646 [June 18, 



with mercuric or stannic chloride nor with arsenic acid is this sub- 

 stance converted into aniline-red. 



Aniline derived from henzol was next submitted to examination. 

 The benzol employed for the preparation of the base was partly 

 obtained by the distillation of benzoic acid with lime, partly by the 

 fractional distillation of coal-tar naphtha, and the ultimate solidifica- 

 tion of the product, boiling between 80 and 83. 



Both varieties of benzol were treated with fuming nitric acid, and 

 the nitro-compound thus obtained converted into aniline by means of 

 iron and acetic acid. 



The base prepared from benzoic benzol boils at 182. Like 

 indigo-derived aniline, it refuses to yield the red colour by treatment 

 with the agents previously mentioned. 



Aniline obtained from coal-tar benzol, as might have been expected, 

 likewise boils at 182, and neither mercuric nor stannic chloride nor 

 arsenic acid converts this substance into aniline-red. 



When I communicated these observations to my friend Mr. E. C. 

 Nicholson, I found that in this case, as in so many others, practice 

 is far in advance of theory. The facts which I have mentioned had 

 been long known to this distinguished manufacturer, who in reply to 

 my note transmitted to me a gallon of absolutely pure aniline boiling 

 at 182, prepared from coal-tar benzol, and perfectly incapable of 

 yielding aniline-red. 



During the last few months I have had occasion to examine a great 

 variety of commercial specimens of aniline, more especially samples 

 which had been kindly supplied to me by Messrs. Simpson, Maule, 

 and Nicholson, of London, and by Messrs. Renard Brothers and 

 Franc, of Lyons. All these specimens furnished, by the ordinary 

 processes, very notable quantities of aniline-red, but they also invari- 

 ably boiled at a higher temperature, exhibiting in fact boiling-points 

 varying between 182 and 220. 



It is thus obvious that commercial aniline contains a base different 

 from normal aniline, the cooperation of which is indispensable for 

 the production of aniline-red. 



Is this base an isomeric variety of aniline, an aniline holding to 

 the normal aniline a relation somewhat similar to that which obtains 

 between alpha- and beta-phenylene-diamine ? * It is well known 

 * Phil. Mag. S. 4. vol. xiii. p. 415 (June 1857). 



