54 



DIVERS AXD HAGA. 



hydroxy-lead imidosulphonates with a solution of ammonium car- 

 bonate. Triargentum imidosulphonate (p. 93) stirred with a solution 

 of its equivalent of ammonium bromide has-been our source of the 

 diammonium salt. Triammonium salt is thus produced, and the 

 solution decanted from the silver bromide needs to be evaporated on 

 a water bath until amuKjnia almost ceases to escape, and then to be 

 filtered from a little silver bromide. To crystallise the salt the 

 solution generally requires further evapcjration and, in (^rder to guard 

 against hydrolysis into amidosulphonate during the operation, is kept 

 alkahne by occasionally adding a droj) of strong ammonia-water. 



Diammonium imidosulphonate- forms monosymmetric prisms, 

 isojuorplious with the potassium salt (Mlinzing and Raschig). In 

 its general reactions it is like the sodium and p(jtassium salts. It 

 reddens blue litmus, even while still quite free from sulphuric acid 

 (Jacquelain). 



The effect of heating it was tried by Rose, and is described in the 

 first of his papers upon the sulphatammons. iVccc^rding to him the 

 products differ little from those coming from heating ammonium 

 sulphate, except in the absence among them of water. Anmionia 

 and sulphur dioxide are evolved, first the former, then ])rincipa]ly 

 the latter. Acid ammonium sulphate makes the residue, at not too 

 high a temperature. In the retort-neck ammonium sulphite and 

 sulphate are formed; in the receiver the former salt <3nly. He also got 

 a little of the yellow compound of the same gases. When the salt is 

 heated in ammonia gas, he found that but little sulphate is obtained. 



This account of Rose's <3f the effect of heating diammonium 

 imidosulphonate is essentially incomplete, but is true to the extent 

 thîit anmionia first, and then sulphur dioxide are evolved, that these 

 two partly condense as a sublimate, and that acid-sulphate is formed. 

 Heating in a, roomy retort, and thus permitting the action of moist 



