396 SALTS 



up : the quantity exceeds twice the weight of 

 the acid heat is produced during the solution 

 the liquid is transparent and colourless like water; 

 on cooling, it deposites a very considerable num- 

 ber of white crystals, which constitute the salt in 

 question. I have not myself been able to deter- 

 mine the shape of these crystals ; but they are 

 said to be octahedrons with their apexes trun- 

 cated. I have always obtained them in prisms, 

 seemingly four-sided. This salt is not altered 

 by exposure to the air ; it has the disagreeable 

 taste which distinguishes the soluble mercurial 

 salts. When digested in water, it dissolves only 

 partially, leaving a green powder which is a sub- 

 nitrate of mercury ; but it dissolves with facility 

 in water acidulated with nitric acid. 50 grains 

 of this salt were decomposed by caustic potash. 

 The protoxide of mercury (not quite free from 

 peroxide) weighed 37'6 grains. Now, as the 

 atomic weight of protoxide of mercury is 26, we 

 have 26 : 6*75 : : 37*6 : 9*76 = nitric acid of the 

 salt. 50-- 37-6 = 12-4, and 12-4 - - 9*76 = 

 64, the water contained in 50 grains of the 

 salt. Hence, the constituents ought to be 



Nitric acid . 9'?6 or 6'?S 



Protoxide of mercury 37*60 - 26 

 Water 2-64 - 1-825 



50 



The water amounts to If atom. As the oxide 



