949 EDWARD DIVERS AND TAMEMASA HAG A ; 



digestion with much diluted nitric acid. Mercuric chloride and potas- 

 sium amidosulphonate mix together in solution without change, 

 but, with the former not in excess, potassium hydroxide, in quantity 

 not exceeding the equivalent of the chloride, gives rise to the above 

 salt, as a white precipitate. The acid can precipitate almost all the 

 mercury from a solution of mercuric nitrate, leaving only nitric acid 

 in solution ; and is itself completely precipitated by a slight excess of 

 mercuric nitrate. 



To prepare the salt, it is best to mix a dilute solution of the acid 

 with a concentrated solution of mercuric nitrate in the minimum of 

 nitric acid, when the salt forms as a snow-white, voluminous, and very 

 finely divided precipitate, troublesome to wash, either by décantation 

 or on the filter, and taking long to dry on the tile, all in consequence 

 of its fineness of division. It is very stable and may be washed 

 with hot water. Air-dried, at the common temperature, it contains 

 two mol. water, which it easily loses when heated (at 115°). The 

 results of its analysis are as follows : — 



Found. 



70.80 

 7.4Î) 

 4.65 



The mercury found is too high through imperfect determination ; for, 

 when calculation is made, the total a little exceeds 100. The error 

 does not affect the formula adopted. 



The salt requires comparatively strong nitric acid to dissolve it 

 in the cold. Hydrochloric acid dissolves it, of course ; but, what is 

 very remarkable, potassium hydroxide does so, too. By using an in- 

 sufficient quantity of alkali, it is possible to decompose the salt partly, 

 and thus to get a little yellow mercuric oxide from it, which remains 



