346 On the Colouring-matters derived from Coal-tar. [June 16, 



very concentrated solutions, a platinum-salt is deposited exhibiting an un- 

 desirably blue tint. 



When a mixture of diphenylamine and toluidine is submitted to one of the 

 processes (treatment with chloride of mercury or arsenic acid) which, if 

 phenylamine and toluidine had been employed, would have furnished ros- 

 aniline, a mass is formed which dissolves in alcohol with a magnificent 

 blue coloration, and possesses the characters of a true colouring-matter. 



An alcoholic solution of diphenylamine furnishes, on addition of bro- 

 mine, a yellow crystalline precipitate, difficultly soluble in cold alcohol, 

 but crystalhzing from boiling alcohol in beautiful needles of a satiny lustre. 

 According to analysis, they contain 



C,,H,Br,N, 



a formula which renders the grouping 



CeH3Br,l 

 C,H3Br,lN' 

 H j 



probable. 



A mixture of diphenylamine and chloride of benzoyl, when heated, fur- 

 nishes a thick oil, which solidifies on cooling. Washed with water and 

 alkali, and recrystallized from boiling alcohol, in which it dissolves with 

 difficulty, the new compound is obtained in beautiful white needles. Ana- 

 lysis has confirmed the theoretical anticipation, 



C„H.,NO=C,H, In. 



C,H,0j 



This substance has become the starting-point of some experiments which 

 I shall here briefly mention, but to which I intend to return hereafter. 

 On addition of ordinary concentrated nitric acid, the benzoyl-compound 

 liquefies and dissolves. From this solution, water precipitates a light- 

 yellow crystalline compound, 



C H 1 



c.,h„n,03=c.h:(nojIn. 



C,H,0 J 



which dissolves in alcoholic soda with a scarlet colour, splitting on ebulli- 

 tion into benzoic acid^and reddish-yellow needles of nitro-diphenylamine, 



C,,H,,NA=C,H,(NO,)J^N. 



If, instead of ordinary nitric acid, a large excess of the strongest fuming 

 nitric acid be employed, the solution deposits, on addition of water, a crys- 



