1863.] 645 



beautifully crystalline mass, Jdnonamide t C 6 H 5 NO, which stands 

 midway between kin one and diphenine, 



C 6 H 4 O 2 +H 3 N=C 6 H 5 NO+H 2 O. 



Kinone. Kinonamide. 



Another similar step of transformation would lead to diphenine, 

 C 6 H 5 NO+H 3 N=C H 6 N 2 +H 2 0. 



Kinonamide. Diphenine. 



The preparation of azobenzol in large quantity, its transformation 

 into dinitrazobenzol, and, lastly, the conversion by means of sulphide 

 of potassium of the mtro-compound into diphenine, present so little 

 difficulty, that treatment of diphenine with nascent hydrogen affords 

 the easiest and simplest means of procuring beta-phenylene-diamine 

 in appreciable quantity. 



VII. "Contributions towards the History of the Colouring 

 Matters derived from Aniline." By A. W. HOFMANN, 

 LLD., F.R.S. Received June 2, 1863. 



In a short paper recently submitted to the Royal Society, I pointed 

 out the existence of two aromatic diamines, both represented by the 



formula (C 6 H 4 )" 



C 6 H 8 N 2 = H 2 



and closely resembling each other, but differing in some of their 

 fundamental characters to such an extent that I did not hesitate to 

 assert their individuality, and to distinguish them as alpha-pheny- 

 lene-diamine and beta-phenylene-diamine. 



The existence of two closely allied bodies among the diatomic 

 derivatives of the phenyl-series very naturally suggested the idea of 

 searching for two similarly related monatomic bases of the same group, 

 and accordingly I undertook during the last week a careful comparison 

 of specimens of aniline prepared by different processes. This com- 

 parative study is still incomplete, but I beg leave to record even now 

 an observation which appears to merit the attention of chemists. 



I have, in the first place, examined aniline obtained by distillation 

 of isatin (indigo) with hydrate of potassium. 



The base prepared in this manner boils at 182, and possesses the 

 general characters attributed to aniline. But neither by treatment 



VOL. XII. 2 Z 



