1864.] 



in which Nitrogen is substituted for Hydrogen. 



377 



Hydrobromate of diazobenzol is very unstable. The beautifully white 

 crystals change so rapidly that in a few moments they acquire a reddish 

 colour, and in a few days the decomposition is almost complete. They 

 explode on heating almost with the same violence as was experienced with 

 nitrate of diazobenzol. 



Bibromide of Hydrobromate of Diazobenzol^ OgH^^N^, HBr, Brg. 



On adding excess of bromine-water to an aqueous solution of any one of 

 the compounds previously described, an orange-coloured oil is obtained which 

 rapily solidifies, after the mother-liquor has been removed, to small orange- 

 coloured plates. The crj^stals of dibromide are obtained in a perfectly pure 

 state by washing with a little alcohol. This compound is rather difficultly 

 soluble in cold alcohol and ether ; and the solutions are rapidly decomposed, 

 particularly on the application of heat. 



Platinum-salt of the Hydrochlorate of Diazobenzol, N2, HCl, PtClg. 



This salt forms beautiful yellow prisms which are almost insoluble in 

 water. The gold-salt, €g N^, HCl, AuClg, can be recrystallized from 

 alcohol, and is obtained in very fine golden-yellow brilliant plates. 



It has thus been sufficiently shown that diazobenzol deports itself like 

 an organic base, being capable, like aniline, of forming salts with various 

 acids. It possesses, however, also the property of combining with the 

 hydrates of the metals, thus playing the part of a weak acid. 



Compound of Hydrate of Potassium with Diazobenzol, G^'^^'N^, KHO. 



This body is obtained when a concentrated aqueous solution of nitrate of 

 diazobenzol is treated with excess of concentrated aqueous potassa. By 

 evaporating on the water-bath, the liquid solidifies, when sufficiently con- 

 centrated, to a magma of yellow crystals consisting of nitre and the com- 

 pound of hydrate of potassa Avith diazobenzol. The crystalline mass is 

 pressed between porous stones, and thus partly freed from moisture. By 

 dissolving in absolute alcohol and treating with ether, the new compound 

 of hydrate of potassium with diazobenzol is obtained in a pure state, 

 crystallizing in small soft white plates, which rapidly become reddish, 

 especially in the moist condition. It is very readily soluble in water and 

 alcohol ; the solutions, however, decompose slowly, and deposit a reddish 

 amorphous body. Heat does not seem to accelerate this decomposition 

 materially. 



Compound of Hydrate of Silver loith Diazobenzol, H^ AgHO. 



This substance is obtained in the form of an almost white precipitate 

 when a solution of silver is added to an aqueous solution of the former 

 compound. It is very stable. Similar compounds are obtained with lead- 

 and zinc-salts. 



