Aniline Gray.

Manufacturer and builder, 6/1869

THE following recipe has been published by M. Bloch, to produce an aniline gray color: - 1 kilo. of aniline at 190°, and 5 kilos. of arsenic acid in a liquid form at 75°, are taken and heated on the open fire in a cauldron, care being taken to maintain the heat at the boiling point till the substance thickens and rises, when the operation is terminated, and the vessel is removed. The substance obtained presents a blackish appearance; it is thick, and insoluble in water. In order to purify the product, about 20 litres of water, and 1 kilo. of muriatic acid are taken and boiled with steam for half an hour; after which the mass is filtered. The matter which is deposited on the filter is collected, washed with boiling water, and operated upon a third time by a small quantity of carbonate of soda in solution, so as to completely neutralize the acid. Finally, the collected matter is dried, and gives a fine black powder. The solution of this product is made by treating it with alcohol, with an addition of ten per cent of sulphuric acid. Nothing now remains to be done but to filter it. With this liquor, magnificent grays of all shades are dyed, by submitting its mordant to the dyeing bath. For the dyeing and printing of this gray color, the matter must first be passed through a water bath, strongly acidulated with sulphuric acid. A skein of silk or wool is dyed by five drops of this liquor.

- Moniteur Scientifique.