Polytechnic Association. 975 



the application lias not met with success. The most useful color for 

 cotton is undoubtedly the black. In 1864, I made my first attempts 

 in this direction, having observed that a mixture of chloride of ani- 

 line (acid) and chlorate of potash, when heated in a porcelain dish, 

 would (after a very powerful reaction had taken place) leave a bril- 

 liant black residuum. I was convinced that an aniline black could be 

 produced by the sole action of a powerful oxidizing agent (like chloric 

 acid) upon a salt of aniline. I then, for the first time, applied the 

 old method of producing chloric acid in the laboratory to calico print- 

 ing in the following manner. I prepared first the fluosilicate of ani- 

 line by heating together the aniline oil with hydrofluosilicic acid ; the 

 fluosilicate of aniline produced is a beautiful salt, very much like white 

 naphthaline. This salt suitably thickened with starch, then mixed with 

 a certain quantity of chlorate of potash, constituted my first aniline 

 black color. In the cloth the black is produced in the following 

 manner : 



The fluosilicate of aniline combines with the potash of the chlorate 

 of potash. The chloric acid thus freed oxidizes the aniline and pro- 

 duces the black. This process was not very practical, as it sometimes 

 rendered the cloth tender. I mention it to you mainly for the novelty 

 of the application of hydrofluosilicic acid to decompose the chlorate of 

 potash in calico printing. In 1865 I obtained good results by using, 

 for the first time in the confection of aniline, black chlorates more 

 soluble than chlorate of potash, such as chlorate of soda, ammonia, 

 etc. About that time, when I was personally presenting my results 

 before the Industrial Society of Mulhouse, a pol'emique took place, 

 headed by such chemists as Rasenstiehl, Charles Lauth, Camille 

 Kolchlin, all of them trying to prove that no aniline black could be 

 produced without the use of a salt of copper or iron. My process 

 was criticised in the scientific papers at the time. I never answered 

 them, but, by the following discovery, proved, in the end of 1866, 

 that they were wrong. I succeeded in obtaining beautiful aniline 

 blacks on cotton, with an entire neutral color, composed solely of a 

 neutral salt of aniline, a little chlorate of potash, and chromate of 

 chromium (also called the binoxide of chrome). Under the heat of 

 the aging process this chrome salt, insoluble when cold, decomposes 

 into green oxide of chrome and chromic acid, which oxidizes the salt 

 of aniline and produces the jet black. 



For more particulars about this important color, I refer you to my 

 United States patent, No. 60,546. This process is extensively used 

 for all the aniline blacks at the Merrimack print works at Lowell, 



