SALTS 



<S atoms. Xo salt of zinc examined contains 5 

 atoms of water. 



15. SALTS OF CADMIUIM. 



I have mentioned in a former chapter of this 

 work, that by the kindness of Mr. Harepath of 

 Bristol, I was favoured with a quantity of the 

 sublimation that attaches itself to the roof of the 

 apartment in which zinc is smelted. This sub- 

 limate had a pretty deep brown colour, and con- 

 tained a good deal of vegetable matter. After a 

 few preliminary trials, I found that it contained 

 about ten per cent, of oxide of cadmium ; by far 

 the greatest portion of the remainder was oxide 

 of zinc. I therefore dissolved it in sulphuric 

 acid, and precipitated the cadmium by means of 

 a plate of zinc. I obtained by this simple pro- 

 cess, about 500 grains of metallic cadmium, 

 which enabled me, not merely to verify the ex- 

 periments of Stromeyer, but to make a set of 

 experiments on the salts of that metal : for with 

 the exception of the sulphate and nitrate, Stro- 

 meyer has not determined the water of crystal- 

 lization which they contain. I shall here state 

 the results of these investigations. 



Sulphate, i. Sulphate of cadmium. I have given a de- 

 scription of this salt in a former part of this 

 work. Its constituents, when in crystals, are 



