OF COBALT. 



the heat rather increased, fumes of nitric acid 

 came over in abundance, and the matter in the 

 crucible concreted into a black mass, which, 

 after exposure to a red heat, weighed 4*8 grains : 

 it was peroxide, and equivalent very nearly to 

 4*25 grains of protoxide of cobalt. 1775 grains 

 of the crystals were dissolved in water, and di- 

 gested with carbonate of barytes till the liquid 

 became colourless. The supernatant liquid being 

 then drawn off and evaporated to dry ness, left 

 15%5 grains of nitrate of barytes, equivalent to 

 6-34 grains of nitric acid. This is somewhat 

 less than 6'75, the atomic weight of nitric acid. 

 The cause of this diminution of weight is the 

 filter, through which the solution of nitrate of 

 barytes was passed. It contained some sulphate 

 of lime which decomposed a portion of nitrate 

 of barytes, substituting nitrate of lime in its 

 place. From the preceding analysis it is evi- 

 dent, that the constituents of this salt are 



1 atom nitric acid . 6-75 



1 atom protoxide of cobalt 4-25 

 6 atoms water 6*75 



17-75 



4. Carbonate of cobalt. This salt was ob- Carbonate, 

 lained by precipitating the nitrate of cobalt by 

 carbonate of soda, collecting the precipitate on 

 a filter, and washing it thoroughly with water. 

 When dry, it is a light powder having a pink 



