Proceedings of the

Seventeenth Annual Congress

OF THE

South African Sugar Technologists' Association

HELD IN DURBAN

20th-21st April, 1943

[The Copyright of these papers is the property of the Association]

The Association does not hold itself responsible for any of the opinions expressed in papers published herein.

To assist in conserving the supply of paper, the Association has co operated with the Printers by publishing this year's Proceedings in a reduced size of type, and hopes that the present emergency will exist for a temporary period only.

P U B L I S H E D B Y T H E

South African Sugar Technologists' Association

S T A B I L I T Y B U I L D I N G S

DURBAN

PRINCIPAL CONTENTS PAGE

OFFICERS OF THE; SOUTH AFRICAN SUGAR TECHNOLOGISTS' ASSOCIATION . . . iii.

LIST OK ME.MBERS AND GUESTS . . . iv.

OPENING ADDRESS by MR. H. F. JONES . . . 1

PRESIDENT'S ADDRESS . . . 2

EIGHTEENTH ANNUAL SUMMARY OK CHEMICAL LABORATORY REPORTS, by H H

DODDs and J. L. DU TOIT . . . 1

SURVEY OF LABOUR-SAVING AND COST-SAVINGS DEVICES, by F. MACBETH, G.

BOOTH and G. C. DYMOND . . . 23

LABOUR-SAVING DEVICES, by F. MACBETH :30

SURVKY OF PAN BOILING PRACTICE IN TIIE S O U T I I AFRICAN SUGAR INDUSTRY,

by K. M. BECHAED 36 CLARIFICATION OF NATAL JUICES WITHOUT TIIE; A I D OK SULPHUR, by M.

VIGER 41

ANALYSES OK BOILER-FEED (MAKE-UP) WATER IN NATAL, bv J. L. uv T O I T . . . 45

N E W TABLE FOR USE WITH JACKSON AND GILLIS METHOD OK SUCROSE D E T E R ­

MINATION, by G. S. MOBERLY 48

R E D ROT IN SUGARCANE IN NATAL, by A. MCMARTIN 51

HABITATION WASTES AND COMPOSTING IN THE SUGAR BELT, by G. C. DYMOND. . . 53

A PRELIMINARY SURVEY OF RECENT FERTILIZER EXPERIMENTS FOR SUGAR­

CANE, by H. H. DODDS 64

Two N E W INSECT PESTS OF SUGARCANE IN NATAL, bv J. DICK til

NINTH PROGRESS REPORT ON EXPERIMENTS AT UMPOLOZI, by P. FOWLIE and

F. L. ALMOND " t;o

OFFICERS I943-J944

President. G. BOOTH.

Vice-President. F. B. MACBETH.

Hon. Secretary. (MRS.) I. M. ASHTON.

Hon. Technical Secretary.

J. L. DU TOIT.

Former Presidents.

1926-27 1927-28 1928-29 1929-30 1930-31 1931-32

M. M. H. H.

G. G.

MCMASTER.

MCMASTER.

H. DODDS.

H. DODOS.

S. MOBERLY.

C. DYMOND.

1932-33 1933-31 1934-35 1935-36 1936-37 1937-38

G B. E. G. G

J.

C. DYMOND.

E. D. PEARCE.

CAMDEN SMITH.

C. WILSON.

C. WILSON.

RAULT.

1938-39 1939-40 1940-41 1941-42 1942-43

P. P. E. F. A

MURRAY.

MURRAY.

P. H E D L E Y

W. HAYES.

MCMARTIN

1926-27 1927-28 1928-29 1929-30 1930-31 1931-32

L. H G. G. G. A.

E. H S. S.

c. c.

ROUILLARD.

. DODDS.

MOBERLY.

MOBERLY.

DYMOND.

WATSON.

Former Vice-Presidents.

1932-33 A. C. WATSON.

1933-34 G C . DYMOND. E. CAMDEN SMITH.

1934-35 B. E D. PEARCE.

1935-36 E. CAMDEN SMITH.

1936-37 J. RAULT.

1937-38 1938-39 1939-40 1940-41 1941-42 1942-43

P. E. E. F. A. G.

MURRAY.

P. H E D L E Y

P. H E D L E Y

W. HAYES.

MCMARTIN.

BOOTH.

G. BOOTH.

W. BUCHANAN.

H. H. DODDS.

J. L. DU TOIT.

Council of the Association.

G. C. DYMOND.

P. FOWLIE.

W. G. GALBRAITH.

E. P. HEDLEY - .

F. B. MACBETH.

A. MCMARTIN.

G. S. MOBERLY.

J. MUNGLE.

J. RAULT.

V. SIMPSON.

in.

South African Sugar Technologists' Association.

4 If U« »

Seventeenth Annual Conference

The Seventeenth Annual Conference of the South African Sugar Technologists' Associa­

tion was held at the South African Sugar Association's Board Room, 31 Stabil i ty Buildings,

Smith Street, Durban, on Tuesday, 20th, and Wednesday, 2.1st April, 1943.

The following members and visitors were present:—-

A. McMARTIN, President.

G. BOOTH, Vice-President

ALMOND, F. L.

A VICE, C.

BEATER, B. E.

BIGARA, L. C.

Bijoux, J. C. R. Bijoux, L. H. BOOTH, G.

BRAITHWAITE, F. G.

BUCHANAN, W.

BUCHANAN, W. F.

CAMPBELL, W. A.

CARTER, R. A.

CHARTER, A. E.

CHIAZZARI, L. F.

CHRISTIANSON, Sgt. W. 0.

COBLANS, Dr. H.

DAWSON, C

DE BROGLIO, A.

DICK, Dr. J.

DISNEY, W./C. H. A. P.

DODDS, Mrs'. H. H.

DODDS, H. H.

Du TOIT, J. L.

DYMOND, Mrs. G. C.

DYMOND, G. C.

FOURMOND, T.

FOWLIE, P.

GALBRAITH, W. G.

GARNER, J.

HALLIDAY, I. G.

HAYES, F. W.

HEDLEY, Dr. E. P.

HENDRY, D. W. W.

HULLY, W.

HUSBAND, Sgt. H. E.

JONES, H. E.

KIRKWOOD, J. V.

MACBETH, F. B.

MCINTYRE, A.

MCKENNA, H. G.

MCMARTIN, Dr. A.

MARCHAND, R. H.

MILLAR, J. D.

MOBERLY, G. S.

MUNGLE, Major J. MURRAY, P.

NELSON, W. F.

POOLEY, W. L. POUGNET, J.

POUGNET, J. F.

POWELL, L. H.

RAULT, J .

SIMPSON, A. V. SIMPSON, J. R.

SMITH, E. CAMDEN.

SMITH, H. O.

STEYN, C. L.

TAYLOR, A. J.

VAN VUUREN, J. P. J.

VIGER, M.

WALSH, W. H.

WARNER, A. F.

WATSON, Lt. R. G T.

WOUTEKS, W. L.

IV.

1

SEVENTEENTH ANNUAL CONGRESS

Proceedings of the Seventeenth Annual Congress, held at the South African Sugar Association's Board Room, 31 Stability Buildings, Smith Street, Durban, on

Tuesday, 20th, and Wednesday, 21st April, 1943.

Dr. A. McMARTIN (President) was in the Chair.

OPENING CEREMONY.

The PRESIDENT: Ladies and gentlemen, it is my pleasure to introduce to you this morning Mr. Jones, who has consented to come and open our Annual Congress. Last year this Congress was opened by a gentleman in whoso hands lay the training of our future agriculturists. This year we have called again on the educational side of the Industry, but have asked a gentle­man in whose hands lies the training of the future mill tech­nologists. Mr. Jones really requires no introduction, because his name is so well-known in the Sugar Industry, especially to technical men. He knows all the younger ones by their per­formances in the classroom, and they know him as the man in whose hands lies the reports that are sent out to those interested in their welfare. I feel that this is an opportunity which has been long overdue—telling us, as a technical man, how he thinks technical men should be trained. I have therefore great pleasure in calling upon Mr. Jones to give us his views and to open this Congress.

OPENING ADDRESS BY MR. H. E. JONES.

Mr. H. E. JONES: Mr. President, ladies and gentlemen, I wish to thank the Association for the honour and privilege of being invited here this morning to open the Proceedings of the Seventeenth Annual Congress. The Principal of the Technical College is supposed to know a great deal, but his knowledge is made up of a very little knowledge of a vast number of subjects. He is supposed to know something about art; he is supposed to know something about domestic science in all its branches, about engineering—civil, electrical, mechanical—about com­merce, and about the training of all manner of people from the ages of three—we have a number of children of three or four who come to our Saturday morning art classes—to ages well beyond the allotted span—we have quite a number of people who are well over seventy coming to take art classes and to renew their youth in this interesting way. It is what I hope to do quite soon myself. But you know the difficulty is that when you come to address an audience of experts, within a very few minutes indeed you prove to them how very little knowledge you have of anything in particular. None the less, I do appre­ciate the privilege, ladies and gentlemen, and I want to speak to you very, very briefly indeed, about three things.

The first thing 1 wish to say is to impress upon you the need for research in pure science in this country. You would not expect a Technical College man to stress the need for research in pure science, but I think that is one of the greatest needs of to-day. You know many of us are interested in the develop­ment of a University of Natal. We have had a University College in Natal working now for just over a third of a century, and the time for the establishment of a University of Natal is really long overdue. We now belong to a Federal University, which embraces such institutions as Grahamstown and Wellington at the Cape, Grey's College at Bloomfontcin and others. We have also in Natal our own University College, unfortunately split into two branches, one at Pictermaritzburg and one in Durban

and that has tended to hamper the development of a uni­versity work in Natal. The time has come when we should get together and have a new constitution, establishing a University of Natal, with University Colleges at Pictermaritzburg and Durban, and possibly the Agricultural College at Cedara coming into the scheme, and perhaps also certain Native institutions, working on their own, such as Adams Mission Station, and so on. Well, I am not going to say anything more about that, except to stress again that when wc have our own university we shall be able to devote more time to research in pure science.

I have the report hero of an address delivered by my friend Dr. Phillips at the last annual meeting of the South African Association for the Advancement of Science, held on the 29th June last year. He stresses the same need. He also points to the fact that the history of science is not the history of some­thing that makes progress by leaps and bounds, coinciding with the appearance of great men. That is only one aspect of its make-up—an important one, no doubt. It is really the history of a tremendous amount of work done quietly and methodically over a number of years by a multitude of people in every civilized country in the world. Some of these people, gentlemen, one never hears of. Their names are destined to go down to posterity unknown by most of you, unheard and un­sung. But nevertheless they are the people to whom we owe a tremendous debt of gratitude. Day in and day out they pursue researches, which apparently occasionally lead them nowhere. But the sum-total of these researches are tremendous in their effect, and in their influence upon the march of ciliviza-tion. We in Natal do not have the knowledge we need. If there is any Province of South Africa where we have a number of extraordinarily difficult problems, I think that Natal is that particular Province; and we should have an University institu­tion of our own, with a trained band of workers to work out our local problems. In this way, a great deal of difficulty would be avoided in the future, I think.

I hope I am not going beyond the terms of my reference, but I say this—that physical science has made tremendous progress during the last 200 years, tremendous progress: but the moral and mental sciences have not advanced in pace with physical science. And it may well be true that what we call our racial difficulties in South Africa, especially in Natal, where we have a number of races—not only the two main races, but a number of others—it may well be true that the solution of those prob­lems might be found in knowing more about the nature of the problems. You cannot just say that this or that or a third thing is due to prejudice, unless you are prepared to define what you mean by prejudice and what factors have gone into this prejudging. You say, "Why are you talking to us like this, as Sugar Technologists3" For this reason, that you carry a great deal of weight with the Industry. The Industry has done a great deal for Natal. It is because I feel that the Sugar Asso­ciation and the Technologists' Association and other allied bodies can do so much to help on the studying of these problems that I make such an appeal to you.

2

Coming to the next point, which Dr. McMartin mentioned, I was going to speak of what we ought to do in the training of technologists. For thirty years and more students at the College have been taking chemistry, the technology of sugar and allied subjects. In 1927, in consequence of the Fahey Agreement, it was necessary to appoint a number of cane testers, and the Sugar Association approached us and asked us to help them. They also financed us on very generous terms —they always have done so, we are very thankful to them. Well, we trained them for the South Kensington examinations for a time. But the depression came along and then those classes went by the board. In 1933 we re-started them and we gave a. loss generous and less rich course, due to the exigencies of the time. That went on for about six years, and then the war broke out and the classes vanished again, completely this time. Just before the war the Sugar Association and the Technologists' Associa­tion helped us, with the aid of experts like Mr. Dodds, Mr. Moberly and others, to try out a new scheme altogether. This scheme was to be on a four-years' basis, four-months-a-year training during the non-crushing season. Instead of working for the South Kensington examination, we were going to work for our own examination, and the Sugar Association, with the aid of the Technologists, was going to issue the qualifying certifi­cates. We had devised between us a very excellent scheme to suit local traditions here. Not only were students to be trained in sugar technology and chemistry and physics and allied subjects, but also they were to be trained in the elements of agriculture and also to study Zulu, elementary statistics, mar­keting and so on. The idea was that there would be a pre­liminary examination at the end of the first two years, and the successful candidates would be allowed to carry on the course for another two years, and then there would be a final examina­tion for a qualifying certificate to be awarded by the Industry.

We hope that after the war is over we shall be in the position to start this scheme. 1 should like to say this, that whatever scheme we adopt, we should not look upon it as in the nature of the laws of the Medes and Persians. There is far too much docility in education in this country, far too little readiness to experiment. I say this, as I have for many, many years been trying to influence the authorities to set up a board to study the question of how to teach modern languages, particularly Afrikaans and English—the two main languages. I feel that we should have far more interesting methods of language teaching. When you realise the fact that you may have a pupil of three or six or sixteen or sixty years of age, it is only reasonable that you should teach them on different lines and not all much in the same way. If we had such a board we would get some­where, and I hope that after the war there will be a period when we shall be prepared to experiment, and prepared to modify our schemes in the light of experiment. I believe if we are going to avoid disastrous results in the first decade after the war we must try and produce people who are mentally agile and not afraid of making mistakes; and who are prepared to change their system quickly, if necessary, and to modify it in the light of experience gained.

The last point I want to come to, very briefly—it all hinges upon the same thing, this need for research—and that is the need for research into the question of the marketing of produce. Again and again we hear, and we read it in the press, of people saying that before the war there was over-production. The way we tried to solve that over-production was to throw fish back into the sea, burn coffee, plough-in crops—in Austria, for instance, for three years in succession they ploughed wheat crops back into the ground without even bothering to replant, because they didn't know what to do with the product. I myself think that there is a groat truth in the old verse in the Old Testament where it says that "The Almighty shall laugh in derision." We have to go into these questions. These are questions that can be settled. If we go scientifically into the subject of marketing on a world basis we would find that the question is not one of over-production, but a question of under-production. So long as there are countless millions of people in the world lacking this or lacking that which is necessary for their mental, their moral or their physical well-being, we cannot say tha t there is over-production. But it is frankly true to say that it appeared to be over-production, because we did not know what to do with the stuff, we did not know how to market it. Could we not set up some body whose job it should be to study the marketing of produce on scientific lines and in a scientific way,

co-ordinating it with the question of transport from the be­ginning to the end '! If I plead for this, gentlemen, then I have at least: been true to my job as Principal of an educational institution, in that I have pleaded for more education- -educa­tion of technologists, education of producers, education of agricultural workers, and other kinds of training in the direc­tions indicated. And, above all, the education of people who will study the problem whatever problem it: is in a dispas­sionate manner, no matter what the results may be. We need not necessarily fake their advice in everything, because xvc may want to move a. little more slowly titan they want us; but at least let us have the knowledge and understanding of these difficult questions.

I wish to pay a tribute to this Association and to the Sugar Association for a great deal of splendid work that: they have done in the past. In my official capacity I have had nothing but help from them. These institutions and members thereof have given between them thousands of pounds to lite College from time to time, and if I, like Oliver Twist, should ask for more not for my own institution, but lor the country in general

1 am perfectly satisfied that 1 shall not ask in vain.

Mr. President, ladies and gentlemen, with those few some­what cursory and inadequate remarks, I have again to thank you for inviting me here, and I have very in itch pleasure in declaring open the Seventeenth Session of your Congress, and I wish you every success in your deliberations.

Mr. HOOTI1: Mr. President, it is my very pleasant duty and privilege to return thanks to Mr. Jones for having come here to open this Seventeenth Congress of ours. Mr. Jones must not take the size of this room and the number present as a. measure of our enthusiasm or vitality. It is well understood that during these days we have to limit our activities very considerably.

Speaking on a personal note, it is something like, thirty years ago since I. first interviewed Mr. Jones - n o t on a technical but on a scholastic subject and 1 have followed ever since the activities of the Technical College in relation to the training aspect of our Industry, and I can assure Mr. Jones that it is our enthusiastic desire that one of these days—-not so far dis­tant, I hope—we shall have a Chair of Technology in this single Natal University. We were reminded in a broadcast quite recently that the Sugar Industry now takes second place in South Africa's industrial field to-day, so I think we are well justified in pressing for such a Chair; and I am sure that Mr. Jones will be only too pleased to give us the benefit of his vast experience and his advice in establishing this Chair of Tech­nology, which will provide not only for the training of chemists and engineers, but will embrace all subjects required in sugar technology.

I am glad Mr. Jones referred to marketing, because, to my mind, the marketing of our products after this war is the biggest subject in the world.

With these few words, I will ask the company to join with me in expressing our appreciation of Mr. Jones' visit and his fine talk to us. (Applause.)

PRESIDENT'S ADDRESS.

In these days, when thoughts of men are largely concerned with the problems of to-morrow, when social and political reconstruction after the war are subjects attracting an increasing amount of attention in the popular press, it might not be out of place for us to spend a little while and consider the role of individuals such as we, scientists and technical men in an agri­cultural industry, in a world which will probably place greater demands on the services we can offer.

I am instantly aware that whenever then; is a demand for greater efficiency from any section of the community to-day, it appears to be one of the first ideas tha t spring to the mind that more organisation is required, or reorganisation must be carried out; planning committees must be brought into being and a complicated structure erected in which the individual plays the part of a cog in a wheel.

I must therefore disillusion you that I have no intention of presenting any ideas on how we can be better organised; my own purely private opinion, as one engaged on full-time research

3

work, is that more organisation will not in itself contribute much towards solving the problems with which we are faced as scientific investigators; indeed, I fear that over-organisation might be disastrous, creating an atmosphere which is stifling of initiative and that freedom of thought and action which is so necessary in investigating a problem.

It appears at this point, however, only fair to point out that what I have to say may apply only to research more directly connected with the growing crop rather than the manufacturing of the final product, and that my views as a biologist are not necessarily those of the chemist or engineer.

Speaking, then, as one whose problems are mainly those of the field, and being fully aware of the vast strides that have been made by the; application of science to agriculture, I never­theless feel that in looking round to see what further contribu­tions we can make, I cannot help but feel that our best con­tribution at the moment would be a. thorough self-examination; and I would rather see a change in our own mental outlook towards research problems than an inspiring array of research committees.

fn the scientific method of approach towards the unravelling of the unknown, we have probably one of the best tools ever invented, ami yet we so often fail when we come face to face with that which ought to be the final outcome of our experi­mental work- the prediction of events when the results of our work are applied.

The scientific method, consisting of observation, formulation of a working hypothesis, tin; experimental testing of that hypo­thesis, and its final confirmation, ought to lead to the prediction of future facts; and when dealing with the inanimate world it does so to a. very large degree. When working with the animate world, however, its success has not been so pronounced.

How often do we find, for instance, the results of experiments of plant nutrition, e.g., fertilizer trials, or those of experiments to assess the value of different varieties, apparently invalidated when these trials are repeated under what are seemingly similar conditions ?

I do not wish to imply that such experiments are valueless. I wish, however, to draw attention to the fact that the results of these trials cannot be used with the same degree of certainty to predict their applicability elsewhere as can the results of an experiment on inanimate objects.

Wherein lies the fault—the method, our use of the method, our interpretation of results or the material we deal with ? The answer probably lies between all of these.

It is obvious, of course, that the inherent variability of our material is one of the factors militating against the deduction of results which can be used for the purpose of prediction; is this, however, overwhelmingly so, that it is useless to do other­wise than merely discuss it as a natural phenomenon which cannot be overcome, or does it not rather point to the necessity for examining more closely the relationship that exists between the organism and all the factors which summed up, constitute, its environment ?

As an example, we may take the search for varieties suitable for different areas. At the Experiment Station, where it is first tried out, a. variety reacts towards the complexities of soil and climate and produces a crop which may be better or worse than other varieties grown in close proximity to it; such results we rightly accept as being true, but must add the reservation that we regard them as valid only for that experiment; we cannot predict that the answer we got will be the correct answer under other circumstances, although we might feel justified, depending upon the degree of certainty with which the results were'obtained, in saying that under certain conditions it might be a likely answer.

To test the validity of our results, trials must be repeated elsewhere, often with results which contradict the original ones, and which, make somewhat difficult the task of utilising them for determining the utility of a variety. The question arises, how can we proceed with our experimental testing to increase the probability that our results will have a wider applicability?

The answer lies, I think, in the fact that we do not know enough about the environment where a variety is first tested, and of other localities; we know a good deal about the soil, but of the other factors I fear we know only too little; the effect of even small differences in other environmental factors on cane growth, I feel, is still very much a closed book to us.

How can these factors be evaluated ? There is, of course, the meteorological station, which yields data which can be recorded with precision, which when correlated with plant; growth have proved of no mean value.

There is, however, another method—that of the study of nature herself. One of the most recent developments in biology is the evolution of the science of ecology—-the science which studies the relationship between organisms and their environ­ment, between the inner factors of the plant and the outer. One aspect of the ecological study of the flora is that of the composition of its vegetation, how a collection of species comes to be assembled together in any area, whether such a com­munity of plants is stable or in a state of flux in short, the ecologists use the natural vegetation as a book and in it read the story of the evolution of the type of plant cover which exists in relationship to the climatic factors which have favoured it.

The differences in vegetation type in our own coastal area are obvious in their broadest aspects even to those uninitiated in ecology- -the dense coastal bush, the open park-like savanah, the thornbiish veld are examples.

The ecologist, however, reads deeper: he sees within the broad types further subdivisions, he separates them into further components, and can map the countryside into units of vegeta­tion, each with their own peculiarities derived from their adaptation to environment.

When, therefore, we are considering suitability of varieties of a crop for different areas, could we not use the ecologist's areas as a guide? At present we attach an importance to the soil alone, which I feel is over-emphasised.

I would like to see a search for varieties for different vegeta-tional areas rather than for merely soil types: the latter, of course, is one of the operating factors, but how great or how little we do not know, and will not know until we consider the question of varieties from the broadest possible angle.

Such a change in our concepts would, I feel, go deeper for us as experimentalists than the possible benefits to be derived from the immediate question of variety testing—it would involve a radical change in our whole approach to the method of experi­menting; it would be a move from the hide-bound empirical method towards a more purely scientific approach. We would be forced to formulate some ideas on the natural phenomena of our own part of the earth of which at present we have no con­ception; we would have to open our eyes more to the problems of the field as they occur in the field—the field would become a laboratory.

I quote this as an example of what I meant when I referred earlier to a change in our mental outlook towards our research problems. The essence of such a change would largely be the abandonment of our ideas of plant growth as related to a separate component of the environment, and its relationship to natural events as a whole.

It must not be inferred that I am advocating that the effect of single factors on growth do not merit study; we have our fertilizer problems. Here again, however, it occurs to me that this work is still hampered by the pursuance of investigations along largely empirical lines—the more fundamental aspects of sugarcane nutrition are forgotten while we hurry to ascertain the response from stereotyped fertilizer field trials which may, like variety trials, give an answer which is easily repeatable, or they may not.

We grow cane in plots in the field, or in pots, to which varying amounts of plant-foods are added, but do not ask what happens to those materials when taken in by the plant, if they are taken in, or if they are exuded again. In so doing we probably miss the fundamental facts which would weave a thread through our observations. Facts which might lead to theoretical speculations

4

which would open the door to an understanding of nutritional problems as yet puzzling as they are numerous.

Again, much time is devoted to the properties of different varieties of our crop from the point of view of their milling values, but to what extent have been investigated the events which occur in a stick of sugarcane when passed between rollers of a mill ? What is the physics of crushing cane—what happens to the various components of the stick—the tracheids, the xylem and phloem; the cellulosic cells and the selerenchymatous fibres ?

In all tha t type of investigation I see the necessity for a departure from the present methods, which are largely empirical, towards a method of experimentation which follows more closely the methods of pure science, a method which would entail more theoretical thinking, and the testing of hypothesis built out of observations already made.

I stated earlier that my remarks were devoted more to the present status of our scientific investigation into the animate world; this is naturally so, particularly because my own line of work is concerned with the realm of living things and I am biased, but more perhaps because the change in outlook 1 suggest must come has already materialised in the enquiry into the nature of things inanimate.

I refer to the recent developments in physical science. What, in effect, has taken place there has been the abandonment of empiricism, and the ensuing use of theoretical speculation (in which intuition has played not a small part); the resulting pro­gress being such that the imagination is staggered.

I think at the present time it is highly important that the mathematical conception of the universe, as evolved by present day physicists, be more fully realised by biologists, who are more and more being forced to apply the tools of the mathe­matician to the unravelling of the mysteries of living things. The statistician has evolved methods intended to increase pre­cision of our experiments, but, as has been stated by one eminent biologist, the more he pursues precision the further he leaves certainty behind.

An example of this unhappy state of affairs I have met with in my own work. In an attempt to assess experimentally the effects of a fungoid disease upon sugarcane stems, experiments were conducted according to the rules of modern mathematical experimental technique, with the object in view of applying the accepted mathematical analysis to the results. When this was done, however, I found that I could not prove with the degree of certainty required by the statistician tha t the disease had any effect on sugarcane, cuttings great enough to be considered significant. And yet I know that it has; the lack of mathe­matical proof cannot influence my belief t ha t the disease is caused by a fungoid infection.

It has been said that there is just so much science in a subject as there is mathematics in it, but when we consider the implica­tions of modern physics, it should be clear tha t a law does not necessarily require to be quantitative to be scientific.

If we compare our present knowledge of living organisms with that of the physical world, we find that biology stands to-day where physical science stood a generation ago—in most urgent need of theoretical developments; our knowledge, however great, but derived empirically, will not lead to a systematised science.

Theoretical developments, however, will only come with the collapse of dogmatism, with the use of imagination and the

widening of our intellectual horizon, by the use of the intuitive speculations and philosophical criticism.

I come back to where I started that I believe the greatest possible developments can only come from a reorientation of our ideas, of our methods and of our beliefs; the last generation has witnessed the chemical and physical exploitation of the world, with the exploitation of biological knowledge beginning; the world of to-morrow will be one of unknown potentialities to the student of living matter and of mental activities. The role of the scientist, whevener and wherever his work is concerned with, or even impinges upon, the animate world will be of vital importance, and increasingly difficult, as new discoveries are utilized for the benefit of the human race.

The difficulties can be faced, however, I feel, if the old pre­judices are broken down, if the so-called pure and applied sciences become dovetailed, if we have more science in our technology, and if the research worker in pure .science substi­tutes the real problems of everyday life for the theoretical problems of his laboratory. The industrialist must realise thnt many of the problems which affect his dividends have their solutions in the hands of the worker who seeks knowledge for his own sake, and the educationalist must see to it that the human material he moulds will enter a career of technical direc­tion or scientific research with a mental equipment capable of sensing the things that lie beyond the horizon of the data he accumulates, and with a philosophy which will enable him to see the threads that run through the results of his work, weaving them together into a. pattern in which part can be seen in its relationship to the whole, and to correlate an apparently dis­jointed or disorderly array of phenomena info a. scheme, orderly and purposeful.

Mr. DODOS: Ladies and gentlemen, I have much pleasure in expressing our appreciation and thanks to I.)r. McMartin for another excellent Presidential address. He has discussed a subject of very great interest to me—the need for scrutiny of the bases of scientific research. This is a very big subject, which I do not at present propose to discuss, except to call attention in passing that human intelligence was no doubt evolved primarily for the purpose of helping the individual to maintain his life in an environment that was not always very favourable, and not necessarily for the purpose of elucidating the facts of nature. However, as far as we can see, the human mind is a fairly suitable instrument for studying the facts of nature, but we must always bear in mind the weaknesses of the human mind, and particularly in its interpretation of facts that we observe.

My first thought was to condole with Dr. McMartin on having to prepare and deliver yet another Presidential address entirely different from his previous one. But I realised that this was no occasion for soft-heartedness, and where we have got such an excellent Chairman and President as Dr. McMartin, we are right in holding on to him as long as we can possibly induce him to stay. I may say that he took office at very short notice at a crisis in the history of this Association, and it was largely due to his tact and good nature and good sense tha t the crisis was successfully passed, and he has been a tower of strength ever since he took the office. I have great pleasure in moving a very hearty vote of thanks to him.

The HON. TECHNICAL SECRETARY read telegrams from Mr. F. D. Wheeler and Dr. J. P. van Zvl and letters from Mr. J. W. H. Morris, Mr. G. M. Coates and 'Dr . V. M. Hinchy ex­pressing regret that they could not attend, and wishing the Technologists' Association a very successful Conference.

5

EIGHTEENTH ANNUAL SUMMARY OF CHEMICAL LABORATORY REPORTS.

FROM SOUTH AFRICAN SUGAR FACTORIES. Season 1942-1943. By H. IT. DODDS and J. L. DU TOIT.

In the Annual Summary for the 1941-42 season presented last year, it was recorded that the crop of cane and of sugar was the lowest for six years, because of the very unfavourable weather conditions during 1940 and 1941.

For the 1942-43 season there was a considerable improvement in output because of the greatly improved weather conditions during 1942, so that the crop was 4,704,430 tons of 2,000 lbs. cane and 524,975 tons of 2,000 lbs. (476,254 metric tons) of sugar. However, this also is much below the record of the seasons 1939 and 1940 inclusive, because most of the cane harvested in 1942 had suffered from the record low rainfall of 1941. The ratio of cane to sugar is 8.96, corresponding to a yield of 11.16 per cent, of sugar on weight of cane.

During 1942 the. average rainfall from 44 recording stations within the sugar-growing belt was 49.41 inches, a total that had been only once exceeded during the 14 years that systematic records have been compiled, in 1936, when it was 50.10 inches. The rainfall for 1942 was 19 per cent, above the fourteen-year average of 41.55 inches and was normally and very favourably distributed for the growth, ripening, harvesting, and planting of the sugarcane crop. This rainfall was associated with a high mean annual temperature, free from injurious extremes, high, humidity, and plenty of sunshine, all favourable factors in the sugar crop. These favourable weather conditions have on the whole continued through the present year to date, so that if good conditions are further maintained a very good crop may be expected for the coming season.

CANE VARIETY POSITION.

The relative proportions of the crop formed by the different varieties commercially grown over recent years are as follow :—

The proportion of Uba has further diminished, together with Co.290 and the P.O.J, varieties. The factories crushing more than 10 per cent, of the latter draw much of their supplies from the alluvial flats of Zululand.

Co.281 continues to increase greatly in popularity, and is very widespread, no factory now crushing less than 37 per cent, of this variety. Two of the factories already crush more than 22 per cent, of Co.301, which is also rapidly increasing, especially in the central North Coast area.

The average cane analyses for the season carried out by the Central Board, as before, were done at 13 factories, representing 61.5 per cent, of the total crop. They show similar relations between the average sucrose contents of the individual varieties to the general average of all varieties as in the previous season; also, as before, the proportion of P.O.J, canes in their returns is somewhat lower and the proportion of Co. 281 somewhat higher than those for the total crop, because of the omission of such factories as Umfolozi crushing over 52 per cent, of P.O.J, canes.

Weighted average analyses of cane milled at 13 factories serviced by the Sugar Industry Central Board :—

The returns by months confirm the facts already pointed out by one of us, that: Uba is a late-ripening variety that does not maintain its maximum sucrose for long, and therefore should be cut during the peak months of August to October inclusive for the best results, using other varieties for early or late harvesting. It is realized, however, that Uba nowadays consists mainly of old ratoons which it is advantageous to cut early, especially if they are to be ploughed out.

The monthly analyses indicate again that Co.281 and Co.301 are relatively early-ripening varieties and that P.O.J.2725 is of outstanding value for late harvesting, since it holds its sucrose remarkably late compared with other varieties.

it is too early yet to have any information concerning general harvesting results from Co.331, which was released for com­mercial planting for the first time in 1941.

GENERAL QUALITY OF CANE. Notwithstanding the generally favourable distribution of rain­

fall of last season the general average sucrose content of cane for the season, 13.40 per cent., is considerably below the high content for the 1941 season, 14.00 per cent., and slightly below the 15-year average of 13.49 per cent. The average sucrose for the optimum manufacturing period of July to November in­clusive was, however, slightly above the average for tha t period, so that the low general average may be attributed to the un­usually low sucrose contents in May and June so soon after the abundant rains of the growing season, and the very low sucrose contents in November and December due to the very heavy rainfall of those months. This position was no doubt accentuated by the relatively high proportions of Uba cane harvested in May and June, Uba not being an early-ripening variety. In any case a favourable season for cane-growing such as 1942 is not usually associated with a very high sucrose content of cane, which is more likely to occur in dry seasons.

The peak months for sucrose content of cane were August and September, when it was 14.09 in both months.

Only twice before, in 1929 and 1930, was the peak reached as early as August. In 11 seasons the peak was in September, which has therefore the highest monthly average sucrose of 14.18 per cent., and on four occasions it occurred in October.

The lowest sucrose content in 1942 was in May, when it was only 11.89 per cent., one of the lowest on record for that or any period. For November it was 13.38 and for December 12.33 per cent., both much below the averages for those months.

The general average fibre content of cane for the season was 15.24 per cent. This is considerably below that for the two previous seasons of deficient or badly distributed rainfall, and is appreciably less than the 15-year average of 15.50 per cent., but is higher than for any of the four seasons ending 1939. This is probably caused by the steady increase in the proportion of Co.281 grown, which is a high-fibred variety, especially when harvested late in the season. The fibre content of cane was at its lowest in July, 15.10 per cent., and from thence steadily increased to a maximum of 15.66 per cent, for the December period. As pointed out last year, this progressive increase in

6

fibre content throughout the main harvesting season is charac­teristic of the Co. canes.

The purity of mixed juice for the season, 85.96, is above the average of previous seasons and was only surpassed in 1935 1938 and 1939. The peak of the season was in September, as in the previous season. Over recent years the highest purity of mixed juice occurred once in August, five times in September, nine times in October, and twice in November. The lowest for 1942 was in May, when it was only 8;5.38.

The reducing sugar ratio in mixed juice for the season was 3.07, which is much below the 14-year average and the lowest since 1936.

It has already been pointed out that the difference in sucrose content of cane between what we call the "optimum period" of the season from July to November inclusive and the earlier and later months, is much greater than usual. The same applies to the purity of the juice and consequently to the ratio of cane to sugar, and unfortunately the quantity of cane harvested out of season, which was 23 per cent, in 1941, has again readied the 13-year average proportion of 25 per cent., entailing a consider­able loss of sugar through this cause.

Comparison of results from cane harvested during the July— November period, compared with those of earlier and later months of the harvesting season.

GENERAL FACTORY PERFORMANCE.

This continues to show the progressive improvement that has characterized recent seasons. Again the smaller crop has made possible less overloading of factories, and the quality of the cane, as we have seen, was not below normal. Consequently there was continued scope for improvement in technique and performance, which was well maintained notwithstanding acute shortage of skilled labour for the factories.

The mill extraction, 92.69, and reduced extraction, 94.19, reach new levels for this country ; the same may be said of the boiling house recovery, 88.98, and reduced boiling house re­covery, 88.10, and consequently of the overall recovery, 82.48, and reduced overall recovery, 82.98.

The ratio of cane to sugar, 8.93, or 8.69 based on sugar of 96° pol., is not as good as for the seasons 1937, 1938 and 1941, when, however, the sucrose content of cane was considerably higher.

The sucrose content of bagasse, 2.88 per cent., and the primary juice loss, 40.66, arc the lowest recorded for any season in this country, as is the total sucrose per cent, of cane, 2.34, lost in manufacture.

Taking the sucrose losses in manufacture per cent, of total original sucrose in cane in detail, the loss in bagasse, 7.31 per cent., is the lowest on record for this country. The same may, be said of the loss in filter cake, 0.41 per cent., and of the total losses of sucrose, 17.52 per cent., which is, of course, the difference between the overall recovery and 100. The loss of sucrose in molasses, however, is somewhat higher than in the 1938 and 1939 seasons, when lower purities of final molasses were gained.

Unfortunately, it is not possible to discriminate accurately between losses in molasses and undetermined losses, with which they have to be included in our crop returns, since there are still several factories that do not indicate weights of final molasses.

The average purity of final molasses for the season, 43.24, is well below the 14-year average, but has been better in several seasons. As usual in recent seasons, it attained its maximum in November, when it was 44.38, and its lowest during the first month of the season.

The moisture content of the bagasse, 51.24 per cent., is the lowest since 1931, but still leaves much room, for improvement when compared with other countries or with certain individual factories in this country.

The same may be said of our recovery figures generally, which show considerable improvement over recent seasons but are still a long way below the best international standards, some of which are shown in the accompanying tables.

INDIVIDUAL FACTORY RECORDS.

The 19 factories represented and their code numbers are the same as before, and there are, as before, three small factories, producing 1.56 per cent, of the crop in all, tha t are not included in our factory returns. Taking these factories into account, the ratio of cane to sugar for the crop is 8.96, not 8.93 which is the ratio for the 98.5 per cent, of the crop of which we have detailed manufacturing records.

As in past years, there are wide differences between the opening and closing dates of manufacture at different factories, so that crop conditions vary very considerably both for this reason and because of wide differences in the quality and pro­portions of varieties of the cane milled ; these differences must greatly influence individual factory performances and efficiencies.

The highest average sucrose content of cane for the season is again recorded at factory No. 21 with 14.19 per cent., three other factories also showing over 14 per cent. Generally speak­ing, the factories showing the higher sucrose contents of cane draw most of their supplies of cane from relatively high altitudes at some distance from the coast.

Factories 2 and 3 both have fibre contents of cane of under 14, 13.39 and 13.92 per cent, respectively; at the other ex­treme, one factory recorded over 17 per cent, fibre.

7 The high average purity of mixed juice is shown by factory

No. 3, 88.42, only one other factory, No. 21, topping the 88 mark.

Of the factories recording reducing sugar ratio of mixed juice, No. 6 had a season's average as low as 2.28.

The highest extraction was again recorded by factory No. 3 with 95.89, associated with a moisture content of bagasse of only 44.02 per cent. This factory gains also the lowest milling loss, 4.23, the lowest extraction ratio, 0.30, and the lowest primary juice loss, 25.42. No. 1 factory comes second in ex­traction with 94.96, as well as in the other milling efficiency figures.

Factory No. 20 gained the highest boiling house recovery, 91.83, only one other factory, No. 16 with 91.73, exceeding the 91 mark. No. 20 also leads in overall recovery with 86.30, and No. 10 takes second place with 85.96. No. 1 factory is also over 85, this factory producing sugars of a much higher average polarization, mainly for direct consumption without the inter­vention of the refinery.

There is a range of 7.5 points between the highest and lowest overall recoveries.

Several factories show considerable improvement over last year's overall recovery. Outstanding in this respect is No. 1.1, followed by Nos. 19,17 and 4.

The lowest ratio of cane to sugar is gained by factory No. 21 with 8.22, or 7.93 based on sugars of 96° pol. Other factories with very satisfactory records in this respect are Nos. 9, 3 and 17, that is to say, all those with a sucrose content of cane of over 14.

There were seven factories this season with a moisture content of bagasse of 49 or less, but some had over 53 per cent.

Thtf lowest purity of final molasses was gained by factory No. 20 with 36.80 (apparent purity); five others had purities of less than 40 and four had over 46.

No. 1 factory crushed 535,157 tons of 2,000 lbs. of cane in a single train of mills to make 61,137 tons of sugar at an average crushing rate of 135.5 tons of cane per hour. No. 5 also crushed over half a million tons of cane to make 60,339 tons of sugar at a crushing rate of 128.76 tons of cane per hour, while No. 12 made 50,727 tons of sugar; both Nos. 5 and 12 are double-tandem mills.

WORLD PRODUCTION OF SUGAR.

It has been our custom in recent years to quote estimates of the world sugar crop concurrent with that of the South African Experiment Station,

South African Sugar Association, Mount Edgecombe.

March, 1943.

crop under review, so as to assess the proportion of the whole contributed by this and certain other countries. On this occa­sion, however, no estimates of world production of sugar for the 1942-43 season are yet available from any authoritative sources, so that this feature will have to be omitted.

SUGAR PRODUCTION IN SOUTH AFRICA IN RECENT YEARS.

As last year, output of cane and sugar of South Africa since 1920 is tabulated. Production figures are in tons of 2,000 lbs. according to South African usage.

ACKNOWLEDGMENTS OF RESULTS FROM OVERSEAS SUGAR INDUSTRIES.

The receipt cf technical information and reports from countries oversea continues to be subject to many obstacles and delays arising out of the war conditions. We are glad, however, to be able to reproduce records of recent seasons in Mauritius, Puerto Rico, Hawaii and Trinidad.

For these we are greatly indebted to the Sugar Industry Reserve F"und Committee of Mauritius, the Sugar Producers' Association of Puerto Rico, the Experiment Station of the Hawaiian Sugar Planters' Association, and the Sugar Manufac­turers' Association of Trinidad.*

13

EXTRACTION AND RECOVERY FIGURES, 1931/1942.

14

15

APPENDIX.

SUGARCANE STATISTICS, 1941/42 CROP, BASED ON THE DEPARTMENT OF CENSUS "SPECIAL CENSUS OF SUGARCANE PLANTATIONS (EUROPEAN ONLY)."

This census report was received later than usual this year, so that it was not possible to include extracts and comments based on it in the "Annual Summary" presented to the South African Sugar Technologists' Association Annual Conference in April last.

The report embodies data for the period 1st Mav, 1941, to 30th April, 1942, and therefore refers to the 1041/42" cane crop, which had been influenced not only by the very unfavourably distributed (though not generally deficient) rainfall of 1940, but also by the equally badly distributed and record low rainfall of 1941. The rainfall for 1941 ranged from about 20 inches in the extreme north and south of the sugar-growing belt of the coast to 39 inches in the wettest part of the coast, an average, of 26.18 inches or 63.9 per cent, of the 13-year annual average from 44 recording stations in the sugar belt.

The area of cane harvested showed a considerable falling off in every district except those of Mtunzini and ICshowe, where there was a slight increase in acreage of cane harvested but, like everywhere else, a great falling-oil' in quantity of cane harvested and in yield of cane per acre.

The area of cane harvested, Hi 1,137 acres, has shown no tendency to increase since 1934, the first season when an appre­ciable proportion of cane varieties other than Uba was harvested (4 per cent.) and the area harvested was 172,447 acres.

There are indications, however, from the great increase in area of plant cane, from 78,564 acres in 1941 to .106,702 acres in 1942, that the crop to be harvested during the next few seasons at least will be considerably greater than in the past, given anything like normal or better than normal weather con­ditions. During the 1941-42 season 66,965 acres of land were ploughed out for replanting, of which 28,621 acres were re­planted the same season and 5,570 acres of virgin land recorded planted; during the 1940-41 season 62,135 acres of land were ploughed out, of which 21,192 acres were planted the same season as well as 4,308 acres of virgin land.

This tendency to replant extensively has unfortunately re­duced the ratio of long-fallowed to short-fallowed land from 2.88 in 1939 to 1.93 in 1940 and 1.34 in 1941, thus reverting to the proportions prevailing in the years previous to 1938, before the benefits of long-fallowing with green manuring were so much realized and before effects of over-production of cane became very acute.

As already indicated, the total quantity of cane harvested in 1941-42 was relatively small, being 3,602,389 tons, or over 1,000,000 tons less than in the two preceding seasons and the smallest since 1935.

The deficiency was particularly marked in the lower Scuth Coast area, where the rainfall deficiency was the greatest both in 1940 and 1941. Thus the Port Shepstone division, with only 43,704 tons of cane, and Umzinto, with 457,518 tons, had the smallest crops since 1927.

Compared with these figures the shortfall in the Zululand areas were comparatively light.

These comparisons conform to those of the relative yields of cane per acre by districts. Thus the average yield of cane per acre was only 13.73 tons in Port Shepstone district and 16.47 tons for Umzinto, compared with averages over the four pre­ceding seasons of 23.88 and 23.72 tons respectively. Every district showed a considerable falling-oil in yield, the least diminution being shown in the Mtunzini and Eshowe areas, where it was only 2.47 and 2.78 tons per acre respectively com­pared with the average of the four preceding seasons ; these two areas, as usual, had the highest rainfall during 1941, as well as the lowest relative deficiency of rainfall.

The yield of cane per acre for the whole crop was 22.36 tons per acre, the lowest since 1936 ; but when the crop consisted wholly of Uba this yield was only exceeded once, in 1930, when it was 22.39 tons after the abundant rains of the latter half of 1929.

The highest yield of cane per acre was again recorded in the Inanda district for the third successive year, with an average of 28.20 tons per acre ; Hlabisa came next with 26.31 tons, closely followed by Lower Umfolozi with 26.10 tons. The yield for Zululand as a whole was 24.55 tons per acre, and the rest of Natal 21.18 tons, comprising the North Coast (between the Umgeni and Tugela Rivers) 23.64 tons, and the South Coast 17.05 tons of cane per acre.

The yield of Uba cane per acre ranged from 10.67 tons in the Port Shepstone area and 11.73 tons in Hlabisa to 20.78 tons for Inanda district. The yield for all other varieties combined varied from 14.17 tons per acre for Port Shepstone to 30.56 tons for Inanda, 27.17 tons for Hlabisa and 26.98 tons for Lower Umfolozi.

The proportion of new varieties under cultivation by districts ranged from 80.1 per cent, in Umzinto and 85.9 per cent, in Lower Tugela to 96.4 per cent, in Lower Umfolozi, 96.5 per cent, in Hlabisa, and 96.6 per cent, in Eshowe.

There is now very little Uba cane younger than second ratoons, the proportions being as follow :—

Total area under cane 30th April, 1942—

Hi

T h e f igures for t h e 1941-42 c rop ha rves t ed show s imi lar rela­t ions.

There were in April, 1942, still 8o,206 acres of virgin land suitable for sugarcane not yet planted, and 318,457 acres on established sugar farms not available or unsuitable for planting

cane. The production of sugar is therefore capable of consider­able expansion extensively by increasing the area under cane, as well as intensively by improving the yield of cane and of sugar per acre ; but the question naturally arises of a per­manent remunerative market for this potential output.

We have mentioned previously the difficulty of arriving at the average age of the cane of each crop when harvested. There is evidence, however, to show that there has been a slight but definite tendency to cut cane at a lesser age since the new varieties came into cultivation.

Thus during the five seasons ending 1931, when practically no varieties other than Uba were harvested, the average propor­tion annually harvested of the total area under cane was 4o.l percent. , while for the ten years ending 1041, during which the proportion of Uba in the crop diminished from 90.007 per cent, to 8.7 per cent., the average proportion of the crop harvested each season was 48.1 per cent., and was 48.7 per cent, over the latter three years.

1

21

SHORT REPORT ON 1942 SEASON'S WORK AT DOORNKOP. By G. Booth.

General.—The season was a short one of twenty-three weeks. Up to August ending, harvesting conditions were good and some record outputs obtained.

The season began with 12 per cent, sucrose in cane, which figure rose steadily until August, when 15 per cent, and over was obtained—the season's average being 14.5 per cent.

On a fixed Java Ratio Co.281 cane yielded 1 per cent, higher sucrose over all others.

Fibre content was lower than anticipated, considering the preceding two unfavourable years, the average being under 15 per cent, until October, when wet weather produced trashy and badly topped cane- conditions tha t make any figure for fibre possible.

Although the proportion of Uba cane was high—exceeded only by two other mills—the overall recovery was the highest yet obtained by this mill. Both milling and boiling houses con­tributed to this end, although long stops for cane naturally adversely affected efficiency in both stations.

The advantages of a six months' harvesting season are demonstrated in this year's figures.

Chemicals.—During the season efforts were made to reduce consumption of sulphur. This could be done only to a limited extent, and only as long as new variety cane in clean, fresh conditions was being crushed. Our opinion generally coincides with a finding published in Hawaiian records, viz., the benefits of sulphur are to be seen not so much in the juice preparation

Mr. RAULT explained that at Natal Estates too, the sucrose content of cane for the past season had been one of the lowest for a number of years. There was no evidence that in their district the advent of new varieties had produced a rise in the average yearly sucrose content of cane. Fibre also did not seem to have decreased. Last season, with practically 90 per cent, new variety cane, the sucrose and fibre per cent, cane were respectively 13.3 and 15.4, compared with 13.7 and 15.3 repre­senting the average figures over twenty-five years of 100 per cent. Uba canes. The field returns, however, were still im­proving. Last season, with a better rainfall, the tons of cane per acre was 37.5 compared with 31.0 for the previous year of unprecedented drought, and a still better return might bo ex­pected for the coming season. In their programme of planting they were now concentrating on Co.281 and Co.301. Planting this year consisted of over 50 per cent. Co.281 and 40 per cent. Co.301, with only a half per cent. Uba. Co.301 was a quick grower and its performance generally was very satisfactory. Its sucrose content was moderately high, but it had the undesirable feature of poor resistance to wind.

Once again he could find no proof for the assertion that low-fibred canes were an asset for extraction and capacity, or that extraction decreased with an increase in fibre. Their best results both as regards extraction and through-put coincided with periods of high-fibred canes. He thought that sucrose content of cane also had an effect on extraction as the final bagasse was fairly constant in sucrose per cent, and they preferred a com­bination of high sucrose and high fibre for optimum milling results. For example, during six weeks with 12.2 per cent, sucrose and 14.!) per cent, fibre the. extraction was only 94.5, but for four weeks with cane of 14.0 per cent, sucrose, and in spite of a rise in fibre per cent, to 15.0, the extraction rose to 95.23.

Although it was not sound practice to neglect the first units of a crushing plant, it seemed, however, that the work of the first units was not always an indication of final results. They had found at Natal Estates equally good results in total extrac­tion, in spite of the first units having dropped in efficiency.

Attempts were made to run the factory on a continuous carbonatation process for seven weeks in order to economise

in the quicker and more complete settling, but rather in the rapidity with which the vacuum pans and centrifugals, especially in low grades, can maintain their output. However, it is doubt­ful if the elimination of sulphur would conduce to good recovery.

Filtration.—Filtration by the Oliver filter was generally satis­factory, although there were times when Uba cane provided a stiff proposition. With the slimy muds, dilution had to be stopped and boiling-point temperatures maintained.

The off-seasonal maintenance of the filter is a big job, and every year sees some alteration installed to lessen depreciation.

Centrifugals.—For 1942 season a factory-made revolving hot-water coil was placed in the low grade battery mixer, the heat­ing element being evaporator condensate. Roughly speaking, the maintaining of a temperature of 115 degrees of the masse-cuite in the mixer increased the capacity of the battery by about 25 per cent., a better and cleaner purged sugar being obtained. This temperature of 115 degrees is well within the safety zone, and will not be increased until saturascope control can be obtained.

Now that our factory labour, in respect to both numbers and' efficiency, is under drastic review, ways and means of tightening things up are being sought.

Any source of information concerning the latest type of high­speed machines equipped with methods of heat conservation of massecuites would be welcomed. It is agreed that the average centrifugal station is capable of much all-round improvement.

labour and plant, and further experimentation on this line is being carried out.

The proportion of No. 1 refined sugar made was very high and a good deal of remelting was resorted to. This increased the pan work very considerably. The recording cuitometer was found to be extremely useful, especially for controlling the boiling of last massecuites. It helped a good pan boiler to visualise graphically his best result and it was an inducement for him to reproduce such results.

It was found that by finishing the last massecuite at a higher temperature it was possible to reach a very high brix and crystallization during cooling was accelerated. This was one method of increasing capacity. As a result of remelting such a large quantity of sugar the syrup purity was high—over 92. The purity of the last massecuite was therefore also high, nearly 69, but there was only a small quantity of it. Similarly, the amount of molasses was small, but its purity fairly high. There was a progressive increase in the molasses purity as the season advanced. The same was true for the average of all our mills, although some chemists maintained that they could keep molasses purity constant, this had not been the speaker's experience.

The speaker wanted to know how the Central Board obtained the different Java Ratios for Co.301 and P.O.J. He was sur­prised that the Java Ratio for Co.301 was so low.

Mr. MOBERLY, in reply, said that different average Java Ratios were obtained from the various factories crushing varying proportions of the varieties. The reason why the Java Ratio for Co.301 was so low was probably due to the fact that the factories crushing the highest proportion of this variety had low Java Ratios. He did not attach much significance to these comparisons.

He thought the reason for high extractions being obtained with canes of a high fibre content might be partly explained by the fact as illustrated in results of crushing experiments carried out at the Experiment Station by Dr. Hinchy, that increasing amounts of trash increased the fibre content of the cane out of all proportion to the small decrease in extraction. This was to be expected, as trash did not retain as much juice

22

as pith fibre, for example. He did not suggest that this was a complete explanation of the phenomenon, but thought it would go some way towards explaining it.

Mr. DODDS, in reply to a question by -Mr. Wouters, said that it was impossible this year to discriminate between plant and ratoon crops for the different varieties, as the authors were de­pendent on information from the Agricultural Census Returns, and this had not yet been received. It could be said, however, that nearly all the Uba and Co.200 were old ratoons, since little had been planted of these varieties in recent years.

Mr. DU TIOT pointed out that the effects of fibre on extrac­tion became progressively less as the extraction increased. It. therefore followed that the effects of fibre would be more obvious at mills having a lower extraction than was the case at Natal Testates. There was also the seasonal fluctuation in extraction to be taken into consideration.

Mr. DODDS said that Mr. .Kault had pointed out that there was no appreciable increase in sucrose content of canes since the introduction of new varieties. This must, however, be due to the general conditions in recent years not favouring a high sucrose. The returns from the Central Board, which drew its cane from a considerable part of the total crop, indicated most clearly, year after year, the superiority of the new varieties over Uba as far as sucrose content was concerned. Co.281 now made up more than half the crop, and the high average fibre content of cane for the year was probably largely due to this high-iibred cane. The Industry, however, seemed well satisfied with the milling properties of Co.281, and it seemed that variety largely determined the nature of fibre and, as such, had more effect on extraction than the content of fibre itself as a whole. Co.281 had proved a very valuable variety to South Africa much better, in fact, than one could have reasonably expected

from canes selected in other countries. Importation of estab­lished varieties offered lesser possibilities compared with seedlings raised here from imported seed and selected under our condi­tions. He believed the time, would come when we would have our own varieties selected from seedlings that would be far superior for our conditions to any imported variety.

The PRESIDENT pointed out that fibre as defined by sugar technologists was not lignified tissue, and he had often wondered whether lignin determinations would not perhaps give a better correlation with milling results.

Mr. DU TOIT, in reply to Mr. Dodds, said that one of the reasons that such a wide discrepancy existed between the purities of final molasses in this country was due to the fact that brix determinations of final molasses were not done in any standard way. Some factories adhered to our recommended method and diluted the final molasses one to two; others, however, used one to five and one to ten, while in a few cases the brix was deter­mined by means of a refractometer. That, being the case de­ductions derived from the S.J.M. formula were also to be accepted with reserve.

Mr. RAULT mentioned the remarkable fact that this year low sucrose content of cane was associated with an extraordinary low reducing sugar ratio.

The PRESIDENT, in concluding the discussion on the paper, pointed out that experiments conducted in Hawaii on transpira­tion of canes, led to the conclusion that during heavy rains the leaves could absorb water and transport it to the: roots. It was therefore possible that rains following a drought might actually have a diluting effect on the juice inside the stem as well as encouraging growth.

23

SURVEY OF LABOUR-SAVING AND COST-SAVING DEVICES.

By F. M A C B E T H , G. B O O T H , and G. C. D Y M O N D (Chai rman) .

The first s tep in th i s p re l imina ry review of l abour -sav ing and cost-saving devices has been to p repa re a rough g r o u n d w o r k on which future inves t iga t ions on specific sub jec t s m a y conve­nient ly be buil t .

A survey of all ava i lab le sugar l i t e ra ture lias been m a d e a n d tha subjects indexed .

However ske tchy our efforts m a y a p p e a r to be, i t i s a p p a r e n t t h a t t he re axe m a n y phases in sugar p roduc t ion where non­essential or surp lus l abour m a y be cur ta i led or e l imina ted . W i t h th i s general isat ion everyone will agree, b u t difficulties imme­dia te ly arise when be t t e r m e t h o d s and p rocedures are p u t in to prac t ice . Thus , local condi t ions a t our factories va ry g rea t ly , changes m u s t be capi ta l ised aga ins t ex is t ing l abour costs , whi le new mach ine ry is difficult, if n o t impossible, to o b t a i n .

I t is obvious, however , t h a t the upward t r end of indus t r ia l wages, in field and factory, will force i n d u s t r y to s t u d y a n d app ly t h e experience of o the r coun t r i es in m a n y forms of mechanisa t ion .

In the 1!)-U Proceedings of the Br i t i sh Association for t h e A d v a n c e m e n t of Science, i t is s t a t ed t h a t before t h e cessa t ion of hostili t ies, and for some years thereaf ter , every c o u n t r y will be forced to produce foodstuffs to t h e l imit of its capac i t i e s a n d a t the cheapes t possible r a t e .

Wi th these poin ts in view, the C o m m i t t e e h a s p r epa red a basic index of overseas repor t s on sub jec t s of specific in te res t , toge ther wi th c o m m e n t s a n d p lans on a few sa l ient po in t s app l i ­cable to t h e N a t a l Sugar I n d u s t r y .

The su rvey i s d iv ided in to th i r teen major head ings . T h e first four deal w i th t h e agr icu l tura l s ide :—

1. P repar ing t h e land.

2. I r r igat ion.

3 . Hau lage .

4 . Ha rves t i ng , loading and off-loading.

While deve lopmen t s in o the r coun t r i e s du r ing t h e p a s t ten years have been impress ive , agr icu l tu ra l m e t h o d s in N a t a l h a v e remained compara t i ve ly s t a t i c .

In 1939, Mr. D o d d s wro te : " O n e of our largest p l a n t a t i o n s in th i s coun t ry has a g r aveya rd of all k i n d s of e l abo ra t e field ins t rument s , t h a t have been t r ied o u t a n d even tua l ly d i s c a r d e d . "

This is a h ighly i m p o r t a n t s t a t e m e n t to make , for a n y inves t i ­gat ion in to t h e possible adop t i on of agr icu l tu ra l l abour - sav ing devices m u s t first answer t h e ques t ion : W h y h a v e t h e y failed in t h e pas t ? Secondly, i t is likely t h a t fai lure u n d e r one se t of condit ions m a y p r o v e successful u n d e r a n o t h e r .

The only new factor which has to be faced in the nea r future is t h e fact of " scarcer a n d deare r l a b o u r . " Th i s is sufficient to w a r r a n t a closer s c ru t i ny of t h a t " g r a v e y a r d of e l a b o r a t e i n s t ru ­m e n t s " with a view to fu ture possibil i t ies and necessit ies.

1.—-Preparing the Land.

Apar t from agr icu l tu ra l imp lemen t s in t h e p repa ra t i on of t h e land, such as p loughs and har rows , cu l t iva to r s , subsoilers, p l a n t ­ing and fertilizing mach ines , weeding control , e tc . , t he re are cer ta in major po in t s in t h e recent l i t e ra tu re which deserve s t u d y .

The f irs t is an i m p o r t a n t art icle by Dr . B. A. Keen of R o t h a m -sted, ent i t led "Soi l Phys ics , T h e o r y a n d P r a c t i c e " (Proceedings of t h e Roya l Society of Ar t s , Ju ly , ' 1942) .

The following is an e x t r a c t from his s u m m a r y : " T h e resu l t s , even on a cau t ious in t e rp re t a t ion , lend no s u p p o r t to t h e idea t h a t ex t r a cu l t iva t ions increase c rop yields. T h e y show t h a t , p rov ided—

(a) A reasonable seed bed is ob ta ined ,

(b) Weed compe t i t ion is p r e v e n t e d d u r i n g t h e ear ly g r o w t h of crop,

(c) The wors t of t h e weeds are k e p t down a f te rwards , t hen a n y work in excess i s was ted a n d m a y even be harmful , so far as t h e c rop yield is conce rned . "

Since the ordinary cultivation of a cane-field is an expensive item, experiments should be conducted to test out Keen's observations, as to the illusionary effects of capillarity with a cane crop.

The second subject, which occupies a prominent position in overseas reports, is trash. There are articles on trash as a weed preventer ; the burning', burying or composting of -trash ; the effects of trash in factory operations, together with the mechanical devices which have been evolved to deal with the abnormal trash from drag-harvesting in Hawaii.

AU these items are of interest in Natal, where clean cane is rather the exception than the rule.

2.— Irrigation.

This subject is. as yet, of specialised interest to-the few. It is therefore passed over by simply refering to the references in the index.

3. Cane Haulage.

lughteen articles cover this important subject of individual local interest.

The Committee considers that investigations should be carried out on the principle of centralising transport facilities with a view to minimising haulage costs. There are various systems which have given satisfactory results, such as motor transport, light portable railway track, and the use of diesel engines.

4. —Harvesting, Loading and Off-Loading.

Overseas developments in these three sections have been spectacular in recent years. The following is a summary of mechanical harvesting results in Hawaii from 1938 to 1940.

No accurate estimate has yet been made of the damage to fields and milling plants by the use of mechanical harvesting.

Rake and grab-harvesting are the two principal systems. Neither of these tops or cleans the cane, with the result that costly stripping and washing plants have had to be installed. The resulting effluent is quite a problem.

Rake-harvesting, as practised by the McBryde Sugar Co., affords a good general picture of the results of this system.

Depending on the type of cane, the rake can handle from 500 to 600 tons of cane per day, the cost per ton delivered at main line being 62.75 cents. For comparison, the older method of hand-cutting and grab-loading was 86.25 cents.

Against this saving of 23.50 cents are to be marked the following disadvantages.

There is a large percentage of crushed and bruised sticks, which rapidly deteriorate. The accompanying dirt, trash, stones, etc., vary from 5 per cent, to 30 per cent., according to the type of cane and soil. Replanting is as high as 40 bags of setts per acre, instead of the customary one or two.

The effects in the factory are likewise serious. Cane tonnages decreased from 51.fi to 44.7 tons per hour. The crusher juice dropped 3 • 5 degrees in purity, with a corresponding drop in the mixed juice polarization and purity.

The milling loss increased from 2.93 to 3.04, and the extrac­tion dropped from 96.47 to 95.99 per cent. The yield of sugar per acre decreased by half a ton.

The costs during the test of mechanical versus hand-harvested cane, were as follows : - -

24

N o n e of t h e companies using mechanica l ha rves t ing of this t y p e considers t h a t t h e u l t i m a t e h a s been ob t a ined , nor do t h e y know w h a t t h a t u l t ima te m a y be-- e i ther in reduct ion of costs, e x t r a cap i ta l on milling p lan ts , or in d a m a g e to t h e fields.

Mechanical ha rves t ing of th i s type is a field of exper imen ta t ion open on ly to large moneyed interests . Of t h e t rue cane har­ves t ing machines , t h e compara t ive ly s imple windrowing machine (now fitted with a topp ing device) m a d e by t h e Thomson Machinery Co. of Labadieville, has great possibili t ies. Us cost in 1930 w a s " a b o u t / l , 0 0 0 .

Considering, however, our con tours and o u r hills, together with t h e probable deve lopmen t of more a n d more small farms, the possibilities of mechanical harves t ing , except on a coopera­t ive basis, or by special ha rves t ing gangs, a p p e a r s imprac t icable in N a t a l .

The me thods of field-loading cane, as pract ised in Louisiana, seem to be of more pract ical in teres t to th is c o u n t r y at the m o m e n t .

Loading Cane at Sidings. The loading of cane in to S.A.K. t rucks is usually performed by manua l labour , f ive to six boys being employed per t r u c k .

At var ious sidings, where mechanica l m e a n s a re used, four or live boys m a y load seven or e ight S.A.K. t r u c k s per day , whereas by the old me thod SO to 33 boys would lie requi red .

Here is u n d o u b t e d l y a field for inves t iga t ion a n d co-opera t ion . The c ranes required can be ope ra ted by electr ic motor , as a t Duffs Road, or by oil, paraffin or petrol , as at. Frasers , at a ve ry low economical cost . W i t h t h e except ion of t h e electric, motor or engine, the rest of the e q u i p m e n t can be m a n u f a c t u r e d in this coun t ry .

Fa i l ing power engines, s imple windlass and der r ick devices ope ra ted by animal power are s imple and successful. The a m o u n t of l abour and money t h a t can be saved by t he se me thods i s impressive. A t e n t a t i v e inves t iga t ion revealed t h a t t h e cost per t on of c ane loaded in to S.A.K. t r u c k s las t season ranged from 0 .3d . to 0 .8d . T h e f i rs t figure refers to a s iding, which loaded 42,000 t ons of cane by m a n u a l labour, a n d t h e second f igure to a p l a n t e r loading six S.A.R. t r u c k s wi th a de r r i ck a n d cha ins .

N a t a l Es t a t e s h a s k ind ly suppl ied t h e following c o m p a r a t i v e cos ts a t Duffs Road a n d F ra se r s :—

The foregoing figures refer to estates with large tonnages. For the average planter loading one S.A.R. truck per day, the number of boys required is rive or six, which means a loading cost of between 4d. and 5d. per ton, and sometimes even higher.

Compare, now, one individual planter's costs using a derrick, chains and animal power :—

Cost of outfit (pre-war) ^738. Cost of loading 1 S.A.R. truck (30 tons)... 3.0d. per ton cane. Cost of loading 3 S.A.R. trucks (30 tons)... 1.4d. per ton cane. Cost of loading fi S.A.R. trucks (30 tons)... 0.8d. per ton cane.

The pecuniary benefits that would accrue to planters by co-operation, along these lines, are obvious.

OFF-LOADING.

The problem of off-loading cane, either from tram trucks or from S.A.R. trucks, is a matter of local conditions and individual concern. There is, however, room for improvement at many of the factories in this country. For example, the methods of off­loading cane from ox-wagons, motor transport, and S.A.R. trucks, and thereafter dumping it onto inclined platforms, from whence it is fed to the carrier by manual labour, leaves much to be desired.

[n other countries a mechanical arm, operated by one boy, is employed.

Other mechanical means, such as hydraulic lipping platform the ordinary tippers and off-loading rakes, are suitable f< meeting the individual requirements of each factory.

J.. Boilers, Steam, Bagasse

These subjects arc covered by 23 indexed articles, which dej with fuel economy ; boiler control instruments ; storage, handling baling and briquet ting bagasse ; boiler feed water, automati bagasse feeders, etc.

2. Milling, Milling Control, Lubrication and Maintenance.

The application of a central milling control can be applied cither for steam- or electrically-driven tandems. There are man' instances in this country, where: each of the three or four stem engines is operated by separate drivers. A central plat lorn with extension controls for each steam valve would necessitati only one driver. A simple but effective control for slopping th< engines in cases of emergency can be incorporated in this system This consists of butterfly valves inserted in the steam pipe t<. each engine. These are controlled by small clcetrically-operatec magnets. When the current is disconnected from the magnets the butterfly valves automatically close and shut off the steair to the engine.

Speed variation for each engine can be controlled by a smal servo-motor and a gearbox arranged for the governor control Several of these installations have already been fitted in one oi two of our factories.

Lastly, automatic control of a mill engine can be arranged according to the thickness of the blanket entering the mill.

3. Weighing and Recording.

Like many other departments in the sugar business, the installation of automatic devices is only warranted when the increased capital will yield increased accuracy, speed, and a reduction in costs, commensurate with the outiay over a stipu­lated number of years.

This is obviously the case with weighing and recording machines. Automatic weighing is simply a matter for local calculation.

4.—Filtration and Clarification.

The literature covers the Oliver Campbell filter, automatic liming devices, and the Bach continuous subsicters.

Mr. R. A. Carter, of the Umfolozi Co-operative Company, has recently patented a continuous subsider without moving parts ; also a new method of juice clarification.

5. Evaporators.

The trend of invention is towards the automatic control of this station. The Mobiey control system is in operation at Doornkop. The possibilities of operating the entire evaporator station automatically are given in the literature.

6. - Pan Boiling and Vacuum Pans.

For several years much attention has been devoted to the development of pan-boiling by instruments, and if advantage is to be taken of these modern methods the pan-boiling station will require a personnel of higher education and adaptability.

Unfortunately, the design of our average factories is such that there must always be a certain amount of unskilled labour to attend to pan requirements, discharging massecuites and

25

other multifarious roundabout jobs. Future developments must lie along lines tha t will help to eliminate that type of labour, whose greatest capacity lies in "opening and shutting cocks or valves under supervision," and its replacement by the skilled educated operator, it is farcical to boil a good massecuite to cuitometer control, and then have to shovel it into a crystallizer SO yards away, after steaming the pan for 30 minutes to enable the massecuite to get there. Few factories are incapable of improvement in this regard.

G. S. Moberly, in his 1035 report on Australian conditions, lolls us that in a 00-ton factory the pan staff usually consists of one man and one boy. In that year automatic feed and control of pans were undeveloped. Either the type of labour or the layout of the factory must have been advantageous in comparison with our normal Natal conditions.

It is obviously the duty of every responsible party in the factory to visualise how best to reorganise the layout of pan supplies, pipe connections for rapid tank cleaning, re-locating crystallizers where possible, so that improvements in efficiency and labour economy from vacuum pan to sugar elevator may be the result.

7.—Centrifugals.

The latest self-operating centrifugals will no doubt solve the labour problems at this station. Up to the present time full details are not available, but it is obvious that here is a fruitful field for capital expenditure.

8.-—General.

The literature is full of articles which might be included under this heading— 51 have been selected.

The last item which the Committee has included under th i s

heading is the contentious subject of chemical control. Efforts have been made by the International Society to standardise all chemical terms, formula? and calculations. This has been fairly successful, but the quantity of work done is largely a matter of individual preferences.

In some overseas factories the laboratory is situated in a convenient place in the factory. This enables a number of sample pipes to be led through the laboratory, with consequent simplicity in sampling.

The trend in this country during the last fifteen years has been towards multiplicity of samples, based on the principle that the larger the number of samples and analyses made, the smaller the possible error. Added to the very large amount of work conducted at some of our factories, is the complicated system of cane testing. In many cases the chemical personnel is very high, and yet comparatively low in others.

The Committee feels tha.t in view of the high wages now in force, it is time that the whole subject of chemical control and cane testing requirements should be reviewed.

That such an enquiry should investigate the pros and cons of more convenient laboratory sites ; the limitation of routine sampling and analyses necessary in order to maintain an agreed standard of accuracy ; more co-operation with the centralising of cane testing and factory control in one laboratory and, in general, greater simplification of routine with directed oppor­tunities for co-operative research.

Such a system, we feel, would pay dividends.

INDEX OF LABOUR-SAVING AND COST-SAVING DEVICES

FOUND IN THE LITERATURE.

A.—Preparing the L a n d .

1. Agricultural Staff, Bureau of Sugar Experiment Stations. Queensland (1935): Caneland Cultivation in Queensland. Int. Soc. of Sugarcane Tech., 71.

2. Alexander, W. P. (1926): Determination of Plantation Fer­tilizer Policy at Ewa. Reports Assoc, of Hawaiian Sugar Tech., 132. '

3. Alexander, W. P. (1932): Cultivation of Ratoons under Unirrigated Conditions on Kauai. Reports Assoc, of Hawaiian Sugar Tech., 3.

4. Austin, S. L. (1931): Whys and Wherefores of Plowing and Planting. Reports Assoc, of Hawaiian Sugar Tech., 31.

5. Bacon, Burt (1938): Methods of Weed Control on Oahu. Reports Assoc, of Hawaiian Sugar Tech., 21.

6. Barr, Harold T. (1938): Notes on Labour-Saving Devices. Int. Soc. of Sugarcane Tech., 544.

7. Bond, J. I). (1931): Weed Control. Reports Assoc, of Hawaiian Sugar Tech., 35.

8. Borden, R. J. (1938): The Effect of Fertilization upon the Quality of Sugarcane. Reports Assoc, of Hawaiian Sugar Tech., 85.

9. Bryan, R. (1932): Cultivation on Unirrigated Plantations on the Island of Hawaii. Reports Assoc, of Hawaiian Sugar Tech., 31.

10. Coombes, A. North (1938): Caneland Cultivation in Mauri­tius. Proc. Int. Soc. of Sugarcane Tech., 271.

11. Doolan, M. A. (1939): Manufacture: Report of Mr. M. A. Doolan. Proc. Queensland Soc. of Sugarcane Tech., 218.

12. Ednie, Douglas (1938): Weed Control as Practised on the Island of Hawaii. Reports Assoc, of Hawaiian Sugar Tech., 5.

13. Foss, A. L. (1935): Gyrotilling at Aguirre, Puerto Rico. Proc. Int. Soc. of Sugarcane Tech., 81.

14. Gibb, J. A. (1938): Land Preparation for Sugarcane. Proc. Int . Soc. of Sugarcane Tech., 536.

15. Gibson, W. G. (1932): Horse and Tractor Power in Farm Practice. Proc. Queensland Soc. of Sugarcane Tech., 53.

16. Hay, G., and Jennings, W. C. (1936): New Developments on Unirrigated Plantations. Reports Assoc, of Hawaiian Sugar Tech., 123.

17. Jennings, W. C. (1931): Fertilizer Practices and Problems on Unirrigated Plantations. Reports Assoc, of Hawaiian Sugar Tech., 93.

18. Kay, R. B., and Plaus, R. A. (1933): Welding, with Par­ticular Reference to Plantation Requirements. Reports Assoc, of Hawaiian Sugar Tech., 157.

19. Kerr, H. W. (1931): Tillage and Cultivation. Proc. Queens­land Soc. of Sugarcane Tech., 182.

20. King, N. C. (1934): Trash Conservation. Proc. Queensland Soc. of Sugarcane Tech., 245.

21. King, Norman (1939): Agriculture: Report of Mr. Norman King. Proc. Queensland Soc. of Sugarcane Tech., 178.

22. Moir, W. \V. G. (1926): Plantation Fertilizer Control. Re­ports Assoc, of Hawaiian Sugar Tech., 120.

23. Moragne, Wm. (1938): Weed Control as Practised in Kauai. Reports Assoc, of the Hawaiian Sugar Tech., 27.

24: Nicol, J. L. (1930): Soil Preparation—Ploughing, etc. Re­ports Assoc, of Hawaiian Sugar Tech., 83.

25. Pulsford, T. W. (1932): Suggestions for Improving Efficiency between Field and Mill. Proc. Queensland Soc. of Sugarcane Tech., 58.

26. Ross, Geo. (1931): Cane Cultivation on Unirrigated Districts of Hawaii. Reports Assoc, of Hawaiian Sugar Tech., 13.

27. Spalding, A. T. (1.926): Weed Control and Cultural Practices. Reports Assoc, of Hawaiian Sugar Tech., 53.

28. Spalding, A. T. (1928): Field Problems on an Unirrigated Plantation. Reports Assoc, of Hawaiian Sugar Tech., 53.

29. Taylor, H. J. W., and Fiddes, Robert J. (1938): Present-day Status of Weed Control on Maui Sugar Plantations. Reports Assoc, of Hawaiian Sugar Tech., 7.

30. Tester, Keith H. (1929): Chemical tt'&'il Control on Irrigated Plantations. Reports Assoc, of the Hawaiian Sugar Tech., 161.

31. Yon Stieglitz, C. R. (1935): Cane Trash and Soil Organic Matter. Proc. Int. Soc. of Sugarcane Tech., 191.

32. Williams, C. Holman B. and Forte, I.. A. (1938): Double versus Single Planting. Proc. Int. Soc. of Sugarcane Tech., 266.

33. (1933): Mechanization in the Cane Fields. I.S.J., 300.

34. (1933): Recent Work in Cane Agriculture in Hawaiian Islands. I.S.J., 133.

35. (1939) Recent Labour-Saving Devices. I .S.J. ,298.

B.—Irrigation.

1. Kerr, H. W. (1933): Irrigation Principles. Proc. Queensland Soc. of Sugarcane Tech., 95.

2. Tapiolas, B. (1935): Irrigation in the Lower Burdekin Dis­trict. Int. Soc. of Sugarcane Tech., 412.

C—Cane Haulage .

1. Anderson, T. J. (1937): The use of Concrete in Permanent Way Construction. Proc. (Queensland Soc. of Sugarcane Tech., 135.

2. Anderson, T. J, (1938): Further Xotes on Concrete Work in Tramline Construction and Maintenance. Proc. Queensland. Soc. of Sugarcane Tech., 23.

3. Dahl, O. S. (1940): Timber in Mill Tramlines. Proc. Queens­land Soc. of Sugarcane Tech., 139.

4. Dahl, O. S. (1941): Unfair Wear and Tear of Cane Trucks and Tramlines. Proc. Queensland Soc. of Sugarcane Tech., 193.

5. Doolan, M. A. (1939): Manufacture: Report of Mr. M. A. Doolan. Proc. Queensland Soc. of Sugarcane Tech., 218.

(i. Fanning, G. S. (1940): Comparative Data -Steam and Diesel Locomotion. Proc. Queensland Soc. of Sugarcane Tech., 71.

7. Farden, C. K. (1934): Loading and Hauling Cane at Pioneer Company. Reports Assoc, of Hawaiian Sugar Tech., 49.

8. Ford, Ray W. (1934): The Improvement on old Tramway Lines and their Effect on Cane Haulage Costs. Proc. Queens­land Soc. of Sugarcane Tech., 141.

9. Ford, Ray W. (1936): Some Notes on Cane Haulage Costs. Proc. Queensland Soc. of Sugarcane Tech., 75.

10. Ford, Ray W. (1937): The Construction and Maintenance of Permanent Way as Applied to Sugar Mill Tramlines. Proc. Queensland Soc. of Sugarcane Tech., 213.

11. Ford, Ray W. (1939): Locomotive Boiler Maintenance. Proc. Queensland Soc. of Sugarcane Tech., 73.

12. Horton, H. (1935): Diesel Locomotives. I.S.J., 218. 13. Kruse, W. j. (1929): Diesel Locomotive for Plantation

Haulage. Reports Assoc, of Hawaiian Sugar Tech., 49. 14. Ladlau, G. P. (1933): Motor Transport on a Sugar Planta­

tion. Proc. S.A. Sugar Tech. Assoc, 7, 105.

15. Tromp, I.. A. (1938): Field Transport of Cane on Steel and Rubber. I.S.J., 388 and 422.

16. Wheeler, Roy D. (1940): Truck Hauling of Sugarcane. Reports Assoc, of Hawaiian Sugar Tech., 79.

17. (1927): Report of the Committee on the Handling of Cane from Field to Crusher. Proc. S.A. Sugar Tech. Assoc, 1, 65.

18. (1936): Haulage of Sugarcane by Motor Lorry. Proc. S.A. Sugar Tech. Assoc, 10, 184.

26

D.—Harvesting, Loading and Off-Loading.

1. Beveridge, H. D. (1927): Field Trash in Cane. Reports Assoc, of Hawaiian Sugar Tech., 132.

2. Blomfield, R. G. (1939) Engineering: Report of Mr. R. G. Blomfield. Proc. Queensland Soc. of Sugarcane Tech., 252.

3. Crosby, L. \V. (1936) Field Pre-Harvest Juice Sampling with the Hand Refractometer at the Wailuku Sugar Company. Reports Assoc, of Hawaiian Sugar Tech., 11.

4. Doolan, M. A. (1939): Manufacture: Report of Mr. M. A. Doolan. Proc. Queensland Soc. of Sugarcane Tech., 218.

5. Eckart. Thos. G. (1930): The Use of the Hand Refracto­meter at the Lihue Plantation Company Limited. Reports. Assoc, of Hawaiian Sugar Tech., 5.

0. Eldon. J. A. (1936): Cane Handling from the Yard to the Conveyor. Reports Assoc, of Hawaiian Sugar Tech., 289.

7. Hansen, Hans W. (1940): Mechanized Harvesting. Reports Assoc, of Hawaiian Sugar Tech., 57.

8. King, Norman (1939): Agriculture: Report of Mr. Norman King. Proc. Queensland Soc. of Sugarcane Tech., 178.

9. Lennox, C. G. (1936): A Method of Pre-Harvest Sampling Using the Hand Refractometer. Reports Assoc, of Hawaiian Sugar Tech., 21.

10. Mead, J. R. (1936): Pre-Harvest Juice Sampling by the Refractometer. Reports Assoc, of Hawaiian Sugar Tech., 27.

11. Pulsford, T. W. (1939): Mechanical Cane Harvesting. Proc. Queensland Soc. of Sugarcane Tech., 229.

12. Wiley, Frank; McLean, James and Kahlman, A. F. C. (1937): Difficulties in Milling Machine-Loaded Cane. I.S.J., 361. Abstract from Hawaiian Sugar Planters' Assoc.

13. Wyllie, Joseph (1924): Labour-Saving Devices. Proc. Second Annual Conv. Philippine Sugar Assoc, 51.

14. (1924): Report of the Committee on Labor-Saving Devices. Comp. of Com. Reports for the Second Annual Conv. Philip­pine Sugarcane Assoc, 149.

15. (1939): Mechanical Harvesting in Hawaii. I .S .J., 272. 16. (1939): Report on Labour-Saving Devices. I.S.J., 179.

Abstract from Hawaiian Sugar Planters' Assoc.

E.-—Boilers, Steam and Bagasse.

1. Blomfield, R. G. (1939): Engineering: Report of Mr. R. G. Blomfield. Proc. Queensland Soc of Sugarcane Tech., 252.

2. Connon, Geo. W. (1926): Heat Economy in Sugar Factories. Reports Assoc, of Hawaiian Sugar Tech., 176.

3. Eigenhuis, J. (1936): The Utilisation of Surplus Bagasse in Java. Proc. Queensland Soc. of Sugarcane Tech., 33.

4. Harper, W. J. (1934): Notes on the Storage and Handling of Surplus Bagasse. Proc. Queensland Soc. of Sugarcane Tech., 179.

5. Jenkins, G. H. (1938): Automatic Bagasse Feeders. Proc. Queensland Soc. of Sugarcane Tech., 59.

6. McAllep, W. R. (1928): Boiler Feed Water. Reports Assoc, of Hawaiian Sugar Tech., 203.

7. Montgomery, J. \V. (1929): Steam Economy in the Opera­tion of Sugar Factories. Reports Assoc, of Hawaiian Sugar Tech., 51.

8. Mott-Smith, S. (1930): Care and Operation of Factory Boilers. Reports Assoc of Hawaiian Sugar Tech., 51.

9. Mott-Smith, S. (1934): Utilisation of Waste in the Boiler Room. Reports Assoc, of Hawaiian Sugar Tech., 177.

10. Mott-Smith, S. (1938): Combustion of Bagasse and Factory Steam Balance. Reports Assoc of Hawaiian Sugar Tech., 109.

11. Pitcairn, R. C. (1938): Utilisation of Bagasse. Proc. Int. Soc. of Sugarcane Tech., 925.

12. Renton, J. Lewis (1928): Steam Accumulators. Reports Assoc, of Hawaiian Sugar Tech., 130.

13. Rex, D. R. (.1932): Automatic Bagasse Feeders. Proc. Queensland Soc. of Sugarcane Tech., 185.

14. Shillington, Arthur F. (1939): The Economic Combustion of Bagasse. I.S.J., 258.

15. Singleton, John D. (1937): Factory and Locomotive Boiler Water Sampling, pH Control and Treatment. Reports Assoc, of Hawaiian Sugar Tech., 87.

16. Smith, Walter E. (1929): Boiler Feed Water Control and Treatment. Reports Assoc, of Hawaiian Sugar Tech., 21.

.17. Thorp, Val. (1931): Some Observations made in Connection with Steam Consumption and Fuel Economy in a Sugar Mill. Queensland Soc. of Sugarcane Tech., 1.58.

18. (1926): By-Products and Chemical Control. Comp. of Com. Reports Fourth Annual Conv. Philippines Sugar Assoc, 110.

19. (1931): Report of Committee on fuel Economy. Proc Queensland Soc. of Sugarcane Tech., 149.

20. (1934): Report of Committee on Fuel Economy. Proc. Queensland Soc. of Sugarcane Tech., 27.

21. (1934): Report of the Committee on By-Products. Proc. Queensland Soc. of Sugarcane Tech., 5.

22. (1935): Important Addition to Sugar Refining Plant. Ruth's Accumulator Installed at Hulett's. S.A. Sugar Jour., 19, No. 10, 615.

23. (1939): A New Steam Accumulator Plant for the Sugar Industries. I.S.J., 144.

F.—Milling and Milling Control.

1. Becker, Geo. I). (1933): Relative Effect of Trash upon the Factory Operations. Reports Assoc, of Hawaiian Sugar Tech., 91.

2. Broadbridge, L. W. (1940): Mechanical Application of Lubricants to Sugar Mill Machinery. Proc. Queensland Soc. of Sugarcane Tech., 129.

3. Dennis, Edwin L. (1938): New Equipment for Improving the Efficiency of Mills. Proc. Int. Soc. of Sugarcane Tech., 1019.

4. Gibson, R. C. (1931): Crushing Engines. Yearly Overhaul and Clearances Allowed on Various Bearings. Proc Queens­land Soc. of Sugarcane Tech., 216.

5. Godfrey, J. B. M. (1939): Maintenance and Care of Electrical Plant in a Sugar Factory. Proc. S.A. Sugar Tech. Assoc, 13, 97.

6. Hadfield. H. F. (1933): Field Trash. Reports Assoc, of Hawaiian Sugar Tech., 95.

7. Harding, G. W. (1933): Bearing Maintenance. Proc. Queens­land Soc of Sugarcane Tech., 159.

8. McAllep, W. R. (1928): Maceration. Reports Assoc of Hawaiian Sugar Tech., 193.

9. Mason, K. E. (1933): Lubrication of Heavy Oil Engines. Proc. Queensland Soc. of Sugarcane Tech., 175.

10. Orth, W. K. (1928): Quality of Milling Cane: Field Trash. Reports Assoc, of Hawaiian Sugar Tech., 114.

11. Montgomery, J. W. (1936): Milling and Boiling Characteris­tics of New Seedling Canes. Reports Assoc, of Hawaiian Sugar Tech., 189.

12. Peck, S. S. (1931): Loss in Recoverable Sugar due to Field Trash. Reports Assoc, of Hawaiian Sugar Tech., 99.

13. Renton, J. Lewis (1927): Factors in Milling. Reports Assoc, of Hawaiian Sugar Tech., 158.

14. Smith, E. Camden (1938): Some Notes on Machinery Main­tenance in a Cane Sugar Factory. Proc. S.A. Sugar Tech. Assoc, 12, 114.

15. Smith, Walter E. (1929): Analysis of Mill Conditions. Reports Assoc, of Hawaiian Sugar Tech., 27.

16. Wallace, A. F. (1938): Cane Washers. Reports Assoc, of Hawaiian Sugar Tech., 89.

17. Wolters, Win, (1930): Reduction of the Trash Content of Harvested Cane. Reports Assoc, of Hawaiian Sugar Tech., 65.

18. (1932): Report of Committee on Maintenance. Proc. Queens­land Soc. of Sugarcane Tech., 11.

19. (1933): Report of Committee on Maintenance. Proc. Queens­land Soc of Sugarcane Tech., 67.

20. (1934): Report of Committee on Maintenance. Proc. Queens­land Soc. of Sugarcane Tech., 35.

27

G.—Weighing and Recording. 1. Bailey, E. C. (1939): Weighing in Queensland Sugar -Mills.

Proc. Queensland Soc. of Sugarcane Tech., 75. 2. Giacometti, O. (1938): A Suggestion for a Bagasse Scale.

Reports Assoc, of Hawaiian Sugar Tech., 103. 3. Taylor, Chas. R. (1936): Control of Mixed Juice Weights.

Reports Assoc, of Hawaiian Sugar Tech.. I Of). 4. (1941): Electric Cranes in Sugar .Mills. Proc. Queensland

Soc. of Sugarcane Tech., 147.

H.—Filtration and Clarification. 1. Fleshman, Ward S. (1034): Clarification. Reports Assoc, of

Hawaiian Sugar Tech., 12J. 2. Fleshman, Ward S. (1938): Progress in Clarification. Reports

Assoc, of Hawaiian Sugar Tech., I05. 3. Jenkins, G. H. (1939): Rotary Filters in Queensland Mills.

Proc. Queensland Soc. of Sugarcane Tech., 15. 4. McCleery, W. L. (1940): Manufacturing Qualities of New Cant-

Varieties. Reports Assoc, of Hawaiian Sugar Tech., 137. 5. Orth, W. K. (1927): Kopke Separators at Ewa. Reports

Assoc, of Hawaiian Sugar Tech., 124. 6. Orth, W. K. (1928): Kopke Separators at Ewa. Reports

Assoc, of Hawaiian Sugar Tech., 117. 7. Povve, Wm. A. (1933): The Oliver-Campbell Filter Compared

with the Plate-and-Pramu Press in the Cane Sugar Factory. I .S.J. ,33.

8. Praeger, A. H. (1938): Automatic Juice Liming Controlled by Juice Flow. Proc. Queensland Soc. of Sugarcane Tech., 49.

9. Praeger, A. H. (1.939): Automatic Juice Liming Controlled by Juice Flow. I.S.J., 111).

10. Rhodes, Leon J. (1936): Bagasse Screening for Vacuum Filters. Reports Assoc, of Hawaiian Sugar Tech., 207.

11. Smith, Walter E. (1926): Disposal of Settlings. Plate-and-Frame Filter Presses. Reports Assoc, of Hawaiian Sugar Tech., 145.

12. Southwick, B. S. (1936): Sulphitation. Reports Assoc, of Hawaiian Sugar Tech., 203.

13. Wickey, S. A. (1935): Survey of Oliver Filter Performance. Reports Assoc, of Hawaiian Sugar Tech., 43.

14. (1932): Reducing Sugar Losses in Cane .Muds. The Oliver Campbell Filter. I.S.J., 350.

15. (1938): The Principle of "Sealed" Clarification. Its Applica­tion to the Bach Continuous Subsider. I.S.J., 340.

16. (1939): Advantages and Disadvantages of a Rotary Mud Filtration Plant. Proc. Queensland Soc. of Sugarcane Tech., 27.

I.—Evaporation.

1. Barnhart, G. H. W. (1929): Overflow Type Juice Level Regulator for Evaporators. Reports Assoc, of Hawaiian Sugar Tech., 97.

2. Clark, Lee E. (1929): Spray System for Cleaning Evaporator Tubes. Reports Assoc, of Hawaiian Sugar Tech., 17.

3. Clayton, J. L. (1941): Juice Level Control in Evaporators. Proc. Queensland Soc. of Sugarcane Tech., 25.

4. Donald, J. W. (1933): Entrainment. Reports Assoc, of Hawaiian Sugar Tech., 105.

0. McKenna. H. G. (1941): The Mobrey Juice Level Control. Proc. S.A. Sugar Tech. Assoc, 15, 64.

6. Smith, Walter E. (1931): Automatic Control for the Sugar Factory. Reports Assoc, of Hawaiian Sugar Tech., 121.

7. Weight, N. E. (1927): Cleaning Evaporator Tubes. Reports Assoc, of Hawaiian Sugar Tech., 122.

J .—Pan Boiling.

1. Barnhart, G. H. W. (1929): Overflow Type Juice Level Regulator for Evaporators. Reports Assoc, of Hawaiian Sugar Tech., 97.

2. Conklin, D. G. (1934): Conductivity Control of Pan Boiling. Reports Assoc, of Hawaiian Sugar Tech., 115.

3. Fabius, A. (1936): Pan-Control Instruments. Reports Assoc. of Hawaiian Sugar Tech., 221.

4. Fleener, C. J. (1936): Circulation of Vacuum Pans. Report Assoc, of Hawaiian Sugar Tech., 213.

5. Jenkins, G. H. (1941): Mechanical Circulation in Vacuur Pans. Proc. Queensland Soc. of Sugarcane Tech., 35.

6. Kelly, F. H. C, and Newman, I. G. (1938): Automatic Pa: Feed Control. Proc. Queensland Soc. of Sugarcane Tech., 39

7. McCleery, W. L. (1935): Molasses Investigations and Treat merit of Low Grade Massecuite. Reports Assoc, of Flawaiiai Sugar Tech., 25.

8. Murray, G. F. (1930): Seeding Low-Grade Massecuites Reports Assoc, of Hawaiian Sugar Tech.. 3.

9.. Murray, G. F. (1931): Handling of Low-Grade Massecuite Reports Assoc, of Hawaiian Sugar Tech., 107.

10. Pratt, J. H. (1935): Sugar Boiling Systems. Reports Assoc of Hawaiian Sugar Tech., 13.

11. Smith, Walter E. (1929): Vacuum Pans at Honolulu Planta-tions. Reports Assoc, of Hawaiian Sugar Tech., 79.

12. Smith, Walter E. (1934): Vacuum Pan Design and Operation. Reports Assoc, of Hawaiian Sugar Tech., 143.

13. Wickey, S. A. (1930): Slow-Cooling Massecuites. Reports Assoc, of Hawaiian Sugar Tech., 5.

K. Centrifugals.

1. Beiter, R. E. (1937): Mechanical Dischargers for Low-Grade Centrifugals. Reports Assoc, of Hawaiian Sugar Tech., 115.

2. Bromley, George (1937): Crystallization in Vacuum Pans and Crystallizer. Reports Assoc, of Hawaiian Sugar Tech., 49.

3. Eklund, W. .V, and Pratt, J. II. (1934): Drying Low-Grade Sugar at Higher Speeds at Waialua. Reports Assoc, of Hawaiian Sugar Tech., 203.

4. Eklund, W. X., and Pratt, J. H. (1935): Drying Low-Grade Sugar at Higher Speeds at VVaialua. I.S.J., 184.

5. Elliott, Raymond (1936): Crystallizers and their Control. Reports Assoc, of Hawaiian Sugar Tech., 261.

6. Click, Dallas K. (1934): Notes on Low-Grade Massecuites. Reports Assoc, of Hawaiian Sugar Tech., 141.

7. Henderson, B. B. (1926): Mechanical Sugar Dischargers. Reports Assoc, of Hawaiian Sugar Tech., 153.

8. Henderson, B. B., and Barnhart, G. H. W. (1933): Crys­tallizer Massecuite. Reports Assoc, of Hawaiian Sugar Tech., 131.

9. Johnson, Ralph B. (1935): High-Speed Centrifugals. Reports Assoc, of Hawaiian Sugar Tech., 67.

10. Johnson, Ralph B. (1936): High-speed Centrifugals. Some Satisfactory Results Obtained at Ewa. I.S.J., 220.

11. McCleery, W. L. (1934): Molasses Investigations and Special Treatment of Low-Grade Massecuites. Reports Assoc, of Hawaiian Sugar Tech., 127.

12. McCleery, VV. L. (1940): Ewa Massecuite Experiments, 1938 and 1939. Reports Assoc, of Hawaiian Sugar Tech., 113.

13. Murray, G. F. (1927): Crystallizers versus Cooling Tanks. Reports Assoc, of Hawaiian Sugar Tech., 131.

14. Murray, G. F. (1929): Observations on Forced Cooling in Crystallizer. Reports Assoc, of Hawaiian Sugar Tech., 33.

15. Olcott, C. A. (1939): High-speed Centrifugals. I.S.J., 104. 16. Williamson, I. H. C. (1939): Hydraulic Coupling for Centri­

fugal Machines. I.S.J., 221. 17. (1937): High Gravity Factor Centrifugal Machines. I.S. [.,

134.

L.— General.

1. Atherton, J. Ballard (1938): A Plantation Safety Programme. Reports Assoc, of Hawaiian Sugar Tech., 1 13.

2. Best, S. B. (1940): Extraneous Matter in Cane: Effects on Process Work, Mill Efficiency, Plant and C C S . Formula. Proc. Queensland Soc. of Sugarcane Tech., 49.

3. Bihl, J. E. (1929): The Use of Sand Blast for Cleaning Operations in the Mill. Proc. S.A. Sugar Tech. Assoc, 3, 112.

4. Bonmonti, H. F. (1926): The Hydrogen Ion and its Applica­tion to the Sugar Industry. Reports Assoc, of Hawaiian Sugar Tech., 139.

28

29

5. Bryan, L. W. (1929): Forestry on the Plantation. Reports Assoc, of Hawaiian Sugar Tech., 1.05.

6. Cbristianson, W. O. (1940): Experiments on a New Method of Cane Sampling. Proc. S.A. Sugar Tech. Assoc, 14, 135.

7. Cochran, S. F. (1942): The Relationship Between Electricity Supply and the Sugar Industry. Proc. Queensland Soc. of Sugarcane Tech., 148.

8. Cook, H. A. (1932): Care and Use of p.H Equipment. Reports Assoc, of Hawaiian Sugar Tech., 175.

9. Cook, H. A. (1937): From Evolution to Revolution in Sugar­cane Growing and Manufacture. Reports Assoc, of Hawaiian Sugar Tech., 59.

10. Corven, J. B. (1939): The Sampling of Hot Sugar Juices. Proc. Queensland Soc. of Sugarcane Tech., 69.

11. Crites, Newton (1935): pH Control. Reports Assoc, of Ha" waiian Sugar Tech., 41.

12. Duker, W. van H. (1927): Value of Hawaiian Final Molasses. Reports Assoc, of Hawaiian Sugar Tech., 1 Mi.

13. Duker, W. van H. (1930): Practical Use of Records. Reports Assoc, of Hawaiian Sugar Tech., 21.

14. Duvall, Allan R. (1940): Cane Washer Effluent and Sedi­mentation. Reports As.soc. of Hawaiian Sugar Tech., 103.

15. Eigenhuis, J. (1938): Instruments and Sugar Factory Con­trol. Proc. Queensland Soc. of Sugarcane Tech., 05.

16. Fabius, A. (1936): The Hydrogen Ion Potential or pH. Reports Assoc, of Hawaiian Sugar Tech., 281.

17. Fabius, A. (1936): Sugar as an Industrial Haw Material. Reports Assoc, of Hawaiian Sugar Tech., 275.

18. Fabius, A. (1937): The Fifth International Technical and Chemical Congress of Agricultural Industries. Reports As.soc. of Hawaiian Sugar Tech., 79.

19. Foster, J. P. (1930): The Application of Activated Carbons to the Sugar Industry. Reports Assoc, of Hawaiian Sugar Tech., 11.

20. Gow, Paul (1932): Potentiometers and Hydrogen Electrode. Reports Assoc, of Hawaiian Sugar Tech., 179.

21. Horton, H. (1934): The Possible Application of Photo-Electric Cells to Sugar Practice. Proc. Queensland Soc. of Sugarcane Tech., 131.

22. Keys, S. \V. (1928): Treatment of Timber with Creosote against Infestation and Rot. Reports Assoc, of Hawaiian Sugar Tech., 123.

23. Lewis, Chas. T. (1926): Labor-Saving Devices in Hawaii. Reports Assoc, of Hawaiian Sugar Tech.. 158.

24. Lloyd, R. H. (1929): Operation of Small Centrifugal Pumps in the Sugar Mill. Reports Assoc, of Hawaiian Sugar Tech., 59.

25. Lloyd, R. H. (1931): Spray Ponds and Cooling Towers. Reports Assoc, of Hawaiian Sugar Tech., 147.

26. McCleery, \V. L. (1932): A Resume of Articles and Develop­ments of Interest in the Sugarcane Factory. Reports Assoc, of Hawaiian Sugar Tech., 187.

27. McLarkey, W. E. (1930): Some Electrical Developments for 1928-29. Reports As.soc. of Hawaiian Sugar Tech., 63.

28. McPhee, J. G. D. (1940): Shadow Boards in a Sugar Factory. Proc. Queensland Soc. of Sugarcane Tech., 251.

29. Maze, W. J. (1927): The Caterpillar and the Sugar Planta­tion. Reports Assoc, of Hawaiian Sugar Tech., 106.

30. Miller, Slater M. (1940): Safety in the Field. Reports Assoc, of Hawaiian Sugar Tech., 5.

31. Moberly. G. S. (1937): Cane Sample Signalling Devices. Proc. S.A. Sugar Tech. Assoc, 11, 43.

32. Montgomery, J. VV. (1935): Performance of Multi-Jet Con­densers. Reports As.soc. of Hawaiian Sugar Tech., 81.

33. Mott-Smith, S. (1935): Maintenance and Repair in Cane Sugar Factories. Reports Assoc, of Hawaiian Sugar Tech., 05.

34. Peake, W. B. (1938): The Influence of Cane Trash on First Mill Extraction and C C S . Proc. Queensland. Soc. of Sugar-cane Tech., 219.

35. Pratt, J. Scott B, Jr. (1929): Reducing Production Costs. Reports Assoc, of Hawaiian Sugar Tech., 171.

30. Miller, Slater M. (1938): Effect of Mechanical Loading on Labora­tory Control. Reports Assoc, of Hawaiian Sugar Tech., 95.

37. Puckett, R. F. (1931): Factors Affecting the Filterability of Commercial Sugar. Reports Assoc, of Hawaiian Sugar Tech., 109.

38. Purcell, H. G. (1933): Metal Spray Coating. Reports Assoc. of Hawaiian Sugar Tech., 87,

39. Shearer, A. (1940): A Novel Sampling Device for Light Liquids. Proc. Queensland Soc. of Sugarcane Tech., 81.

40. Smith, Walter E. (1931): Automatic Control Equipment for the Sugar Factory. Reports Assoc, of Hawaiian Sugar Tech., 121.

41. Smith, Walter E. (1940): New Hawaiian Developments in Factory Equipment and Practice. Reports Assoc, of Ha­waiian Sugar Tech., 139.

42. Strugnell, R. H. (1934): Automatic Timing Device for Cane Sampling. Proc. Queensland Soc. of Sugarcane Tech., 183.

43. Taylor, A. S. (1935): The Use of Special Alloys and Other Metals. Reports Assoc, of Hawaiian Sugar Tech., 85.

44. Tompkin, G. W. (1929): Temperature and Pressure Regula­tion. Reports Assoc, of Hawaiian Sugar Tech., 13.

45. Tompkin, G. W. (1937): Latest in Control Instruments. Reports Assoc, of Hawaiian Sugar Tech., 63.

46. Trist, G. L. (1931): Fire Protection for Sugar Mills. Reports Assoc, of Hawaiian Sugar Tech., 135.

47. Verret, J. A., and Doty, R. E. (1933): Progress Report on Molasses Fertilization. Reports Assoc, of Hawaiian Sugar Tech., 69 and 75.

48. Waddell, G. E. (1939): A New Method of Obtaining Juice Samples for Cane Payment. Proc. Queensland Soc. of Sugar­cane Tech., 55.

49. Walker, S. G. (1932): A Discussion on Fire Protection. Reports Assoc, of Hawaiian Sugar Tech., 141.

50. Wright, B. (1941): A Simple Arrangement for Roller Turning. Proc. Queensland Soc. of Sugarcane Tech., 177.

51. Wright, F. B. (1941): Note on a Bag Bumper. Proc. Queens­land Soc. of Sugarcane Tech., 45.

30

LABOUR-SAVING DEVICES. By F. MACBETH, Chief Engineer, The Natal Estates, Limited.

The advent of the Wage Determination Act as applied to the Sugar Industry recently, with its award for higher wages for the factory labourer, the question of labour-saving devices has no doubt been passing through the minds of many factory executive staffs, especially the engineering stall, since the Act became law.

Although in the past most engineers and factory executives have endeavoured to reduce the number of labourers in the factory, present day conditions call for a radical revised plan for future development and operation.

Unfortunately, in the past the general layout of factories and extensions have not always been arranged with the view of labour saving, principally due, no doubt, to existing arrange­ments which have been added to over a great number of years, and to a lesser degree to cheap labour which has been available. The question of rearrangement of plant in many instances will now prove difficult without extensive capital expenditure. How­ever, there are quite a number of inexpensive arrangements which can bo adopted and certain modifications to plant which will prove advantageous and operate satisfactorily. Further, the use of gravity has not been utilised and developed to the fullest extent possible as a labour-saving means. In many fac­tories to-day the amount of pumping employed is considerable, necessitating labour for the operation of the pumps and so on.

In making any alterations, rearrangement of plant or addi­tions to reduce labour, it will always be necessary to take into account the interest on capital expenditure plus depreciation. In other words, it would not be economical to install expensive plant to do away with, say, a couple of labourers and find that the interest on capital and depreciation is in excess of the annual cost of the two labourers, and further find that it is necessary to employ an extra artisan to maintain the plant.

It is a question also of co-operation on the part of the staff to bring about these changes, as it is difficult sometimes to break dlown the old methods which have existed for some years and, like everything new in this direction, is viewed with certain misgivings, especially by the labourer, who is naturally afraid of being displaced by a machine.

This is ideally illustrated by Oliver Lyle in his excellent book1, where he wrote as follows : "Some years ago one of T. & L.'s directors was walking down the Edgeware Road and stopped at a new bridge that was being built, to watch three riveters working a pneumatic hammer. An unemployed man came up to him and said, If it wasn't for that bloody thing there would be ten men working there instead of three.1 J . J . R . replied, 'If it wasn't for that bloody thing there would be no bridge being built and those three men might be looking for jobs.' "

We are now beginning to experience and encounter some of the same problems that have occurred in other sugar producing countries such as Australia and the Hawaiian Islands, where it was necessary for the factory staffs to investigate and create ways and means of introducing labour-saving devices if the industry was to survive in those countries and approach an economical standard.

Of course, there are limits to this problem, especially when viewed on the conditions prevailing in Australia with its white labour policy and, in spite of a great number of labour-saving devices, the industry was subsidised directly and indirectly to the extent that the cost of sugar to the consumer was 5d. per pound in 1934, and still is, so far as the writer is aware.

With these few introductory remarks, it is the writer's inten­tion to pass on to some detailed suggestions and arrangements which may prove of interest at this stage.

DRIVE SHAFT WiTH

BEVEL GEARING

COUNTER SHAFT MOTOR

WICKS CANE UNLOADER

LOADING CANE AT SIDINGS.

The loading of cane into S.A.R. trucks at sidings, in the majority of cases, is performed by manual labour, and in these cases as many as five or six boys per truck are employed. The labour requirements for this duty could be reduced consider­ably if mechanical means of handling the cane from the siding to the truck were installed. It is known that at various sidings where mechanical means are in use the number of boys to load seven to eight S.A.R. trucks per day (eight hours) is four to five, whereas by the old means of handling the cane, as many of 30 to 35 boys were employed for this duty. Where a number of planters use the same siding for despatching their cane, it is possible for them to come to some arrangement amongst them­selves for the purchase of a crane to load their respective daily deliveries. These cranes can be operated either by electric motor if electric power is available, or by oil, paraffin or petrol engines at a very economical cost. The whole of the structure of the cranes could be manufactured in this country, with possibly the exception of the electric, motor or the engine. In the case where a number of planters are using the same siding, the question may crop up as to the maintenance and running repairs of the crane. It may be possible for them to have some understanding with the nearest factory, so that should it be necessary to carry out repairs a mechanic from the factory con­cerned could be despatched to do this work. The number of boys used throughout the sugar belt on this duty during the crushing season must be considerable, and it is" felt that if mechanical means of loading cane into S.A.R. trucks was adopted, the labour requirements in this direction would be very much reduced.

HAULAGE.

Under this heading investigations should be carried out on the principle of centralising transport facilities in an endeavour to minimise haulage costs of cane. There are various systems under this heading which may be employed with satisfactory results, i.e., motor transport, light portable railway track and the use of diesel engines, and in some instances aerial transport.

OFF-LOADING.

The problem of off-loading cane, either from tram trucks or S.A.R. trucks, is really a matter which concerns each individual factory, according to the topographical position in which they are placed, but there is room for improvement in the way of mechanical handling at quite a number of factories in this country. Improvements could be made in the off-loading and handling of cane from S.A.R, trucks to the cane carrier. For instance, some factories employ a crane for removing the cane from ox wagons, motor transport and S.A.R. trucks respectively, and the cane is dumped on to slightly inclined platforms. The removal of the cane from these platforms to the cane carrier is performed by manual labour, whereas this operation could be carried out by mechanical means, such as the mechanical arm which can be operated by one boy. A detailed drawing of this mechanism is available and should be investigated by those concerned or interested. Other mechanical means could be adopted, such as hydraulic, tipping platforms, the ordinary tippers and mechanical off-loading rakes, any or all of which may be suitable to meet the requirements of each factory. See tigs. I and 2.

MILLING.

The application of central control for the operation of the milling tandem as a whole could be applied in the case where mills are steam-driven as to those arranged for electrically-driven plant, or at least on similar lines. In many instances in this country, milling tandems have from three to four steam engine-driven mills, and in all instances each engine is operated by an engine driver. By central control all these engines could be operated by one or two drivers, by providing a central plat­form with extension controls from each steam valve to this platform. In addition to this arrangement an emergency stop could be fitted for each engine. This emergency control consists of butterfly valves inserted in the steam pipe to each engine, which is controlled by a small magnet, and upon the current being disconnected from this magnet the butterfly valve auto­matically closes and shuts off the steam to the engine. See fig. 3.

Speed variation for each engine can be arranged by a small servo-motor and a gear box for the governor control. This could be operated from the mill platform. Several of these installations have already been installed in one or two factories in this country. Further, automatic control of a mill engine can be arranged according to the thickness of the blanket entering the mill. Although it may not be practicable to arrange this control to all carriers feeding mills, there are instances where it can be applied with satisfactory results. See fig. 4.

Where central control is adopted on a milling plant the use of mirrors can be used with satisfactory results. These can be

arranged in such a position as to reflect the amount of feed entering individual mills, and hence convey to the operator on the central platform the actual amount of feed entering each unit. Mirrors can also be utilised in other departments as well for various purposes.

Mill bed plates are not always arranged to be self-cleansing, and in many instances it is necessary to employ labour with the usual squeegee to remove bagasse which collects on these beds. The most improved type of bedplate is the one arranged on the inverted pyramid principle, but, unfortunately, this cannot always be installed, due to existing arrangements not lending itself towards its adoption.

AUTOMATIC CONTROL VALVES.

There are numerous duties where the ordinary float valve can be used to advantage, especially where centrifugal pumps are in operation to control liquor levels in tanks and so on.

There is also the mechanically-operated valve, which can bo utilised to discharge given quantities of liquor over specified periods, such as from continuous subsiders. This valve could possibly be used in other directions as well. Sec fig. 5.

CENTRIFUGING.

Investigations should be carried out on the latest self-operating centrifugals which are being offered at the present time. Full details on the operations of these machines, however, are not available, so far as the author is aware.

31

32

CONCLUSION.

These few suggestions only touch on the fringe of a subject which has tremendous possibilities, and although some of them in a number of instances may not be practicable, they may be applied in others. The contents of this paper may provide sufficient interest to others to investigate the problems which now confront the Sugar Industry as a whole. It is really a matter for each individual concern to endeavour to solve some of the

items under the heading of this paper, so that they may main­tain an economical standard through increased efficiency ; and this can also be achieved by co-operation in the exchange of views between the staffs of the factories and should be en­couraged by all companies concerned.

Reference. 1 Lyle, Oliver (1941) : Technology for Sugar Refinery Workers. Chapman arnd

Hall, 316.

The PRESIDENT, in opening the papers on Labour-Saving Devices for discussion, said that one of the most pressing problems facing the South African Sugar Industry was that of labour. There already seemed to exist an acute shortage of labour on many farms and estates. These papers were therefore most opportune.

Mr. MOBERLY, referring to automatic control of mill engines, said that one of the best examples he had seen was a very simple device in Queensland. There, however, the general rule was that each mill had its own engine. He had seen the working of this device well demonstrated by adding an extra lot of bagasse on to the carrier and at each mill in turn the plate on the bagasse carrier lifted, the engine was speeded up and the particular mill was able to take the extra load. In this country, where the general practice was that one engine drove several mills, the extra bagasse entering one mill would give unwar­ranted control to the other mills. At Natal Estates mill, one of the few in this country with individual engines at every mill, automatic control certainly was very successful.

If a mill bed could be so designed as to be self-deanring, it would obviously be by far the best. Where that could not be done, however, mechanical scrapers operating from the same linkage which worked the pushers, as was done in Queensland, could be made use of. This would save a great deal of labour.

The speaker thought the Committee had passed rather hur­riedly over the problem of weighing. Useful information could have been given, as we had had considerable experience of automatic weighing in this country and it appeared to be very satisfactory. Automatic weighing of cane by electric scales as carried out at New Guelderland and Gledhow in particular worked very well after initial mechanical problems such as suitable oil had been overcome. Automatic weighing of water and juice seemed to be very adequately met by the vertical type of Maxwell-Boulogne scale. Horizontal scales of this type were also in use, but in his opinion the vertical type was to be preferred. Automatic scales for water and juice were rendering good service at Doornkop and some of the Hulett mills.

The new laboratories at the Tongaat Sugar Company provided a. good example of careful planning in selecting a convenient

site. He thought more co-operation between the mill and cane testing laboratory staffs should be possible if the latter were recognised as a legitimate and essential service. It might even be possible to dispense with some personnel, although he himself was not of the opinion that in the majority of cases surplus labour was employed.

Mr. MACBETH, in replying to Mr. Moberly, said that he realised that automatic control could not very well be applied to engines operating three mills with the same degree of effi­ciency, nevertheless the principle could still be adopted by many factories in this country. He thought that it would still work satisfactorily with an engine driving two mills.

In some factories overseas the mill beds from the crusher to the last mill were on a slope from the side of the mill cheeks to the centre, with a central trough right through. This arrange­ment obviated the accumulation of bagasse collecting on the bedplates, to be removed by labour.

In this country he thought that the slat carrier was preferred to the drag type of carrier, because of the more efficient feeding to the mills.

Mr. PATRICK MURRAY drew attention to the fact that a cane-cutting machine invented here in 1920 was tried out here in 1921 and 1922. The machine was built in Glasgow, and after considerable alteration a good workable machine was evolved which cut, trashed and topped the cane. The power available proved too small for the duty. The machine was not proceeded with, as the cost of cutting was higher than the present hand method, but with rising costs and shortage of labour it might be worth while to go ahead with its development now. The machine would not be suitable for steep hillsides as encountered here.

He agreed with Mr. MacBeth that the pyramid type of mill bed juice trough which was self-cleaning was the best. Some were in use in this country, and one was being made in Durban now, and would he in use this season.

The speaker suggested that the Committee be strengthened and continue the work, which he considered of great value to the Sugar Industry.

33

Automatic Juice Limer.

He said it had been designed by Mr. Jelly and was in opera­tion at Darnall. It was very suitable for a. factory with a large production, but not so satisfactory for a small mill. Praeger, in the International Sugar Journal, March, l!)3i), described several interesting automatic limers and discussed their advantages and disadvantages. The Helmer automatic limer, the Merang method, Zitkowski continuous device and the Redjoagoeng device were mentioned, and Fraeger suggested a design which incorporated the Zitkowski and Redjoagoeng limers.

Mr. DODDS said that he had been quoted as referring to a certain graveyard of labour-saving devices. That graveyard existed on the property of Natal Estates, as this enterprising company had always been in the forefront in trying out new devices. He would like to know what their opinion was of the gyrotiller compared with ploughing, fn England experiments quoted by Keen had shown the plough to give uniformly better results.

Cane loaders were considered a necessity in Louisiana, but few had tried them in this country, though not without success. Many attempts were made in different parts of the world to devise cane harvesters, but none of them had ever been quite successful. Topping had always been one of the greatest diffi­culties. The Luce harvester, which was worked for some time in Louisiana and Cuba, overcame this in a most ingenious way. The canes were subjected to pressure from a lever which gradu­ally travelled up the stem, and as resistance suddenly gave way when the top was reached, a knife cut the cane at tha t point. The machine was, however, too clumsy and expensive and could only be used on perfectly level land on well-grown cane in very long rows.

Mr. \V. A. CAMPBELL assured Mr. Dodds that the gyrotiller had come to stay. He said the cane-cutting machine referred to by Mr. Murray certainly did cut, trash and top the cane, but in those days it could only do the work of about three or four men.

Mr. SIMPSON said that it was many years ago that that particular machine was tested out thoroughly but unsuccessfully. The cutting device was a pair of discs, set angularly to each other; but it was quite unable to handle an average stool of cane. It was an expensive experiment, which was finally discarded owing to its many insuperable mechanical defects.

Mr. MACBETH thought that the graveyard mentioned by Mr. Dodds referred to old implements used in connection with the steam plough in the olden days. He had, however, noticed

various discarded modern instruments in their yard, but lie considered if further investigated most of them could be made to work satisfactorily. Subsoiling machines had been greatly improved in recent years and were doing excellent work through­out all the fields of Natal Estates. The agricultural staff spoke very highly of the gyrotiller.

The speaker said that he saw a very ingenious little liming device during a recent trip, and thought that it would suit a s m a l l factory where large quantities of lime were not necessary. It consisted of a small tank with sprockets arranged to take an Ewarts chain with small buckets attached. The driving shaft was driven from the pintal of one of the first mill rollers. As the chain revolved the buckets lifted the lime from the tank and delivered it on to a feed or splash-plate which was re­gulated to supply the desired amount of lime to the juice; the lime ran down a small chute to the juice gutter and mixed with the juice on its way to the cush-cush. He illustrated this device on the board by rough sketches.

Mr. RAULT maintained that while we were ail in favour of saving labour and kept this in mind in our work, he felt that by cutting labour in the laboratory there existed the greatest danger of practising false economy. Essential, if less obvious, information might be lost which financially would by far out­weigh the meagre immediate saving accomplished.

Mr. BOOTH said that research should not be curtailed, but the idea was that every chemist should revise his methods a

. little bit. This hint had already been conveyed by him to the Chemical Control Committee. He doubted" whether all the analytical work done was as necessary as previously thought.

Mr. DYMOND stated that the Committee did not in any way want to decry the vast amount of work that chemists had to do in order to maintain and improve efficiency and obtain accurate records. He thought, however, tha t certain work, such as possibly the Clerget method of analysis, might be cut out so as to leave more time for co-operative research. The chemist should be in a position to help in the investigation of anv item of special interest such as the Oliver Campbell filter, subsiders or factory costs.

The PRESIDENT referred to Dr. Keen's conclusions that cultivation could be greatly overdone. The validity of these conclusions had also been borne out by some of the experiments at the Experiment Station, where it was shown that, provided weeds were kept down, cultivation itself did not lead to any increase in yields.

3-4

35

Mr. DODDS said that a record of cultivation experiments carried out at the Experiment Station on Uba cane had been published in our Proceedings some years ago. The experiments showed that eradication of weeds was the important factor. Last year a field of Co.281 and Co.301 in alternate plots was left uncultivated after harvesting, except that the larger weeds were removed. The cane forced its way through a dense blanket of trash, and it was surprising what an excellent stand of cane

resulted. This offered a key to further investigation to see whether we could dispense with some cultivation at least.

Mr. DYMOND said that the index to the literature showed what an enormous amount of references were available at the Experiment Station on the various aspects of labour-saving problems. He thought it would be necessary to condense all these articles under the various headings, as few had the oppor­tunity of consulting the originals at the Experiment Station.

SURVEY OF PAN BOILING PRACTICE IN THE

SOUTH AFRICAN SUGAR INDUSTRY.

PRELIMINARY. Table 2. Pan Equipment.

In order to clear the way for any subsequent study of pan boiling conditions in South Africa, a questionnaire was prepared. This was sent to all factories whose results are included in the comparative statements of laboratory returns issued by the South African Sugar Experiment Station.

The response was very encouraging: all factories but two answered the questionnaire, and of these I wo one factory operates the Suchar process, and on that account did not see its way clear to separate the factory operations from those in the re­finery. The other claims its technique to be so far in advance of common practice, that patent rights on the methods used are about to be registered. Until these are. granted, the manage­ment is unwilling to publish them.

Factory No. 1 operates a double carbonatation process, making about 85 per cent, high grade white sugar. The others, 18 in all, operate a sulpho-defecation process. They make either a proportion of plantation white sugar or a high-grade raw of 98 to 99 polarization sugar.

RATE OF THROUGHPUT.

The first question required both the average and the peak of milling and sugar production rates. With this were to be in­cluded the average and peak boiling house recovery.

Unfortunately, most of the factories did not realise that the boiling house recovery asked for, was that obtained while peak production was being maintained, and gave the peak boiling house recovery. No doubt this omission was primarily due to loose wording of the questionnaire. It is possible, however, to correlate high production rate and variations in recovery from the answers given. The answers to this question are summarised thus :—

* The numbers of the factories are identical with tho*' used bv the Experiment Station in the Annual Summary.

PAN BOILING EQUIPMENT. The next question asked for the following details of the

pans : number in use, construction, area of heating surface and cubic capacity. From this data the square feet of heating sur­face and the cubic feet of capacity per ton sugar produced per hour were calculated. The highest, lowest and average ratio of heating surface, to that of capacity, was also worked out and are given in the next summary.

The largest pan in operation has a heating surface of 3,500 sq. ft. and a working capacity of 1,620 cubic feet of niassecuite.

The 17 factories are equipped with :— 40 calandrias with flat tube plate.

7 calandrias with conical plate. 6 floating calandrias. 5 stepped calandrias. 2 inclined tube plates. 1 calandria with stream-line construction. 5 coil pans.

It is evident that some factories have ample capacity, pro­vided, of course, that supply of injection water, vacuum pumps and steam are adequate. Capacities of others (more particularly as regards the least elastic, viz., heating surface) are, however, altogether too low. especially where the equipment has not been studied with a view of obtaining a high circulation rate, or where the ratio of heating surface to capacity is less than 1.50 sq. ft. heating surface per cubic foot capacity.

The highest ratio is found in a pan of heating surface of 1,400 sq. ft. and capacity 550 c. ft., this ratio being 2.55 ; while the lowest was found in a small pan with flat tube plate which has a ratio of only 0.98.

PAN BOILING METHODS.

Graining.- One factory seeds by means of the sugar from third massecuites. These again are seeded in the general way.

Three factories claim to seed with sugar dust, the quantity per 100 cubic feet of finished niassecuite being between 5 anil 8 grams of fine sugar. This would mean a crystal growth of approximately 220,000, which appears optimistic.

Including these three, thirteen factories in all list: line sugar as an accelerant to graining. Some shock with svrup after (lusting.

Two factories shock with syrup, one of which after mingling with blanket.

One factory grains by the waiting method, while another one, whose reply is not too clear, appears to do the same.

36

Feeding of Pan.—The methods of feeding the pans, which can be either continuous or by repeated "drinks," appear to be well divided in equal proportions. It is fairly evident, however, tha t those with better boiling house recoveries favour the continuous method.

Massecuites made.— I factory works 2 massecuites and no jelly. 4 factories work 3 massecuites and no jelly. 5 factories work 2 massecuites plus jelly. 7 factories work 3 massecuites plus jelly.

Those factories producing jellies all boil the raw molasses from their lowest grained massecuite to string proof.

One factory works back the final ma.ssecuite sugars into a syrup magma to seed first and second massecuites.

One factory remelts almost all the sugar from the final masse­cuite so as to raise the proportion of the first massecuite.

All factories build their last massecuite from a footing of grained syrup, which is then fed by molasses from the imme­diately higher class so as to obtain the lowest purity possible from the combination. The majority use the smallest quantity of grain that will cover the heating surface.

All but one factory build the second massecuite from a looting of grained syrup built up from molasses of the preceding higher grade. In the case of those working second massecuites, the wash from all magmas is used.

One factory is believed to build the second massecuite from wash of mixed magmas, which is grained with dust plus a little-syrup admixed, the whole boiling being done almost entirely out of wash. It is perhaps significant that this factory has for some years led in excellence of boiling house recovery.

Of the 1] factories which work a third massecuite, few operate on pure syrup, which in this country has a very high purity. It is preferred to reduce the purity of the syrup by boiling back a certain amount of wash from mixed magmas.

Most factories work a relatively low brix of syrup ranging from 47° to 58°, but most at a range of 540. This comparatively low range is found more practical, as higher densities coupled with higher purities crystallize too rapidly to allow good control of crystal building.

Molasses Working. --Only two factories do not dilute, all fac­tories heat, some being more particular than others in limiting the temperature to 65/670 C., whilst some heat even higher.

Only three factories settle after liming to neutral point plus heating and dilution.

The final brix of the treated molasses ranges from 55° to 700.

Circulation Water in Pans.— Eight factories employ circulation water for promotion of crystal growth, and find its use particu­larly valuable during graining stages in clearing up unwanted crops in the final stages of the low grade massecuite.

One factory applies a discharge of water and molasses to ease striking, which is of course not circulation water.

Eight do not employ circulation or movement water ; three factories apparently are not aware of the practice.

Boiling Control Instruments. - Only five factories make use of these instruments, of which only one continuously on all pro­ducts. All instruments are of the, electrical conductivity type, and all users report advantages, particularly in detecting poor pan circulation and faulty construction.

The control of low grade massecuites particularly benefits from its use. No success, however, is claimed for conductivity chart duplications, and it seems certain that there is no possi­bility of automatic pan boiling methods until pan construction and other requirements are improved.

Boiling Cycles.—Pan boiling practice appears to have three main variants.

No. 1 variant allows for further boiling from the original grain and a variation of quantity of molasses according to purity range, predetermined for the massecuite.

It is significant that the variants Nos. 2 and 3 are practised by factories which produce low purity exhaust molasses.

Crystallizers.—In operation there are :— 5 Lafeuille.

152 Herisson coil equipped. 8 other types water-cooled. 1 Werkspoor.

140 ordinary air-cooled type.

Capacities vary from 728 c. ft. of watcr-cnoled types to 4,248 c. ft. of air-cooled per sugar hour, the equipment being fairly well distributed amongst the various grades of massecuites. Water-cooling is seldom if ever practised on low grades, though good results have been reported when preliminary cooling followed by reheating prior to curing has been tried. In general, however, observations are that the high viscosities found in this country make it essential that the time factor be allowed for in the lower grades of inassecuites. The water-cooled crystallizers have been beneficial in the case of the higher grade inassecuites with their lower viscosities, thus increasing the crystallizer capacity.

Masseeuite Dilution. - In almost all cases massecuites are diluted during the cooling in the crystallizers. Water (through sprinklers and otherwise) and molasses of approximately the same purity of the mother liquid are used.

Blowing-down of Pans. -The practice of blowing-down of pans with steam is general. In one or two cases the "injection" is isolated and afterwards used for pan feeding, with good results reported; in other cases the injection simply goes to the crys­tallizers.

Jelly Tanks.- Twelve of the 17 factories boil jelly from the molasses from low-grade grained massecuites.

Few factories appear to have adequate capacity, since the cooling time varies from two weeks to several months. It is considered that a cooling period of from 6 to 8 weeks is required.

Centrifugals. Foreworkers. Only one battery of 48in. machines is in operation, the majority being 42in. for higher grade and 36in. to 30in. for lower grade massccuites.

Various types of drives are in use, but belt drives from a shaft driven by a high-speed steam engine or a motor are most common. Direct electric drives are also in use, as also are the hydraulic types.

Almost all foreworkers are of the self-dumping conical bottom type ; no mechanical ploughs are reported to be in service.

When white sugar is produced each grade of massecuite is handled separately. Ordinarily there is enough first massecuite to make a factory's quota of wdiite sugar, and second and third inassecuites are cured and bagged as raws.

For final low-grade massecuites the 30in. high-speed machine is mostly favoured, although one or two factories have the larger type of 36in. or 42in.

Capacities vary according to type of equipment—speed and size of machines. The average appears to be 0.9 machine of 42in. at 900 r.p.m. for foreworkers per ton of sugar per hour, which equals 1.4 machines of 36in. at 1,100 r.p.m.

The following is the inventory of the machines in the 17 factories under review :—

37

38

39

required, especially in raw sugar work, for the purpose of boiling massecuites to a prescribed purity, which of course is essential in an organized boiling scheme. Nevertheless, the fact remains that this is bad practice ; it is wasteful in pan capacity, since the speed of boiling is reduced and, incidentally, a loss of avail­able sugar results.

Webre4 gives his observations that it is quite, common practice to boil 7 or 8 feet above the top tube place, which, together with the 4 feet length of tube, makes 11 to 12 feet under the surface. At normal vacuum on top the theoretical temperature at 12 feet below is 200ºF. No boiling takes place at this depth. Destruction of crystals and under-saturation takes place, the extent of which depends largely on the pan operator and the design of the pan itself. The pan thermometer shows only the average temperature resulting upon the balance of the tem­peratures of the explosions. In localized spots, however, varia­tions in temperature up to 50°F have been observed.

These points are of supreme importance in the judging of a pan's performance. It is interesting to recall that Mr. Bechard himself made observations on comparative yields from masse¬ cuites boiled by two separate pans of identical design, the work of one being consistently better than the other.

Yet another point follows, namely, the system and layout of the condensing plants, the air line, water line and steam supply.

There can be no doubt that the central condensing system, with or without the separate condensers, has many disadvantages. Continuous density recorder on the outflow from the last pot of an evaporator will reveal large variations due to fluctuations in steam pressure and condenser water supply, especially where the one pipe supplies all the condensers.

Continuous ciiitometer records on low purity massecuites boiling over a long period in a pan coupled up to the same vacuum pump as quick boiling high grade pans, demonstrate the tremendous obstacles placed in the way of such a pan main­taining its equilibrium. It is obvious that, where several pans and the evaporator are coupled to the same air and water line, and especially where one pa.n at time of concentrating for grain has an evaporating rate up to and exceeding 171bs. of water per square foot of heating surface, the other pans, particularly at an average thermometer temperature of 130°F., are simply having a bad time. They stop working, the massecuite becomes slack and undersaturated.

The limited use of the ciiitometer control and movement (or circulation) water in our factories is a matter for surprise, con­sidering the publicity these aids to pan boiling have received these past ten years. The use of movement water, especially at graining time, is "as old as the hills."

Attention might be drawn to Alewyn's articles1 on the use of movement waters. It is interesting to record that the var iant No. 2 in Mr. Bechard's survey was tried with much success in one Natal factory after private communication with Alewyn in Java. The method was eventually adjusted only because of the difficulty of maintaining the massecuites equilibrium during the constant interruptions inherent in a central condensation system as referred to above. Shortage of crystallizer capacity was also a drawback. The scheme, however, marks a definite advance on the orthodox ideas where the plant and layout are suitable for its addition, and Mr. Bechard's remarks on the excellence of the boiling house recovery of the factory that practices this or a similar method are to be noted.

These points are contributed to Mr. Bechard's paper because the best way of recognising its importance is to broaden the scope of the work. As already mentioned, our Association hopes tha t some day it will be in the position to open up an intensive s tudy on the economy and efficiency of our vacuum pans and methods employed. The term "undetermined losses" is anathema to all conscientious technicians, and many of these losses can surely be attributed to faulty pan designs, inadequate condensing systems and also, of course, to operating methods that are capable of improvement.

References. 1 Alewyn, W. F. (1933) : Simple Method of Boiling After-product Sugars, and

Further Notes on Boiling After-product Sugars. I.S.J., 35, 352, 465. 2 Smith, Walter E. (1935) : Vacuum Pan Design and Operation. I.S.J., 37, 20. 3 Tromp, L. A. : Machinery and Equipment of the Cane Sugar Factory. Norman

Rodger. 4 Webre, Alfred (1935) : Temperatures in Vacuum Pans. Proc. Int. Soc. of

Sugarcane Tech., 536.

SUMMARY. Boiling house equipment and technique of the South African

Sugar Industry has been reviewed. Wide variations are recorded in pan, crystallizer and centri­

fugal capacities, the indications are that 600 sq. ft. heating surface to 400 c. ft. capacity are required per ton of sugar made per hour.

Pan technique consists generally of grain production by shocking with sugar dust and building up massecuites with syrup and molasses of predetermined purity to the required standard.

Pan control instruments are not in general use and the use of circulation or movement water is gradually being accepted. The system of blank boiling of low grade molasses is still much in evidence.

Herisson coil-equipped crystallizers are in common use throughout the industry, but the cooling of low grade masse­cuites is not favoured. Crystallizer capacities vary widely. It would appear as if approximately 1,000 c. ft. of water cooled plus 2,000 c. ft. of air cooled capacity per ton of sugar per hour would fill our normal requirements.

As regards centrifugals, the South African practice seems to prefer the smaller diameter machine, and the requirements are approximately as follow:-

0.9 machines of 42in. diameter or 1.4 machines of 36in. diameter as foreworkers, and 2.0 machines of 36in. diameter or 3.0 machines of 30in. diameter as afterworkers.

The development of high-speed curing together with preheating of massecuite has not made much headway in this country, although those who have introduced the moving heating coil in the centrigufals mixers speak highly of the results obtained.

ADDENDUM. By G. BOOTH.

It is to be hoped that in the not too distant future this survey will develop into an opportunity to have all individual factory installations examined for capacities and efficiencies. An analysis of the questionnaire points out the necessity for this. One cannot but be impressed by the wide variations existing in pan designs and capacities per ton of cane crushed or sugar made.

In particular, as Mr. Bechard has indicated, in calculating the ratios of heating surface to volume of completed massecuite, and more especially in comparing the diameter of the centre well with the pan diameter, this lack of uniformity in pan design is obvious.

In the past pans and evaporators were sold on area of heating surface and not on performance. Recent years, however, have brought new ideas, which now compel the question whether our older types of calandria should not be rebuilt so that increased circulation and, in consequence, increased capacity may be obtained.

Tromp3 quotes the case of a 1,200 c. ft. capacity 12 ft. diameter pan having a central down take of only 3 ft. diameter. The ascend­ing tubes (418 by 5in. diameter by 4ft. long) provided a free area of 7,600 sq. in. and the downtake area was only 1,017 sq. in., thus the circulation going down had to be seven times as fast as the upgoing, with consequent impaired circulation efficiency. Tromp further mentions a modern pan whose proportion of face tube area to area of downtake is about 2.1 : I. Walter E. Smith of Hawaii2 also stresses this point in discussing designs, giving the ratio of central well to diameter up to 50 per cent. The propor­tion of heating surface to volume is also surveyed.

In Natal pans this figure is fairly constant, being about 1 c. ft. of capacity to about 1 .5 sq. ft. heating surface, although one factory reports 1 to 2.54. This may be a. special design.

Another point of importance is the ratio of graining volume to total massecuite volume.

So far as can be observed, most of our pans are out of balance judged by modern design, in that the graining volume occupies too much space in the pan, the result being that the pan is boiled far too high before striking.

This extra capacity to over full mark (fixed by the chief factory operator and invariably over the maker's mark) is

40

Mr. WOUTERS wanted to know whether it would not be possible to use sodium carbonate instead of lime for neutralising molasses.

Mr. BOOTH said that very few factories ever attempted to neutralise molasses. A few gave the molasses for the final boiling1

a small drink of lime in the pan; but he did not believe in adding any alkali to molasses. In fact, the tendency in recent years had been not to add any chemicals to molasses.

Mr. RAULT regretted that cubic feet of individual ma.sse­cuites per ton of cane were not given. Tons of sugar actually bagged per hour did not give a true indication of pan work, especially where a lot of remelting had to be resorted to in mak­ing white sugar. He would have liked to see a record of the cubic feet of individual massecuitcs boiled per ton of cane or per hour. Mention was made of a 48-inch battery of centrifugals. These machines were in use at Natal Estates, but they were not very satisfactory, as it was found that they did not cure the sugars drv enough. During the war it might be difficult to get crys-tal'lizers; but he thought the days of making jelly boilings were past. Ours was one of the few countries which still per­sisted in this inefficient method of crystallization, which could not be controlled and was dependent on time of cooling and luck for results. Water-cooling for last massecuites should not be condemned without further experimentation. At Natal Estates, working admittedly with a rather higher purity product of less viscosity than that of sulphitation factories, excellent results were obtained. At Kwa, in Hawaii, water-cooling of low massecuites had been very favourably reported upon and no false grain was noticed with massecuites of less than 60 purity. Water-cooling increased crystallizer capacity.

Mr. VIGHR said he could not agree with Mr. Booth that no chemicals should be added to molasses. There was a big drop in pH from syrup to molasses, and lower grade molasses might become so acid as to cause inversion. Two years ago he was asked to do the pH of molasses from a certain factory; the undetermined losses had increased to a high level. The manage­ment was rather surprised to find the pH so low. He thought it necessary to add a small quantity of trisodium phosphate to molasses. In normal times the cost of this chemical was not excessive, the amount used was very small, therefore the in­creased manufacturing cost would be negligible. The use of trisodium phosphate in molasses gave good results because it consolidated the alkalinity.

Mr. BOOTH agreed with Mr. Rault that cubic feet of masse­cuites referred to the ton of cane was a valuable figure, but as many factories did not have this information it was omitted.

In regard to adding chemicals to molasses, the practice of liming molasses was now practically abandoned, although some chemists add a little lime water to their low grade massecuites whilst in the pan to guard against a drop in pH.

Referring to pan steamings, Mr. Booth gave his opinion that to isolate steamings into a special tank, with all its at tendant fittings, was not worth while, although admittedly a certain amount of resolution of sugar took place when running steam­ings into the crystallizor. The best method was to guard against excessive steaming. A surprising amount of time and steam could be wasted in this operation.

CLARIFICATION OF NATAL JUICES WITHOUT THE AID OF SULPHUR

SOME FACTORY AND LABORATORY TRIALS By M. VIGER.

INTRODUCTION. In general, it is the consensus of opinion that simple defeca­

tion of Natal juices, without the aid of sulphur, has never been successful.

Many chemists in this country have spent a considerable amount of time on research, and the latest ideas from overseas have been tried out in the laboratory. The efforts of these in­vestigators have not been crowned with success. In most countries simple defecation is the usual routine t reatment for raw sugar manufacture. The treated juices settle completely in an hour, or at the most in an hour and ten minutes. The juices are bright and clear, the mud volume is even lower than our highly sulphited juices, and the insoluble solids content of the settlings is fairly high. The question naturally arises : Why does the floc produced by only liming the juices in other coun­tries, settle rapidly and yield a low mud volume? The writer has, for many years, carried out a certain amount of laboratory work on the purification of juices without sulphur, and con­sidering that the proportion of variety canes has reached the high figure of 80 per cent., it was thought that the time would be most opportune to put these laboratory experiments to the acid test. The process was tried out: for a week in the factory —it failed utterly.

LABORATORY AND FACTORY PROCEDURE. In these tests the mixed juice was first heated to 185ºF.,

then pumped to the correcting tanks, where it was limed to pH 8.4. The limirg of the juice was conducted in such a way so that the bulk of the milk of lime (about 95 per cent.) was first introduced into the empty tank before filling it with the hot juice. When the tank was filled, it was adjusted to pH 8.4 and then corrected with phosphoric acid paste solution to pH 7.8. The juice was then reheated to boiling point and settled. The clarified juice was at a pH of 7.4.

The chemicals used per ton of cane were approximately as follows:—

Lime 3 . 5 lbs. Phosphoric acid paste 1. 1 lbs.

OBSERVATIONS OF LABORATORY EXPERIMENTS. It was quite evident, from laboratory tests, that the settling

rate of these juices was slower and gave a larger mud volume

Some fifteen years ago a similar run was conducted in the factory. The process used was that of Charles Muller.1 The mixed juice was superheated to a temperature of 241°F., then cooled to 175"F. through a heat exchanger, limed to pH 8.0 and corrected with phosphoric acid paste solution to pH 7.8 and then heated to boiling point.

The process was tried over a period of three weeks. It was

than the juices treated with sulphur. The insoluble solids content of the muds was also low. The quality of the clarified juice was fair and compared favourably with juices obtained by our standard method of clarification.

OBSERVATIONS OF FACTORY TRIAL. During the trial it was observed that the settling rate of the

clarified juice was slower than with sulphitation, the capacity of the subsiders had to be increased by 33 per cent. There was also a larger volume of settlings to be filtered. The Oliver Camp­bell filters could hardly cope with the muds, they were strained to the utmost.

The purity rise from mixed to clarified juice was slightly inferior, being 1.3 as against l.6 for hot sulpho-defecation. The clarity of the juice was not at all times satisfactory, it was rather erratic. The sulphated ash per cent, brix for the mixed a.nd clarified juices did not show any appreciable differences in comparison with juices treated with sulphur, the ligures were 3.49 per cent, for the mixed juice and 3.52 per cent, for the clarified juice. Sucrose in filter cake rose from 0.7 per cent, to 1.6 per cent.; this was probably due to the very much lower insoluble solids content of the settlings, which varied from 2.2 per cent, to 3. 1 per cent, as against 6 per cent, to 7 per cent, for sulphitation. Under these conditions a larger amount of cush-cush must necessarily be added to the settlings previous to filtering. There was no appreciable change in the yield of sugar per cubic foot of niassecuite cured. The amount of final molasses per cent, cane and its purity compared favourably with figures obtained from sulpho-defecation. The sugar produced was very good, it polarized 99.24 with a safety factor of 0.151. The filtration rate (Elliot test) gave a figure of 116.

Another good feature was the fact that the factory output was not reduced. The massecuites were free and cured easily and there was no apparent increase in viscosity. From a recovery point of view, the results were most disappointing. The recovery of sucrose from the mixed juice dropped to the extent of 3 per cent. Undetermined losses were exceedingly high. The process was abandoned.

For comparison the figures obtained for the laboratory ex­periments and those obtained for the factory trial are tabulated. It will be seen that a fairly close agreement was obtained be­tween the two sets of figures.

observed that the factory output was reduced by 25 per cent. through the slower boiling of the massecuites and greater diffi­culty was experienced at the centrifugals due to the viscosity of the products. The quality of sugar produced was fair, it polarized 98.5. In this case also the sucrose recovery dropped to the extent of 3 per cent.

41

Table 1.—Average Figures showing Results of Laboratory Tests.

42

Table 2. — Results of Analyses, Carter's Process.

CARTER'S CLAY PROCESS. A patented process of simple defecation using clay as a clari­

fying agent has recently been evolved by Mr. R. A. Carter, acting chemist to the Umfolozi Co-operative Sugar Planters, Ltd. '

It must be said at the outset, of all the various simple defeca­tion processes tested in the laboratory, this new method of clarification, without the aid of sulphur, has given the best and most promising results.

A series of laboratory experiments were undertaken ; in this way a procedure was found which best suited our juices at Darnall.

The clay used in these trials had a yellow ochre colour. The material is found near the mill.

Results obtained by this new method of clarification were compared with the figures obtained by hot sulpho-defecation, which, so far, has given excellent results in this country.

The modus operandi with clay is as follows :-A clay suspension in water equivalent to 3£ grains of clay is

first added per litre of cold mixed juice. This is followed by liming with milk of lime at 10ºBe. to pH7.6, then 0.250 grams of phosphoric acid paste (about 41 per cent, soluble P2O5 dis­solved in water is added. The mixture is again corrected with milk of lime to pH 7.5, heated to boiling point and decanted during 1 1/2 hours. This time of settling represents usual factory

practice. The amount of chemicals used as above, clarified all types of juices at Darnall. The colour and clarity compared favourably with juices defecated by hot sulpho-defecation. The chemicals used per ton of cane are approximately as follows :~ -

Clay 7 lbs. per ton cane. Lime 2.5 lbs. per ton cane. Phosphoric acid paste 0.5 lb. per ton cane.

The following analyses were made :-Mixed juice : Brix, purity, reducing sugars, sulphated ash,

and calcium.

Clarified juice : Brix, purity, reducing sugars, clarity kopke, pH, sulphated ash, and calcium.

At the same time the settling rate was plotted during 1 1/2 hours at intervals of fifteen minutes, the final mud volume was noted and the amount of insoluble solids therein was determined.

It was also thought that some quality index of the juices could be obtained by filtering the defecated hot juice under standard conditions of temperature, filter cloth, time and vacuum.

It will probably be argued that this test is arbitrary. This may be so, but it does give an idea of the quality of juices treated by various methods of clarification.

In these tests an Elliot filter leaf was used.

The analyses are as follows :-

Table 3. Quality Index Obtained by Filtration. The clarified juice from the clay treatment shows a better reduction of ash, although the lime salts have increased in the clear juice, the proportion is smaller than with sulphitation.

The settling rate is slower and the settlings have a larger volume than juices treated by sulphitation. This would probably necessitate an increase in the settling capacity and a larger filtering area.

Insoluble solids content of the settlings is low for juices treated with clay. This is a disadvantage for the filters.

The quality index, although arbitrary, is inferior to juices treated by sulphitation.

The simple defecation of juices with clay has great possibilities. ft also has many advantages over .sulpho-defecation. This is especially true in war-time, when sulphur is not only expensive bu t at a premium. On the other hand, further studies are required to improve the settling rate. An increase in the amount of insoluble solids of the muds is also desirable.

Experiments to improve the rate of settling by passing carbon dioxide through the milk of lime used for tempering the juices gave encouraging results.

Reference. 1 Milller, Charles (1921) : Cause and Remedy of Difficult Defecation of Cane

Juice . I.S.J.,23., 597.

The PRESIDENT said that one of the problems arising out of the war was the shortage of materials. The Sugar Industry especially felt the shortage of chemicals for processing. Atten­tion had recently been drawn in the local press to the possibilities of clarifying Natal juices without the aid of sulphur. Mr. Viger's paper was therefore of particular interest at the present moment.

Mr. BOOTH said he had tried to cut down the use of sulphur without eliminating it entirely, but his experience was that with insufficient sulphur, although a fair defecation might still be obtained, the work of the boiling house was slowed down and it made a big difference to the massecuites.

Although the Muller process was not commented on very favourably in this paper, his own investigations and communica­tions with various authorities led him to believe that the process might still find application in this country.

In Mr. Viger's factory trials in clarification without sulphur there was a loss of 3 per cent, in recovery, but the ash, the yield and purity of massecuites and molasses, as well as the viscosity, remained the same. Under these circumstances he could not see to what the loss of recovery could be attributed.

He found the process very interesting and had received samples for experimentation, but had not had the time as yet to carry out experiments with it. Canes after rains were often dirty with adhering mud and clay, which gave a lot of trouble in the factory. The speaker would like to know what the difference was between such clay and that used by Mr. Viger. Was it a special type of clay found by Mr. Carter, with pro­perties suitable for clarification?

Mr. VIGER, in reply, stated that the losses were undetermined losses and it appeared to be bound up with the process, as both before and after the factory trial they did not occur. He gave the following sucrose profit and loss account as a percentage of sucrose in juice :—

The juices treated with clay gave, a total volume of 1,797 ml. and those treated bv sulphitation gave a total volume of 2,326 ml.

In these tests the juices treated by the hot sulphitation method are of a better quality.

EXPERIMENTS ON SETTLING RATE WITH MODIFIED MILK OF LIME.

Experiments have been done with a view to improving the settling rate and also the insoluble solids of the muds. Some success has been achieved in this direction. Although the pro­cedure used may be interesting from a laboratory point of view, its practical application remains to be proved.

It was found that by passing carbon dioxide through the milk of lime used for tempering the juice, a much faster settling rate is obtained. The figures run very close to sulphitation. The insoluble solids content of the settlings were somewhat im­proved—an average figure of 3.98 per cent, was found. The milk of lime used in these experiments had a calcium carbonate content of about 55 per cent.

The settling rate figures are as follows: —

Table 4.—Settling Rate.

SUMMARY OF RESULTS.

The clarification of Natal juices without the aid of sulphur was tried both in the laboratory and the factory. Of all the methods tried, the Carter clay process has proved the most promising.

The purity rise from mixed to clarified juice in this process is good. It compares favourably with sulpho-defecation.

The loss of reducing sugars is negligible. This is to be ex­pected, as the juices were limed in the cold, whereas hot liming followed by sulphitation, as a rule, shows a larger destruction of reducing sugars.

43

44

The Muller process was also tried with sulphitation and there, unlike the trial without sulphur, no trouble was experienced.

The clay used at Darnall was not the same as used by Mr. Carter at Umfolozi. Its composition was as follows : 2!).5 per cent, silicate, 39.5 aluminium oxide, and 34 per cent, moisture, with small quantities of iron and magnesium.

It was interesting to note that the literature had for some years mentioned bentonite as a clarifying agent in sugar manu­facture.

Mr. CARTER said that he had tried many different types of clay, and nearly all of them were quite satisfactory. In the factory, however, enfrainmenl was encountered as a result of the juices boiling so exceptionally freely in the evaporators. It was also noticed that the juice from the evaporators, though clear, was almost jet black for the first couple of hours. It was found afterwards that most of the scale from the evaporators and syrup tanks had been removed.

Mr. WOUTERS said that sodium carbonate was made in this country, but also imported from East Africa at a much lower cost. He suggested that it be used instead of lime in pre-liming and also for the removal of scale.

Mr. YIGER said that Smith in Australia was working on a method of clarification using sodium carbonate. He had not seen the results yet, but thought that sodium carbonate would be found a rather expensive chemical.

Mr. CARTER stated that working with an acid instead of an alkaline clay the. juices settled much quicker. In reply to certain questions by Mr. du Toit, Mr. Carter said he had tried the clay process with and without phosphoric acid, and also with a small quantity of sulphur dioxide. For Umfolozi juices, which are comparatively rich in phosphates, the addition of phosphoric acid was in his opinion unnecessary, and had the disadvantage of giving a light precipitate of larger volume. Clay with lime and carbon dioxide gave the same result as that obtained with­out the carbon dioxide. The addition of 0.5 gram of sulphur per litre gave a very nice juice, but did not improve the volume of precipitate.

Mr. BIJOUX said that as a result of recent investigations the MacMar process was patented in America. In this process carbon dioxide from flue gases was dissolved and later regenerated from alkali carbonate lye in the presence of ammonia. A very-high efficiency of carbon dioxide recovery was claimed.

About 2.2 tons of carbon dioxide were required per 100 tons of cane in the double carbonatation process, allowing for 40 per cent, unavoidable wastage. The average bagasse per cent, cane

in South Africa was about 35 per cent, of 52 per cent, moisture, which on combustion, according to Noel Deerr, would give rise to 28 tons of carbon dioxide per 100 tons cane. Only part of the carbon dioxide from the flue gases need therefore be recovered for double carbonatation, and even less for a single carbonatation.

The concentration of the carbon dioxide from the lye would probably be at least double that of the original in the flue.

If ammonium phosphate were used in treating the partially tempered juices there would be a liberation of ammonia, at the higher pH, and this could again be used in the process of re­covering the carbon dioxide.

The lye solution for absorbing the carbon dioxide was found best when made from potassium carbonate, or failing that sodium carbonate, but calcium carbonate might also be found sufficiently effective.

The speaker thought that the necessary plant might be erected largely from material already in the factory. If this could be done the cost should not be prohibitive, and a change to a semi-carbonatation process, using largely waste products, ought to be both more economical and efficient than sulphitation.

Dr. MEDLEY thought that, with the present acute shortage of sulphur, this was certainly a question which deserved con­sideration. Germany had shown that it was practical to recover carbon dioxide from flue gases and utilize it industrially. Carbon dioxide from bagasse furnaces was not only purer, but should he at a higher concentration than that in the flue gases from coal. He had often thought that experiments should be carried out to see whether the carbon dioxide in our flue gases could not he used in clarification. Its concentration was practically the same as that of sulphur dioxide required for sulphitation. Natal Estates, with double carbonatation, used about double, 30 per cent., the concentration of carbon dioxide in the flue.

Mr. RAULT said that they found the speed of gassing and neutralising in their process dropped very rapidly if the concen­tration in carbon dioxide dropped below the normal 28 to 30 per cent. Even with a comparatively small quanti ty of lime and carbon dioxide a quick settlement was obtained with the muddy carbonated liquors, and it was not necessary to use the large volumes of lime as practised in Natal Estates Limited in refining juices by the double carbonatation in order to substitute carbon dioxide for sulphur dioxide. All that would be necessary to work a simplified carbonatation process at any factory would be the erection of a small kiln and gas pump. This ought not to cost much and would be easy to work. The large lime con­sumption was only necessary for easy filtration but not so much for quick settling.

ANALYSES OF BOILER-FEED (MAKE-UP) WATER IN NATAL.

By J. L. DU TOIT.

ANALYSES OF WATERS.

The following are the analyses of the waters used in the factories:—

The specific conductivity is expressed as ohms— 1 cm—1 and the inorganic constituents as parts per 100,000 with alkalinity as calcium carbonate.

Sodium concentration was found high in waters containing large amounts of chlorides. Thus the sodium as Na20 parts per 100,000 in the waters from factories 16, 15, Pros., 11 and 0 were 30.1, 12.5, 11.1, 6.7 and 9.1.

It will be seen that a rather close correlation exists between conductivity and total solids as well as chlorides. This is the case in a series of analyses where the soluble solids vary in com­position, the usefulness of routine conductivity tests at a factory working with a water containing the electrolytes in an almost constant relative proportion, can therefore be readily realised.

"Loss on ignition" does not necessarily mean organic matter, as some carbon dioxide is probably also given off, especially where magnesium carbonates are present.

From these analyses the hardness can be calculated. This was done and the results compared with that obtained by the potassium palmitate method and the soap solution method for total hardness. The agreement between the results was good. The potassium palmitate method is, however, preferred, as it is far less tedious than the soap method. In certain cases the soap method cannot be relied upon either. The permanent hardness was also calculated from the analyses and by subtracting this figure from the calculated total hardness, the calculated tem­porary hardness was obtained. This figure was compared with the temporary hardness obtained as alkalinity. The soap method

45

INTRODUCTION.

In the report4 for the year ending April, 1940, the Chemical Control Committee stressed the necessity for strict boiler control — a field which in the past had been rather overlooked. The water used as make-up in Natal is in most factories obtained directly from rivers or clams, and only in a few treated before entering the boilers. Chemical control leaves a lot to be desired, considering the valuable plant involved.

The Committee afterwards decided that a general survey of the inorganic constituents of the water used in our factories may serve a useful purpose. Arrangements were made to send samples of make-up water from all the various factories to the Experi¬ ment Station, where the necessary analyses were done.

GENERAL.

The crushing season in Natal coincides with the dry season. This may give rise to stagnant water contaminated with a certain amount of organic acids, as was pointed out by Camden Smith3. The inorganic impurities are also increased. This un­favourable condition was accentuated by the fact that 1941, the year in which this survey was undertaken, was one of the driest on record. It is therefore likely that the waters will be of some­what better quality in normal years.

The sugar belt is situated mostly on the following geological formations: Ecca, dwyka. Table Mountain sandstone and granite. Table Mountain sandstone and granite are generally found some­what further inland. The former has the reputation of being a good water-bearing formation and the water is of a high purity. There is therefore a fairly wide variation in the amounts of soluble solids in the waters obtained from different localities and from various formations. Waters from factories Glen, and Nos. 9 and 3 are very pure, and it is interesting to compare the analyses of waters from factories Nos. 9 and 12, both drawing their water from the Nonoti, and factories Glen, and No. 19, getting their supply from the Umvoti.

Even in the same locality, however, variations are found. The following are the analyses of the Marshall and Dumat

dams, both of which are on ecca formation but the Marshall dam draws most of its water from the Umgeni.

Waters derived from boreholes or springs may vary even more. The anlayses of two borehole waters from much the same locality as these two dams are given. The one water is from a borehole on the Experiment Station and the other from a nearby farm.

Phenolphthalein alkalinity was found in water from factory No. 2 to the extent of 2.0 parts per 100,000 as calcium car­bonate. Water from this factory as well as from lief, and fac­tory No. 17 was treated before analysis.

DISCUSSION.

Scale Formation.—Matthews2 points out that scale and sludge may consist of any salt present in the water, and mentions that cases are on record of where sodium sulphate formed the major part of the scale. This, however, is the exception. In practice boiler deposits consist mainly of calcium and magnesium sul­phates, carbonates and silicates. Of these the sulphates and silicates form very hard scales and are the more objectionable. Magnesium scales are not generally found as often as calcium scales, but with our boiler waters which contain a relatively high proportion of magnesium salts, magnesium is often present in the scales.

Two scales from a certain sugar factory were sent in and analysed at the Experiment Station. The analyses on a dry weight basis were as follows :—

Corrosion.2 Of the numerous causes of corrosion, only those that are caused or influenced by the constituents of the waters given in the tables will be briefly discussed.

The most obvious danger is the comparatively high concen­tration of magnesium and chlorides.

Magnesium chloride is, of course, very objectionable, as on hydrolysis hydrochloric acid is formed, which reacts with the iron (corrodes it) to form ferrous chloride, which in turn reacts with water, forming hydrochloric, acid again, and the process of corrosion is continued. Magnesium nitrate reacts in the same way, forming nitric acid as the corrosive agent. The fact that some of our magnesium may be present in the form of sulphate is no consolation, as this is generally associated with a large amount of sodium chloride and the magnesium chloride is formed in the boiler if not already present in the original water.

Calcium salts may give rise to similar reactions.

Sludge formed in the boilers may be preferable to scale, especially hard scale ; nevertheless, it may assist corrosion by helping on differential aeration and trapping hydrochloric acid liberated, carbon dioxide and organic acids.

Soft waters may still be dangerous on account of small amounts of free acid or acid-forming salts. Corrosion under these con­ditions may proceed almost unchecked because of the relatively small amounts of carbonates present.

Mention may be made here of a rather interesting case where a gauge glass was virtually eaten up. At one of the factories it was found that the gauge glass had worn very quickly and an incrustation formed round a leak. The dry deposit was found to have the following percentage composition:—

46

was also tried here, but the results were so unreliable that the method was discarded. Bond1 also found that the soap method for total hardness, except in cases of waters containing large amounts of magnesium and chlorides, gave fairly reliable results,

but as a method for determining temporary hardness it was very misleading.

These comparisons are given as parts per 100,000 calcium carbonate in the following table :—

It can be seen tha t in both cases the scale consisted mostly of calcium and to a lesser extent magnesium sulphate.

Waters from the two dams were also analysed, with the following results:—

Although the calcium salt is the predominating constituent of the scale, the water analyses show that magnesium is actually present in greater concentration.

Water from the drip of the gauge glass had the following extraordinary analysis:—

47

Iron oxide, etc. (Fe2Oa etc.) 0.7 parts per 100,000 Calcium oxide (CaO) 17.0 parts per 100,000 Magnesium oxide (MgO) 0.2 parts per 100,000 Sodium oxide (Na..O) 197.5 parts per 100,000 Total hardness 32.4 parts per 100,000

as CaC03

Total alkalinity 40.3 parts per 100,000 pH 8.55

Foaming and Priming.2—Without going into the theory of foaming and priming, it may be stated that the chemical causes are mainly oil and suspended solids. Oils, especially those con­taining saponifiable matter, are very dangerous when found in an alkaline water. The effect of suspended matter increases rapidly with increase of soluble solids ; or, in other words, as the soluble solids increase a progressively smaller amount of suspended matter can be allowed.

SUMMARY.

Analyses of water used as boiler-feed (make-up) are given. They vary considerably in composition. Waters from factories further inland were found to be far more pure than those nearer the coast. In many cases the concentrations of calcium, mag­nesium, sodium and chloride arc rather high.

The effect which the inorganic constituents can have on scale formation, corrosion, priming and foaming is briefly discussed, and some further analyses of scales and waters are given.

The so-called rapid methods, conductivity test and total hardness test were found to give very regular results consider­ing the varying nature of the water constituents. They will be of even more use in the factory where the same water is dealt with all the time. This does not mean, however, tha t complete water analyses are not necessary. On the contrary, the nature of our boiler-feed waters makes it absolutely essential tha t the strictest control should exist at each factorv.

References. 1 Bond, G. W. (1936): A Comparison of Routine Methods of Determining Hard­

ness of Water. Jonr. S.A. Chem. Inst., xix. No. 2, 50. 2 Matthews. F. J. (1939) : Boiler Feed Water Treatment. Second edn. Hutchin­

son's Sc. & Tech. Pub. 3 Smith, R. Camden (1938) : Some notes on Machinerv Maintenance in a Cane

Sugar Factory. Proc. S.A. Sug. Tech. Assoc, 12, 114.

4 (1940) : Committee for Standardization of Chemical Control. Report for the w a r ending April, 1940. Proc. S.A. SUG. Tech. Assoc, 14, 100.

Experiment Station, South African Sugar Association,

Mount Edgecombe. March, 1943.

Mr. RAULT welcomed the paper, as so little had been done on the subject and we had no standards to go by in classifying a boiler-feed water.

Mr. BUCHANAN expressed the opinion tha t water with a total hardness more than two should be treated with lime or soda ash. It was, of course, also necessary to analyse blow-down water, especially for hardness and total solids. Waters intended for sugar factories should have a higher alkalinity than was usual for boilers in other industries, in order to neutralise acids developed in sugar boiling.

Mr. BOOTH said that they found the water at Doornkop very pure. He always made a point of bringing the water up to pHH, however. All the water used at Doornkop, except the actual effluent, went back to the river, and he wanted to know whether this had added appreciable impurities to the water and had affected Darnall factory water adversely.

Mr. DU TOIT, replying to some questions, said that the analyses would help in discriminating between good and bad waters along the coast and eventually in drawing up standard specifications. He agreed that the alkalinity of our natural waters should be brought up a good deal to safeguard the boilers against acid formation from the high content of chlorides present. There was a considerable increase in total solids, hardness and chlorides in the water used at Darnall as compared with Doornkop, but he would not necessarily put that down to contamination of the water supply at Doornkop. There were other natural explanations. Not only was Darnall much nearer the sea, but before reaching it, the river left the Table Mountain sandstone formation and ran along the Ecca-Dwyka border.

Mr. RAULT said that in analysing the waters of various estate clams it was also found that the sodium chloride content of the water showed an increase on approaching the sea. He said the paper provided a good example of the co-operative work that could be and was being done at the Experiment Station.

NEW TABLE FOR USE WITH JACKSON AND GiLLIS METHOD OF SUCROSE DETERMINATION.

By G. S. MOBERLY.

* Tables given in South African Sugar Technologists' Association Recommended Methods of Chemical Control.

48

The present recommended method for carrying out the Jackson and Gillis polarization calls for the following procedure after the readings of P, P1 and t have been made :

1. Subtract P1 from P.

2. Refer to Table IV* to find divisor corresponding with P- P1.

:i. Refer to Table V* to find temperature correction corre-sponding with t.

4. Subtract temperature correction from divisor.

5. Divide P-P1 by corrected divisor to find clerget reading.

(i. Refer to Table III* to find sucrose percentage correspond-ing with clerget reading.

The new table, reduces steps 2, 3, 4 and 5 to one step, thereby saving time in reference and calculation, and obviating the use of a calculating machine.

TO USE THE TABLE.

The table must: be used in conjunction with pencil and paper. The necessary decimal extensions cannot satisfactorily be done mentally. The information already obtained and available will be P - - P 1 and t.

1. Find the figure at the intersection of the whole numbers of P—P1 and t. Write this down.

2. In the column of the whole number of t, find the figure at the intersection of the line of "decimals of P— P 1 " (at the foot of the table). Write this down below the previously found figure.

TABLE FOR CALCULATING SACCHARIMETER READINGS WITH THE JACKSON AND GILLIS METHOD.

DECIMALS OF P—P1.

50

51

RED ROT IN SUGARCANE IN NATAL. By A. McMARTIN.

INTRODUCTION.

It has repeatedly been stressed that the introduction of new-varieties of sugarcane to replace those which suffer from the virus diseases, mosaic and streak, does not mean that the problem of disease in Natal has been successfully settled. The quarantine restrictions at present in force greatly reduce the risk of intro­ducing diseases not already present; there always remains the risk, however, of some species of pathogen adapting itself to cane from some of our local flora, or of some sugarcane disease which might have been introduced in the early days of the industry, and which has been perpetuated as a minor disease, becoming a major disease when another suitable variety is grown.

Prior to the days of strict quarantine restrictions, over seventy varieties had been introduced from more than a dozen countries, between which existed all the principal major and minor sugar-cane diseases. It is not unreasonable, therefore, to suppose tha t diseases were introduced in those days — mosaic almost certainly was—when their true nature perhaps would not be appreciated nor their identity established; if a variety failed, it would probably be considered unsuited to the country and the mat ter left there. The disease organisms, however, might not be eradi­cated, but perpetuated by growing on varieties of sufficient resistance to keep the pathogen from becoming a serious disease, but susceptible enough to keep alive a source of infection for any more susceptible variety grown subsequently.

Ranking among one of the worst sugarcane diseases in some other countries is red rot, caused by the fungus Colletotrichum falcatum. It is widely distributed throughout the tropics, and is one of the most serious diseases in India, Louisiana, and Aus-tralia; it has been attributed with losses of from 25 to 50 per cent. of the crop.

APPEARANCE IN NATAL.

Its absence in Natal has been remarked upon, and although numerous examinations of canes have been made in past years no sign of this disease could be found.

It was first found by the writer towards the end of 1941, while examining dead sticks in some new seedling varieties, and almost simultaneously was identified as a disease in the Eshowe district, where it was causing considerable damage on Co.290. Since then it has been found in the areas of Upper Tongaat, and Powerscourt, with, in addition, two cases on unreleased varieties under trial at Empangeni and Tongaat; in the latter two cases particularly susceptible varieties were concerned, and none of the neighbouring commercial cane was found infected.

SYMPTOMS.

The symptoms of this disease, briefly, are a wilting of the cane, accompanied by a red discoloration of the inside, which is not uniformly red, but striped or mottled with white.

In doubtful cases microscopic examination has to be resorted to, as spores of the disease can usually be found on the outside of a cane which has died from this disease.

The disease appears to become plainly visible about July or August, and increases in severity up till the next growing season.

The mottled appearance of the inside of the stem, together with the death of the cane, serve to distinguish this disease from the red discoloration so commonly found on Co.290, from which the fungus formerly known as Cephalosporium sacchari has re-peatedly been isolated; moreover, this fungus has never been observed to kill the cane.

VARIETIES AFFECTED.

Of released varieties, Co.290 and P.O. J.2725 are the only two on which it has been found; Co.281 and Co.301 appear resistant, while the position of Co.331 remains to be ascertained; in India, however, it has proved susceptible, though no cases have been found here yet of red rot on this variety. The position of Uba will be discussed later.

SEVERITY IN NATAL.

In areas where the disease is severe considerable loss of crop is being experienced—a reduction of about 50 per cent, seems not uncommon. In one case the cane yielded only 5 tons of cane per acre. In some seedlings at the Experiment Station counts have been made of the dead sticks in the infected plots, and a reduction of the number of unliable sticks by half has been obtained. An interesting fact is that Co.290 and P.O.J.2725 have so far remained much more healthy here than in those other areas specified previously, which perhaps indicates that these varieties suffering badly here are much more susceptible than these two released varieties.

TRANSMISSION OF THE DISEASE. Apart from the question of how this disease arose, it is im­

portant to know how its spread is effected, and why it is con­fined, at any rate in a severe form, to certain areas.

That it is transmitted by cuttings seems fairly certain, as many canes suffering from red rot in its earlier stages, before the actual wilting commences, have been used as planting material. One case shown, to the writer of a field of Co.290 with red rot, grown immediately after wattles, no doubt could be attributed to diseased planting material.

On the other hand, careful selection of planting material would probably not offer any measure of control if the disease is in the field to be planted, and selecting healthy sticks from an infected field has led in one case to disaster—as probably, although they appeared healthy, they may have had spores of t he disease on them, derived from neighbouring infected sticks.

A specimen found at the Experiment Station of Colletotrichum sporulating on trash on the cane suggests that this portion of the cane could transmit the disease, although the stalks them-selves were not affected.

The possibility of other plants, e.g., some grasses, harbouring the disease must be considered, but so far none have been seen seen here with it.

COURSE OF THE DISEASE. The development of the disease in a field is not fully under-

stood. Badly infected cuttings die, but probably slightly infected ones germinate if conditions for growth are favourable enough.

The question arises—does the fungus penetrate from the infected cuttings, to the inside of the stems which arise from these cuttings ? On this point, evidence in different countries is conflicting; here, however, no case has been seen in which the fungus has been found to do so. Nevertheless, it must be borne in mind that these young stems are surrounded at their base by disintegrating infected material which might prove a source of infection for penetrating the stem from the outside when con­ditions are suitable. In support of this view, some specimens have been found by the writer, of cane about one year old, in which the leaf sheaths had discoloured areas on them not unlike large eye-spot markings, but which proved to be lesions of Colletotrichum; these discoloured areas penetrated to the stem and were causing a slight discoloration on the young soft rind cf the young internodes. This does not appear to have been recorded in any other country; it suggests that here the fungus perhaps can grow from the infected material in the ground, up the outside of the stem or the leaf sheaths, and ultimately pene­t ra te the stem itself. The sticks after death produce spores externally, which under suitable conditions would spread the infection.

CONDITIONS FOR SPREAD.

It is naturally of interest to know why the disease has only become serious in certain areas; as will be stated later, red rot is now suspected to be more widespread than at first thought, bu t not with any degree of severity except in the areas men­tioned previously. It seems apparent then, that climatically Eshowe and these other areas are more suited to the spread of the disease. Till more is known about the cycle of the disease

52

in a crop, suggestions are tentative, but it has occurred to the writer t ha t the mists experienced in these high altitudes, main-taining a dampness over the fields for a longer period than the lower lands nearer the coast, might be a contributing factor, providing more suitable conditions for the germination of spores.

CAUSE OF THE DISEASE.

Red Rot has always been attributed to the fungus Colle-totrichum falcatum. It was early noted here, however, that C. falcatum was constantly associated with the fungus previously known as Cephalosporium sacchari, that cultures from red rot cane were usually a mixture of these two fungi, it is now con-sidered that C. sacchari is more correctly a species of Fusarium, of the F. moniliforme group, a fungus well known in other countries as causing a top rot of sugarcane, and has been known in Natal as causing an internal red discoloration of the stems of this plant. It has recently also been found causing a top rot here.

Its regular occurrence in red rot cane led the writer to investigate the possibility that it might not be playing an unim-portant role in causing the disease, and experiments are being conducted to elucidate this point.

It has been found that F. moniliforme can be grown in culture for a longer period than C. falcatum and remain capable of rotting cuttings; also, in one case, canes inoculated with both fungi from pure cultures produced more typical symptoms of red rot as found in the field than were produced in canes inoculated with these two fungi singly.

The symptoms produced by inoculating with a pure culture o f C. falcatum appear to vary considerably: the age of the culture used appearing to be one determining factor; sometimes by using a culture of from four to six days old the most typical symptoms have been produced.

It has also been found that a. thirty-days'-old culture of F. moniliforme reduced germination when inoculated into cut­tings, while the same age of C. falcatum did not, while the two mixed produced the same result as the F. moniliforme alone, suggesting that it was the latter component of the mixture that was causing the rotting. It may therefore be that F. moniliforme is not merely a secondary invader in diseased canes where red rot is most severe, but might eventually prove to be playing an important role in the damage done.

ORIGIN OF THE DISEASE IN NATAL. The question naturally occurs when a, disease breaks out, as

has red rot here where has it come from ? As stated at the outset, the possibility must be borne in mind of diseases having been introduced in the early days; and being kept latent till a susceptible variety is grown. This possibility has led to the examination of dead sticks of Uba wherever the opportunity offered itself.

Never, however, have sticks been found with symptoms of red rot, nor have spores been found on the canes, nor cultures obtained of either C. falcatum or F. moniliforme from dead Uba. It has, nevertheless, been puzzling to find cases of wilted canes of Uba when grown in close proximity to varieties which are suffering from red rot, but which on examination show no cause for the wilted condition : no red discoloration has taken place internally—the canes have just died. At the same time from other areas samples of dead Co.290 have been examined which showed similar symptoms—viz., white internal tissue, but with a dead top.

It has further been found during close examination of the varieties at the Experiment Station, that sometimes, prior to finding typical cases of red rot in some varieties, the first stick or so found dead would have no discoloration.

It began to appear, then, as if this condition might be one caused by red rot, but not in its typical form; it only remained to find the fungus or fungi associated with such canes.

Recently one such case has been found—a specimen of Co.290 with a dead top, but no discoloration internally; C. falcatum spores, however, were found on the outside of some of the internedoes.

This suggests, then, the possibility that these other cases may also have been red rot, in which perhaps the disease did not run its full course; if so, then isolated cases of dead sticks in Uba may also have been suffering from the same disease, which would account for the origin of the present outbreak.

It also suggests the possibility of dead sticks of Co.290 found in other areas having died from red rot although they showed no symptoms of it, in which case the infection may be fairly widely distributed throughout the sugarcane area, only de­veloping into a disease of importance in areas with the suitable climatic conditions.

SUMMARY.

Investigations into the recent outbreak of red rot in Natal have shown that a cane can bo dead and producing spores of Colletotrichum falcatum without showing any internal symptoms of that disease, in that no red discoloration has been produced.

This suggests the possibility that this disease might have existed undetected, especially if the incidence of infection was low, and also that it might exist in this form over a larger area than originally thought.

Its development into a serious disease in certain areas 4s probably conditioned by the climatic factors of the areas.

One method of infection in the field has been found to be through the leaf sheaths, where it produces lesions not unlike large eye-spot markings, from these passing into the young internodes.

Laboratory studies have suggested that C. falcatum alone might not be the only fungus concerned, but that a Fusarium of the F. moniliforme type might be of equal importance.

Experiment Station, South African Sugar Association,

Mount Edgecombe. March, 19-13.

Dr. McMARTIN, in reply to Dr. Medley, said that the burning of cane was a measure recommended to combat the spread of red rot disease. It was, however, still possible to get cultures of Colletotrichum from cane after burning. Planters were, of course, also advised to plant resistant varieties, and where possible to fallow the land after ploughing. He had seen a field planted with Co.301 immediately after ploughing-out badly infected Co.290. The Co.301 was then one year old and the field was full of stalks of Co.290 which were getting red rot, but there was no sign of it in the Co.301.

In reply to Mr. Rault, the author stated that, unlike streak disease, red rot usually appeared suddenly and with epidemic intensity. It seemed as if conditions were not so favourable for the spread of red rot in tlie Mount Edgecombe area. A focus of infection existed at the Experiment Station, and yet only a few stalks of Co.290 and P.O.J.2725 had thus far been found with red rot.

Colletotrichum had not yet been found in Co.281, but this year for the first time Fusarium had been isolated from a stalk taken from a patch of dead Co.28l.

Dr. McMartin stated that the association of the two fungi Colletotrichum falcatum and Fusarium moniliforme had been reported in India. So far, however, the Fusarium moniliforme had been considered a secondary invader, while it was his opinion that it might be playing a more important part in causing red rot. In reply to questions by Mr. Hayes, Dr. McMartin stated that the two fungi were not antagonistic to each other, but neither did they appear to assist each other. Fusarium was, however, so much easier to grow, that cultures had to be examined microscopically very frequently to find out whether Colletotrichum was still present. He had found Fusarium but no Colletotrichum present in certain cases of cane dying from what appeared to be red rot.

Mr. HAYES suggested that a line of investigation would be to grow cultures to see whether the resistance was due to the fibrous or rind structures of the cane or the presence of some antiseptic substance.

Dr. McMARTIN, in reply to Mr. Dodds, said that: inoculation experiments indicated that P.O.J.2525 could be infected with red rot as readily as Co.290. It was difficult to compare field results, however, as P.O.J.2725) was not planted to the same extent in the existing red rot areas. P.O.J.2725, however, ap-peared to be extremely resistant to red rot.

I

53

HABITATION WASTES AND COMPOSTING IN THE SUGAR BELT.

By G. C. DYMOND.

You may at first wonder what the subject of habitation waste disposal has to do with our Association. I have recently had the privilege of seeing a little of the work being done in this connection, by a few of the townships in the Union, and of dis-cussing the subject with Government extension officers. After that experience, I felt that here is a matter of importance to the Natal Sugar Industry and its townships, both from a health and from an agricultural point of view.

There are to-day 15 townships in the Union actually pro-ducing compost from wastes, and there are another 13 under construction. One town, which has been in production for more than a year, has kindly supplied me with the following data. There are others yielding better quality compost at less cost, but at the time of writing the detailed data was not available. The population of this town consists of 3,000 Europeans and 1,086 Natives. The quantity of compost made during the first year was 900 tons. This was obtained from the following materials :-

Nightsoil approximately 500 gallons daily. Domestic refuse 3 tons daily. Extra grass added 6 Scotch carts daily.

In addition, ail the blood and condemned offal from the abattoir, together with a large amount of coal ash, are used.

The completed compost (3 per cent. moisture) is bagged and sold at 2s. per bag. The analysis of the material is as follows :— Moisture 3.06 per cent. Total organic matter 30.21 per cent. Nitrogen 0.78 per cent. Total P2O5 1.49 per cent. Lime 4. 50 per cent. Potash 0.11 per cent.

At Ficksburg, experiments and improvements in technique are being carried out by the Government under the enthusiastic direction of J. P. J. van Vuuren. The analysis of the compost produced here is as follows : —

Average. Maximum. Moisture 7.46 14.43 per cent. Total organic matter 46.95 52.31 per cent. Nitrogen 1.54 1.74 per cent. Total P2 O5 1.00 1.41 percent. Potash 1.33 3.19percent.

I do not propose in this article to discuss the actual practice and technique of waste disposal, except in one respect—its mechanization. At one town the staff consists of one European and 14 Natives, at a probable wage bill of about £900. As this is the price realised for the product, there is no profit. At Ficks-burg the comparative capital cost was £400 and the quality, though less in weight, is better.

Now, the principal cost and difficulty in compost-making of any kind lies, first, in the construction of the heaps or piles ; secondly, in the turning ; and, lastly, in the final stacking for disposal. In England, large quantities of materials are being composted, the pits holding charges of from 1,200 to 2,000 tons of material. No description is, however, given as to whether the bulk is man-handled, or dealt with mechanically. It appears to me, therefore, that if large schemes are likely to come into practice, this aspect of the subject should be considered.

I have in mind two possibilities. The first, some simple adaptation of the gantry and grab common in sugar mills for off-loading cane, and, secondly, the possible use of the mechanical arm.

With regard to aeration, I think that experiments should be conducted to test out the use of compressed air for aerating the heaps. This could to some extent reduce the quantity of turnings required, with the exception of that necessary for fly-control.

SANITATION AND HEALTH.

Fears have been expressed that such schemes may lead to an increase in disease, in particular amoebic dysentery. Actually the reverse; is true, provided the process is properly controlled and conducted on scientific lines. I can only deal briefly with this angle, but here are my authorities for such a statement. (Others are appended.)

J. W. Scarff3 Chief Health Officer, Singapore, writes : " I am prepared to prophesy that composting of refuse in our villages, kampongs and estates will cause a revolution in the sanitary organization of our rural areas."

The Secretary of Public Health states: "In the opinion of this Department, there is no likelihood of the matured compost, used as a fertilizer, acting as a medium for the dissemination of the infective material of amoebic dysentery and parasitic worms, provided the process of composting has been carried out in accordance with instructions issued by the Department of Agriculture and Forestry, where temperatures of 150° to 160°F. are attained in the compost pits for two or three weeks."

The principal diseases which have as their focal point night-soil, e.g., human stercus and urine, are:—

1. The enteric group of fevers. 2. Cholera. 3. Dysenteries. 4. Helminthic infestations. 5. Tetanus.

All the pathogenic organisms responsible for these diseases would be killed under the conditions of properly controlled com­posting. Thus, A. L. Thomson4 writes : "We know that the heat generated by bacterial activity in properly conditioned and managed compost heaps will destroy all pathogenes, whether bacillary, protozoen or helminthic, inhibit fly-breeding and eliminate nuisance."

From a health point of view, therefore, the establishment of these international methods at our factories, estates and villages, is a matter worthy of immediate attention.

AGRICULTURAL VALUE. The day has indeed gone when we can take Mr. G. Ingham's1

"pleasing delusion cherished by the makers of compost" seriously.

" The mounting evidence, that in properly composted soils there is a "pleasing something" which Sir Albert Howard terms the mycorrhiza association, which, however, cannot as yet be weighed on the chemist's balance, nor added up in simple unit values, is to-day indeed a "pleasing actuality" to the makers of nature's jowly compost.

What is this evidence ? I can only give a fraction. I have recently found that Uba cane cures itself of streak disease when treated with compost, over a period of four years. It is possible tha t some of my fellow scientists will not accept this as proof. Years must no doubt pass before science, by tedious tests, will find a name, explain the cause, and finally confirm the facts.

It is a hard thing for agricultural science to do, for it means that all the years and nearly all the work on artificial fertilizers and poison dusts and sprays have been largely wasted in acquiring a vast mass of negative knowledge.

The Western literature on agriculture is full of articles on plant diseases and their treatment. New diseases are constantly being found, and new poisons devised to combat them. Have

we all been go ing d o w n t h e wrong garden p a t h ? F o r i f th i s is n a t u r e ' s law in t h e West , how is i t t h a t t h e p l a n t life of the Or ien t h a s n o t died ou t long ago ? Those a n c i e n t people have neve r had a n y poison sprays , nor powders t o c o m b a t the " r u n n i n g o u t " of var ie t ies so c o m m o n in o u r en l igh tened pa r t of t h e world ,

For example , the var ie t ies of g rapes grown in Persia, Af­g h a n i s t a n a n d on t h e wes tern frontier d i s t r i c t s of Ind ia , have been c u l t i v a t e d for a very long t ime , but: t h e y show no signs of weakness , whereas in the v i n e y a r d s of the south of F rance , new var ie t ies are c o n s t a n t l y needed to replace t h e old.

In t h e United Provinces of India, i nd igenous var ie t ies of suga rcanes h a v e been grown mixed for some t w e n t y centur ies , as is ind ica ted by the fact t h a t t hey have r e t a ined the i r Sansk r i t n a m e s . W h y d o v a r i e t i e s pers is t i n t h e F a s t a n d run o u t u n d e r Wes te rn cond i t ions ? Is i t not possible t h a t the ba lance be tween a rab le and l ivestock farming has been upse t ? T h e t r a c t o r has m a y b e much to a n s w e r for !

Of China, F. H. King 2 wri tes : " T h e ave rage of seven Chinese holdings ind ica tes a m a i n t e n a n c e capac i t y of 1,78.3 people , 212 ca t t l e or d o n k e y s and 399 swine. T h a t i s 1 ,995 c o n s u m e r s and 300 rough food t r ans fo rmer s pe r s q u a r e mile of farm land in t h e rura l a reas . In t h e U.S.A. t h e rura l popu la t ion in 1000 was placed at 01 per s q u a r e mile of improved farm l a n d and there were 30 horses a n d mules .

" I n China , the. m a i n t e n a n c e in hea l th of a p o p u l a t i o n of 500 millions depends on the sys t ema t i c use of vege tab le a n d an ima l wastes , carefully compos t ed toge the r by age-old sk i l l . "

Sir Alber t H o w a r d s t a t e s that: in t h e h igh ly m a n u r e d a reas s u r r o u n d i n g the half-million vil lages in India , which c o n s t a n t l y receive dress ings o f b o t h h u m a n a n d a n i m a l m a n u r e , he never on a n y occasion found a n y t r ace of disease.

In 1938, I v i s i t ed Sir Alber t H o w a r d a t h is h o m e a t Black-h e a t h . He told me t h a t in 1934 t h e g a r d e n was "a. ve r i t ab le pa tho log ica l m u s e u m " — t h e fruit t r ees in p a r t i c u l a r be ing smothe red w i t h e v e r y k ind o f b l igh t . S t e p s were t a k e n to conve r t all t h e vege t ab l e was t e s in to h u m u s w i t h t h e he lp of s t ab le l i t t e r . 'Even a f te r o n e y e a r t h e p e s t s began t o r e t r e a t . I n t h r e e y e a r s all h a d d i s appea red , t h e wool ly aph i s on t h e app le t r ee be ing t h e l a s t to leave . D u r i n g t h i s per iod no insect ic ides were used a n d no diseased ma te r i a l w a s eve r d e s t r o y e d . I t w a s all c o n v e r t e d i n t o h u m u s . " I saw t h a t ga rden a n d , as a resul t , on my r e t u r n to Africa I c o m m e n c e d my four y e a r s ' t e s t on s t r e a k disease in U b a c a n e .

One more: recent example. Sir Albert Howard grew a collec­tion of Koyal Sovereign strawberries, which were badly infected with a common virus disease, alongside with healthy stock. The soil was heavily composted. In 1942 he found no trace of the virus disease. These results have since been confirmed from other sources.

There are many other cases, but to-day composted soils need fewer and fewer advocates. Kverv farmer who tries it becomes a disciple for life.

The question is often asked, "How can I make compost at a reasonable cost and in sufficient quantities to fertilize my farm i"

The answer is simple. Start in a small way and work up, with the thought of the 40 centuries of China before you. In regard to sugar, every planter knows more or less what seed cane he will require in the following year. Whatever compost he has, or can make on the basis of 10 to I 1 tons per beast per year, should be liberally used in specially prepared seed beds or fields. If this becomes universal practice in the sugar belt, there will be little talk in the future of varieties "running out" and less need for the continuous replacements with new varieties which face our industry under our Western agricultural methods'

There is, however, one clanger. "Wars ," it has been said, "never settle, anything." War, on the other hand, often enforces practices through necessity. Owing to the diminishing artificial fertilizers available! to-day, composting has become such an en forced necessity.

It is possible, however, that after the peace bells ring again, our agriculture will again be flooded and may succumb once more to the propaganda of cheap and easily applied artificial fertilizers. [Cn forced necessity has laid the foundations of com­posting in the Union. Enthusiastic Government extension officers are doing a great work. I'annors outside the sugar belt are seeing the results for themselves. Let us continue the good work now and after the war, and compost for the. future health of plants and beasts and human beings in this land of ours.

APPENDIX. ova and larva1 of neca to r are de s t royed w h e n h e a t e d to : 40CC. (104°F.) for 24 hours , 42 3C. (108°F.) for 12 h o u r s , 45°C. (1I3CF.) for 2 hours , (c) All he lmin th i c o v a a r e r a p i d l y des t royed d u r i n g t h i s process of c o m p o s t i n g .

(2) Year Book of Agriculture, 1931 (pp. 353-335), U.S. Depart­ment of Agriculture. T h e m a x i m u m t e m p e r a t u r e s r e c o r d e d were close to 170°F. b u t t h e larva; a n d p a r a s i t e s p r e s e n t in horse a n d cow m a n u r e are killed after 10 m i n u t e s e x p o s u r e to a t e m p e r a t u r e of I2o"F .

T h e resul t s of these t e s t s showed conclus ive ly t h a t a f t e r a b o u t t w o weeks ' s to rage , horse m a n u r e a n d cow m a n u r e which were or iginal ly infested w i th live pa r a s i t e eggs a n d larva?, no longer c o n t a i n e d t h i s infest ive m a t e r i a l . S u c h m a n u r e w a s safe for sp read ing on p a s t u r e s . (Ben j . S c h w a r t z , Senior Zoologist ; E. W. Pr ice . Paras i to logis t ; Allen M c i n ­tosh, Asst . Zoologist (Bureau of An ima l I n d u s t r y ) .

(3) A Guide to Human Parasitology (Black and Southwell). C y s t s of E n d . H i s to ly t i ca r e m a i n al ive in faecal m a t e r i a l for a few d a y s only . Should t h e y reach c lean w a t e r t h e y r e m a i n a l ive m u c h longer ; t h e y d o n o t w i t h s t a n d dess ica t ion . L o w t e m ­pe ra tu re s are r equ i red for the i r s u r v i v a l ; e x p o s u r e to 50°C. (122CF.) kills t h e m in two m i n u t e s .

(4) Mamon's Tropical Diseases, Ph i l ip M a n s o n - B a h r , 9 th e d n . , p . 404. Cys t s of E n d . Hi s to ly t i ca can s u r v i v e ou t s ide t h e b o d y of m a n for a b o u t ten d a y s i f k e p t mo i s t a n d cool . Dessicat ion kills t h e m i m m e d i a t e l y a n d t h e y s u r v i v e a t a low m u c h longer t h a n a t a h igh t e m p e r a t u r e .

The PRESIDENT said that the fact that certain varieties-still retained their Sanskrit names did not necessarily imply tha t the East was free from disease; in fact, Noel Deerr related to the speaker that the very first reference to red rot he could find was in the Sanskrit.

Mr. VAN VUREN, co-ordinating officer of the compost cam­paign in this country, said the Government started the campaign of getting the municipalities interested in compost-making from nightsoil, and so far about forty small municipalities were going in for it. The mechanization of the process was, however, essential, not only to reduce costs of production but to make such a scheme possible for large municipalities.

At Kicksburg the temperature of the compost heaps was maintained for three weeks at 157' to l(>9F., and where high temperatures over a long period were necessary to kill or destroy pathogenic, organisms lie considered the compost quite safe. Temperatures of the heaps varied, of course, with atmospheric temperatures, but a drop of 10T'\ was very rarely experienced. He had found, however, that nightsoil buried even for five years remained fresh and was still a source of infection.

The cost: of production was important, and if mechanical means of turning the heaps could be obtained which would reduce costs, it would be definitely a step forward. Some muni­cipalities sold compost at 10/- per ton, while others who like to make a. profit charged as much as £] per ton. Mealie farmers often judged the effect of fertilizers by the colour of the leaves of plants, and they maintained that compost gave very good results. Properly controlled experiments and statistical analyses of the results were, however, necessary, and it was hoped that such results would shortly be forthcoming from the Department of Agriculture. Sir Albert Howard attached great importance to what he called mycorrhiza association and claimed that the health of plants and animals was improved as a result of com­posting. If these claims could be substantiated it would leave no option but to use. compost most extensively, but he con­sidered it still an open question.

The cane-growing areas of Natal were in a. unique position to experiment with compost. Not onh' were supplies of cellulose adequate for all the available nightsoil, but high rainfall ought to ensure good results. The best results from compost had so far been obtained with irrigation.

Mr. DODDS wanted to know how long the Uba cane that had been cured from streak by repeated treatments of compost remained streak-free. Manganese, for example, helped cane to resist streak for some time, or at least to inhibit the leaf symp­toms, but it was no cure.

Certain primitive cane varieties were remarkably resistant towards diseases, not only in the East but everywhere. Creole, cane was introduced to the West nine or ten centuries ago, and it still would grow and give reasonably good crops. Neverthe­less, authorities in India and elsewhere in the East encourage planters to get away from old natural varieties and to plant new artificially-bred varieties capable of better yields. Over-populated countries like China and India could not afford to go on with old methods giving poor crops. The development of new varieties of plants and new breeds of live stock, as well as the application of chemical fertilizers throughout the world, had done much to put the world in a position to support its vastly increased population.

Compost field trials were at present being carried out by the Experiment Station staff. Figures were not 5'et available, but there did not seem to be much more response at Mount Edge­combe to compost compared with plots receiving similar amounts of nitrogen from ammonium sulphate in a stiff clay soil. At Chakas Kraal, however, compost, equally with Karroo manure and filter cake, showed a spectacular increase over control plots without fertilizer in a coarse sandy soil. Dr. Fisher was of the opinion that where farm manure was not available for compost making and legumes had to be resorted to mstead, the ploughing-in of the green legume would probably be as good a way as composting it, and it would certainly be more economical. Mr. Dodds considered this worthy of further investigation.

Mr. DVMOND said by "running out" he implied that a cane variety became susceptible to diseases and so was of little further agricultural value. He referred to a paper to be printed in the International Sugar Journal by Sir Albert Howard, in which it was pointed out that in Barbados, after many years of artificial fertilizer application, the running-out of varieties had become so common that it was very difficult to get any suitable variety at. all.

55

In reply to Mr. Dodds, he said that the Uba. cane in question was cut yearly. Last year, throughout its growing period of twelve months, it had about 25 to 30 per cent, streak. This year there was no signs of streak and the cane was now eight months old.

The PRESIDENT considered it a. pity that Mr. Dyniond did not plant a control line of Uba along with the one grown on compost. It was possible for plants to throw off streak. Uba and P.O.J.2723 had been known to do it, and he had also seen a remarkable case where streak in Co.200 had decreased appre­ciably. A stool of Co.419 badly infected with streak was planted in a pot for identification purposes and it had been growing there now for several years, and was completely root-bound, but there was no streak. The disappearance of the streak in these cases could certainly not be put down to compost applica­tions. In a field experiment with compost it was found that an outbreak of rust affected compost plots and controls to an equal extent. He therefore believed in planting disease-resistant varieties.

Mr. HAYES maintained that Mr. Dyniond had made very important claims in his paper, which, if correct, would mean that, given enough compost, we could eliminate disease. Mr. Dyniond might be convinced of the efficacy of these age-old treatments, but he thought it would be very difficult to convince farmers and doctors. He was treading on dangerous ground trying to correlate the influence of nutrition against disease resistance. It; was a problem that had plant and human patholo­gists guessing. His own information was to the effect that the 500 millions of China, in spite of all their manuring with com­post, were in anything but a state of health and prosperity.

Mr. DYMOND referred Mr. Hayes to the references given, and in particular to "Medical Testament of the I.oeam Medical and Panel Committees of the County Palatine of Cheshire," in which many cases of the effect of vegetables grown with compost on the health of school children and animals were given. In the London area, for example, the children from three schools were fed for three years on fruit and vegetables grown on composted soils. There were no cases of infectious disease except one tha t was imported from outside. In all the other schools there were the usual series of infections and epidemics.

Mr. HAYES said that it was estimated that 50 per cent, of the children in India suffered from eye infection and 80 per cent, were due to vitamin A deficiency. The soils on the surrounding areas were heavily manured with nightsoil.

Mr. DU TOIT said the problem of making compost and the effect of compost was very much in the air at present, and he thought that no further papers should be published unless con­crete results were given. He was glad that Mr. van Vuren was present, and hoped that the Government investigation would result in something positive. There was, for example, the ques­tion as to which" carbon nitrogen ratio was nc-'';-;ary for the most profitable results to be obtained from compo.it applications.

The cellulose and pentosan degradation compared with the corresponding lignin accumulation was another problem requiring investigation. He thought that compost might play an important part in manuring, but Mr. Dyniond tended to take us back the forty centuries of China and wanted us to start there.

Mr. TAYLOR said that there was a time when the agriculture of Europe was built up on lime and farmyard manure. Since then artificials became almost the exclusive fertilizer, and now the pendulum seemed to be swinging back once more. Without claiming wonders for farmyard manure or compost, it did pro­vide, apart from its manurial value, the necessary minor elements and also hormones.

Fertilizer shortage was the driving force behind the present Government effort in the direction of popularising compost. The human being was a destructive and wasteful animal and the drain from the country of plant-food was tremendous. The manurial value going to waste of all the food consumed or discarded in a city such as Durban was very great. The Govern­ment scheme of utilizing such waste material and checking the loss of plant-food discharged by sewers into the sea ought to find application on many sugar estates. Mr. Brevis, of the Cedara College of Agriculture, who had been placed in charge of compost work in Natal, was at the service of anyone interested or wanting further information.

Mr. MOBEULY said that one would feel more pleased and satisfied with the advocacy of compost or natural manures if it. were not generally accompanied by an attack on the other line of development, artificial fertilizers. It seemed a human failing for a man to condemn what he was not advocating. Compost and natural manures had an important part to play arid should supplement artificials.

Mr. BIJOUX said that he had found that cake from the Oliver filters took a long time after application before showing any beneficial results. He had used immature compost on rose plants with disastrous results. It might have been the result of fermentation, but some of the roses actually died off.

Mr. DYMOND said he discovered the harmful effects of un-decomposed Oliver filter cake as a result of pot-tests early enough to warn the sugar estates against its use before com­posting. Several planters now used their quota of filter cake as well as Karroo manure as a composting medium on their farms. Molasses were sometimes added, but if dilute the fermentation seemed to be too quick.

Mr. FOWLIE suggested that it would perhaps be advisable to scatter the Oliver filter cake on the fields a few months before ploughing it in, so as to allow the sun and rain to decompose it.

The PRESIDENT mentioned the possibility of sowing a green manure crop in among the trash. The green manure crop would grow through the covering and the two could be ploughed-in together.

O l

A PRELIMINARY SURVEY OF RECENT FERTILIZER EXPERIMENTS FOR SUGARCANE.

By H. H. DODDS.

At the present time when the demand for the maximum amount of sugar from our industry is greater than ever, it is necessary to give renewed study to the various means of main­taining and increasing production. Among these means the use of fertilizers is of great importance, and since supplies are very limited for obvious reasons and are strictly rationed, a survey of fertilizer experiments and indicated fertilizer requirements of (he sugarcane crop over recent years is of interest.

The period taken for review comprises the past ten seasons, which covers an important period of development in local sugar history, annual production of sugar having increased from 325,000 tons in .1931/32 to 595,000 in 1939/40.

The period selected also largely avoids the abnormal acreage yields and responses to fertilizers resulting from the very dry cycle of years from 1926 to 1931, over which the average annual rainfall was only 32.88 inches. The year 1933 was also ab­normally dry, which evidently had its effect on fertilizer results, but thereafter there was no extremely dry year until 1941.

The same period has witnessed a spectacular and rapid change in the predominant cane varieties grown, the proportion of Uba. cane in the total crop harvested having diminished from 95.8 per cent, in 1934 to 1 1. 1 per cent, in 1942.

The experiments outlined are those carried out by the Experi­ment Station, either on our own land at .Mount Edgecombe or

on various plantations and estates in co-operation with the owner or manager.

Since the Experiment Station is naturally limited to a definite area, 96 acres, not all of which is ideally suited for fertilizer experiment, it follows that a considerable proportion of the fertilizer experiments here have shown negative or doubtful results. Further, the [experiment Station has been a testing ground for alternative designs of field experiments, not all of which have proved well adapted for general use in this country.

In co-operative field experiments, on the other hand, the occupier usually offers a considerable area of land from which we can select a. site we consider conveniently situated and most likely to give concordant and significant results because of the apparent uniformity of the soil and other conditions. Such land also has usually had normal agricultural treatment in the past and has not been already subjected to the vngarics of field experiments leading to possible very diverse residual effects. Consequently the co-operative experiments with fertilizers have, on the whole, led to a much larger proportion of positive and significant results. This is particularly the, case where phosphatic fertilizer experiments are concerned, since phosphates can accumu­late in the soil if not fully utilized by the crop, whereas nitrogen is apt to be lost to the soil if not soon utilized, and does not remain to affect further experiments.

i

63

The recent results from the nitrogen experiments confirm the conclusions set forth by the writer last year, namely, that a response to nitrogenous fertilizer may be expected from prac­tically all light soils, and from heavy soils that have not been subjected to severe drought soon after the application of the fertilizer. No application of nitrogenous fertilizer is usually necessary to the plant cane crop if the soil was green manured with a leguminous crop shortly before planting. Inorganic fer­tilizer such as ammonium sulphate should be applied to plant cane, if not green manured, as a top-dressing after the cane has become established, although in light soils there is something to be said for a small application at time of planting, which pro­motes early root development.

Inorganic nitrogenous fertilizers are at present almost unpro­curable, but results show that even at present prices of about £1 per unit of nitrogen, it pays to use this kind of fertilizer if possible, provided that the increased yield therefrom is not less than 0.6 tons of sucrose, say 4] tons of cane per acre from an application of 80 lbs. of nitrogen per acre, equivalent to 400 lbs. per acre of ammonium sulphate or 500 lbs. of sodium nitrate. These quantities in most cases promote the greatest increase in yield, but under present circumstances somewhat smaller appli­cations may be more profitable.

It can be seen that, on the whole, the application of nitro­genous fertilizer has been profitable, both at the Kxperiment Station and at the co-operative field stations, though in the case of phosphatic fertilizer there has not been nearly so high a proportion of favourable responses at the Kxperiment Station as at co-operative stations, for reasons already suggested.

It is evident that in this country the sucrose content of the cane in the great majority of cases is not appreciably affected by the application, of fertilizer. In other countries having less favourable conditions than ours for maturing the cane, it is frequently found that nitrogenous fertilizer diminishes the sucrose content of the cane by delaying maturity. The same thing is noticeable here in certain cases where the cane is harvested after only one season's growth after relatively heavy applications of nitrogenous fertilizer.

It may be noted that the average yields of ratoon crops and sucrose concentrations are much lower than of plant cane crops in our returns. This is not necessarily clue to any considerable diminution in rate of growth of ratoons, but is due in part to many ratoon experiments being cut after only one season's growth instead of the full two seasons usually allotted to the plant cane crop.

In the case of the phosphatic fertilizer experiment ratoon results, it should be clearly understood that the increased yields from the phosphate treated plots in many cases is due to residual effect only of the fertilizer given to the plant cane crop, no further phosphatic fertilizer having been applied. A remarkable case of residual effect may be seen in phosphate experiment No. 21, where significant residual results from superphosphate and other phosphatic fertilizers were recorded up to the fourth ratoon crop, no phosphatic fertilizer having been added after the original application at time of planting. It is evident t ha t in many cases additional applications of superphosphate to

Experiment Station, South African Sugar Association,

Mount Kdgecombe. March, 1043.

ratoon crops have not proved profitable after adequate quan­tities had been supplied at time of planting, but in other cases they have clone so. More experimental work in different repre­sentative types of soil is required to clear up this problem.

In those few experiments where varying quantities of super­phosphate have been applied at time of planting, quantities of 600 lbs. and upwards per acre have proved the most profitable, even where similar quantities have been regularly applied in preceding years.

At present prices for superphosphate approximately 5/- per unit of P2C)5, it will pay to use 600 lbs. of rhe 16 per cent, super­phosphate now available in limited quantities if the resulting increase is not less than 0.2 tons of sucrose or, say, 1.5 tons of cane per acre, or, of course, other quantities of superphosphate with proportional results.

Although several further potassic fertilizer experiments have been harvested there is nothing to add to the conclusion stated last year, that there are very few cases where any response is indicated, and none where any highly important differences were found. We are fortunate that our soils are naturally so well supplied with this important element.

At pre-war prices for fertilizer it was almost invariably found that the quantity of fertilizer promoting the greatest yield in terms of sucrose per acre was the most profitable quantity to apply. Now, that frequently does not occur, fertilizer applica­tions somewhat less than those promoting the maximum yield of sugar being very apt to prove the more profitable at present prices for fertilizers and sugar, if indeed there is any indicated profit from the fertilizer at all.

Fertilizer prices have nearly doubled in unit price, while the value for sucrose paid to the grower for rhe 1042-43 season is slightly under 22 per cent, more than that paid in the last pre­war season of 1038-3').

It is recognised that this paper deals only with concentrated sources of the principal fertilizer elements, and that, in this country at all events, there are other important aspects of soil fertility. There is no getting away from the fact, however, tha t the supply of nitrogen, phosphorus and potassium is of primary importance to our sugarcane crop, and must always receive most careful attention.

I wish to express once more my keen appreciation of the facilities and help we have received at the Experiment Station over many years from the owners and managers of estates where our co-operative experiments have been located ; also of the enthusiastic team-work of the various departments of the Kx­periment Station staff which have contributed to make a com­prehensive record of this kind possible.

SUMMARY AND CONCLUSIONS.

Fertilizer experiments over a period of 10 years are sum­marized and average results compiled. They show that, with certain exceptions, it has been profitable to apply both phos­phatic and nitrogenous fertilizer to sugarcane over a wide range of soil and weather conditions in this country.

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TWO NEW INSECT PESTS OF SUGARCANE IN NATAL. By J. DICK.

NOCTUID LARVAE.

In October, 1942, a local outbreak of Noctuid caterpillars on young Co.281 ratoons was reported from Stanger, and specimens of the larvae were sent to the Experiment Station. Most of the specimens received were diseased or parasitised and no adults were reared. At the end of December a batch of Noctuid eggs was collected on sugarcane leaves at Mount Edgecombe, and the insects obtained from them were reared to the adult stage. The larva; closely resembled those received from Stanger and probably belonged to the same species. The adults have been identified as Spodoptera mauritia Boisd.

These insects have now been reared for two generations and the following observations have been made. The eggs, which are deposited on the leaves in batches of one to two hundred, are covered with a light brown fluffy secretion. Hatching, in January, took four or rive days, and the larval stage lasted 25 to 34 days. The pupal stage required (i to 10 days. Laying commenced four days after emergence and the adults lived 1.0 to 12 days.

The larva; were found to feed on the leaves of maize, sorghum and several varieties of sugarcane, but probably also live on a number of wild grasses. Newly-hatched larva; did not very readily attack cane leaves, so that infestations in the field would probably have to s tar t on wild grasses, maize or sorghum and spread to sugarcane.

Tachinid larva; are probably important parasites of the larva: and pupae, and the Argentine ant was found to destroy the insects in the inactive prepupal and pupal stages.

Spodoptera mauritia was recorded in Mauritius, but is found all over Africa, Madagascar, India, Ceylon, Philippines, Dutch East Indies, New Guinea, Australia and the Polynesian Islands. Professor Janse8 has specimens from various parts of Natal. It is reported to feed primarily on nutgrass, Cyperus rotundits, in Hawaii,3 but has occasionally caused serious damage to young cane,5 although outbreaks are usually soon controlled by para-Experiment Station,

South African Sugar Association, Mount Edgecombe.

March, 1943.

sites.4 It has also been recorded as a pest of sugarcane in Mauritius1 and Formosa7, It is not thought likely that this species will become a serious pest in Natal.

DYNASTID BEETLE.

At the beginning of January, 1943, a species of Dynastic! beetle was found attacking planted setts of Co.281 cane at Umzinto. The damage caused resembled that described for Heteronychus licas," a beetle belonging to the same family. The adult beetles burrowed into the sticks, destroyed or damaged the eyes, and killed many of the young shoots. The larva1

probably feed on decaying vegetable matter in the soil and were not found attacking the cane. Insects of this family often have a long larval period and a relatively short adult life, and in this instance all the adults had disappeared within a fortnight of the damage being observed. Damage to sugarcane would only-take place if the setts were in the ground at the time when the adults were emerging. As this appears to take place over a short period only, the danger from this species is not great.

The insects were identified by Miss van Schalkwyk of the Division of Entomology as Tewnorrhynchits cly peat its Klug. This species, which was collected from a wild shrub in Natal in 1902, does not appear to have been recorded as a pest.

65

TWO NEW INSECT PESTS OF SUGARCANE IN NATAL.

66

NINTH PROGRESS REPORT ON EXPERIMENTS AT UMFOLOZI.

By P. FOWLIE, N.D.A., N.D.D., and F.J. ALMOND.

During the season five experiments were reaped on farm 16, Umfolozi. The variety trial on ULOA. estates was also reaped again. The following tallies give all the available data concern­ing each experiment. Unfortunately, owing to pressure of other work at the Experiment Station, it was not possible for Mr. Kirk-

wood to be at Umfolozi during the whole time the experiments were being reaped. This meant that it was not possible to do the usual full tests on as many samples of the canes, and explains why the figures for fibre per cent, cane, reducing sugar ratio, etc., are not given for some of the experiments.

UMFOLOZI EXPERIMENTS Nos. 3 and 4. Now combined as a Fertilizer Trial on Old Ratoons .

Variety P.O.J.2725. Fourth Fertilized Ratoons , harvested at 12 months old, 2 0 t h - 27th November, 1942 .

When working out the results of this experiment for the 1942 crop it was discovered that the results for 1938 and 1940 crops had been calculated on one-tenth acre plots instead of one-twelfth acre plots, as they ought to have been. This mistake has been corrected in the above summary, which therefore differs from that previously published.

In the 1942 crop 400 lbs. of ammonium sulphate gave an increase over controls which was highly significant. The double

dressing of 800 lbs. also gave a highly significant increase over 400 lbs., though at £16 per ton for ammonium sulphate it was not profitable to apply 800 lbs. As shown in the summary, 400 lbs. of ammonium sulphate per acre per crop gave a. profit of £6 11s 2d. over the four crops, whilst 8O0 lbs. very little more than paid its way. At peace-time prices both dressings would have given a profit of approximately £'1 per acre per crop.

UMFOLOZI EXPERIMENTS Nos. 7 (A and B ) . Variety Trial, Seventh Ratoon Crop.

Harvested at 12½ months old, 12th—16th December, 1942.

The canes in this experiment are still giving good yields as seventh, ratoons, although no fertilizer of any kind has ever been applied to them.

In the seventh ratoon crop P.O.J.2878 beat Co.290 by a very narrow margin. One of the things to be noted is the very even level which has been maintained by P.O.J.2878 right through. P.O.J.2725 dropped in the seventh ratoon crop to last place due to excessive early flowering. In spite of this it still holds first place in the totals for eight crops. In view of the fact that Co.281 is now being largely planted at Umfolozi, it is interesting to note that it does not compare very well with the P.O.J.

varieties in this experiment. Except for the fourth and seventh ratoons, when P.O.J.2725 was injured by excessive flowering, it has always been lower than that variety.

In the first three crops Co.281 gave more sucrose per acre than I' O.J.2878, but in the older ratoons P.O.J .2878 has yielded somewhat better than Co.281. Over the eight crops Co.281 has only given three-quarters of a ton more sucrose than P.O. J.2878. P.O.J.2878 gives a higher average sucrose of cane than Co.281 and is usually an easier cane to handle, so it looks as if it ought to be more extensively planted than it has been in the past.

UMFOLOZI EXPERIMENT No. 10 . Variety Trial, Fourth Ratoon Crop.

Harvested at 12 months old, 2 8 t h — 3 0 t h November, 1942.

(iS

(»9

Summary of Yields of Four Crops in tons Sucrose per acre.

In this experiment P.O.J.2725 does not show up so favourably as in Experiments 7 (A and B). This can be explained by the fact that in 1939 when this experiment was harvested as plant cane, and again in 1942, heavy flowering took place in P.O.J.2725,

reducing its yield in these seasons. Even so, it is not much behind Co.290 over four crops and is slightly ahead of Co.281. Co.301 has increased its lead and is now 6 per cent, ahead of Co.290 and 9½ per cent, ahead of P.O.J.2725.

No. J.J Spacing and Fertilizer Trials. Summary of Yields of Four Crops in tons sucrose per acre.

Spacing Trial. Fertilizer Trial.

As before, there is a slightly larger yield from the closer spacings, but the difference between 4 feet and 7 feet is just under 4 per cent., which is not enough to be significant under the conditions of this experiment.

It has been suggested that some of the varieties may react to spacing differently from others, so the yield from each variety at each spacing is given below.

UMFOLOZI EXPERIMENT No. 12. Fertilizer Trial on P.0 .J .2725, Plant Cane.

Harvested at 22 months old, 1s t—8th December, 1942.

70

From these figures it is so obvious that there was no response to fertilizer in this crop, that it is not considered necessary lo go into the question of cost of fertilizer in detail. It can only be said that there is no evidence to show that the fertilizer did any-good to this crop at all.

In last year's report the number of tests which had been done of the various varieties in these experiments was given, with the average sucrose per cent, cane for each. The figures for 1942 have now been included in the averages and the results to date are as follows :--•-

Nllll l l i lT AviTilRl ' SIKT.1W

Variety. of tf.sls. per cent. can.-.

P.O.J.2725 fiili) 15.06 P.O.J.2H78 171 14.56 Co.290 295 13.61

Conclusions.

This variety trial was described in last year's report, when some notes on the varieties in the trial were included. On the yields given in the summary for two crops M.P.K.28 gave nearly 6 per cent, more sucrose per acre than P.O.J.2725, whilst the yield from P.R.809, the third best variety, was about 15 per

Number Average sucrose VanVcv. of tests. per cent. cane.

C'o.28] 208 13.55 Co.301 94 13.96 Ifba 151 11.89

Conclusions.

There has been no reason to alter the general conclusions expressed in the last report concerning the qualities of the different varieties, so it is not considered necessary to cover the same ground this year. It is, however, considered necessary to point out that Co.281 does not appear to be the best variety to cultivate on the alluvial lands, and that where it is desired to change from P.O.J.2725 because of borer or for any other reason, P.O.J.2878 is probably a better variety than Co.281 for Umfolozi flats. In saying this, there is no intention to imply that Co.281 is not the best variety for very many sugar lands.

cent, lower than P.O.J.2725. The lead of 6 per cent, gained by M.P.R.28 is not enough to be statistically significant under the condition; of this experiment. In other words, this lead might have been due to M.P.R.28 being lucky in the position of its plots in the field or in some other way. Whether M.P.R.28 holds this lead by luck or by merit is something which ought to be tested out by further experiments, and so far three such

71

experiments have been planted at U.L.O.A. The first, planted in January, 1940, was ruined by flood water. The second, planted in October, 1941, germinated so badly due to drought after it was planted that it had to be replanted in October, 1942. It is to be hoped that this time the canes will grow and that reliable data will be obtained. If M.P.R.28 should prove itself at least equal to P.O.J.2725 and its release for commercial planting could be obtained, it would be a very useful variety at Umfolozi. It has many desirable agricultural qualities, such as freedom from flowering, forming a good canopy, producing heavy in­dividual sticks, and giving a high sucrose per cent. cane. It does not appear probable that any other cane in this trial will prove good enough to be released.

ACKNOWLEDGMENTS. To Mr. E:. Stanley Murphy, Mr. G. M. Higgins, the staff of

the Umfolozi Co-operative Sugar Planters Ltd., the staff of U.L.O.A. Estates, and Mr. J. V. Kirkwood of the Experiment Station Staff, the authors are deeply indebted for their assistance in carrying on the work connected with the care and harvesting of these experiments. They wish to thank all whose assistance made the production of this report possible.

Kxperiment Station, South African Sugar Association,

Mount Edgecombe. March, 1943.

Mr. MOBERLY deprecated the lack of support for a paper of this nature. He suggested that in future the assistance and

co-operation of the Cane Growers' Association be sought. Present day conditions made it difficult to hold the ordinary field days at the Experiment Station or to circularize planters with copies of papers. An attempt should be made by the Technologists' Association to arrange a planters' day on such a date that members of the Cane Growers' Association attending their annual general meeting could take advantage of it.

Mr. DODDS found it remarkable that Co.281 should be increasing rapidly at Umfolozi in spite of the results of these experiments, which indicated clearly that it was by no means an ideal variety for those conditions. Co.281 was, of course, more resistant to borer attacks, but then he had never considered the borer infestation really very serious at Umfolozi, and at any rate it appeared to be rapidly diminishing.

Mr. RAULT considered it possible that the higher fibred Co.281 might be preferred at Umfolozi for fuel purposes. He again drew attention to the fact that these hand-sampled tests showed a higher sucrose per cent, cane than was obtained at the factory. This invariably seemed to be the case with small hand samples compared with large mill tests. He realised, of course, that trash would depress the sucrose per cent, cane, but was doubtful whether it could to the extent often experienced.

Mr. DODDS said that the difference at Umfolozi was not very big. Experiments at the Experiment Station indicated that normal factory cane had about 5 to 10 per cent, trash adhering to it and gave a correspondingly lower sucrose per cent. cane. Experiments at Chakas Kraal indicated a progressive diminu­tion of sucrose content; while the cane was in the milling process.

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INSTRUCTIONS TO AUTHORS.

1. All papers for the Congress must be in the hands of the Technical Secretary fourteen days before the meeting. It is requested rhat authors will endeavour to send their papers earlier than this date so as to facilitate the work of printing.

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Brown, S. J. (1933): Study of Streak Disease. Proc. S.A. Sugar Tech. Assoc, 7, 101.

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