212 EDWARD DIVERS AND TAMEMASA. HAGA ; 



apatite, was got in small good crystals by treating oxymercuric hydrogen 

 imidosulphonate with calcium chloride solution, in the proportion, 

 HNS 2 6 Hg 3 2 .' CaClg. Much mercuric oxychloride remained insolu- 

 ble, and the solution evaporated in a desiccator gave the salt in 

 question. By dissolving in water and precipitating by absolute alcohol, 

 the mercuric chloride can, for the most part, be removed from the 

 mercury calcium imidosulphonate, but only with great loss of the 

 latter, in consequence of its own solubility in alcohol. 



Mercurous imidosidjihonate. — No mercurous imidosulphonate has 

 yet been described. There seems to be only one, a basic salt, which 

 is formed when two-thirds normal sodium imidosulphonate is added 

 to mercurous nitrate. Being a basic salt, having Hg 4 '. S 2 its form- 

 ation is accompanied by that of nitric acid, which again, is a solvent 

 of it ; so that under the most favourable conditions a third, at least, 

 of the imidosulphonate remains in solution. The normal sodium 

 imidosulphonate would, therefore, be preferable to use, were its use 

 not subject to a disturbing effect, to be noticed presently. In order 

 to limit the quantity of nitric acid, the norma! mercurous nitrate, in 

 powder, is stirred with hot water until it has all become a solution, 

 holding in suspension a little of the soft, voluminous basic nitrate, and 

 free from any yellow granular particles. It has to be in some excess, 

 and we have taken about one-fifth more than the calculated quantity ; 

 but with moderate excess only, there will be no liability of any basic 



