.Petroleum Oil.--27uchsine. 885

ferred. In printing, the dye is first mixed with gum, and the colored mucilage is subsequently stirred up with the desired quantity of alha, men. The printed fabric is then steamed in order to fix the color.

Messrs. W. H. Perkins and Mathew Gray (the former the discoverer of tile purple, and the latter the skilful director of the great prlnting estt~blishment at Dalmonaeh near Glasgow,~ have tak i " , '

' ' . ' ] ' , e ~ o u t a p a t e n t for a new method of mordantmg for the purple. They effect this b~, means of oxide' or carbonate of lead. The acetate, of le~i[is, first., prmt~a: -~ on, and the fabric is afterwards passed through a bath of ammonia, or an alkaline carbonate. By this means the lead becomes fixed in the fibre of the cloth. The purple dye bath should then yield its color to tile mordanted portions, to the exclusion of the other. But it is found in practice that the patterns printed in this manner are not sharp or well defined. The purple runs into those parts of the cloth which should remain white. To prevent this the goods are washed with soap and water after the fixation of the lead, before subjection to the bath; this clears the whites to some extent, but the patentees sometimes add soap to the bath itself, so as to purify the whites. But if the quantity of soap employed at first to wash the mordantcd cloth has been in the proportion of one pound to twenty-five yards of cloth, they do not pug any amongst the color in the bath.

It is evident that this process contains within itself sources of error. :By the necessity for soaping after the mordanting, it appears that the lead does not adhere with sufficient firmness to the spot where i t has been printed on; the soap is therefore to remove the feebly attached portions of mordant and prevent the color from passing its~proper limits. If, however, the first soaping has been insufficiently permrmed the dye spreads. This c~n to some extent be avoided by the objec- tionable process of putting soap into the dye bath. The patentees also put oily or fatty m~tters into the bath to prevent the spreading of the color. We have reason to believe that this patent process is not successful in practice.

-petroleum Oil. Mr. George Wilson, of London, the eminent maker of stearie acid,

has greatly improved the distillation of natural petroleums, by adding 'to the useof superheated steam, that of ~ vacuum, by means ot an ap- paratus similar to the one used in sugar-making.~Cosmos, March, 1860.

A Suhstiatte for Cochineal. xVuchsine. MM:. Renard and Frank by causing certain ~nhydrous me~allle chlo-

rides to re-act upon the alkMoids extraeCed from the.,_.~ :__~a,,,;,,~,inpr°ducts of coal,

a regular and practical way, a new eotormg matt ~ --' . . . . d ~ehsine of real bed anal of incomparable richness or coLOr ~ , la tre, it a ;antageo sl eplaoes cochineal, aria w,n e,t,ro,y : ) : a n : ~ u r ~ e £ v ~ f f s dyed with tills color h~ve already bee: m

a e a received with surprise ~nd admiration. ffosmos~ M a r o h ~ 1 8 6 0 .