210 H. Caro and J. A. Wanklyn on the relation of [June 21, 



I. On the Relation of Rosaniline to Rosolic Acid/^ By H. Caro^ 

 and J. Alfred Wanklyn, Professor of Chemistry at the London 

 Institution. Communicated by Dr. Frankland. Received June 

 5, 1866. . 



At tlie Meeting of the British Association held in Bath in the year 1864, 

 it was pointed out by one of us that rosaniline and rosolic acid might be 

 represented as ethylene which had undergone substitution : — 

 Type. Rosaniline. Rosolic Acid. 



NCgH.H 



N Cg H. H ' ^'^ 

 H 



Rosaniline and rosolic acid became members of the same family, the former 



{C H 

 |j 3 in place of hydrogen, the latter also 



an ethylene, but containing O Cg H. and O H in place of hydrogen. Some 

 of the reasons for assigning these formulae were given in the communica- 

 tion made to the Bath Meeting. 



The relationship between rosanihne and rosolic acid is very well brought 

 out by the facts which will presently be brought forward. 

 Griess has shown that aniline and nitrous acid yield water and diazobenzol : — 

 Aniline. Diazobenzol. 

 C.HjNH^ + HNO^ = CeH,N, + 2H,0. 



Diazobenzol is a most remarkable compound, forming salts which are very 

 explosive, and which undergo certain very interesting transformations under 

 the influence of reagents. It is moreover the representative of a nume- 

 rous class of compounds derived similarly by the action of nitrous acid on 

 different bases, and for the most part resembling itself in the explosive 

 character of the salts. One of the most remarkable reactions presented by 

 diazobenzol is that with water, wherein the whole of the nitrogen of the 

 diazobenzol is evolved, and its place supplied by an atom of water : — 



Nitrate of diazobenzol. Carbolic acid. 



CeH,N,HN03 + H,0 = CeH.O + HNO3 + N,. 



This elegant form of reaction appears to be characteristic of the class to 

 which diazobenzol belongs ; and Griess has resorted to a measurement of 

 the quantity of nitrogen set free during the reaction, as a means of arriving 

 at the composition of the azo-compounds. 



Hofmann showed, some years ago, that rosaniline, after treatment with 

 nitrous acid, is capable of forming a platinum compound endowed with ex- 

 plosive properties, but appears not to have followed the investigation further. 



Paraf has recently shown that rosaniline salts are converted by nitrous 

 aeid into a dye, which he considered to be rosolic acid. We have also 

 investigated the action of nitrous acid on rosaniline, and arrive at the fol- 

 lowing results : — 



