TMIDOSULPHONATES. IO3 



nate, p. 64). Hen ted more strong-ly in an o])en tube, it yields a 

 small sublimate of an ammonia-sulphite salt, Jiiercurous sulphate, and 

 mercury, along with sulphur dioxide and nitrogen as gases, and 

 mercurous, mercuric, and sodium sulphates as residue. 



Heated slowly in the vacuum of the Sprenii'el-pump, it suffers 

 change in a way that can be more closely studied. Even at 444:° no 

 material alteration t tikes place in the salt, but just below a red heat, it 

 decomposes steadily, temporarily blackening through formation of 

 mercuric sulphide, and giving much mercury as a sublimate, nitrogen 

 and sulphur dioxide in the proportions of two volumes of the former 

 to three of the latter, a little, very volatile, white ammoniacal sublimate 

 along with a very little water, and another white sublimate volatilising 

 sigain at o5*)-4()().° The residue is sodium sulphate. The margin, 

 remote from the heai, of the sublimate last mentioned consists of mercu- 

 rous sulphate, but the rest of this sublimate, which adheres to the glass 

 firmly, is of a peculiar nature but imperfectly made out. It is, how- 

 ever, a mercury compound scarcely affected l)y potassium hydroxide, 

 boiling water, or dilute nitric acid, and is api)arently a nitrogen-hold- 

 ing derivative of mercuric sulphate. 



The main changes by heat appear to l)e — 



'2HgN2(S03Na),=4SO,Na2-l-HgSO,-l- HgS -H 2SO2+ 2N„ 

 and then by further heat — 



4S04Na2+2Hg + 4S02-t-2N2. 

 The ammoniacal sublimate and moisture are evidently due to water 

 retained by the salt, prol:)al)ly tin'ough hydrolysis ; while mercurous 

 sulphate will have come from mercury and mercuric sulphate. 



With soluti(jns of ordinary mettiUic salts, the mercuric disodium 

 salt gives the various double mercury imidosulphonates noticed by 

 Berghmd. For exam[)le, with barium ch'oride it gives a precipitate of 

 mercury Ijarium imidosulphonate. 



