1863.] Dr. Hofmann on Aniline-blue. 9 



monochloroplatinate and a dichloroplatinate, combining with more or less 

 water of crystallization. 



The composition of chrysaniline places this substance in immediate juxta- 

 position with rosaniline and leucaniline. These three triamines simply 

 differ by the amount of hydrogen which they contain. 



Chrysanihne C^^ H^^ N3 



Rosaniline C^q H^g N3 



Leucaniline C^o N3. 



Chrysaniline is monacid or diacid ; rosaniline monacid or triacid, but with 

 essentially monacid predilections ; leucaniline forms exclusively triatomic 

 compounds. 



The formula of chrysaniline suggests the possibility of transforming this 

 substance into rosaniline and leucaniline, or of producing chrysanihne 

 from rosaniline or leucaniline. Up to the present moment this trans- 

 formation has not been experimentally accomplished. The constitution 

 and genesis of chrysaniline remain to be made out. 



VI. " Researches on the Colouring Matters derived from Coal-tar. — 

 II. On Aniline-blue." By A. W. Hofmann, LL.D., F.R.S. 

 Received June 30, 1863. 



Among the several stages which mark the development of the industry 

 of coal-tar colours, the discovery of the transformation of aniline-red into 

 aniline-blue will always hold a prominent position. This transition, for 

 the first time observed by MM. Girard and De Laire*, two young French 

 chemists of M. Pelouze's Laboratory, and subsequently matured by M. 

 Persoz, De Laynes, and Salvetatf, has become the foundation of an 

 enormous industrial production, which, having received a powerful im- 

 pulse by MM. Renard Brothers and Franc in France, and more recently by 

 Messrs. Simpson, Maule, and Nicholson in this country, has rapidly attained 

 to proportions of colossal magnitude. 



The transformation of aniline-red into aniline-blue is accomplished by a 

 process of great simplicity, and consists, briefly expressed, in the treat- 

 ment at a high temperature of rosaniline with an excess of aniline. The 

 mode of this treatment is by no means indifferent. Rosaniline itself cannot 

 in this manner conveniently be converted into the blue colouring matter ; 

 the transformation is, however, easily accomplished by heating rosaniline 

 salts with aniline, or, vice versa, rosaniline with salts of aniline. Again, 

 the nature of the acids with which the bases are combined is by no means 

 without influence upon the result of the operation ; manufacturers give 

 a decided preference to organic acids, such as acetic or benzoic acids. 



The production of the new colouring matter on a very large scale has 

 already ehcited a good deal of most valuable information regarding the 



* French patent, January 18G1. 



t Comptes Rendus, March and April 8th, 186L 



