OF AMMONIA. 249 



vegetable blues, and is very soluble in water. 

 When heated it melts and loses its water and 

 ammonia ; a dark green matter remains, which 

 speedily becomes solid, exhibiting the rudiments 

 of crystallization on the surface. This matter is 

 brittle, has a cooling and sharp taste, and partly 

 dissolves in water, forming a deep yellow solu- 

 tion, and partly remains in the state of a deep 

 green insoluble matter. It is obvious, that by 

 the heat the chromic acid had been partly con- 

 verted into protoxide of chromium ; so that the 

 dark green matter left was a kind of chromate 

 of chromium. 



1 7'375 grains of this salt were just deprived 

 of the whole of their chromic acid by 41*5 grains 

 of nitrate of lead. Hence, the constituents of 

 the salt are 



2 atoms chromic acid 13 



1 atom ammonia . . 2*125 



2 atoms water . 2'25 



17-375 



13. Bitungstate of ammonia. I have already 

 given an account of this salt in a preceding 8 

 chapter of this work. Its constituents I believe 

 to be 



2 atoms tungstic acid 37-5 



1 atom ammonia . 2-125 



2 atoms water . . 2-25 



41-875 



