CADMIUM. 391 



truncated, rendering the prism hexagonal, and it 

 was terminated at both extremities by an elon- 

 gated hexagon. These crystals, after four suc- 

 cessive crystallizations, still reddened vegetable 

 blues. Hence, I conclude that oxide of cad- 

 mium, like oxide of zinc, js incapable of com- 

 pletely neutralizing sulphuric acid. The taste 

 of the salt has some resemblance to that of sul- 

 phate of zinc ; but it is rather more acrid and 

 disagreeable. 



Guided by the analysis of Stromeyer given 

 above, I dissolved 17*5 grains of these crystals, 

 dry, but quite free from efflorescence, in water, 

 and mixed the solution with one of 13'25 grains 

 of chloride of barium. After the sulphate of 

 barytes had subsided, the supernatant liquid was 

 tested by sulphate of soda and muriate of ba- 

 rytes, but it was not affected by either. From 

 this we see that 17'5 grains of crystallized sul- 

 phate of cadmium contain just 5 grains of sul- 

 phuric acid. 



17*5 grains of the same crystals, heated very 

 cautiously to redness in a platinum crucible, lost 

 just 4-5 grains, which is equivalent to 4 atoms of 

 water. 



The acid and water in 17*5 grains of sulphate 

 of cadmium amounting to 9*5 grains, it is obvi- 

 ous, that the 8 grains wanting to make up the 

 whole weight must be oxide of cadmium ; and 

 that the true composition of the salt is 



