CADMIUM. 389 



though not rigidly exact, approach exceedingly 

 near the truth. 



According to Stromeyer, sulphate of C3L ^" 

 mium has a good deal of resemblance to sul- cadmium 



by Stro- 



phate of zinc in its appearance. Its crystals are meyer. 

 four-sided rectangular prisms, which are very 

 soluble in water, and effloresce rapidly when 

 exposed to the air. Heat easily drives off the 

 water of crystallization ; but the salt may be 

 exposed to a red heat without losing any of 

 its acid ; this makes it easy to determine its 

 water of crystallization. The constituents of 

 this salt as determined by Stromeyer are 



Sulphuric acid . 28-5230 

 Oxide of cadmium 45*9564 



Water . . . 25-5206 



100* 



Now, these numbers bear to each other the 

 same ratios as the following : 



Sulphuric acid . 5 

 Oxide of cadmium 8-056? 



Water . . 4-454 



It will be obvious to the reader that 5 is the 

 number which denotes the atomic weight of sul- 

 phuric acid ; 4*454 is so near 4%5, which repre- 

 sents the weight of four atoms of water, that we 



Gilbert's Annalen, LX. 202. 

 Bb3 



