2^4 EDWARD DIVERS AND TAMEMASA HAG A; 



tion sodium chloride precipitates all the mercury. Rubbed with 

 sodium-chloride solution, the salt becomes of a permanent, dull, and 

 somewhat greenish orange colour, though quite free from the mercuric 

 radical. The sodium-chloride solution becomes very alkaline to 

 litmus, no doubt because of the formation of normal sodium imidosul- 

 phonate. Concentrated hydrochloric acid soon causes, even in the cold, 

 the formation of some mercury and mercuric chloride, and, on heating, 

 this change becomes complete.* Concentrated solution of potassium 

 iodide at once in the cold dissolves it all but half its mercury, left as 

 metal. 



Normal sodium imidosulphonate converts it into mercury and 

 the sparingly soluble mercuric sodium imidosulphonate. This fact it 

 is winch makes the normal sodium salt, otherwise desirable, not very 

 well suited for preparing the mercurous salt. When it is used in 

 place of the two-thirds normal sodium salt, each addition, however 

 small and in however dilute, solution, causes a blue-grey cloud of 

 mercury to form, and consequently some mercuric salt. However, by 

 incessant and violent stirring for ten minutes from the time of adding 

 the normal sodium salt, not in excess, to the mercurous nitrate (which 

 may here be used in a very dilute nitric-acid solution), the grey 

 precipitate becomes almost completely white, and is then the mercu- 

 rous imidosulphonate. Thus prepared, we have found it to contain 

 78.20 and 78.55 instead of 79.22 per cent, mercury, but the right 

 quantity of sulphur, namely, (5.20 (twice), theory requiring 6.18 per cent. 



The most probable constitution of oxymercurous imidosulpho- 



/ Hg 2 N(S0 3 ),Ho-, 

 nate is that formulated as 0<; , 6ri 2 0, but other represent- 



\Hg 2 N(S0 8 ) 2 Hg, 



at ions of it are, of course, possible. 



* Owing to the production of aimdosulphonic acid (see the following paper on this acid). 



