweet; and, therefore , made f romwort: rich in free maltose and mal to-dexl r ins approachingthereto, and readily reach condition in the cask. Theserequired conditions are obtained w i t h i n the narrow rangeof r.|5" to 155" 1<\, at which mashing is carried out , the-diastasebeing extremely sensitive to s l ight , v a r i a t i on of tempera-ture 1 ; if mashing is done near the lower t empera ture thewort: is suitable for mild and sweet: ale, at the higher, forstock beer. When raw grain is used in conjunc t ion w i t h maltit requires to be gelatinized so t h a t the starch may be actedon by diastase during mashing, or it may be treated in aconverter with a little pale malt at; a high t empera tu re toform soluble starch, otherwise it would form a viscous mash.Tlu* above infus ion method of mashing is best suited forbrewing Knglish beers, but as all malt is liable to conta in someunmalted grain this por t ion remains unacted on dur ing t l u *process and is lost as regards the production of beer. < )nthe Continent and in the United States the decoction methodof mashing is used. The malt is first mixed w i t h water at alower temperature than in the infusion method and the mashthen heated in successive stages nearly to the boiling-point ;or, a portion of wort is run off and the contents of the mashtun heated nearly to boiling-point by steam, then cooled tomashing temperature, and the portion of wort containingactive diastase returned to it and mashing allowed to

MASHING 147

complete. By this means any unmodified corns in the maltare gelatinized and rendered capable of being saccharified sothat the extraction is more complete. The density of thewort is taken by a special form of hydrometer giving theoriginal gravity of the beer to be brewed from it.

Influence of the Water used for Brewing.—Water isone of the most important requirements for brewing, and aconstant and abundant supply of suitable clear water istherefore an indispensable condition for a brewery. Thewaters best adapted for brewing purposes are those whichare of organic purity and not contaminated with poisonousmetals, or more than a trace of iron, and contain inorganicsalts within certain limits. Experience has proved thatsome waters are more suitable for the production of ales ofa particular character, but not for those of another class.The Burton pale ales and the black beers of Dublin andLondon furnish cases in point. The Burton water containslarge quantities of calcium sulphate (over 70 grains pergallon), while the Dublin water contains only a small quantityof calcium sulphate, but a somewhat larger amount of calciumand magnesium bicarbonates, which are almost completelyprecipitated on boiling, leaving the water soft. Water mostsuitable for brewing the best mild ales contains intermediatequantities of calcium sulphate (5 to 7 grains per gallon) buta large amount of sodium chloride (35 grains per gallon).On the addition of the necessary amounts of the salts lackingit is possible in many cases to make certain waters moresuitable than they would otherwise have been for a specificpurpose. The addition of calcium sulphate, magnesiumsulphate and calcium chloride in proper amounts to watercontaining a deficiency of these salts will make it suitablefor use in brewing good pale ale.

SUCTION III . - I M ) I L I N < ! A N D H O V P i N C J

Tine sweet wort, from the mash tun is collected in the under-back, a copper vessel provided wi th a. steam coil to heat thewort; immediately it enters to such a temperature as to renderthe diastase* inactive and prevent full her conversion of themalto-dcxtrins. From the under-back, or sometimes directlyfrom the. mash t u n , the wort is run by gravity or pumpedto the boiling-copper, which may be arranged to take thewhole of the wort brewed, or the sttonj' .er and weaker worthsare boiled separately. The copper may be heated by l i reor steam, and boiling is cont inued for about two hotus,during which the* hops are added in port ions, the best hopsbeing added last, just before the b i t t e r woi t is nm off. Asa result of the boiliiu; the wor t becomes completely s tc i i l i / ed ,the various bacteria, moulds and yeasts on the barley andmalt beiiij; killed, some of t he proteid ma t t e r s ate coagulated,the action of the diastase is anested unless this was done inthe under-back, t lu* aroma and llavoutin^ const i tuents ofthe hops are extracted, as well as the antiseptic re-sins, andtannin, and the wort becomes mote concentrated.

The Chemical Constituents of the Hops. The portionof the hop plant used by brewers is the stiobile or cone, thearomatic smelling blossoms of the hop bine. The strobilesof the female plant; only are used ; these consist of pai t lyoverlapping scales or petals which are of two kinds, oneseedless, the other containing the f r u i t or seed. At the basesof the scales is a yellowish powder, lupul in, spoken of by thebrewer as "condition," since it contains the i lavouiin^essential oil, the resins, the bitter principles and otheringredients to which hops owe their value. The essential oilwas shown by Chapman to consist of two hydrocarbons,

BOILING AND HOPPING 149

myrcene, which possesses a penetrating odour and readilychanges into a resin, and humulene, which has very littleodour and is not so prone to change, as well as other oxygen-ated bodies in small amount, but which contribute largelyto the odour of the oil. The oil is only very slightly solublein water, but somewhat more so in the dilute alcohol of beerand is yet sufficient to confer its flavour on this. The oil isvolatile with steam, and on boiling the wort some of thearoma is lost. It is for this reason, in order to minimize theloss, that the hops are added in portions to the wort, thebest hops last just before the wort is run off. The resins andbitter substances not only confer flavour but act as anti-septics and prevent the ready development of bacteria inthe beer. There are several resins present, but the chiefdistinction made is into the soft and the hard, the former ofwhich is preservative, and being unstable readily passes intothe less effective hard form. It has been found that if hopsare stored at a low temperature the rate of deterioration ismuch lessened. The bitter principles of the hop are due tocertain acids closely allied to the resins. A certain amountof tannin is extracted from hops during the boiling, and thiscontributes to a small extent in precipitating proteins andthus enabling them to be removed.

Cooling and Refrigerating.—The boiled wort is run intothe hop back, a wooden vessel provided with a perforatedfalse bottom, to keep back the hops which act as a filter andallow the clear wort to flow through. The hops are some-times sparged to remove the wort retained, or they arepassed through a form of press to squeeze out the wort.The filtered wort is pumped up to the cooler, a large shallowrectangular vessel in which the wort was formerly cooled tothe temperature suitable for fermentation. Although thetank is usualty placed in a room at the top of the brewery,and ample provision made by having louvre-board windowsfor ventilation, it takes a long time for the wort to cool downto the required temperature, especially in warm weather, andthe large surface exposed to the air offers great liability toinfection by microbes from the air. It is now the practice

150 CARBOHYDRATES

to cool only to about 140° F., and then complete the coolingby allowing the wort to flow over the refrigerator. Besidescooling, however, the wort becomes aerated, and certainproteid matters are thereby rendered insoluble and areprecipitated as a slime in the cooler. Aerating cooled wortdoes not effect this result at least to the same extent, andwort aerated cold gives a turbid filtrate. Recently thedesired result has been attained by spraying the hot wortinto a deeper cooler, thus saving considerable space with lessliability to infection from the air, while the refrigerator ismade to do the principal part of the cooling. The re-frigerator consists of a series of horizontal tubes throughwhich cold water passes from the lowest tubes to the highest,the wort meanwhile flowing over the outside in a thin streamuntil it leaves at a temperature of 60° F. to enter the fermen-tation tank. The tubes need to be kept scrupulously cleanto avoid infection by microbes which may lodge at the angles,more is to be feared from colonies of these which have grownhabituated to the wort than to the chance infection fromthose falling into it from the air during the comparativelyshort time it is thus exposed.

SECTION IV. —FERMENTATION

Tiro cooling of the wort completes the brewing proper, thesubsequent operation being the fermentation in which themaltose is converted by the action of the yeast into alcoholand carbon dioxide, and the liquid changed thereby from asweet wort into an alcoholic fermented beverage, beer. Assoon as the wort from the refrigerator, cooled to about60° P., has started running into the fermentation vessel aquantity of yeast, called the pitching yeast, is added in theproportion of one to three pounds to the barrel of 36 gallons,according to the various conditions of working and thequality of beer to be made. The yeast is first well roused upwith a portion of wort in order to secure its uniform distri-bution. At this point the excuse official takes the dips andgravities to determine the duty chargeable.

After a few hours small bubbles of carbon dioxide maybe seen rising to the surface of the liquid, and these sooncollect into a frothy layer which is fancifully named from itsvarious appearances as cauliflower head and rocky head, andultimately becomes more compact and yeasty through whichlarge bubbles of carbon dioxide penetrate and burst, keepingthe whole in a state of continuous motion. In. about 48 hoursthe yeast is skimmed off, either with skimmers by hand ormechanically, and rejected, and the operation of skimming isrepeated at intervals several times, this yeast being collectedin the yeast backs for pitching subsequent charges. Whenfermentation has proceeded far enough, as shown by theliquid appearing dark and free from suspended yeast whena portion of the yeast head is brushed aside, the last head isallowed to remain and act as a protection against contamina-tion by air-borne microbes, and the whole is allowed to rest

CARBOHYDRATES

to settle and clear, and then drawn off into casks, or it isrun off into a special racking vessel where, after ;i rest: notexceeding 24 hours, it is then filled into casks. The ruckingvessel affords a convenient means 'for adding sugar or otherpriming instead of adding it to each cask. In t in- ruckingvessel little or no further fermentation occurs. Instead ofcompleting the fermentation in one vessel us in the skimmingsystem several other methods are employed. The firstpart only of the fermentation may be allowed to take placein the vessel, and then the partly fermented wort is run out ,either into rectangular vessels known as dropping si/mitrsor into a series of large inter-connected casks, which, fromtheir use in the breweries of Burton-on-Trent, are culledBurton unions. In these the fermentation is completed.

The simplest form of a fermenting tun is u square orround vessel of wood, often lined with copper or a lumin ium,and provided with an attemperator, a coil of piping throughwhich cold water may be passed to keep down the rise oftemperature which takes place owing to the vital ac t iv i ty ofthe yeast. The rise should not be allowed to exceed about70° F. The difficulty of producing a good, drinkable beerin hot climates is well known.

Besides the above primary fermentation in which all thereadily fermentable sugar has been decomposed, and anequivalent proportion of alcohol formed, there is anotherslower secondary fermentation which takes place in the caskand serves to keep the beer from becoming Hat. and t in-drinkable. This is due to a different yeast, which is either awild yeast obtaining access during the cooling, or whichexists in small proportion in ordinary brewing yeast, and theaction of which was overwhelmed during the more vigorousand preponderating activity of the ordinary yeast in theprimary fermentation. In the cask this yeast is now free todecompose slowly the malto-dextrins and ferment theresulting maltose into alcohol and carbon dioxide and Hutskeep the beer sound.

Yeast—Ordinary brewers' yeast, when observed underthe microscope, is seen to consist of a number of minute,

FERMENTATION 153

slightly ovoid cells, 8 to gp. in diameter. Each cell forms adistinct plant, bounded by a transparent cell wall enclosingthe protoplasm and other cell contents. In young cells theprotoplasm is clear and transparent, but in the older cellsappears granular and contains one or more apparently emptyspaces, the vacuoles. Many of the cells have smaller onesattached to them so as frequently to form chains. This isthe usual mode of reproduction, a protuberance ftr bud form-ing on the side of the cell, and after growing sufficientlybecoming detached. Another mode of reproduction is bythe formation of ascospores, which are produced when youngyeast is kept at a suitable temperature, about 25° C., on amoist surface. The protoplasm becomes granular and sub-divides to form two, four or eight separate portions whichbecome invested with a membrane and constitute the spores.When the cell bursts each of these spores becomes a new yeastplant and can reproduce by budding as before. Thisproperty of forming spores has been utilized by Hansen indifferentiating the various yeasts, the shape of the cellsalone not affording a sufficient criterion for this purpose,since the form alters considerably under different conditionsof cultivation. The importance of distinguishing the variousyeasts will be apparent when it is realized that they differvery greatly in fermenting power and in the quantity ofalcohol, and the acidity they produce, and also in the amountof nitrogen consumed and of new cells produced, while theflavour of the beer is also largely dependent on the specificcharacter of the yeast used.

The Chemical Changes during Fermentation.—Beforethe maltose present in the wort can be fermented it mustbe converted into a corresponding amount of dextrose whichis effected by the enzyme maltase secreted by yeast. In.like manner cane sugar must first be converted into equalmolecules of dextrose and levulose by the enzyme invertase,which is also secreted by yeast. It is only the hexoses whichare directly fermentable. The conversion of dextrose intoalcohol and carbon dioxide according to the equationC6H12O6 = 2C2H6O + 2CO2 is only the main portion of the

154 CARBOHYDRA TES

reaction brought about by the enzyme zymase of the yeast,5 per cent, of the dextrose being converted into glycerine,carbon dioxide and other products, and also utilized for thegrowth of the yeast and for the production of new cells. Thesmall proportion of higher alcohols and succinic acid alwaysformed during fermentation are derived from the amino-acids present in the wort.

High and Low Yeasts.—There are two kinds of yeastin general use in breweries, the one used in England for thefermentation of infusion worts with frequent aeration, andknown as high yeast from the temperature, 60° to 70°,at which fermentation is allowed to proceed. It is alsocalled top yeast, since it rises to the surface of the fermentingliquid. The other kind is used with decoction worts onthe Continent for the production of lager beer, and isfermented at a lower temperature, 5° to 6° C., hence calledlow yeast, and from the fact that it settles to the bottom ofthe fermenting tun, bottom yeast. Both these cultivatedyeasts represent types of one species, Saccharomyces ceri-visa, and although low yeast may be made to produce atransient top fermentation, this soon ceases, and it doesnot appear probable that the one kind can be convertedinto the other at least by the few fermentations of an experi-ment. There appear to be three sub-varieties of each ofthese two brewery yeasts with markedly different properties,and it has been suggested that the different flavour ofbeer made from similar worts may be due to a preponderanceof one or other of these forms in the yeast used.

Pure Cultures.—A great reform in the fermentationindustry was made in 1879, when Hansen, of Copenhagen,introduced yeast produced by culture from a single cell,and was thus able to show that yeast which, when examinedunder the microscope, was apparently pure, in reality con-sisted of several types or varieties, to some of which un-pleasantness of flavour and turbidity was due. A portionof malt wort mixed with enough gelatine to" enable it toset when cold is inoculated with yeast so dilute that whena drop of the wort is spread on a microscope cover glass

FERMENTATION 155

only a few separate cells are visible, and these so far apartthat after incubation the colonies formed from them wouldnot come into contact with each other. After these havesufficiently developed a portion of each is removed andplaced in a flask containing sterilized wort. In a few daysfermentation will have taken place, and sufficient yeast willhave been produced for the pitching of a larger flask ofwort, and by a repetition of the operations, using at each alarger quantity, at length sufficient yeast will be obtainedto carry out a fermentation on the brewery scale, and thusenable the quality of the resulting beer to be examined.When a yeast is found which, under the conditions of thebrewery gives the quality of beer desired, its use on thelarge scale conduces to rational working instead of theusual chance results, and diseases of the beer with attendantlosses are obviated so long as the yeast is kept pure. Itis not necessary to pitch each fermentation with fresh pureculture yeast, since the yeast remains sufficiently pure forpractical purposes for some time, and only requires theperiodical addition of pure yeast to maintain its satisfactorycharacter. Each brewery requires to select the type ofyeast best suited to its conditions to produce the characterof beer for which it is known. The use of pure cultureyeasts has met with a large measure of success in Continentalbreweries, but has not proved so advantageous in Englishbreweries, chiefly owing to the necessity for the secondaryfermentation in cask essential for these beers. The secondaryfermentation is produced by a different yeast from thatwhich gives the primary fermentation, and without it thebeer, although sound and of good flavour, is thin and flat.The secondary yeast is present in ordinary pitching yeast.Single yeast cultures, however, are more satisfactory withquick running ales, for which the secondary fermentationis .less essential.

Aeration, Temperature and Duration.—Yeast cellsrequire oxygen for carrying on their vital activities, andalthough fermentation will go on in the absence of air,unless the necessary oxygen is supplied the cells soon lose

156 CA RBOH YDRA TKS

their fermentative faculty and die. The wort is aerated tobegin with during its passage over the refrigerator, and thecontents of the fermenting tun arc roused from t ime to timeto supply air. Kxcessivc aeration, on the other hand, leadsto an unnecessary development of yeast: cells at the expenseof the sugar, and is attended with a diminution in theyield of alcohol.

The temperature at which fermentation is allowed toproceed varies with the kind of beer made, weaker qualitiesarc usually worked at a temperature not exceeding 70° K.,but with stronger beers the temperature may be allowedto rise as high as 75° 1<\, and this is also the case with stoutand dark beers. J<ow temperature conduces to the pro-duction of a finer flavour, and more stable beer and morecarbon dioxide is retained in solution. The higher tempera-tures tend to favour the development of bacteria, but thisis somewhat: counterbalanced by the more vigorous fermenta-tion, and dark malts contain, moreover, products of an anti-septic character. Higher temperatures lead to irregulardevelopment of yeast. In the case of bottom yeasts thetemperature is from 38° to 48" P., and fermentation is muchmore sluggish.

When fermentation takes its normal course the yeastis ready for skimming about 48 hours after pitching, andthe primary fermentation lasts usually about 8 days,after which some qualities of beer are sent out for consump-tion immediately they are racked into casks, while othersare kept: for some months to mature. The bottom fermenta-tion conducted at a lower temperature proceeds more slowly,and is prolonged to 12 or 15 days, and the beer is then kept,in casks stored in cellars at a low temperature until filledinto delivery casks. It must be quickly consumed afterbeing removed from the protective influence of the coldcellar, as it docs not: keep so well as the more heavily hoppedKnglisli beer.

Density of Wort and Attenuation.—A quarter of malt,336 Ibs., is usually taken to yield four barrels of 36 gallonseach of wort of a specific gravity of 1*055. The density of

FERMENTATION 157

the wort is arranged to suit the strength of the beer to bebrewed, and .is spoken of as the original gravity of thebeer. Brewers also describe worts as of so many pounds,this being the excess of weight of the wort over that of abarrel of water, 360 Ibs. Thus a wort of a gravity 1*055would be called one of 55 X -36=19*8 brewers' Ibs., the weightof a barrel of such wort being 36o+i9'8=379'8 Ibs.

Yeast cannot readily ferment worts containing 20 percent, of fermentable sugar, equal to 51 Ibs., and its actionis inhibited by the alcohol it produces, so that 14 to 15 percent, of alcohol is the maximum attainable. The gravityof the wort is taken dining the course of fermentation afterpouring a sample from one vessel to another to disengagethe gas, and is found to diminish steadily as sugar is usedup and alcohol produced. The final gravity, termed theattenuation, reached may be i '016 =5 76 Ibs. This determina-tion is affected by the presence of the alcohol, albuminoids,caramel, and hops, and gives only the apparent gravity.Yeasts differ considerably in the attenuation the}'- are ableto produce.

Bakers' Yeast.—Yeast is mixed with the dough inbread making in order that the carbon dioxide and alcoholgenerated may confer the desired sponginess to the breadwhen baked. Brewers' yeast formerly in use for thispurpose is, owing to its hop flavour, not so suitable as dis-tillery yeast. The manufacture of pressed yeast is carriedout in this country and abroad as an adjunct to the distilla-tion of spirit. The well aerated mash of grain is fermentedvigorously at a high temperature, and the }>-east skimmedoff when the production of young cells has ceased. Theyeast is separated in filter presses and preserved in tin-foilwrappers.

Yeast Food Product.—The high percentage of nutritivematerial in yeast has led to its use as a food product sincedried yeast contains 45 per cent, of albumenoids derivedfrom the protoplasm of the cells. Yeast extract, preparedby heating well-washed beer yeast and evaporating in avacuum pan to a syrupy consistency, has the appearance

158 CA RBOHYDRA TES

and odour of meat extract, but is somewhat paler in colour.The chief characteristic difference is the absence of thebases creatine and creatinine which are present in meatextracts. Dried yeast forms a good fodder for sheep, butis not so easily digestible by the human subject. It forms abulky mass of light-brown flakes, and is excellent for dairycows, giving an increase in milk yield over cotton seed meal.The bitter taste due to hop resin is removed by treatmentwith alkali carbonate or disguised by addition of fats andstarchy meals.

Diseases of Beer.—Beer should be brilliantly clear, anycause of dimness or turbidity is to be scrupulously avoided.Bacteria produce not only undesirable alterations in odourand flavour, but often cause a turbidity not removable byfinings. It is advisable, therefore, by the strictest attentionto cleanliness to avoid contamination by these organisms.Certain species of yeast also may cause turbidity, as wasshown by Hansen, but the wild yeasts SaccharomycesPastorianus and S. ellipsoidcus are only harmful whenpresent in too great a proportion in the pitching yeast.When this is the case it has been suggested to wash theyeast and separate the noxious forms by decanting themoff, while the larger and more useful cells remain behindin the sediment. Yeast turbidity is removable by finings.The finings which it is customary to add to beer are madeby soaking isinglass in water acidulated with tartaric,acetic, or sulphurous acid, or sour beer, and adding a portionto each cask of beer when it is sent out from the brewery.Ropiness of beer is due to an organism which produces agum-like body, dextran, and renders the beer so viscousthat it may be pulled out in strings. The malady appearsto be caused by Bacillus mscosus, and is more frequentlymet with in lightly hopped beers than in those heavilyhopped as in pale ales, and is discouraged by increase ofacidity. A sarcina form, Pediococcus viscosus, has alsobeen shown to cause this trouble, originating in aerialinfection of the worts on the refrigerators. Bacteria alsosecrete diastatic enzymes which may render the higher

FERMENTATION 159

maltodextrins fermentable by yeast, and thus lead to lossof condition by the beer becoming thin in flavour and losingits palate fullness. The acids produced by bacteria renderbeer sour and undrinkable. Bacterium aceti promotes theoxidation of alcohol and forms acetic acid, as is done pur-posely in the manufacture of vinegar. Others generatetraces of butyric and other fatty acids of disagreeable odour.Other bacteria reduce sulphates and sulphites and yieldsulphuretted hydrogen. Casks affected in this way areknown as stinkers.

Zymase.—The enzyme invertase may be extracted fromyeast by water, to which it is advisable that chloroform ortoluene should be added. The limiting membrane of theyeast cell is sufficiently permeable to allow the invertaseto pass out, but better results are obtained if the yeastcells are allowed to disintegrate by autolysis. The enzymezymase which brings about fermentation cannot be obtainedin this manner, for as this enzyme is intra-cellular the cellsrequire to be disintegrated first, as was first shown byBuchner in 1897. He ground yeast thoroughly with sandand diatomite in a mortar, and then subjected the thickdough-like mass to a pressure of 300 atmospheres in ahydraulic press. The diatomite is essential both as a filterand to act as a support for the cells, so that the immensepressure may squeeze out the fluid contained in them.The great surface of the diatomite holds back a very con-siderable portion of the enzyme, but a further yield may beobtained by rubbing up the press cake with water andpressing again. The pressed juice containing the enzymeforms a clear opalescent liquid which, when added to wort,causes an evolution of carbon dioxide and production ofalcohol in the same proportions as when living yeast isused. Succinic acid and glycerine are also formed as by-products. I^ike living yeast, it shows specific charactersin fermenting, also dextrose and Isevulose, but not lactoseor mannitol. That the action is not due to minute particlesof protoplasm is evident, since the fermentation goes onin the presence of chloroform, which prevents the vital

i6o CARBOHYDRATES

activity of living protoplasm. Moreover, it is still activewlieu filtered through a Chamberland filter. Harden andYoung, in the endeavour to effect a more complete separationof colloidable substance, passed the yeast juice through aMartin filter formed by soaking a Chamberland filter inmelted gelatine and allowing the latter to set in the pores.Colloidal matter, soluble in water, was retained on thegelatine, but neither this nor the filtrate were capable ofinducing fermentation separately, although when mixedthey would do so. It was thus shown that two substancestake part in producing fermentation. On the filter was theenzyme with other colloidal matter, and the liquid thatpassed through the filter was the co-enzyme. Furtherexperiments showed that a hexose phosphate is formed asan intermediate compound during the fermentation andagain decomposed. The yeast juice suffers a rapid loss ofactivity on keeping. This has been shown to be due tothe presence of a proteo-clastic enzyme which not onlydissolves albumin but also the zymase. Enzymes in a drystate are more resistant to heat than in the presence ofwater, and retain their activity for a more prolonged period.Emil Fischer dried yeast by spreading it in a thin layeron glass plates and drying as quickly as possible in a currentof warm air, and subsequently heating to about 70° C. Thezymin or permanent yeast described, by Albert was made byfiltering yeast mixed with alcohol and drying with ether.It forms an impalpable powder in which the more detailedstructure of the yeast cell is no longer recognizable, theprotoplasm of the cells is dead, but the zymase present iscapable of inducing fermentation.

REFERENCES.W. J. Sykes and A. R. Ling, " The Principles and Practice of Brewing."

London. 1907.H. E. Wright, " A Handy Book for Brewers/' London. 1897.A. Chaston Chapman, " Brewing." Cambridge. 1912.C. Oppenheimer and C. A. Mitchell, " Ferments and their Actions.'*

London. 1901.A. Jorgensen, translated by S. H. Da vies, " Micro-organisms and

fermentation." London. 1911.W. M. Bayliss, " The Nature of Enzyme Action." London. 1919.G. J. Fowler, " Bacteriological and Enzyme Chemistry." London. 1911.A. Harden, " Alcoholic Fermentation." London. 1915.

PART IV.—WINE

ALCOHOLIC beverages prepared by the fermentation offruit juices containing more or less sugar are classed aswines, the juice of grapes being understood when the termwine is used without the qualification ustial in describingBritish wines, as Currant wine, Gooseberry wine, Applewine (cider), etc. These latter are made in countries witha temperate climate from white, red, or black currants,mulberries, gooseberries, elderberries, or raisins. Theyrequire the addition of sugar or honey before they arefermented to make up for their deficiency and raise thepercentage of alcohol to the requisite amount. Grapewines are variously classified as white or red from theircolour, as dry or sweet on the amount of sugar in the finishedproduct, and as still or sparkling according to their contentof carbon dioxide. They are given geographical names toindicate their place of origin, since wines from differentdistricts possess special characteristics. Thus we haveBurgundy, Port, Sherry, Madeira, Moselle, Champagne,Tokay, California!!, Australian, Cape, etc. These aredistinct in colour, flavour, aroma or bouquet, alcoholicstrength, and content of sugar. Taste often demands strongwines so that they are sometimes fortified by the additionof spirit. If brandy distilled from wine is used for thispurpose the product may still be regarded as genuine, butwhen the alcohol added is derived from other sources theresult is not true wine in the proper sense. The amount ofethyl alcohol in natural wine varies from 6 to 13 per cent.,with small quantities of higher alcohols. The acids presentare tartaric and malic acids derived from the grape juiceand tannic acid from the skins and stalks with carbon

Q- TI

162 CARBOHYDRA TES

dioxide, and succinic acid produced by fermentation andalso a little acetic acid. The free acid present, calculatedas tartaric acid, amounts to 03 to 07 per cent. The saltspresent are chiefly potassium tartrate and phosphate. Thecharacteristic aroma of wine is due to cenanthic and otheresters, but some of the constituents which confer the highly-prized bouquet of certain vintages or the wines of particulardistricts are still beyond chemical determination; it isdependent on the particular variety of vine, the locality,the season, and is influenced by the yeasts. The colouringmatter in wine is extracted from the skins by the combinedaction of the alcohol and acid during fermentation, whenthe skins are left in the mash, otherwise the juice from blackgrapes, fermented without the skins, gives white wine.The browning of wine, which takes place in course of time,and which is known as ageing, is due to the oxidation andprecipitation of the colouring matter; this change can beaccelerated by the addition of an oxidase.

Few wines are sold without being mixed. The intoxi-cating properties of wine are found to be increased by mixingthem with other wines of a different age and growth. Theflavour is at the same time often improved. Thus a thinport is considerably improved by the judicious addition of asimilar wine of full body, or by a little Malaga or rich sherry ;and an inferior old sherry may be improved by admixturewith a small quantity of full-bodied wine of the last vintage.This art of cellar management is a matter of experience andartistic taste, and is employed to so great an extent thatprobably few wines reach the consumer in the unmixed ornatural state.

SECTION I.—GRAPES AND THE VINE

GRAPHS are the fruit of the vine, Vitis Vinifera, of which agreat number of varieties are cultivated and many othersgrow wild. It is probable that the cultivated strains arederived from wild varieties indigenous to the countries inwhich they are grown, as it has been frequently found thatvines transplanted from one country to another graduallylose their valuable character and yield grapes which produceinferior wines. Not all grapes are eatable, grapes good forwine are often not suitable for eating, and the best grapesfor eating make inferior or bad wine. In the unripe stategrapes contain malates and tartrates chiefly of potassium,but as they ripen tartrates preponderate. Although theactual amount of acid increases during ripening the per-centage is less due principally to the increase of sugar in thejuice. In some vineyards the grapes are allowed to hanguntil they reach the maximum of sweetness and maturityand are beginning to decay. Thus highly-flavoured sweetwines as Sauterne and Rheingau are produced, the sweetnessbeing due to inositol. In dry and hot climates the grapesare allowed to passulate or wilt and change into raisinswhile still on the vine. These give sweet thick syrupywines as Tokay or, mixed with alcohol, Malaga. Red orblack grapes are vintaged between maximum volume andpassulation, as the latter destroys the blue colouring matter.

Pressing and Must—The grapes are crushed to extractthe juice, and the latter is then separated from the skinsand stalks in wooden screw-presses. The juice, or must,obtained in this manner when fermented yields white wine.In the case of red wine it is necessary to allow the skins toremain in contact with the fermenting must for a considerable

164

time for the colouring matter to be extracted, and it is thenadvisable to remove the stalks before the grapes are pressed,otherwise the wine acquires an astringent, harsh taste dueto the tannins derived therefrom, and takes years to matureand become drinkable.

Constituents of Must.—The proportion of must obtainedfrom the grapes varies from 60 to over (jo per cent., accordingas the stalks are present or not. It contains from 50 to <Soper cent, of water, 12 to 35 of sugar (glucose and fructose),2 to 3 of extractive matters (pectin, gums, albuminoids,and colouring matters), 0*2 to 1*0 of acid, and 0-3 to 0*5of ash. The ash consists of 60 to 70 per cent, of potash,3 to 5 of lime, 3 to 5 of magnesia, 3-5 to 5*5 of sulphuricacid, 14 to 17 of phosphoric acid, and smaller quantit ies ofsoda, iron, manganese, chlorine', and silicic acid.

The must produced by the first pressing yields thebest wine, the richest and ripest grapes being the first, togive up their juice, while wi th increased pressure the mustobtained is from juice of grapes less ripe, which are moreacid, and contains more tannins from the skins and stalks.The ratio of acid to sugar present, in the must .lias beenused as a criterion of the quality of the vintage; highacidity indicating a bad season.

Marc.—The residue after pressing, consisting of the.skins and stalks, is called the marc, and is sometimes usedto make inferior wine by fermenting it a f te r the additionof sugar. This petiotizcd wine is distilled to obtain brandywith which to fortify other wine, or is used to prepareacetate of copper or to make wine vinegar. It is also ul ili/.cdas a cattle food and as a fertilizer.

II.—FERMENTATION

o must from the press readily enters into spontaneousfermentation from tlie development of wine yeasts whichare always present on the skins and stalks of the grapes,or which fall into it from the air. These yeasts are varietiesof Saccharomyccs ellipsoideus, and are capable of with-standing a high acidity and alcoholic content. Whitewines are fermented in barrels with the bung-hole left opento allow of the escape of carbon dioxide. Valuable redwines arc fermented in conical wooden vats open above,since the skins or husks require to be stirred up during thefermentation.

Port wine is fermented in shallow receptacles of masonryin which the grapes are trodden and, after fermentation,pressed. Fermentation in Italy, Spain, and the south ofFrance is carried out at 15° to 24° C., and is a top fermenta-tion, but in Germany and with the finer French wines, abottom fermentation is made at 5° to 12° C. At the highertemperature* the fermentation takes from 3 to 8 da}^s, andthe wine produced is fiery, high in alcohol, and lacking indelicate aroma. At the lower temperature the first fermenta-tion lasts a few weeks, but yields a wine of delicate flavour.When fermentation is complete, and the wine has becomeclear, all the yckast and other suspended matters are depositedon the bottom of the cask or vat, constituting the lees.From this the young wine is racked, i.e. decanted or siphonedoff, and run into a clean cask.

Slow Fermentation.—The casks are filled quite full, thebung inserted, and the wine allowed to remain at rest forseveral weeks to undergo the slow or still fermentationduring which colouring matters, albuminoids, and acid

T64 CARltOllYDKATKS

lime for the colouring m a i l e r to be extracted, and it is thenadvisable to remove the stalks before the grapes are pressed,otherwise the wine acquires an astringent, harsh taste dueto the tannins derived therefrom, and takes years to mat tin*and become drinkable.

Constituents of Must. The proportion of must obtainedfrom the grapes varies from 60 to over <jo per cent., accordingas the stalks are present or not. It contains from 50 to Hoper cent, of water, iiJ to 35 of sugar (glucose and fructose*),2 to 3 of extractive matters (pectin, gums, albuminoids,and colouring matters), 0*2 to ro of acid, and 0*2 to 0*5of ash. The ash consists of 60 to 70 per cent, of potash,3 t° 5 °f lime, 3 to 5 of magnesia, 3*5 to 5*5 of sulphuricacid, 14 to 17 of phosphoric acid, and smaller q u a n t i t i e s ofsoda, iron, manganese, chlorine, and silicic acid.

The must, produced by the first, pressing yields thebest wine, the richest, and ripest grapes being the first, togive up lh(iir juice, while w i t h increased pressure the mustobtained is from juice of grapes less ripe, which arc moreacid, and contains more tannins from the skins and stalks.The ratio of acid to sugar present, in the must has beenused as a criterion of the qua l i ty of the v in t age ; highacidity indicating a bad season.

Marc. —-The* residue a f t e r pressing, consisting of theskins and stalks, is called the marc, and is sometimes usedto make inferior wine by ferment ing it a f t e r the additionof sugar. This pctiotiml wine is distilled to ob ta in brandywith which to fort ify other wine, or is used to prepareacetate of copper or to make wine vinegar. It is also utilizedas a cattle food and as a fert i l izer .

SECTION II.—FERMENTATION

THE must from the press readily enters into spontaneousfermentation from the development of wine yeasts whichare always present on the skins and stalks of the grapes,or which fall into it from the air. These yeasts are varietiesof Saccharornyces ellipsoideus, and are capable of with-standing a high acidity and alcoholic content. Whitewines are fermented in barrels with the bung-hole left opento allow of the escape of carbon dioxide. Valuable redwines are fermented in conical wooden vats open above,since the skins or husks require to be stirred up during thefermentation.

Port wine is fermented in shallow receptacles of masonryin which the grapes are trodden and, after fermentation,pressed. Fermentation in Italy, vSpain, and the south ofFrance is carried out at 15° to 24° C., and is a top fermenta-tion, but in German}?- and with the finer French wines, abottom fermentation is made at 5° to 12° C. At the highertemperature the fermentation takes from 3 to 8 da3^s, andthe wine produced is fiery, high in alcohol, and lacking indelicate aroma. At the lower temperature the first fermenta-tion lasts a few weeks, but yields a wine of delicate flavour.When fermentation is complete, and the wine has becomeclear, all the yeast and other suspended matters are depositedon the bottom of the cask or vat, constituting the lees.From this the young wine is racked, i.e. decanted or siphonedoff, and run into a clean cask.

Slow Fermentation.—The casks are filled quite full, thebung inserted, and the wine allowed to remain at rest forseveral weeks to undergo the slow or still fermentationduring which colouring matters, albuminoids, and acid

166 CARBOHYDRATES

potassium sulphate separate out and form a crust calledargol. After this the wine is usually quite, clear and bright,and after being racked into fresh casks for storage usuallyremains so.

Storage and Treatment.—Many chemical changes occurduring the time of storage whereby the wine becomesmatured. Various esters are formed from the acids presentand bring out the bouquet or aroma. In consequence ofthe loss of alcohol by evaporation during storage the contentsof the casks diminish in volume, and it is necessary to addmore wine from time to time to keep the cask full lest thereshould be a development of moulds and bacteria whichwould spoil the wine. White wines do not clear so well orso quickly as red wines, and although frequent rackingstend to help the clarification, this method is generally notsufficient to make white wine quite clear. Recourse, istherefore had to finings. Isinglass softened with wine isadded and roused up with the wine. Brandied white wines,such as sherry, are fined with white of egg. Coarser kindswith skimmed milk. vSpanish earth, kaolin, and gypsumare also used to clear and brighten wines. Pasteurizingwine at 60° C. stops the tendency to acidification and otherdiseases to which it is liable. Marble was formerly addedto acid wines to correct excess of acidity, but Gall's methodis preferable. The acid juice is diluted with water, and aquantity of sugar added to bring the si:gar content to thenormal amount before fermentation. The method alsoallows of the sour must of bad seasons, which will not fermentof itself, being utilized. The addition of plaster of Paristo must or to the finished wine, technically called plastering,evidently causes the wine to clarify more readily than itotherwise would do, but injurious effects have been attributedto the acid potassium sulphate formed by the reaction withthe tartrates, and several countries have fixed a limit of2 grammes of potassium sulphate to the litre as the maximumallowable.

Sweet, Dry, and Effervescing Wines.—Sweet winesare produced either by the incomplete fermentation of the

FERMENT A TION 167

sugar present in a rich must or by the addition of sugar tothe must or wine, or by the addition of alcohol to arrestfermentation before all the sugar is fermented. When allthe sugar is exhausted during fermentation dry wine isthe result. Effervescing wines are obtained by bottlingthe wine before fermentation is completed. The carbondioxide produced is held in solution under pressure, andwhen the bottle is opened the escaping gas catises theeffervescence. If carbon dioxide is introduced into thebottle from an extraneous source, as in making aeratedwaters, the wine is liable to yield a deposit on keeping.

Medicated Wines and other Alcoholic Beverages,—These are wines containing medicinal drugs; the followingare given in the British Pharmacopoeia, namely Antimonialwine, Colchicum wine, Iron wine, Wine of Iron Citrate,Ipecacuanha wine, Sherry wine, Orange wine and Quininewine. The basis may be either sherry or orange wine.

A number of wines are sold containing small quantitiesof meat extract, these are not regarded as medicated winesby the revenue authorities. Sake is a Japanese drinkprepared by the fermentation of rice with the mouldAspergillus oryzce; it contains about 17 per cent, of alcohol,and is a light yellow colour.

Toddy is a similar beverage made in India by thefermentation of the sugar in the sap of various palms.Arrack is obtained by distilling toddy; it is exported fromCeylon to the United Kingdom, where it is used as aningredient in making " punch."

Koumiss, the drink of the Tartars of South-WesternAsia, is obtained by the fermentation of mare's milk; inSwitzerland an imitation of the Russian koumiss is madefrom cow's skimmed milk, which is sweetened, and fermentedwith yeast.

SECTION III.—TARTAR

Lees.—The solid matter deposited in the fermentationvats and casks at the end of the primary fermentation istermed "lees." It consists of impure hydrogen potassiumtartrate mixed with yeast and other organic substances,and when mixed with water is extremely difficult to filterunless it has been previously subjected to steam heat forsome time to destroy its slimy, colloidal nature. The leesfrom plastered wines contain calcium tartrate instead ofthe potassium salt, consequently it is not of much valuefor the manufacture of tartar.

Argol.—Argol is the thin crust which forms a crystallinedeposit on the sides of the fermentation vessels, and its40 to 70 per cent, of tartaric acid is present chiefly aspotassium hydrogen tartrate. Its solubility diminisheswith the increase of alcohol during fermentation, and theamount of the deposit formed is some indication of thestrength of the wine. By extracting argol or lees with hotwater and recrystallizing the potassium salt is purified, theoperation being aided by the addition of clay and animalcharcoal, the latter having been previously freed from itscalcium phosphate by treatment with hydrochloric acid.The product is known as tartar and, from the circumstancethat a hot saturated solution when suddenly cooled becomescovered with a dense layer of white crystals, it is termedcream of tartar.

Tartaric Acid.—Tartaric acid is manufactured fromtartar by dissolving it in water and adding whiting chalkuntil effervescence ceases, the solution being stirred mean-while and heated by steam. Calcium tartrate and neutralpotassium tartrate are thus formed. The potassium tartrate

TARTAR 169

*^ then decomposed by boiling with calcium sulphate derivedf om a previous operation whereby the whole of the tartaric^*-cid is converted into insoluble calcium tartrate and potassium^"U-lphate which remains in solution, and which is run off"to be crystallized as a valuable by-product. The calcium"tartrate is washed with cold water and. decomposed with"tie calculated amount of sulphuric acid to form calcium

and free tartaric acid which remains in" solution,solution is concentrated in the vacuum pan at 50° to

55° C. and crystallized. In order to obtain crystals of goodoolour the acid is redissolved, heated with animal charcoal,-filtered, and again crystallized; the addition of a littlesulphuric acid facilitates crystallization, as the acid is lesssoluble when sulphuric acid is present. Tartaric acid fromits pleasant acid taste is used in effervescing drinks, and in:tnediciiie. It is also largely used in the manufacture ofdyes, in dyeing, and in calico-printing.

REFERENCES.Thudichum and Dupre, " Origin, Nature, and Varieties of Wine."

ILondon. 1872.Thudichum, " Treatise on Wines." London. 1896.G. C. Jones (Allen's " Organic Analysis," Vol. I.), " Wine." London.

1909.P. Coste Floret, " Vinification." Paris. 1899-1903.Babo and Mach, " Handbuch des Weinbaues und der Kellerwirth-

schaft." Berlin. 1910.Ulyssc Roux, '*La Grande Industrie des Acides Organiques " (Cream

of Tartar, Tartaric, and Citric Acids). Paris. 1912.Thorpe's "Dictionary of Applied Chemistry": 'Tartaric Acid/

X-ondon. 1917.

PART V. DISTILLATION

L ( 5 I I A I N SPIRIT

STARCH is the souree of by f;u the larger part of sugar fromwhieh alcohol is obtained; the staiehv material is firstI'.iound and t ieated \ \ i t h \ \ a t e r to yyiatini/e the- starch,Tim fonns the " mash," which is then saechaiilted by meansof mal t , \\hieh i:- nsualU geiminated bailey ; the resultingliquid is knuun a*, the " \ \ o t t , " and consists chiclly ofmaltosi' and < i t - x t i i n s . The \voi t v*> then fermented by yeast,\vhieh converts the siu'.av into aleohol, and the resultingliquid is kno\vn as the '* wash." I |Vinally the \vat'.h is distilledto separate the alcohol, \\hich !:• :.ub.k.e(|nently M ivclilicd "by fur ther distillation to such a decree nf ,stn%n^,th andpurity as mav be <lesiied.

If molasses or beet roots are used as the source of alcohol,malting is unnecessary, a solution of the material is pteparedto contain a suitable proportion of sugar and fermenteddirectly.

The following cereals are used in the production ofalcohol: barley, rye, mai/.e, millet, oats, wheat, rice, ragi,guinea-corn, and buckwheat.

Malting and Mashing. These starehy substances ategenerally mixed with two parts of water and steamed underpressure in a conical iron vessel known as a " converter,"the temperature being maintained at about 80" C. Aftersteaming for about two hours, a valve in the bottom of theconverter is opened, and the -charge is passed into a mashtun lilted with rotating stirrers, where the gelatinizationfinishes as the mass cools down ; the cooling being assistedby means of an external water jacket. When the tempera-ture reaches 50° to 55" C, about 4 per cent, of malt is mixed

GRAIN SPIRIT 171

with the mash, the effect of malting is to develop the enzymeof the barley known as diastase, which converts the starchinto sugar.

The barle}r used to set up artificial germination is steepedin water for 2 to 4 days, during which period it absorbsabout one-half of its weight of water and the grain becomessoftened ; calcium bisulphite is often added to destroyharmful micro-organisms. The steeped barley is thenspread out in a level heap upon the malthouse floor, whereit commences to germinate, it absorbs oxygen and gives offcarbon dioxide, as the growth of the embryo proceeds asmall white rootlet appears at the end of the corn; whenthe growth has proceeded far enough the heap is spreadout more thinly to allow the grain to gradually dry. Thetemperature is not allowed to rise above 15*5° C.

When the drying is complete the product is known asgreen malt, and it is then removed to the drying kiln, whereit is gradually dried more complete!}7, the temperature atthe finish reaching about 100° C.

The length of time which is allowed for germinationdepends upon the use for which the malt is required. Fordistilling and vinegar making the usual time is 20 days,while the kiln drying occupies 3 or 4 days.

The conversion is complete when the solution no longergives a blue colour with iodine, the time required variesfrom i to 3 hours ; the mash is heated at this stage to about75° C. to destroy injurious bacteria with which the wortmay have become infected. A better method which is nowbeing adopted is to add a small quantity of hydrofluoricacid or ammonium fluoride during fermentation.

This is not harmful to the diastase, while raising thetemperature is liable to impair the micro-organism.

After settling the wort is run off and the residual grainsextracted again with hot water, the weaker worts beingused for mashing the next charge. The temperature is nowallowed to drop to 20° C., and the solid matter removed,the solution is then ready for fermentation with yeast, itsspecific gravity being between 1*030 and 1*055.

172 CARBOHYDRATES

Fermentation.— The saccharified wort obtained in themanner described is run into fermenting vessels and treatedwith yeast to start the fermentation ; special distilling yeastis used, that is, selected culture yeasts adapted to distillingconditions. If pressed yeast is added about 2 Ibs. areemployed for every 100 gallons of wort. Usually, however,a preliminary fermentation is made in a good malt wort,this provides a culture of vigorous young yeast cells, and isadded to the main wort in the proportion of 4 to 5 per cent.

During the early stages of fermentation the growth ofharmful bacteria is checked, in the past lactic acid was used,but now antiseptics, to which the selected yeast has beenacclimatized, are employed. The following substances havebeen used : bismuth nitrate, calcium bisulphite, hydro-fluoric acid, ammonium fluoride, the latter being now mostin favour.

In the early stages of fermentation there is a rapiddevelopment of yeast, for which the best temperature isabout 17° to 21° C. ; the temperature rises as the operationproceeds, and the main fermentation in which the maltoseand dextrose are transformed into alcohol occurs best at26° to 30° C. At this temperature a secondary reactionalso occurs, any dextrins which remain are acted upon bythe diastase and gradually converted into fermentablesugars, which are then attacked by the yeast. The chieffermentation is over in about 48 hours, but the wort, nowknown as wash, is allowed to remain another day at 25° to26° C. to complete the process.

The wash is now ready for distillation, and containsabout 4^ to 7^ per cent, of alcohol, when the original wortbefore fermentation has a specific gravity of 1-030 to 1*055,as is usual in most distilleries in this country.

The principal changes during fermentation are —(i) The conversion of maltose into dextrose.

Maltose. Dextrose.This is brought about by the enzyme rnaltase con-

tained in ordinary yeast.

GRAIN SPIRIT 173

(2) The decomposition of the dextrose into alcoholand carbon dioxide.

C6H1206=2C2HgOH+2C02Dextrose. Alcohol.

This change is produced by the action of anotheryeast enzyme, namely zymase.

However, many secondary reactions result accordingto the nature of the wort and yeast, chief among the by-products as regards quantity are glycerol, fusel oil, succinicacid, other fatty acids, aldehydes, and various esters.

A complete conversion of starch into sugar and alcoholis impracticable, the theoretical quantity would be—

From dextrose, C6H12O6 .. 51-1 per cent.,, maltose, sucrose, C^B^On 53*8„ starch, C6H10O5 ., .. 56-8

About six-sevenths of the theoretical yield is obtained.The Amylo Process of Fermentation.—Certain moulds

secrete diastase and also fermentation enzymes. Thisproperty has been utilized in a process of combined sacchari-fication and fermentation, whereby the use of malt isdispensed with in obtaining alcohol from starchy materials.Moulds possessing this property are Amylomyces Rouxii,Mucor £, Mucor y, and Rhizopus Delmar, the last three arenow generally used, as they produce less acid than A. Rouxii.

The fermentation stage, using moulds is a slow one,and to hasten it yeast is added ; advantages claimed for theamylo process are a better yield of alcohol, a purer product,as the conditions of working exclude bacterial contamination,and an economy of malt; a single gram of the mould issufficient to convert 25 tons of maize. Compared withoperations where 10 to 12 per cent, of malt is used, whenthis one gram of mould is employed, there is a saving ofabout 3 tons of malt.

In this country a legal obstacle prevents the use of theamylo process; it is a statutory requirement that thespecific gravity of distillers' wort before fermentation shallbe ascertained by means of the saccharometer, and, of course,this is impossible.

174 CA RBOHYDRA TES

Distillation.—To separate the alcohol from the by-products the mixture is distilled. There are two processesin use, the pot still and the patent still.

Where malt whiskeys are produced, and it is the objectof the distiller to retain in the product some of the esters,higher alcohols, and other bodies which give the spirit itscharacteristic flavour, the apparatus employed is the pot still.

Pot Still.—This consists of a boiling vessel with a retorthead and a worm condenser; or the head may be attachedto one or more fractionating vessels similar to Woulfe'sbottles, through which the alcoholic vapours pass beforereaching the condenser. Usually the pot still is heated bythe direct flame of a furnace, though steam is now frequentlyused as the heating agent.

The spirit produced by the first distillation is alwaysimpure, and has a disagreeable odour and taste, and isknown as " low wines/' On redistillation of the low wines,the first portion of the distillate, known as " fore shots," iscontaminated with oily matters ; as the distillation proceedsthe oily matter diminishes, and where no turbidity is pro-duced on dilution with water the spirit is considered suffici-ently pure to be collected as potable alcohol. At the endof the process the spirit becomes oily again, and is knownas "tailings/' The " fore shots" and "tailings" aretogether known as " feints," and are redistilled with thesucceeding " low wines " ; it is usual to have two separatestills for the two distillations.

The residue from the distillation of the wash is termed" pot ale," and from the low wines is called " spent lees."The former is sometimes evaporated and the product usedas a fertilizer.

Patent Stills.—By far the greater quantity of ordinaryalcohol is distilled in a patent still, the invention of AeneasCoffey. In this process the alcohol is expelled by blowingsteam through the wash which is spread in layers over aconsiderable surface. The wash enters at the top of thestill and passes downwards over a series of perforatedcopper plates in which are small orifices, where the liquid is

GRAIN SPIRIT 175

met by tlie uprising steam. The latter bubbling throughthe perforations heats the wash and carries off the alcoholvapour, so that by the time the wash reaches the lowestplate, it has been deprived of all its alcohol. The alcohol,steam, and volatile impurities pass to the top of the apparatuswhich is known as the " analyser/' they are then led intothe bottom of a similar column of perforated plates termedthe ''rectifier/' where a process of gradual cooling takesplace by the action of the pipe conveying the cold wash tothe analyser. The alcoholic vapours passing upwardsthrough the plates into one cool chamber after anotherbecome cooled, and deposit more and more of their wateras they near the top, finally condensing as strong alcoholon an imperforated copper sheet, and passing out. Thestrength of the spirit thus continuously obtained is 94 to 96per cent, by volume as against 90 to 92 per cent, by the" pot still " method.

Various other " continuous stills " have been patented,but their essential principle is similar to that of Coffey'sapparatus.

Rectifying.—When alcohol of special purity is required,it is further purified by special rectification. This is usuallydone by diluting the spirit with water to a strength of about45 to 50 per cent., and redistilling it. " Intermittent"stills which fractionate the distillate (the impurities beingin the first and last runnings), and continuous rectifyingstills are used for the purpose.

Purification by treatment with wood charcoal is alsoemployed, the effect is mainly a chemical one due to oxida-tion. This filtration may either precede or follow a rectifica-tion by distillation. The Spiritus Rectificatus or Alcohol(90 per cent.) of the British Pharmacopoeia is defined as" a mixture of ethyl hydroxide and water containing in100 parts by volume, 90 parts by volume of ethyl hydroxide,C2H5OH. Specific gravity 0-8337." It: contains 85*68per cent, by weight of ethyl hydroxide, and 14*32 per cent.by weight of water.

It should be noted that on account of the contraction

174 CA RBOHYDRA TES

Distillation.—To separate the alcohol from the by-products the mixture is distilled. There are two processesin use, the pot still and the patent still.

Where malt whiskeys are produced, and it is the objectof the distiller to retain in the product some of the esters,higher alcohols, and other bodies which give the spirit itscharacteristic flavour, the apparatus employed is the pot still.

Pot Still.—This consists of a boiling vessel with a retorthead and a worm condenser; or the head may be attachedto one or more fractionating vessels similar to Woulfe'sbottles, through which the alcoholic vapours pass beforereaching the condenser. Usually the pot still is heated bythe direct flame of a furnace, though steam is now frequentlyused as the heating agent.

The spirit produced by the first distillation is alwaysimpure, and has a disagreeable odour and taste, and isknown as " low wines/' On redistillation of the low wines,the first portion of the distillate, known as " fore shots/' iscontaminated with oily matters ; as the distillation proceedsthe oily matter diminishes, and where no turbidity is pro-duced on dilution with water the spirit is considered suffici-ently pure to be collected as potable alcohol. At the endof the process the spirit becomes oily again, and is knownas "tailings/' The " fore shots" and "tailings" aretogether known as " feints," and are redistilled with thesucceeding " low wines " ; it is usual to have two separatestills for the two distillations.

The residue from the distillation of the wash is termed" pot ale," and from the low wines is called " spent lees."The former is sometimes evaporated and the product usedas a fertilizer.

Patent Stills.—By far the greater quantity of ordinaryalcohol is distilled in a patent still, the invention of AeneasCoffey. In this process the alcohol is expelled by blowingsteam through the wash which is spread in layers over aconsiderable surface. The wash enters at the top of thestill and passes downwards over a series of perforatedcopper plates in which are small orifices, where the liquid is

GRAIN SPIRIT 175

met by the uprising steam. The latter bubbling throughthe perforations heats the wash and carries off the alcoholvapour, so that by the time the wash reaches the lowestplate, it has been deprived of all its alcohol. The alcohol,steam, and volatile impurities pass to the top of the apparatuswhich is known as the " analyser/' they are then led intothe bottom of a similar column of perforated plates termedthe " rectifier/' where a process of gradual cooling takesplace by the action of the pipe conveying the cold wash tothe analyser. The alcoholic vapours passing upwardsthrough the plates into one cool chamber after anotherbecome cooled, and deposit more and more of their wateras they near the top, finally condensing as strong alcoholon an imperforated copper sheet, and passing out. Thestrength of the spirit thus continuously obtained is 94 to 96per cent, by volume as against 90 to 92 per cent, by the" pot still " method.

Various other " continuous stills " have been patented,but their essential principle is similar to that of Coffey'sapparatus.

Rectifying.—When alcohol of special purity is required,it is further purified by special rectification. This is usuallydone by diluting the spirit with water to a strength of about45 to 50 per cent., and redistilling it. " Intermittent "stills which fractionate the distillate (the impurities beingin the first and last runnings), and continuous rectifyingstills are used for the purpose.

Purification by treatment with wood charcoal is alsoemployed, the effect is mainly a chemical one due to oxida-tion. This filtration may either precede or follow a rectifica-tion by distillation. The Spiritus Rectificatus or Alcohol(90 per cent.) of the British Pharmacopoeia is defined as" a mixture of ethyl hydroxide and water containing in100 parts by volume, 90 parts by volume of ethyl hydroxide,C2H6OH. Specific gravity 0-8337." Jt contains 85-68per cent, by weight of ethyl hydroxide, and 14*32 per cent,by weight of water.

It should be noted that on account of the contraction

176 CARBOHYDRA TES

which occurs, Alcohol (90 per cent.) would not be givenby mixing 90 volumes of true absolute alcohol and 10volumes of water.

Absolute Alcohol.—Anhydrous alcohol is prepared bydigesting 95 per cent, spirit with about one-fourth or one-fifthof its weight of quicklime for some days, and then distillingoft the alcohol slowly from a water bath rejecting the firstand last portions; the resulting product is then treatedagain in the same way.

When strong spirit is not available it may be obtainedby distilling weak alcohol first with potassium carbonateand then with fused calcium chloride.

Other substances which have been used as dehydratingagents are barium oxide, calcium carbide, metallic sodium,and metallic calcium, but, on the whole, quicklime appearsto be the best dehydrating agent.

Commercial absolute alcohol usually contains water inquantities varying from about 0*5 to 1-5 per cent. Theabsolute alcohol of the British Pharmacopoeia is defined asethyl hydroxide, C2H6OH, with not more than I per cent,by weight of water. Specific gravity (at IS'S^S'S0) from0794 (equivalent to 99*95 per cent, of ethyl hydroxide byvolume and by weight) to 0*7969 (equivalent to 99*4 percent, of ethyl hydroxide by volume or 99 per cent, by weight).The test prescribed to exclude excess of water is as follows :Anhydrous copper sulphate shaken occasionally during 2or 3 hotirs with about 50 times its weight of absolute alcoholdoes not assume a decidedly blue colour.

Proof Spirit.—Proof spirit of the British Pharmacopoeiahas a specific gravity of 0*920, which corresponds to a strengthof about 49 per cent, by weight of alcohol. The term" proof spirit " is very confusing to many people, and mightwith advantage be abandoned. Of this there is little chanceat present, as it is adopted in several Acts of Parliament,and is the scale to which Sykes' hydrometer, used by theExcise, has reference. The Excise formerly tested thestrength of spirits by pouring a certain amount on gunpowder.A light was then applied. If the spirit was above a certain

GRAIN SPIRIT 177

strength " proof " the gunpowder ultimately inflamed, butif weaker the gunpowder was too much moistened by thewater to be capable of explosion, and the sample was saidto be " under proof." By Act of Parliament proof spiritis now defined to be a liquid of such density that at 51° F.13 volumes shall weigh the same as 12 volumes of waterat the same temperature. The proof spirit thus producedhas a specific gravity of 0*91984 at 6o°/6oc F., and contains49*2$ per cent, of alcohol by weight, and 57-10 per cent, byvolume at 60° F.

Spirits weaker than the above are described as beingso many degrees under proof, or so much per cent, underproof (TJ.P.). Thus, by the term 20 per cent, or 20 degrees" under proof " is meant a liquid containing, at 60° F., Sovolumes of proof spirit and 20 of water. Pure water is100° tinder proof. On the other hand, liquids strongerthan proof spirit are described according to the number ofvolumes of proof spirit 100 volumes would yield whensuitably diluted with water. Thus spirit of 50° O.P. isalcohol of such a strength that 100 volumes at 6oc F., whendiluted with water to 150 volumes, would be proof spirit.Owing to the contraction which occurs on mining alcoholwith water, the volume of water it would be necessary toadd in this instance would be considerably more than 50measures. Absolute alcohol accordingly is 75*25 O.P.,and contains 175 '25 per cent, of proof spirit, for 100 volumeswhen diluted with water would yield 175*25 volumes ofspirit at " proof."

2- I2

SECTION II.—POTABLE SPIRIT

Brandy is an abbreviation of "brandy wine/' signifyingburnt or distilled wine. It is usually defined as a spirituousliquid distilled from wine matured by age. Real cognac isdistilled from grape juice, and is the most sought-afterbrandy ; the grape is white and small in size and is grownon a calcareous soil. A simple pot still (see p. 174) isgenerally used, and there are usually two distillations : thefirst corresponds to the "low wines " of the whiskey, it isvery impure, and has a disagreeable odour and taste. Thesecond distillation corresponds to the " spirits."

The pot still varies in capacity from about 150 to 200gallons, is usually enclosed in brickwork and heated bymeans of a furnace, wood being used as fuel; some stills,however, are provided with steam pipes and jackets.

In a few districts the spirit is produced from one con-tinuous distillation. Obtained in this way it is not con-sidered so fine as that from the pot still, but is of a higherstrength and suitable after flavouring for liquors.

The strength of the wine used varies from 4*5 to 9 percent, by weight of pure alcohol, or approximately from10 to 20 per cent, of proof spirit; the quantity used in theprocess is relatively great, the amount of brandy producedbeing only 10 to 15 per cent.

The finished spiiit as run from the still contains about64 per cent, by weight of alcohol equivalent to a strength ofabout 25 over proof. When new, brandy is colourless; forsale it is diluted in vats and coloured either by the additionof caramel, or acquires a yellowish-brown colour by storagein oak casks. Genuine brandy has a sweet mellow flavour,whilst inferior and fictitious brandies can usually be recog-nized by their fiery taste.

RUM 179

principal constituents of brandy are acetic, butyric,dc, and valerianic esters, acetic acid, volatile oil,

tannin^ and colouring matter. The flavour is due to theoenanthic ester.

France is the chief brandy-producing country, and thename cognac is defined by French law to be applied onlyto spirits produced from wine grown in certain specifieddistricts.

British brand}- is made by adding flavouring materialssuch, as esters, bitter almonds, spices, etc., to spirits madefrom grain, and is chiefly used for cooking purposes. InFrance, " eau-de-vie," which corresponds to the brand}" ofthis country, is applied to spirit made from a variety offruits. Brandy is also produced in Spain, Egypt, Algeria,Soutti Africa, and Australia. The Egyptian brandies aresaid to be distilled from currant grape grown in Greece andAsia Minor.

" Marc" brandy is derived from the skins of grapesafter the juice has been extracted ; it is used for flavouringother spirits.

Rum.—The name is probably derived from " rum-bullion," an old Devonshire term for an uproar, the wordbeing subsequently contracted to rum. This beverage isthe product of distillation of the sugar cane ; the chiefsource of supply being the West India Islands and BritishGuiana. In France it is distilled from beetroot.

There are two distinct types of rum in commerce..Jamaica and Demerara (British Guiana), the chief differencebeing that the former is the result of slow fermentation ofwash of high specific gravity, while the latter is the productof wash of low specific gravity and rapid fermentation.The nature of the soil and therefore the products from thesugar cane also affect the quality of the rum.

Jamaica rum wash consists of the following substancesmixed with water : (i) molasses ; (2) skimmings from thesugar boiler which sour during storage ; and (3) dunder,i.e. residue which remains in the pot still after the distillationof tite rum; this is fermented and then distilled in a pot

i8o CARBOHYDRATES

still. The slow fermentation allows of the development ofbacterial action in addition to the alcoholic fermentationproduced by the yeast, and this appears to be an essentialfeature in producing the quality and flavour which ischaracteristic of this rum. This flavour is due to esters ofacids of high molecular weight resulting from bacterialdecomposition of the dead yeast found in the distillingmaterials. These esters are absent in rum produced withoutdunder or acid skimmings.

Demerara Rum.—In British Guiana the wash used isprepared by diluting molasses with water and renderingthe solution slightly acid with dilute sulphuric acid inquantity sufficient to set free the combined organic acids,but not enough to leave any free sulphuric acid. The reasonfor making the wash acid is to guard against excessivepropagation of the butyric and lactic organisms, and torender it more suitable for active alcoholic fermentations.Ammonium sulphate is sometimes added to supply availablenitrogenous food for the yeast. Thus in Demerara rumthere is a rapid fermentation due to yeast action, and thebacterial organisms are not allowed time to develop appreci-ably. Both pot stills and continuous stills (see p. 175) areused in distilling Demerara rum, and the proportion of estersproduced is low compared with Jamaica ruin.

There are three classes of Jamaica rum :—(1) For home consumption.(2) For consumption in the United Kingdom.(3) For export to Europe, chiefly Germany.

Rums of the third class are fermented for 2 to 3 weeks,and the process is conducted in a strongly acid wash; theyhave an abnormally high proportion of esters, and aremainly exported to Germany, where they are used formaking artificial rum by blending with neutral spirit.

Rum contains a high proportion of volatile acids, andowes its flavour mainly to a mixture of esters, chief amongthem being ethyl butyrate, formate, and acetate; thecolouring matter employed consists of caramel. Whennew, rum has rather a disagreeable, odour, but the true

WHISKEY 181

develops by storing in wooden casks, and continueso improve for 8 or 10 years.

Tite strength of rum imported into the United Kingdomvaries from 20 under proof to 50 or more over proof, theaverage being 35 over proof, equivalent to 77 per cent, ofabsolute alcohol. The British Customs distinguish betweenrums from Jamaica, rums from other sugar cane-producingcountries, and imitation rums, a term applied to spirits ofrum character made chiefly in Germany b}' the addition oiheavily flavoured rums rich in esters, to plain spirit frompotatoes, or beet molasses, with the addition of colouringmatter.

VVhiskey.—The early history of whiskey is somewhatuncertain, the term does not seem to have been employeduntil the latter part of the eighteenth century ; its intro-duction into Europe is due to the Arabs, but in the grape-growing countries the spirit is naturally produced from.wine, whilst in Xorthern Europe grain is used.

"Xlie finest whiskey is manufactured in Scotland andIreland from malt or mixed malt and grain ; there are twoprocesses in use, the pot still and the patent still.

In Scotland two distillations only are usually made.First, from the " wash still," from which the whole of thevolatile constituents are collected as " low wines." The" low wines " are redistilled from a similar still, the distillatebeing collected in three fractions, viz. : (i) " fore shots " ;(2) clean spirit or whiskey ; (3) feints. The fore shots andfeints are added to the " low wines " of the next distillingperiod. The whiskey fraction is generally rim ofi at astrength of n to 25 over proof.

In Ireland the pot stills are larger, some having a capacityof 20,000 gallons; three distillations are made, and thefractions are more numerous than in the manufacture ofScotch whiskey; the strength of the "whiskey" fractionbeing 25 to 30 over proof.

The patent still, the invention of Aeneas Coffey (fordescription, see p. 174), has been increasingly employed fortlie manufacture of whiskey, especially in Ireland. The

r82 CARBOHYDRATES

spirit obtained from the patent still is stronger than thatfrom a simple pot still.

Scotch whiskeys may be divided into the following fiveprincipal classes : (i) Highland malts ; (2) Rowland malts ;(3) Campbeltowns; (4) Islays, all made from malt in potstills; (5) grains, a name given to patent still. Irishwhiskeys have no similar classification. The first four allcontain a peaty flavour, peat being used in the curing ofthe malt.

The primary constituent of whiskey is ethyl alcohol,the characteristic flavour is due to small quantities (rarelyexceeding | per cent, of the alcohol present) of esters, acids,higher alcohols and aldehydes produced during malting,fermentation, distillation, and maturing. These productsare known as " secondary constituents/'

The flavour of newly-distilled whiskey is crude andunpleasant, particularly in the case of pot still whiskey,which contains more " secondary products" than thepatent still. By storage in wooden casks changes are broughtabout in the character of the secondary constituents, with theresult that the flavour is improved ; this process is "matur-ing." Patent still spirit costs less to manufacture than potstill, and if the two are mixed, a milder, more uniform, andcheaper product is obtained ; by mixing immature pot stillspirit—which is naturally cheaper than the fully maturedarticle—with patent still whiskey, the unpleasant taste ofthe former is toned down so that the mixture becomesmore palatable. The proportion of pot still whiskey incheap blends depends on the price; the cheapest maycontain as little as 10 per cent.

Gin.—This word is a corruption of the word " genifevre,"or junever, the French and Dutch equivalents respectivelyfor juniper, which is the essential flavouring ingredient.It is a spirituous liquor, usually manufactured in a patentstill, and made from cereals of which maize, malt, and ryeare the chief. The principal flavouring ingredients usedbesides juniper are angelica root, almond cake, cassia buds,creosote, turpentine, and liquorice powder; the gin is

GIX 183

usually rectified twice, and then flavoured by actual distilla-tion with the juniper berries and other aromatics.

The principal varieties are the English "gin/' Geneva,Hollands, and Schnapps, the difference being one of flavour,and each manufacturer has his own recipe, which is preservedas a trade secret.

Geneva is made from a mixed wash of malted barley,rye, and maize in equal proportions, the fermented washbeing distilled in a pot still and subsequently flavoured.

Hollands is said to be made as follows : a mixture of2 parts of ground rye, with I of ground bark}- malt ismashed with about 24 gallons of water for each cwt. ofmixed rneal. When the mashing is complete the specificgravity of the wort is reduced by cold water to between1033 and 1038.

It is then fermented and distilled; juniper berries anda little salt are added to the first distillation, and the wholeis redistilled. The spirit which now passes over is flavouredwith essential oils.

Sweetened gin is made by the addition of sugar syrupto plain gin. Plymouth gin is a special variety used exten-sively in the West of England, the characteristic flavour issaid to be due to ether resulting from the addition of alittle sulphuric acid.

The adulteration of gin, except by dilution with water,is not common, alkaline carbonates, alum, and salts of zincand lead have, however, been found. Gin usually contains38 to 50 per cent, of alcohol by volume, or 66*5 to 87*5 percent, of proof spirit. In England it may not be sold below35 under proof unless declared to be diluted.

Potato Spirit.—Potatoes contain on the average 20 percent, of starch, which is used on the Continent for makingalcohol; in 1901 Germany had 12*5 per cent, of her arableland planted with potatoes, the yield being 205 bushels of60 Ibs. per acre. In 1908 about 6400 agricultural potatodistilleries were in operation in Germany, producing 84 milliongallons of alcohol; the production of spirits from othersources in that country being insignificant.

184 CA RBOHYDRA TES

With suitable flavourings it is used for producing artificialwhiskey, rum, brandy, and even wines.

Liqueurs and Cordials.—These beverages are stronglyspirituous, and usually sweetened compounds flavouredwith aromatic herbs, essences, or fruit extracts, and oftencoloured. There is no real difference between them, butthe word "liqueur" is usually applied to foreign products,whilst the British preparations are termed "cordials."

The blending of the flavours in high-class preparationsis the art of an expert. Hence care is taken to have ahighly-rectified neutral alcohol and pure white sugar as thefundamentals, in order that the flavour of the final productmay not be impaired.

Grape spirit is used in high-class liqueurs, but thecommoner varieties are manufactured from grain spirit.

The flavouring ingredients are treated in one of thefollowing methods:—

(1) An essence is obtained by macerating the ingredientsin alcohol, distilling the mixture, and rectifyingthe distillate.

(2) An alcoholic extract is made by digestion of theingredients and filtration, without distilling.

(3) For inferior kinds an essence is prepared by simplesolution of essential oils in alcohol.

In all three methods the resulting solution is mixedwith the required quantity of sugar, syrup, and alcohol,coloured, if necessary, clarified, and filtered.

The recipes for the better liqueurs, such as chartreuse,are, of course, trade secrets.

Physiological Action of Alcohol.—From time im-memorial the action of alcohol on the human body has beena controversial subject, and upon many points contrary-opinions have been held. The Advisory Committee appointedby the Central Control Board (Liquor Traffic) have publisheda report dealing exhaustively with the subject, and suggestingbasis for further research. The following is a summary ofthe unanimous conclusions of the Committee :—

Alcohol as a Food.—Alcohol is completely and rapidly

PHYSIOLOGICAL ACTION 185

absorbed from the stomach and intestine, and distributed"bite circulating blood to the different organs of the body,

disappearance of alcohol from the body, apart from theproportion escaping unchanged, is due to its being

None of the alcohol is known to be convertedirrto any substance which the body can retain. The energyKt>e:rated by- the combustion of a moderate amount of alcoholca.n "be used by the body to its full value.

-Alcohol can, within limits, replace an equivalent amount°f oa.rborrydrate, or fat, in a diet, and has a similar effect ineconomizing proteins. Therefore alcohol has a certain foodvaJLue in a limited sense, namely, as a fuel or supplier ofeiaexrgy, this theoretical value is, in practice, restricted andco-ujtrterbalanced by its other properties ; and in any casei~t lxa.s, from the point of view of its food value alone, noadvantages over a foodstuff like sugar.

^Mental Effects.—On the brain and nervous systemalcoliol acts as a narcotic.

The successive phases of inebriation cannot be sharplydistinguished, yet three main stages can be made out.Tlie first stage shows a weakening of self-control, andSL ~t>lunting of the power of self-criticism. The secondstage is that in which the sense-perception and skilledmovements are disturbed, the drinker begins to show aceirtain clumsiness of behaviour, and emotional instability.Iia "the third stage self-criticism and control are virtuallysuspended, the emotional tendencies are weakened, and onlystirong appeals evoke any response, and in their absence thedirinker sinks into a heavy sleep.

There appears to be no certain evidence that alcoholacts as a stimulant on the nervous system, and recentexperiments support the conclusion that the direct effect ofaJ.coiiol upon the nervous system is, in all stages and upon

parts of the system, to depress or suspend its function,when taken in moderate doses, in dilute form, and at

intervals, it has no effect of any serious andpractical account.

Action on the Digestion.—Under this heading it is

i86 CARBOHYDRA TES

necessary to consider firstly the effect of alcohol on secretionof digestive juices. There is no doubt that the flow of salivaand the gastric juice are increased, but the latter differsfrom normal gastric juice, inasmuch as it is deficient inpepsin, it follows therefore that this increased amount ofgastric juice is of little or no value in the process of diges-tion. The second factor is the action of alcohol on move-ments of the digestive organs. So far as evidence goes,there is no reason to believe the gastric movement is increasedby alcohol, while some forms of contraction are arrested.This lessened movement of the stomach is produced bymany other volatile substances, and may explain the reliefof discomfort and colic-like pains which such substances,including alcohol, may afford. The last factor is the effectalcohol produces on the rate of digestion; I to 2 per cent,of pure alcohol has little effect upon the activity of thegastric juice, 5 to 10 per cent, slightly retards digestion^while a concentration of more than 10 per cent, very definitelydiminishes the rate of digestion.

Thus it has been found that moderate doses of alcoholhave no effect, either one way or the other, upon the digestiveorgans.

The Action on Respiration and Circulation of theBlood.—It has been found by recent experiments that alcoholin moderate doses has no effect on the respiration of practicalimportance. In large doses a paralysis of the respiratorycentre is produced. The old theory that alcohol was arespiratory stimulant has thus been disproved. The suppo-sition that alcohol acts as a direct stimulant upon the heart,increasing the frequency and power of its beat, has yet tobe proved. Most observers, however, agree that an increase,in the pulse rate, lasting about half an hour, follows thetaking of a moderate dose of alcohol. There is reason tobelieve that the accelerated effect noted is due to the weak-ening of the inhibitory centre which restrains the heartbeating, and thus a quickening is observed.

When alcohol appears to promote recovery from fainting,it probably acts simply by virtue of its irritant action on

PHYSIOLOGICAL ACTION 187

the mucous membrane of the mouth and throat, much inthe same way as the fumes of ammonia or ether wiH actwhen inhaled. That the effect is a local and indirect one isevident from the fact that it appears almost at once, longbefore any significant amount of alcohol can have beenabsorbed and carried to the heart. In more protractedweakness of the heart, the beneficial effect of alcohol canbe attributed to its narcotic and sedative action on thenervous centres which affect the action of the heart.

Alcohol and the Performance of Muscular Acts.—Experiments were made on the influence of alcohol on simplereflex action, such as the " knee jerk/' and the "eye closing/'and upon willed movements, such as the ergograph, hill-climbing, and tlie speed of starting the movement of turning ofthe e}-es toward a fresh object. It is agreed that a single doseof less than 40 cubic centimetres of alcohol, or as much aswould be taken in about 2f ozs. of whiskey at proof, or inif pints of beer, in an adult accustomed to moderate useof alcohol, exerts little or no appreciable influence on theperformance by him of a muscular act of simple characternot demanding precision. On the other hand, the perform-ance of acts requiring skill tends to be temporarily impairedby a dose of even 30 c.c., the effect being shown especiallyin a diminution of the speed and nicety of the performance.Reliable evidence that alcohol improves, in normal circum-stances, the efficient performance of any muscular act,unskilled or skilled, seems at present to be altogether lacking.

Effect on the Body Temperature.—Any feeling ofwarmth experienced after drinking alcohol is explained bythe fact that alcohol causes a slight paralysis of the nerveswhich control the size of the blood vessels, thus allowingthem to distend a little. More blood, therefore, reaches thesurface of the body and warms the skin, and the ends of thesensory nerves in the skin, and thus convey to the brain asensation of warmth. But the sensation is illusory; thebody, as a whole, has not really been made warmer, in fact,the temperature has actually been lowered.

It mav be stated that under the normal conditions of

i88 CA RBOH YDRA TES

life the effect of a moderate dose of alcohol on the bodytemperature has no importance. In circumstances of briefexposure to cold the discomfort due to a chilling of theface and extremities may be mitigated by the use ofalcohol, but the use of it during, or as a preliminary to,prolonged or severe exposure to cold, is to be condemned.

Poison Action.—It is stated that f pint of absolutealcohol or nearly a pint and a half of proof spirit is a fataldose for an adult; recent experiments go to show thatdilution does not appreciably affect the rate of absorption,and consequently the concentration of the drug in the blood.

There is an important distinction between the effectsof a single excessive dose of alcohol, and those produced byimmoderate quantities frequently repeated, even thoughthese quantities may be, and usually are, smaller than thesingle dose which gives rise to intoxication. In the lattercase, the drinker returns to his normal state after the alcoholhas been eliminated from the body. It is otherwise withchronic alcoholism.

The symptoms of drunkenness are due to the immediateaction of alcohol in the body, the effect of which is mainlyapparent in disturbance of the functions of the brain.There are two essential factors in the causation of chronicalcoholism. First, the drug must be taken in sufficientquantity to exercise an injurious action on the tissues ; and,second, the action must be more or less continuous. Theregular use of alcoholic beverages does not induce chronicpoisoning so long as only moderate doses are drunk. Chronicalcoholism produces a change in the tissues which may beof a permanent character, and this change is not limited tothe nervous centre, but may affect in one way or anothermost of the organs of the body. largely they are broughtabout by its detrimental action on the lining membrane ofthe stomach and bowel, causing chronic catarrh and failurein the action of the digestive juices, and so promoting theabsorption from the alimentary canal of poisonous microbialtoxins.

Some affection of mind is usually present in chronic

PHYSIOLOGICAL ACTION 189

alcoholism, but it is usually moderate in degree. In deliriumtretrLens more intense, but transitory disorders occur. It3-ppea.rs that in chronic intoxication the nervous system isimpaired in ways which affect its healthy functioning ; italso contributes towards the development of BrightJs diseaseof tlae: kidne}'S, and lowers the defences of the body againstttiicro"bial invasion. There is no evidence to support theP°p "ular belief which attributes to alcohol a protective valuein ca^es of exposure to infection.

Recent observations and experiments appear to indicatethat: parental alcoholism may have a seriously detrimentalinflta^nee on the stock, but in view of the extreme importanceof this conclusion, it is considered well to suspend judgmentuntil the subject has been further investigated.

Longevity.—It is found necessary in drawing conclusionsbetween the consumption of alcoholic beverages and longevityto bo cautious, as the scientific facts are very limited ; but,on tlie whole, the evidence is in favour of the total abstainer,their death-rate is lower, and expectation of life longer.It sliould be added, however, that it does not follow fromthese conclusions that a consistent!}- moderate use of alcoholicbevexages shortens life. Summing up, it ma}- be stated thattlie -temperate consumption of alcoholic liquors is physio-logically harmless; on the other hand, it is certainly truethat: alcoholic beverages are in no way necessary for healthylife.

SECTION IIL-INDUSTRIAL ALCOHOL

Industrial Alcohol—Alcohol is also manufactured for com-mercial use, and during the war, when large quantities wererequired, some of the whiskey and gin distilleries werecommandeered by the Government to.add to the sources ofsupply. Spirit used for heating or as a solvent in chemicalindustry was to be manufactured under the same conditionsof excise control as that used for potable purposes, but it isobvious that questions of flavouring, ageing, and so forth,which give the potable spirits their special characteristics neednot be considered when the alcohol is not to be used for food.

Molasses.—Both beet and cane sugar molasses are usedfor the manufacture of commercial alcohol; the former aresterilized by slightly acidifying the diluted molasses andboiling the solution.

Cane sugar molasses as used in this country are simplydissolved in water to make a wort of specific gravity about1030 to 1040 ; in the tropics juice expressed from the sugarcane and containing 14 per cent, of sugar is fermenteddirectly. A wild yeast is found on the surface of the cane,and this'sets up an active spontaneous fermentation whenthe juice is kept at a temperature of 30° to 35°.

Potatoes.—Potatoes are rarely used in this country formaking alcohol, but on the Continent they are largely employed.They are generally steamed under pressure to gelatinize thestarch as a preliminary to the mashing operation.

The steaming is usually effected in a conical iron vesselknown as a converter/' which is commonly of a size totake a charge of 2 or 3 tons of potatoes. In this vessel thepotatoes are subjected to the action of steam at a pressureof 3 atmospheres during 45 minutes or so, the temperatuierising to about 135° C. On opening the discharge valveat the bottom of the converter when the steaming is finishedthe softened mass of potatoes is forced out by the pressure

INDUSTRIAL ALCOHOL IQI

and passes through a grid or cutting arrangement whichhelps to complete the pulping of the mass. The latter thengoes to a mash tun, where it is cooled by water flowingthrough coils in the tun, or, in some firms, by means of anexternal water-jacket.

The starch is converted into sugar, as alread}- described,by the enzyme diastase, supplied by malt, or by the moulds inthe ff amylo " process. The proper quantity of malt employedamounts to i J to 3 per cent, of the weight of potatoes used.

Alcohol from Sugar Beet.—There are two chief methods.In one process the beet are sliced and extracted with waterin a series of vessels which are so arranged that the waterissuing from the bottom of one vessel passes into the topof the nest, percolates downwards through the packing ofbeet slices, and extracts the sugar as it goes; by the timethe end vessel 01 the series is reached the juice has becomesufficiently rich in sugar to be ready for fermentation.To minimize the action of harmful bacteria during fermenta-tion the juice is slightly acidified with sulphuric acid. Inthe second method the beet are topped, the roots andtops being stored separately, and the tops worked off first,as they lose sugar during storage. The extract is made bysteaming under a pressure of 2 atmospheres maintained forabout ij hours in a conical converter, all the sugar beingthen dissolved, and the beet tissues reduced to a pulp.The chief countries which use beet as a source of alcoholare France, Austria-Hungary, and Germany.

Alcohol Denaturants.—The object of denaturing is toprevent duty-free spirit from being put to uses other thanthose authorized. It should fulfil the following conditions :—

(1) It should impart a taste or smell sufficiently disagreeable to prevent the alcohol being drunk,even after dilution, sweetening, or flavouring.

(2) It should not be capable of being eliminated easilyby filtration, distillation, or any other processwhich can be readily applied or which is ordinarilyused in manufacturing operations.

(3) It should be capable of being easily and certainly

192 CARBOHYDRATES

detected even when present only in minutequantities.

(4) It should mix readily with the alcohol and producea mixture of essentially the same properties asundenatured alcohol, and capable of being used

'in the same way as undenatured alcohol inmanufacturing processes.

(5) Its cost should not materially add to the price ofdenatured spirit as compared with that of ordinaryalcohol.

No single substance has yet been found which fulfilsall the above conditions. Crude methyl alcohol or woodnaphtha fulfils (2), (3), and (4), but as regards the firstcondition, when mixed with ethyl alcohol to the extent of10 per cent, does not prevent the alcohol being drunk.

Wood naphtha does not quite satisfactorily fulfil thefifth condition, inasmuch as it renders the denatured alcoholslightly more costly than pure alcohol.

To render the spirit nauseating some other denaturant,such as mineral naphtha or pyridin are employed, where theconditions under which the alcohol is to be used do notadmit of strict Revenue supervision. Thus we get two classesof denatured alcohol:—

(1) Denatured for general household use and minormanufacturing purposes.

(2) Denatured for manufacturing purposes oi ?a large scale.

In this country the composition of (i) is as follows :—

90 parts ordinary alcohol.10 „ wood naphtha.f per cent, of mineral naphtha and sufficient dye to

give it a violet tint.

Practically the same mixture is used in France,U.S.A., Canada, and other British Colonies. Such a mixtureis undrinkable even when sweetened or flavoured.

(2) Denatured alcohol for manufacturing purposes con-tains :—

95 parts ordinary alcohol.5 ,, wood naphtha.

DENATURANTS 193

The mixture is not undrinkable when diluted, sweetened,and flavoured, and greater precautions have to betaken by the Revenue authorities to prevent itsillegal use. Application for its use must be made tothe Board of Customs and Excise stating clearlythe purpose for which it is to be used. Revenueofficials must be allowed to visit all parts of thefactory, and take samples of the spirits and productsat any stage of the manufacture.

In Australia a special committee have reported in favourof the use of the distillate obtained from coal-tar oil at atemperature of from 170° to 230° C. as a suitable denaturant.Experiments with this material are now being made atthe Government laboratory.

Alcohol and Benzol as a Fuel.—Quite recently theLondon General Omnibus Company have been experimentingwith a mixture of alcohol and benzol as a fuel for the internalcombustion engine. Neither burns so rapidly as petrol,and the use of the mixture necessitates constructional altera-tion in the engine, with special reference to the compression,carburettor, and heating of the induction pipes. A 50 percent, mixture was found to be the most satisfactory, itsefficiency as compared with petrol was as 12*5 is to 15.

As to cost, this may be represented by the number ofB.T.U.s per penny produced by petrol—6050 ; and by the50 per cent, mixture—5000. The cost per mile showed adifference in favour of the former of one-fifth of a penny.The mixture was found to be 12 per cent, more economicalthan petrol; the difference is 8 per cent, only in cost, petrolbeing the cheaper to use if the price per gallon of the two isthe same. It has also been found that the thermal efficiencyincreases with the increased proportions of alcohol for thesame compression; that a higher proportion of alcoholmeans also that the compression can be raised, with a conse-quent rise in the thermal efficiency. Tests with a mixtureof alcohol and ether are now being carried out.

Q. 13

SECTION IV.—SYNTHETIC ALCOHOL

THE rapidly increasing use of alcohol in the arts and sciencesas a solvent and for fuel, and the extensive development ofthe motor industry, has brought about such a demand foralcohol, that it is feared present supplies will be far fromsufficient to meet future requirements. It, therefore,becomes necessary either to increase the production ofmethyl or ethyl alcohol by increasing the number of presentplants if the raw materials required are available, or, ifthese are only obtainable in limited quantities, to discoverother methods of manufacture from other more abundantsources.

Evidently the first part of the question resolves itselfinto. What are the products which are available in unlimitedquantities ? and ordinary experience tells us that we mustdepend on Nature to obtain such materials. In order oftheir importance they may be enumerated as follows :—

(1) Wood.(a) The ordinary wood not suitable for trade

purposes.(5) Sawdust—wood pulp.

(2) Starch.(a) Cereals.(J) Potatoes.

(3) Peat.(4) Carbon.—Easily obtained by the destructive com-

bustion of any organic matter.The work which has been done on each of this class of

materials for alcohol production will, therefore, be brieflyoutlined.

(i) Wood.—There are several ways in which wood maybe treated so as to render a combustible liquid fuel.

SYNTHETIC ALCOHOL 195

(a) Destructive Distillation.—Here wood logs, shavings,and other refuse is burnt in a closed vessel and the productsare condensed and collected. The process is very ancient.Various forms of stills and many modifications of distillationare employed, but the products obtained are as follows :—

Products.

CharcoalRefined turpentinePine oilResin spirit . .Resin oilCreosote oil . .Acetate of lime, 80Wood alcoholPitch

er cen

Per 4 cords.

(High resin.)Rich wood.16,600 Ibs.

4284 Ibs.41-5 gals.11-6 „

• 21-5 „141'° ,.46*5 „

300-0 Ibs.6 gals.

1400 Ibs.

(Low resin.)Lean wood.16,000 Ibs.

4400 Ibs.20-75 gals.

4-2I2'O64'75 .21'0

350*0 Ibs9-6 gals.625 Ibs.

Hardwood.14,000 Ibs.

3600 Ibs.———— —20 gals.

852 Ibs.37-5 gals.720 Ibs.

It is evident that the amount of alcohol (wood spirit)obtained is far too little to enable the wood to be treatedby this process economically—at least for the productionof alcohol.

(b) Conversion into Sugar followed, by Alcoholic Fermenta-tion.—Wood cellulose may be converted into reducing andfermenting sugars by the process of hydrolysis, and thiscan be accelerated by the presence of catalytic agentssuch as acid. Concentrated H2SO4, H2SO3, HC1—all havebeen used. The sugars by fermentation with yeast yieldalcohol.

(i.) The Ewen-Tomlinson Process.—This consists intreating wood pulp with dilute BUSO^ and steam underpressure. 25 to 28 per cent, of the wood is rendered soluble,and of this 80 per cent, is fermentable sugar. A yield of20 to 22 per cent, of saccharoses corresponding to 10 to nper cent, of ethyl alcohol, or 35 gallons of 95 per cent, spiritper ton of dry wood is thus obtained.

The fermentation is carried out in accordance with thestandard practice of four-day fermentation period.

(ii.) Waste Sulphite Liquor.—Here bone dry wood pulp is

ig6 CARBOHYDRATES

heated with calcium bisulphite solution (2*5 to 3*0 per cent,free SO2) tinder pressure to 140° C. for 10 to 12 minutes,or 15 to 20 hours at 135° C., 14 per cent, fermentable sugarsare obtained. The solution is neutralized with lime orcalcium carbonate, allowed to settle, cooled, and run intofermentation vats. High resistant yeast—type XII.—isused to effect the fermentation.

(2) Starch.—Cereals such as barley, oats, maize, andeven potatoes have been used for the production of alcoholfor some time past. The grains (e.g. barley) are first allowedto germinate, whereby the ferment diastase is produced.The ferment converts the starch of the cereals into maltose,and this by the ordinary yeast fermentation producesalcohol.

Cereals and potatoes are, however, a staple article offood, and unless cultivation is enormously increased, thissource of alcohol production will remain too expensive forthe production of industrial spirit.

(3) Peat.—Peat may be carbonized in very much thesame way as wood, and yields the following quantities ofproducts:—

Products.Per *on.

OilsParaffin wax . .PhenolsMethyl alcoholAmmonium sulphateCalcium acetatePitch ..

Oldenburg.31% H20,-7% N.

54-0 Ibs.6-0

26*06-86'2

IO'O4-0

Scotch.1 6% H2O, 2-1% N.

50-0 Ibs.Not determined

28-0 Ibs.5"i ,>

30-2 „8-0 „3*5 »

(4) Carbon.—The direct production of alcohol fromcarbon, hydrogen, and oxygen is attractive, as these primarymaterials are available in unlimited quantities. A successfulprocess of manufacture from the elements would of necessityoust all the other processes, as the latter must depend onvarious natural uncontrolled forces. The processes attemptedare as follows :—

SYNTHETIC ALCOHOL 197

(i.) From Acetylene.—This substance is a gas, and canbe obtained either by passing hydrogen through an electricarc struck between graphite poles, or technically fromcalcium carbide obtained in the electric furnace by theaction of lime on carbon.

CaO+3C=CaC2+CO

Calcium carbide on interaction with water produces acetylene.

CaC2+2H20 =Ca(OH) 2+C2H2

Acetylene by catalytic hydrogenation is converted intoacetaldehyde.

CH=CH+H2O~>CH3CHO

The catalytic agents used are sulphuric acid (20 to 25 percent.). Phosphoric acid 30 to 35 per cent, or solutions oforganic sulphonic acids, glacial acetic acid with a mercurysalt, ferric mercuric sulphate, etc.

The acetaldehyde by catalytic hydrogenation (Sabatier'sprocess) over reduced nickel is converted into ethyl alcoholat 140° C.

CH3. CHO +H2 =CH3.CH2OH

The latter process requires careful manipulation in orderto prevent the reverse reaction taking place. The processhas been successful, and the Longa Electricity Works at Vispwill shortly be able to satisfy the total alcohol consumptionof Switzerland.

Another process of hydrogenation, started in France in1917, consists of electrolysing the aldehyde or paraldehydein an acid medium, the aldehyde being obtained fromacetylene either previously by any process or in theelectrolytic apparatus concurrently with the hydrogenation.Sulphuric acid of 5 to 10 per cent, strength is usuallyemployed, but other acid electrolytes may also be used.The aldehyde or paraldehyde is added to the cathodechamber in two stages, first up to 10 per cent., and then upto 30 per cent. The temperature is kept at about 40° C.,which is maintained by the heat of hydrogenation. Aporous diaphragm is used in the electrolytic cell to prevent

198 CARBOHYDRATES

the diffusing of tlie alcohol and the aldehyde towards theanode. The cathode may be of lead, lead alloy, or mercury.The anode is an inert material, such as platinum, lead, oriron oxide ; the current should be 2 to 3 amperes per squaredecimetre of the cathode. Alcohol may be obtained directlyfrom acetylene by passing it through the cathode chamber,provided the electrolyte contains a mercury salt.

(ii.) From Ethylene.—This is a constituent of coal gas,but no technical synthetic process for producing it has yetbeen devised. The removal of ethylene from coal gas hasbeen attempted, but trouble has been found in the subsequentprocess when the ethylene has to be converted into alcohol.The conversion of acetylene into ethylene by the additionof hydrogen is theoretically possible, but this hydrogenationhas not been successfully accomplished.

Ethylene can be converted by simple hydration intoalcohol. The process is catalytic and occurs by way of theintermediate ethyl sulphuric acid, C2H6HSO4, and givena large supply of ethylene, the conversion into alcohol doesnot offer great difficulties. Its recovery from coal gas inthis way is therefore theoretically possible, and Bury, atSkinningrove Coke Oven Works, has obtained 1*6 gallonsper ton of coal carbonized from runs of 5800 tons of coalcarbonized per week (Chemical Age, 1919, i, 714).

REFERENCES.

Hugh. S. Taylor, " Fuel Production and Utilization." In this series.Charles Simmonds, " Alcohol." Macmillan & Co. 1919.S. Hoare Collins, " Plant Products and Chemical Fertilizers." In

this series.Heriot, /. Soc. Chem. Ind., 1915, 34, 339.Brauer and Malzcr, " Kalendar." 1880.Ling and Davis, Trans. Chem. Soc., 1904, 85, 16.Baker and Hulton, Trans. Chem. Soc., 1914, 105, 1529.K. Autal, Zeitsch. Spiritusuid., 1911, 34, 239, 252.A Harden, " Alcoholic Fermentation."Dr. P. Schidrowitz, " Power Alcohol/' Times Trade Supplement,

April 17, 1920.Robert N. Tweedy, " A Preliminary Statement [Organization of

Distilling Societies]/' Better Business, April, 1916, pp. 193-211 ; November,pp. 31-53 ; February, 1917, pp. 104-26 ; May, pp. 193-213. Reprinted as15. pamphlet.

W. T. Rowe, " Alcohol as a Source of Power/' Bull. Dept. Chem. SouthAustralia, No. 8, 1917, 12 pp.; Engineer, 30 November, 1917, pp. 471-2.

SYNTHETIC ALCOHOL 199

" Die Erzeugung von Sprit aus Karbid. Ihr Wesen und ihre Bedeutungfiir die Schweiz." [From Bund.} Neueste Erfmdungen, Jahrg. 44, 1917,pp. 592-4.

" La Synthese Pratique Falcool," La Nature, 9 June, 1917, pp. 357-8." Production from Wood," Times Engineer. Suppt., July, 1917, p.

H5. i %•" Synthetic Alcohol" [from acetylene, with references to patents],

Perfumery Rec.t September, 1917, pp. 276-7." Industrial Alcohol/* Statist, 29 September, 1917, pp. 527-28; 6

October, pp. 568-69 ; 3 November, pp. 730-1 ; 10 November, pp. 991-2 ;17 November, pp. 1031-2 ; i December, pp. 1121-2 ; 8 December, pp. 1162-3.

" Alcohol Fuel and Engines/1 Nature, 10 October, 1917, p. 129.A. Truelle, " Le prix de revient de 1'alcool de pommes chez les pro-

ducteurs," La Nature, 15 December, 1917, pp. 380-1.Erik Haegglund, " Alcohol from Waste Sulphite Liquor/' Paper,

26 December, 1917, pp. 11-4 and 34 ; 2 January, 1918, pp. 16-7 and 30 :9 January, pp. 13-5, 2 figs. Naturwissenschaften, 18 January, 1918,pp. 25-30.

Ellwood Hendrick, " Alcohol from Sulphite Pulp Waste Liquor,"Paper, 3 April, 1918, pp. 13-5, 2 figs.

" Alcohol in Industry/' Nature, 31 October, 1918, pp. 166-7." Possible Sources of Supply/' [Comparative yields, synthetic pro-

cesses.] Times Engineering Suppt., November, 1918, p. 228.W. R. Ormandy, " The Motor Fuel Problem." [Alcohol, alone, or in

conjunction with benzol, recommended. With discussion.] Jour. Inst.Petroleum Technologists, December, 1918, pp. 33-69.

Paul Baud, " L'alcool de grains ; un nouveau procede de fabrication."[Industrial alcohol, fermentation by Amylomyces Rouxii in confined atmo-sphere,] La Nature, 25 January, 1919, PP- 230-3, 5 figs.

PART VI. -VINEGAR

SECTION I.— PREPARATION OF THE WORT

IK all the processes for the manufacture of vinegaris taken of the oxidizing action of the vinegar fungus ; thetwo chief are Mycodcrma aceti, also known as Mycodcruuivini, and the Bacterium xylinum. These ferments arccapable of converting fermented alcoholic liquors into aceticacid ; they are white gelatinous nitrogenous plants requiringfor their growth proteid substances and mineral salts whichare always present in wines and other alcoholic liquids.The fermentation is due to enzymes in the plant cell.

Pasteur examined the Mycoderma accti, cultivated it. insynthetic media, and proved that it acted as a carrier ofoxygen from the air to the alcohol, and that it was capablewhen no more alcohol was available of oxidizing acetic acidto carbon dioxide and water. The highest concentration ofacetic acid that can be obtained by the use of this organismis 6*6 per cent.

Bacterium xylinum, investigated by Brown, occurs inthe vinegar plant, or mother of vinegar, in which it. isassociated with a yeast. The mixed growth is capable ofconverting cane sugar solution into vinegar, the sugar,which is itself not attacked by the bacillus, being hydrolysedand fermented by the yeast, with production of alcohol,which is then oxidized by the organism. The chemicalactions of this organism were found by Brown to agree ingeneral with those of B. aceti.

A large number of organisms have been found whichhave a similar action on alcohol, and which include thosefound in vinegar breweries. They are not very clearlycharacterized. Further information can be found in various

VINEGAR 201

papers in Centr. Bakt. Par. AU.y ii. 1905-6 ; and Garungs-bacteriologisches Praktikum, Berlin, 1909.

Quick Vinegar Process.— This method is applicable toany alcoholic liquid. It differs from other processes incausing the liquid to expose a very large surface to theaction of the air, I gallon being sometimes exposed overan area of 100 square yards. The vat is usually from 6 to12 feet high, and has a false perforated bottom, upon whichis placed a quantity of thoroughly washed beechwoodshavings, nearly filling the vat. Air holes are bored in thevat about 18 inches from the bottom ; the top of the tunis a perforated disc, through which twists of cotton or stringare passed of sufficient length to touch the shavings. Thevinegar is drawn off by means of a pipe, when it rises to aheight of about 15 inches. Before commencing the fermenta-tion it is necessary to sour the shavings ; the composition ofthis fluid varies considerably ; any alcohol liquid may beused, but the presence of a trace of tany matter preventsthe action.

According to Wagner, the following mixture is generallyused : —

4^ gallons (20 litres)9 ,, vinegar (42*5 per cent, by weight).

27 „ water.

To which is added a mixture of bran and rye to promotethe growth of the vinegar fungus.

Another standard liquor is : —

50 gallons brandy or whiskey (52 per cent, by weight).37 ,, beer or malt wort.3 to 4 volumes of soft water.

Molasses or honey in the proportion of 2 Ibs. to 50 gallonsis added to produce a more- finely-coloured vinegar. Theliquid to be fermented is poured over the upper disc andtrickles slowly down the twisted threads, and over theshavings, becoming oxidized by the action of the air which

202 CA RBOHYDRA TES

is drawn through the air holes on account of the rise intemperature. The acetified liquid collects beneath thefalse bottom; it is drawn off and usually passed throughthe same vat 3 or 4 times before the oxidation is completed.The strongest vinegar that can be obtained by this methodcontains about 10 per cent, acetic acid.

Acetates.—The following are the most important saltsprepared from pyroligneous acid, and vinegar.

Aluminium acetate, known as " red liquor/' or " mordantrouge," is used in dyeing for the production of red colour.One method of preparation is to add a solution of alum toacetate of lime liquor. The lime is precipitated as sulphate,its place being taken by the aluminium forming the acetate.

Calcium acetate is prepared by neutralizing acetic acid, orpyroligneous acid, with chalk. It is used as the source ofother acetates, and acetic acid : it is also employed in calicoprinting.

Copper acetate.— This occurs as the normal salt, and intwo basic forms, as blue verdigris and green verdigris, thecolour and composition changing according to the mode ofpreparation.

Copper acetates are used as pigments in oil and watercolours.

Ferric acetate is prepared by the addition of calcium orlead acetate to ferric sulphate. It is used as a mordant, andin alcoholic solution as a medicine.

Ferrous acetate is prepared by the action of pyroligneousacid on iron turnings, or nails at a temperature of 65° C.It is known as black liquor, and is used in calico printing,dyeing, and colouring furs, leather, wood, etc., black.

Lead acetate is produced by the action of acetic or pyro-ligneous acid on litharge ; two basic acetates are also known.It is used as a mordant, pigment, and in medicine.

Magnesium acetate as a basic salt is known in commerceas " Sinodor."

'Sodium acetate is used as a preservative, and as a sourcefor the preparation of acetic acid. Potassium acetate occursin many plants.

SECTION II.—ACETIFICATION

lalt Vinegar.—This is prepared from au infusion oflalt which has first been fermented to produce alcohol,ix bushels of crushed malt are extracted 3 times with wateri a circular mash tun supplied with a central stirrer, the.rst extraction with water at 72° C., the second at a higheremperature, and the third with boiling water. The extracts,fhich together should not exceed 100 gallons, are passedito a large cast-iron tank, cooled by refrigerators to 24° C.,nd then poured into a large circular vessel, mixed with

or 4 gallons of .good yeast, and fermented briskly forbout 40 hours. The extract is filtered and stored in casksDr some months, whereby the extractive matters whichfould produce putrefaction are deposited. The "wash"lay be treated by the quick vinegar process, or acetifiedi large casks lying on their sides in a temperature of about4° C. The bung holes of the casks are open, and at eachnd near the top an opening is made for the circulation ofir. When conducted in the open air the process is knowns " fielding/' From 8 to 20 rows of casks constitute ainegar field. The operation is commenced in the springnd completed in about 3 months.

Malt vinegar is a brown liquid of a characteristic odour,ue to the presence of esters. It has an agreeable acidaste due to acetic acid. It usually contains alcohol, gum,ugar, and extractive matter, acetates, chlorides, free andDmbined sulphuric acid, and on evaporation and ignitionbaves a residue containing much phosphate.

Wine Vinegar.—The following is the plan of makingdne vinegar as practised in the district of Orleans. Wines

204 CARBOHYDRA TES

which have become sour are generally used, if they containabove 10 per cent, alcohol they are suitably diluted withweaker wines. The wines for acetification are kept incasks with beech shavings to which the lees adhere, the winethus clarified is drawn off to make vinegar. A certain amountof extractive matter is, however, necessary for the propergrowth of the plant. The Orleans casks contain nearly400 pints, and are placed in 3 rows one over another, theupper ones having an aperture of 2 inches in diameter keptalways open. 100 pints of good vinegar, boiling hot, arefirst poured into each cask and left there for 8 days, 10 pintsof wine are mixed in every 8 days, until the vessels are full.The most favourable temperature is between 25° and 30° C.,and is kept up when necessary with a stove.

The casks are never more than half emptied, but aresuccessively filled up again to acetify new portions of wine.In order to judge if the fermentation is completed at theend of the usual time, which is from 8 to 30 days, accordingto the time of year, the workman plunges a spatula intothe liquid. If reddish froth adheres more wine is added,and the temperature raised. A white froth indicates thecompletion of the process.

The casks become foul after 6 years. The deposit ofargol, yeast, and sediment is then removed, and they arecleansed and recharged with hot vinegar, as in the case ofnew casks. Good casks will often last 25 years.

Wine vinegar is of two kinds, white or red, accordingas it is prepared from white or red wine; the former is con-sidered the finer. In addition to the substances usuallymet with in malt vinegar, it contains potassium tartrate,by which it can always be recognized.

Vinegar from Alcohol.—Three million gallons of alcoholare used yearly in Germany for vinegar making. Purealcohol does not suffice as a medium in which acetic fermenta-tion can take place, since nitrogenous substances and saltsare necessary for the growth of the organism. Cane sugaror glucose is usually added in the proportion of I to 3 kilos,per 100 litres of pure alcohol, while the nitrogenous needs

VINEGAR 205

are met with inorganic salts, chiefly acid phosphates ofammonium, sodium, and potassium, about 50 to 150 gramsare used per 100 litres of pure alcohol. The acetificationvessels are cylindrical in form, with a false perforated bottomupon which are beech shavings ; in the sides are air holesfor oxidation.

The alcohol is diluted to a strength of 6 to 10 per cent,mixed with the required nutrient materials and deliveredon top of the shavings ; when starting with a newly-packedvessel a pure culture of the bacterium is mixed with thefirst charge of alcohol; subsequently some of the acetifiedproduct is used for mixing with the charges. The tempera-ture of the vessel is kept at 25° to 35° by controlling theadmission of air and of the alcoholic charge. The resultingvinegar is collected in the bottom of the vessel, and containsfrom 4 to 6 per cent, acetic acid. Double or triple strengthproducts can, however, be produced by mixing ordinaryvinegar with fresh alcohol and treating with suitableorganisms in other vessels ; up to 12 per cent, of acid canthus be obtained.

In addition to wine, malt, and alcohol, vinegar is pre-pared from cider, perry, beer, glucose, and skim milk.

An artificial vinegar is made by mixing acetic acid withwater and caramel, and acetic esters to produce the propercolour, odour, and taste. This vinegar differs from genuinekinds by the absence in the evaporated residue of phosphoric,tartaric, or malic acid.

The vinegar of the B. P. has a specific gravity of 1*017to 1*019, and the minimum of acetic allowed is 6 per cent.Genuine vinegar seldom falls below 5 per cent., and shouldbe condemned as adulterated with water when the amountis as low as 3 per cent.

The chief adulterants are mineral acids, flavouringagents such as cayenne and ginger, and metals derivedfrom the vessels used.

Vinegar manufactured in Germany from denatured brandycontains a certain quantity of pyridine which can be estimated(see Zeitsch. Untersuch. Nahr. Genussm., 1911, 21, 655, 658).

SECTION III—ACETIC ACID

Acetic Acid, CH3COOH.—Acetic acid occurs in nature inthe juices of many plants, especially trees, either as freeacid, or generally as the calcium or potassium salt; andas organic acetates in the oils from many seeds. It is alsofound in certain animal secretions.

Formation.—The greater part of acetic acid used incommerce is obtained by destructive distillation of wood.Hardwood, such as oak, birch, beech, maple, and elm givethe best yields of acid and wood alcohol. A full descriptionis given in H. Taylor's book on " Fuel Production andUtilization " of this series, from which the following extractsare taken :—

There are three processes in use :—(a) Kilns of the beehive type with a capacity of

50 to 75 cords, now almost obsolete, owing tolow yields of charcoal and loss of by-products.

(V) Discontinuous retort plants :—(1) Small retorts holding from I to 5 tons of

bulk wood;(2) Large retorts, or ovens, the charge being

10 to 15 tons in bulk form.(c] Continuous mechanical plants; carbonizing chip-

pings or shavings only.The retorts are usually steel-plate cylinders which can

be revolved to expose new surface to the action of the fire ;others are rectangular steel ovens of large capacity, intowhich the wood may be charged on trucks. The fire inmodern plants is removed from the retort by means of arches,and arrangement is made for circulation of the furnace gasesaround the retort in such a way as to secure the most effective

7*:- ;:::!* r- ^ -A-^:-^ o; n-?:ir^:sip ^t^H

"; ;~ ]:<•"•:• ir;» ir-^r TO

2oS CARBOHYDRATES

Palmer and Cloukey, Jour. Ind. Eng. Chem., 1915, 7. Itwas found that moisture has a favourable influence on theyield of acetic acid in controlled distillation. The effect ofcatalysts is also dealt with by Palmer, Jour. Ind. Eng. Chem.,1918, io} 264. Wood chips impregnated with aqueousphosphoric acid, and then distilled, gave largely increasedyields of acetic acid. An increase from 5*13 per cent, tc13-85 per cent, was obtained in one experiment, in which2'45 per cent, of catalyst was added.

To obtain ordinary commercial acetic acid, acetate cflime is mixed with calcium chloride in proper proportions,and the solution concentrated until it crystallizes. Themother liquid is poured off and concentrated with theproduction of a second crop of crystals; this is repeateduntil about four crops have been obtained. The crystalsare then dissolved in water, filtered through animal charcoalmixed with about 10 per cent, of calcium chloride andrecrystallized. The crystals are distilled with a mixture ofi part sulphuric acid of specific gravity 1*84 and 2 partswater, and the resulting acetic acid concentrated. This acidshould contain 33 per cent, by weight of hydrogen acetate.

Synthetic Acetic Acid—During the war large quantitiesof acetic acid have been manufactured synthetically ; theprocess being the same as that described under syntheticalcohol in this volume, as far as the production of acetalde-hyde. This substance is converted into acetic acid byoxygen obtained by the fractional distillation of liquid airin the presence of a catalyst. According to the Drefuspatents (e.g. French Patent, No. 479656/1916, and BritishPatent, No. 105064/1917), which have been operated in theproduction of acetaldehyde and acetic acid from acetA-lene,the gas is passed with water : (a) into solvents in whichmercury is soluble, e.g. sulphuric, phosphoric, and aceticacids ; or (b) into solvents in which acetylene is soluble, e.g.acetone. In the former case, one or more of the followingconditions are observed :—

(i) With sulphuric acid, a concentration limit of 5 to20 per cent, is set.

jvcv*" *... i::i :. *"...,.r.*r.-i'*, *i • *".•-.•'..*.!,*

with, a Uycr ~: hi : f*al^ aav. •-: ba?:; 1 .1 •treatment with suIyL:r:. a..;! :r nun-r^-i :•: 5".citric adds.

internally Tvi:h ccclir:^ 7:::^^ 7-r^i:ct-:-d ^riirjof acid. Th-< i.eti: u-::J ,' :-;:,. I by :..:- rrhigh purity.

solvent ; in rliov<?cr-t;::y . :n !r:~d,cn^ ^f u. Iand to allay fevtr i and ::; the f rm c: -^vllir:,:

T?« — - 2; ,;..,• * . - - -T, - - - : - ** • • • » . - - . . , , 1 .»Jror mc.^.inj.* ^^.j J -.. . • . • - ^^v^*,. -.-.•.J» r; •.-1*044, diluted with ::•• c ... ^ : *^tcr *h-:ul.I notdischarge tie colour ,,: -r:-. i:'-:.• '• : 3C'!u*:on^ermar::j.i::....*v Al- • " ^ , . 'J-1 :.• ju.:--- :..-:

2IO CARBOHYDRATES

287 c.c. of N. sodium hydroxide. There should be noresidue on evaporation, and no characteristic reactions forcopper, chlorides, nitrates, sulphates, and sulphites.

Glacial Acetic Acid is usually prepared by the distilla-tion of a dry acetate with an equivalent quantity of strongsulphuric acid or acid potassium or sodium sulphate.

Sodium acetate is generally used. The anhydrous saltis fused on sheet-iron pans, the mass is cooled, broken intosmall lumps, and distilled with concentrated sulphuric acid.The first portion distilling contains the water, the latterportion is collected and cooled ; when crystals have formedthe still liquid portion is removed, the crystals are meltedand redistilled as before, producing the glacial acid. 100parts by weight should contain 98*9 parts of hydrogenacetate, the specific gravity of the liquid being 1*058, whichrises on the addition of 10 per cent, of water. Each grammediluted with 50 c.c. of water should require for neutralization16*6 c.c. of N. sodium hydroxide.

Aromatic Vinegar is prepared by distilling crystallizeddiacetate of copper. The acetate is dried at 160° C. andheated in earthenware retorts, when the glacial acid distilsover. The verdigris produces about half its weight of theacid. The pleasant odour is largely due to acetone, whichis always produced when acetates of heavy metals aredistilled. Other flavouring ingredients are, however, alwaysadded. .

In the Acidum Aceticum Aromaticurn of Belgium andRussia, oil of cloves, lavender, orange, bergamot; thyme,and cinnamon are used; while in the French preparationcamphor is the chief flavouring ingredient.

SECTION IV.—ACETONE AND GLYCERLYK

Acetone, CO CH: 2, is a mebil- -nammabl- liquid,boiling at 56" C. with a speciric gravity ?-S:4^ at •: - C.Before the war the main sources of acetonv were the UnitedStates and Austria, in which countries it v\as produced fromacetate of lime made by treating acetic acid with lime.The acetic acid is either obtained synthetically, a? alreadydescribed ?p. 2cS , or by the destructive distillation o:hardwood -p. 2^6'-. The vapours are tai-cd in:-* *.:r-::^htvessels, heated to about 500: C.:. containing rcrcut materialsuch as pumice stone or bricks, the pores have bevri filledwith the carbonate of an alkaline e^rth. such a.? lime crbaryta. The porous material is packed into iron cylindricalretorts, which are heated to =00: C, and heated acetic vapouris introduced. This coming into contact with the largesurface of the alkaline carbonate is decomposed into acetcne,water, and carbon dioxide. The pcrous nature of thepacking material obviates the necessity for mechanicalagitation, which has been found necessary when the carbcn-ates of the alkaline earths are employed in this method inany other form. When war broke cut the demand foracetone was greatly increased. The quantity preducedin this country was practically negligible as ccmtared withthe large and rapidly increasing requirement? c: this solventfor the manufacture of cordite, and later en fcr atrcp.lancdope.

In 1915 Dr. C, Weizmann brought to thx notice c: theAdmiralty the production of acetone by bacterial fermenta-tion from maize or other substances containing starch-

This process had previously been investigated by Fern-bach as far back as 1010, He obtained acetone and tuty!

2I2 CARBOHYDRATES

alcohol from starchy raw material by fermentation, and afactor}' was started by the Synthetic Products Co. at King'sLynn. Potatoes were used as the raw material, and thebacteria were those of Prof. Fernbach.

Up to the time of the war, however, the butyl alcoholwas considered of greater importance, and efforts werebeing made to utilize the product for the manufacture ofsynthetic rubber.

The failure of the Synthetic Products Co. to produceacetone in large quantities from potatoes resulted in thefactor}- being taken over by the Ministry of Munitions, andat the same time other factories were fitted up, but grainwas substituted for potatoes, and Weizmann bacteria used.

When grain became short and had to be reserved forfood, resource was made to horse chestnuts with promisingresults.

The manufacture of acetone by the Weizmann processattained the greatest success at the factory of BritishAcetones, Toronto, I/td., in Canada, where an output ofnearly 200 long tons a month was reached.

In the fermentation of maize or other substances con-taining starch by this process, acetone and butyl alcoholare produced in the proportions of approximately I part ofacetone to 2 of butyl alcohol.

As butyl alcohol had only a restricted use, both for warand industrial purposes, experiments were started by Dr.Weizmann in order to develop a process for convertingnormal butyl alcohol into methyl-ethyl ketone which, inthe pure state, is equally suitable as acetone for the manu-facture of cordite. The process, which was a catalytic one,was worked out on a laboratory scale, and promised to givegood yields; it was decided to erect a large-scale plant atToronto, which, however, only commenced successful opera-tion just before the signing of the Armistice.

The results obtained during the war have proved thatacetone can be produced successfully on a large manufac-turing scale by the fermentation of substances containingstarch. The process cannot, however, be considered as a

ACETOXE 213

°O33ainercial one likely of being capable of competing with-k-^ production of acetone by the destructive distillation

°f wood, because of the relatively high cost of the rawrria-"terial> and the fact that the production of even- part of

involves the production of 2 parts of butyl alcohol,Very little value for industrial purposes, at all events,

"th.e present time. From the purely practical point ofthe chief field for investigation is the utilization of

waste products. In a maize mash fermentation therels a- solid residue of approximately 13 per cent, of the totalrn-aiz;e used. This has a very high oil content, since duringf eirxnentation the maize oil is untouched. The albuminoidc<333-1:erLt is also fairly high, because all the nitrogen presentis not: used up by the bacilli during fermentation.

-Ajnother problem for the technical investigators is theutilization of the waste gases produced, the amount beingappros:iniately 5 cubic feet per Ib. of maize used. Anotherpoint: is the disposal of the butyl alcohol, which before the

was being experimented on for conversion into synthetic

In foreign countries the raw material can be growny and bought on the spot ; for example, in India

unpolished rice might be used. Millet is also available inlarge quantities.

It; seems, therefore, that the future of the \Veizrnarmprocess lies abroad, rather than at home, although fromttue pure research point of view much might be attainedin "tlie laboratories in this country.

Vifeizmann Micro-organism. — The micro-organismfor the production of acetone and butyl alcohol from

containing starch is a bacillus of the long rod type,stained readily with carbol fuchsin, but only lightly

methylene blue. In a vigorous culture spore formationwrill not take place much before the lapse of 20 to 24 hours.G-irowtli occurs readily in various liquid media, that whichis -used most frequently being 5 per cent, maize mash. Itis possible to rear colonies on a solid medium made by

2 per cent, agar to partially fermented maize mash.

2I4 CARBOHYDRATES

A recipe used with excellent results is 1000 c.c. wort ofspecific gravity 1*008, I per cent, of gelatin, I per cent,calcium carbonate, and 2 per cent. agar. Heat gently,filter, sterilize, and make up into tubes. Attempts to pre-pare plate cultures with this medium have been unsuccessful.

Since acetone is inflammable and has a low boiling-pointand gravity similar to petrol, it works satisfactorily in aninternal combustion engine, and could, therefore, if producedeconomically, supplement the latter during the presentshortage.

Glycerine from Molasses.—Pasteur in 1858 observedthat glycerin, and succinic acid, in traces are products ofthe so-called alcoholic fermentation of the sugars. Thereis every reason to believe that the glycerine formed in thisway owes its origin directly to the sugars, and not to thesecondary constituents always present in those fundamentalliquids, worts, must, etc., met with iir commerce. Despitenumerous attempts to obtain glycerine in quantities whichwould be commercially profitable, up to quite recently nosuccess has been met with.

In the summer of 1917 it was known that the Germanswere producing glycerine in large quantities by the fermenta-tion of sugars.

John R. Eoff three months later was able to produceglycerine in such quantities that if the actual cost of therecovery was not too high, the process would be commerciallyprofitable.

The following is an outline of his experiments: Thesugars were fermented with 5 per cent, of sodium carbonate,which must not be added to the liquid all at once. A lessquantity of the alkali diminishes the yield of glycerine,whilst a larger quantity stops fermentation ; other alkalinesubstances may be used, but sodium carbonate is preferableon account of its cheapness. It should be added as soonas the fermentation has well started, and in as large quantitiesand as frequently as is possible without stopping fermenta-tion. The earlier the addition of the alkali, the higher the

GLYCERIXE 215

yield of glycerine will be. Pure yeast cultures are mosts-uitable, and the presence of ammonium chloride in thefermenting liquid augments the yield of glycerine. Thesciost favourable temperature for the fermentation is 30" to3"2'~ C., higher temperatures lead to a loss of alcohol andglycerine and to the formation of objectionable substances,w.uilst smaller yields of glycerine are obtained at lowertemperatures. The most favourable concentration for thes-ugar solutions lie between 17*5 and 20 grains of sugar perloo c.c. \Vhen fermentation is complete, according to this£3.e±h.od, 20 to 25 per cent, of the sugar originally presentin the liquid is converted into glycerine, and practically alltixe remainder into alcohol and carbon dioxide.

When the sodium carbonate has been added to thefermenting solution in sufficient quantity, a copious pre-cipitate is formed, the evolution of gas ceases, and theyeast apparently lies dormant for awhile. The precipitateeventually disappears, and the fermentation again proceeds.It is essential that the above reactions should take place.Solid sodium carbonate produces better results than if it isadded in the form of a solution. The purification of thefermented wash is carried out as follows : The wash isneutralized with sulphuric acid, and a saturated solution ofcommercial ferrous sulphate (copperas) added. The washis then nearly brought to the boil, milk of lime added, untiltlxere is excess of lime in solution, when the wash is boiledfor half an hour. The liquid is then passed through a filterpress and the cake steamed. The lime and copperas treat-ment is then repeated, and after again being passed througha filter press the alkalinity is brought to 0*2 per cent.(ISTa2CO3) by the addition of soda ash. It is then filtered,pressed, and steamed, and the filtrate evaporated to a thicksyrup. It is then distilled in a still resembling that ofJol>bin, only about half the glycerine present in the fermentedwash being obtained.

Experiments have been carried out on a commercialscale, using inedible " black strap " Porto Rico molasses ; asonly half the glycerine present in the fermented wash is

216 CARBOHYDRATES

recovered as crude glycerine, the yield works out thereforeat about 5^ to 6 Ibs. per cwt. of molasses dealt with.

However, the value of the alcohol at the present priceshould balance the cost of all material and overhead chargesentering into the production of the fermented wash ; sothat the only cost to be considered for the glycerine wouldbe that of purification and distillation.

Experiments have also been carried out with cane sugarand starch glucose as fermentable material. It was foundnecessary in these cases to employ yeast foods that deloteriously influenced the purification of the glycerine. Itwas therefore concluded that these materials had ixosuperiority over molasses for the purpose.

As molasses in Australia and Fiji are waste products andrun into the sea, the present process should be of greatervalue in such countries.

In Austria during the war large quantities of glycerinewere made by the Connstein-Liidecke process. In thisprocess the fermentation proceeds in presence of sodiumsulphite, acetaldehyde is produced in equivalent amountto the gtycerine with a maximum yield of 38 per cent.

REFERENCES.

Hugh S. Taylor, " Fuel Production and Utilization." Dr. S. Kidcal'sIndustrial Series.

J. C. Lawrence, Jour. Soc. Chem. Ind., 1918, 375 T.Palmer, Journ. Ind. Eng. Chem., 1915, 7 ; 1918, 10, 262-264.Rideal and Taylor, " Catalysis in Theory and Practice." Macmillan.

1919.F. Hunter and the United States Alkali Co., Liverpool, " Acetone

Improvements in the Manufacture/' Eng. Pat. 2816, 17 December, 1898." Conference on the Recent Developments in the Fermentation Indus-

tries," Jour. Soc. Chem. Ind., May, July, 1919."The Chemistry of Alcoholic Fermentation." E. Zcrner, Her., 1920,

53 [B], 325~334- See also /. C. S. Abstracts, 1920, i. i'2.\; i. 125 and i. 350.

INDEX

ACETATES, 202Acetic acid, 206

synthetic, 208properties, 209glacial, 210

Acetification, 203Acetone, 211Acetylene, alcohol from, 19 /Agnation, 128Alcohol, absolute, 176

physiological action of, 1»*as a food, 184mental effects, 185action on the digestion, respira-

tion, 186poisonous action, 188industrial, 190denaturants, 191synthetic. 194

Alcoholic fermentation, 140Amylo fermentation process, 116Animal charcoal, 129Argol, 168Aromatic vinegar, 210

Bacterium xylinum, 200Bagasse, 61Barium sucrate, 13Barley. 140 .Beet juice extraction, y*

purification, 100Beetroot, 83

cultivation, 84selection, 85composition, 86washing, 94slicing, 94pulp, 99

Beet sugar manufacture, 87history, 88

Black strap, 215Blankit, 65Boiling beet juice, 113

to grain, 116, 130control of, 117

Boivin and Loiseau, 103

Brandy, 178British, 179cognac, 179" marc/' 179

British wines, 161

CALCIUM sucrates, 13, 123Cane mills, 54

sugar, 45nistory, 45production, 48plant, 48

Caramel, 138properties, 138manufacture, 138uses, 139

Carbon, alcohol from, 196I Carbonatation, 691 Carbon dioxide, 108! Cellulose, 1! Centrifugals, 80i Char, 129| Clarification of cane juice, 64

continuous, 66Claassen's method of boiling, 117Cognac, 179Cooling and refrigerating, 149

: Copper wall, 71' Cordials, 184: Crystallization, 77

in motion, 120Crystallizers, 79Cube sugar, 131Curin's method of boiling, 117Curing, 78Cush-cush, 63

DEFECATION, 101single and double, 102agents, 64

Defecators, 66Demerara rum, 180Demdng's superheat clarification, 6Denaturants of alcohol, 191Destructive distillation, wood, 195

peat, 196

218 INDEX

Dextrin, 5, 31torrefaction process, 31acid process, 32uses of, 33references, 43

Diastase, 142Diffusion battery, 95

Hyross Rak, 98process, 67beet, 92theory of, 93

Distillation, 174Drying massecuite, 130Dubrunfaut, 122

and Leplay, 123

ELIMINATORS, 68Elution process, 123Ethylene, alcohol from, 198Evaporation, 71

beet juice, 109Ewen-Tomlinson process, 195Exhausted pulp, 99

drying, 99

FECULOSE, 33Feints, 181Fermentation, 151

changes during, 153Fernbach, acetone process, 121, 211Filtering media, 71Filter press, 106Filtration of cane juice, 128

through char, 129of beet scums, 105

Fore shots, 181Formaldehyde, 65Fructose, 9

preparation, 10properties, 10

Fryer's concretor, 72

GALACTOSE, 11Geneva, 183Gin, 182Glacial acetic acid, 210Gloy, 33Glucose, 7, 34

properties, 8manufacture, 36solid, 39references, 43

Gluten, 20Glycerine from molasses, 214Grain spirit, 170

malting and mashing, 170Granulated sugar, 131Grape sugar, 39

references, 44Grist, 143

HATTON'S continuous defecator, 66Herzfeld, solubility of sugar, 114Hollands, 183Hops, 148Hydro-sucro carbonate of lime, 103Hydrosulphites, 65Hyross Rak's process, 98

INDUSTRIAL alcohol, 190Invertase, 10Invert sugar, 10

properties, 11preparation, 132

Irish whiskey, 181

JAMAICA rum, 179

KESSELER'S extraction process, 61Kestner evaporator, 75

LACTOSE, 14properties, 14

Lees, 168Lillie evaporator, 75Lime kilns, 107Ling, glycerine process, 122Liqueurs, 184

MACERATION and imbibition, 55of beetroots, 90

Maize or corn starch, 20Malting, 141Maltose, properties, 13

preparation, 42references, 44

Maple sugar and syrup, 135Marc, 164Mashing, changes during, 145Massecuite, 118

treatment, 119Megass, 61Melting, 128Molasses, beet, 121

acetone from, 121glycerine from, 122, 214fodder, 100composition, 80utilization, 81

Multiple effect, 112crushing, 56

Muscovado sugar, 77Must, 163

constituents of, 164Mycoderma aceti, 200

vini, 200

NAUDET'S process, cane, 60beet, 97

OSMOSE process, 122

INDEX 219

sugar, 13GI^anela train, 72latent stills, 174JPeat, alcohol from, 196Potato, 183

starch, 24rasper, 27

I^ot still, 174Dressing beetroots, 89"Proof spirit, 176

RAFFINOSE, 14properties, 14

Raw sugars, 127Recovery of sugar from molasses,

122Rectifying, 175Refinery molasses, 132Refining, 127Rice starch, 22Rum, 179

^accharomyces ellipsoideus, 165Saccharum, 11

preparation, 132Sago, 29Saturation, 117Scheibler, 123Schnapps, 183Scotch whiskey, 181Scums, 107

treatment of, 70Separation process, 123Shoemakers' paste, 33Sorghum sugar and syrup, 134Spirit, proof, 176

potable, 178grain, 170potato, 183grape, 184

^Spiritus rectificatus, 175Starch, 3

arrowroot, 29fermentation process, 18maize, 20potato, 24properties, 4references, 43rice, 22soluble, 29sources, 16statistics, 40sweet process, 19uses, 30

Steffen, 123Stills, patent, 174

; Stills, pot, 174CoSey, 174

: Strontia process, 123Strontium sucrate, 13

process, 124: Substitution process, 123| Sucrose, 11, 45| properties, 45I Sugars, 6

Sugar substitutes, 7Sugar cane, 48

varieties, 52seedlings, 52pests and diseases, 52juice extraction, 53yields, 62juice, 63

Sugar beet, S3production, 125

Sulphiting, 105Sulphur burner, 109Sulphuring, 68Supersaturation, 117

TABLE syrups, 132Tapioca, 29Tartar, 168Tartaric acid, 168Triple efiect, 73

VACUUM pan, 73, 78beet, 115

Vinegar, wort, 200quick process, 201malt, 203wine, 203from alcohol, 204aromatic, 210

WASTE sulphite liquor, 195Water for brewing, 147Weizmann, 211WTieat grain, 17Whiskey, 181Wine, 161

must, 163slow fermentation, 165storage, 166lees, 168

Wines, sweet, dry, effervescing, andmedicated, 166

Wort, 145, 148

YEAST, 152

ZYMASE, 159