CADMIUM. 



113 



was prepared by dissolving the carbonate in hydrobromic 

 acid, and the product, dried at 200°, was purified by sub- 

 limation in a porcelain tube. Upon the compound thus 

 obtained two series of experiments were made. 



In one series the bromide was dissolved in water, and a 

 quantity of silver not quite sufficient for complete precipi- 

 tation of the bromine was then added in nitric acid solu- 

 tion. After the precipitate had settled, the supernatant 

 liquid was titrated with a standard solution of silver con- 

 taining one gramme to the litre. The precipitate was 

 washed by decantation, collected by reverse filtration, and 

 weighed. To the weighings I append the ratio between 

 CdBr2 and 100 parts of silver bromide : 



1.5592 grm. CdBr.^ gave 2 



1529 grm. AgBr. Ratio, 72.423 



.0028 



The second series was like the first, except that the weight 

 of silver needed to effect precipitation was noted, instead of 

 the weight of silver bromide formed. In the experiments 

 marked with an asterisk, both the amount of silver required 

 and the amount of silver bromide thrown down were deter- 

 mined in one set of weighings. The third column gives the 

 CdBr2 proportional to 100 parts of silver : 



