390 ZINC, CADMIUM, LEAD, &c. 



can have no doubt that four atoms is the exact 

 quantity of water in an integrant particle of the 

 salt. It is more than probable that the 0*046, 

 which is wanting to complete the weight of the 

 four atoms of \\toter, has been given to the oxide of 

 cadmium. Hence, it is likely that the constituents 

 of the salt should have been stated as follows : 



1 atom sulphuric acid 5 



1 atom oxide of cadmium = 8*0107 



4) atoms water 4-5 



8*0107 denote the weight of an atom of oxide of 

 cadmium, according to this analysis a number 

 approaching 8 so nearly, that we can have no 

 hesitation in making choice of 8 as the true ato- 

 mic weight of this oxide. For it is obvious 

 from the great number of atoms already investi- 

 gated, as well as to be investigated, that all the 

 atomic weights of simple bodies are multiples 

 of 0-&5. Now, 8 is such a multiple ; while 

 neither 8-0567 nor 8-0107 is so. 



To determine the composition of sulphate of 

 cadmium with the requisite exactness, I pre- 

 pared a quantity of very pure crystals, by crys- 

 tallizing a rather concentrated solution of the 

 salt under the exhausted receiver of the air- 

 pump over sulphuric acid. The crystals were 

 large, flat, four-sided prisms, apparently rectangu- 

 lar, but from their efflorescing property, I was 

 not able to measure their angles by the reflecting 

 goniometer. In most of them, the edges were 



