CHEMISTRY. 207 



the solution is treated in the ordinary manner with a salt and the 

 coloring matter is precipitated ; the solution of this substance in 

 alcohol gives a red color, finer and more solid than the colors 

 hitherto extracted from naphthaline and naphthylamine. No analy- 

 sis has yet been given of this body. It distils at 300° ; its vapors 

 form in condensing a deposit which rapidly becomes brown on 

 exposure to the air ; in a state of purity it is solid below 16°, be- 

 coming liquid at a higher temperature. — Mon. Sci. 



'aniline gray. 



M. Bloch publishes the following receipt : One kilo, of ani- 

 line at 190° and 5 kilos, of arsenic acid at 75° are heated in a 

 caldron over an open fire, care being taken to maintain the heat 

 at the boiling-point till the substance thickens and rises, when 

 the operation is terminated. The substance obtained presents a 

 black appearance; it is thick and insoluble in water. ]n or- 

 der to purify the product it is boiled with the aid of steam in a 

 mixture of about 20 litres of water and one kilo, of chlorhydric 

 acid, for half an hour, collected on a filter, washed first with water 

 and then with a dilute solution of carbonate of sodium. Finally 

 the collected matter is dried, and gives a fine black powder. For 

 dyeing, a solution of this product is made in alcohol to which 

 10 per cent, of sulphuric acid is added. With this liquor, when 

 filtered, magnificent grays of all shades can be dyed. 



A NEW METHOD OF DYEING A FAST GRAY. 



It is stated by M. Ban-eswil that protonitrate of mercury is suc- 

 cessfully used as a mordant ; the dye employed is a solution of 

 sulphide of potassium, one kilo, of the salt being employed to 18 

 kilos, of woven tissue or yarn. The gray color thus produced is 

 essentially due to the formation of sulphide of mercury on and in 

 the tissues, and, according to M. Barreswil, the color is fast, that 

 is, it is not destroyed by washing with soap or alkalies, and re- 

 sists acids, but it is destroyed by chlorine. — BuU. d. I. Soc. 

 d^Encour.y June, 1869. 



SOLUBILITY OF INDIGO. 



Koechlin has discovered that indigo is soluble in alkaloid 

 salts, and particularly in the acetates and chlorides of aniline, 

 morphine, etc. 



Stock vis announces the solubility of indigo in chloroform, stat- 

 ing that this solvent takes up the color largely and readily. — 

 Bull. Soc. Chim. 



CHROME GREEN. 



Oxide of chromium prepared in the dry Avay varies in the shade 

 of color, but never possesses such brilliancy or freshness that it may 



