686

DYEING AND CALICO PRINTING.

brought again to a boil, and if the remaining fourth part of the caustic-lye isadded, a black mass is thrown down, which is also cyanin, but which containsall the red colouring matter. This red would have been mixed with the wholeof the cyanin if the total caustic-lye equivalent to the iodine of the iodide ofamyl had been added at once. The last black precipitate dissolves readily inalcohol, forming a splendid purple-red solution. If this purple alcoholic liquidis filtered, there often remains on the filter a deep coloured mass, whichdissolves in benzol with a fine emerald-green colour. The crude precipitateof cyanin dissolves in alcohol with a splendid blue colour, and can becrystallised from the solution.

According to the researches of Hofmann, Madler, and Merz, cyanin is nota simple substance, but a mixture of at least two homologous bodies, the onederived from chinoline, and the other from lepidine.

These two cyanins are very similar in their properties, and the colourswhich they produce upon textile fibres may be considered identical. Thecyanin manufadtured and sold by Mueller, of Basle, is chinolin-cyanin, whilstthat of Menier, of Paris, is lepidin-cyanin, containing mere traces of chinoline.

In purity and beauty the blue shades produced by cyanin, especially uponsilk, are unsurpassed. By artificial light they appear of a splendid violet.Unfortunately the colour is exceedingly fugitive, being destroyed in a fewhours by exposure to the diredt rays of the sun. No method of overcomingthis drawback has yet been discovered, and in consequence cyanin hasgradually disappeared from the market.

3g. Dalleiochin (Quinine Green).—This colour has never become an articleof commerce. It is prepared as follows :—

Sulphate of quinine . 10 parts.

Water.1000 „

Liquid chloride of lime. 134 ,,

Hydrochloric acid. 35 ,,

These substances are allowed to read! upon each other, and 125 parts ofliquid ammonia are added. A greenish resinous matter is thus precipitatedand is colledted upon a filter. Quinine green is insoluble in water, benzol,and ether, but it dissolves in alcohol, wood-spirit, and glycerin. Acetic acidturns it to a blue shade : the mineral acids dissolve it with a brown colour,but on neutralisation the original colour is restored. Salt of tin decolourisesthe solutions. The alcoholic solution diluted with water dyes silk a green,which retains its tone by artificial light. Wool is dyed like silk. Cotton requiresto be animalised with albumen. For printing, quinine green is mixed withalbumen and the colour fixed by steaming. The shades produced are farinferior to those obtained with the aldehyd and iodine greens.

40. Aloes.—The following particulars may be superadded to the informationfound on p. 417 :—

Pure aloetic and chrysammic acids are not commonly employed in dyeingand printing, but mixtures of these acids. In preparing the colour by Sacc’sprocess, the solution of aloes in nitric acid is poured in a very slender streaminto cold water. Lindner heats in the water-bath 1 part of aloes with 60parts of nitric acid until red vapours come off, and introduces then by degreesg parts more of aloes into the solution, evaporating to dryness when therea&ion is over. The resulting mass, which is of a gold-yellow, is washed