972 Transactions of the American Institute. 



cal investigation at the present day. All the aniline colors are derived 

 from 3 N H 3 = N 3 H 9 , converted by the process of substitution into 

 new compounds. The first investigation in this direction, which, 

 however, did not result in any practical product, was that of a German 

 chemist, who found that, by treating aniline with chloride of lime, he 

 produced a violet or purple tint. Perkin, who was the first success- 

 ful manufacturer of color from coal tar, manufactured a substance to 

 which he gave the name of mauve. It is a salt of mauveine, C 26 H24 

 JST 4 . Then came the discovery of the rose aniline, which is produced 

 from commercial aniline, a mixture of aniline and toluidine, pure ani- 

 line not answering the purpose. Subjecting commercial aniline to 

 the action of nitric acid, and then to the action of nascent hydrogen, 

 we obtain crude aniline oil, which, by treatment with chloride of 

 mercury, chloride of tin, or a mixture of arsenic acid and hydrochloric 

 acid yields rose aniline, which is C 20 H 19 JST 3 . The chloride, hydro- 

 chlorate, arsenitate, acetate, nitrate and other salts of this substance 

 produced the beautiful tints, of which I have specimens here. Hoff- 

 mann found that he could change this beautiful red tint of the rose 

 aniline to various shades of violet, by simply boiling it with more 

 aniline. This introduced more phenyl in the place of hydrogen. 

 One atom made it purple, another more bluish, and a third atom of 

 phenyl made it the most beautiful blue that has ever been manufac- 

 tured. 



Replacing the hydrogen with ethyl, C 2 H 5 , or with methyl, CH 3 , 

 we obtain still further colors. In every case the beautiful rose red 

 becomes more and more purple, until the substitution of the last atom of 

 hydrogen converts it into a deep and perfect blue. On carrying the 

 investigation further, it was found that by proper treatment the blue 

 color could be converted into a green, by using the ethyl and methyl. 

 Subsequent treatment developed an entirely different base, having 

 the form C 20 H 17 N 3 , with yellow tints ; and further treatment pro- 

 duced a brown and finally a black ; so that the most durable black 

 for calico printing is now obtained from aniline. 



From the coal tar obtained from a ton of coal, three-fourths of a 

 pound of this beautiful color are produced. The coal, which is worth 

 about $6, produces the gas, the coke, the ammoniacal water, largely 

 used for agricultural purposes, the carbolic acid, used for the preser- 

 vation of timber and as a disinfectant, and finally this beautiful color, 

 which alone is worth nearly as much as the coal originally cost. The 

 amount of this industry has become so enormous that at present five 

 tons of this raw aniline oil are manufactured daily, on the continent 



