376 Mr. P. Griess on a New Class of Compounds [June 16, 



cold dilute alcohol and precipitated by ether. The following equation 

 expresses the reaction : — 



€3 H, N, NHO3 + NHO,=€3 H, N„, NHO3 + 2H2 O. 



Nitrate of aniline. Nitrous Nitrate of diazo- 

 acid. benzol. 



Nitrate of diazobenzol may also be prepared from diazoamidobenzol, a 

 substance described by me on a former occasion*, by treating an etherial 

 solution of the latter with nitrous acid, 



H,, N3 + NHO, + 2 N HO3 = 2(€3 N„ NHO3) + 2H, O. 



Diazoamido- Nitrate of diazobenzol. 



benzol. 



The new compound dissolves very readily in water, more difficultly in 

 alcohol, and is almost insoluble in ether. On heating, the solutions are 

 decomposed with evolution of gas. The dry substance explodes with the 

 greatest violence when gently heated, and it is necessary to observe great 

 precautions whilst working with it. The chemical analysis could not, for 

 the same reason, be performed by the usual methods. Its composition 

 was, however, readily established by studying the products of decomposi- 

 tion to which boiling with water gives rise, according to the equation 



€3H,N„NH03 + H,0=€3H,0 + + NHO3. 



Nitrate of diazo- Phenylic Nitro- 



benzol. acid. gen. 



Sulphate of Diazobensol, H, SH, O^. 

 This salt forms when a highly concentrated aqueous solution of the 

 former compound is treated with a sufficient quantity of cold sulphuric 

 acid diluted with its own bulk of water. The solution is treated, as before, 

 with three times its volume of alcohol, and ether added, which causes the 

 sulphate of diazobenzol to separate in a layer of a very concentrated aqueous 

 solution at the bottom of the vessel. On placing this latter solution over 

 sulphuric acid, crystallization ensues after a short time. The crystals are 

 freed from the mother-liquor by washing with absolute alcohol. In this 

 manner large white prisms, which rapidly deliquesce in moist air, are ob- 

 tained, and which are decomposed with slight deflagration when heated by 

 themselves. 



Hydrohromate of Diazobenzol, Cg H^^Ng, HBr. 

 This compound is obtained in small white soft plates when an etherial 

 solution of diazoamidobenzol is mixed with an etherial solution of bromine, 



[ C,, H,, N3 + 6 Br = Cg H, N,, HBr + C3 H, Br3 N + 2 (HBr) . 



^ . — .-y ^ ■ y ' 



Hydrobromate of Tribromaniline. 

 diazobenzol. 



* Ann. der Chera. und Pharm. vol. cxxi. p. 258. 



