178 



Messrs. Mills and Hunt's Researches 



fulfils the required condition, and partly because it neverthe- 

 less has some strong analogies with the nickel group. 



I. Preparation of the Salts. 



Pure cadmic sulphate was prepared from an excellent com- 

 mercial sample, the only impurity in which was a small quan- 

 tity of zinc sulphate. From an acidified aqueous solution 

 of the sample, cadmic sulphide was thrown down by hydric 

 sulphide. The washed sulphide was then dissolved in pure 

 hydric sulphate, and rendered neutral by careful ignition. 



1-per-cent. solutions of each of these salts were accurately 

 prepared. The sodic carbonate solution was prepared and 

 treated as in Part I.* 



II. Separation of Nickel from Cadmium. 

 From a solution of the mixed chlorides, cadmic sulphide was 

 precipitated as sulphide ; this was washed, dissolved in strong 

 hydric chloride, evaporated with hydric sulphate, ignited and 

 weighed as sulphate. The filtrate and washings were also 

 evaporated with hydric sulphate ; the ignited residue was 

 weighed as nickelous sulphate. 



III. Precipntahility Experiments. 

 The solution of pure sodic carbonate was of such a strength 

 that 1 cub. cent, of it exactly corresponded (Na 2 3 : CdS0 4 ) 

 to 1 cub. cent, of the cadmic solution. The usual series of nine 

 experiments was made, under the same general conditions as in 

 Part I. — the constant weight of mixed metallic sulphates being 

 1 grm., and volume of their solution 100 cub. cent., the constant 

 volume of carbonate solution being 100 cub. cent. The preci- 

 pitates were in all cases allowed one hour's repose ; they were 

 then filtered as rapidly as possible with the aid of an aspirator, 

 and washed with cold water. The results are given in the 

 following table, the precipitate being returned as sulphate: — 



Nickelous 



Cadmic 



Nickelous 



Cadmic 





sulphate 

 taken. 



sulphate 

 taken. 



sulphate 

 precipitated. 



sulphate 

 precipitated. 



Temperature. 



n. 



d. 



v. 



d. 





•9 



•1 



•5705 



•0810 



7-0 C. 



■8 



•2 



•5351 



•1823 



70 



•7 



•3 



•4477 



•2763 



10-4 



•6 



•4 



•3875 



•3546 



120 



•5 



•5 



•3295 



■4807 



9-6 



'4 



•6 



•2563 



•5937 



100 



•3 



•7 



•1876 



•6990 



105 



•2 



•8 



•1358 



•soio 



10-7 



•1 



•9 



•0692 



•9037 



11-3 



For Part I. see antt, p. 169. 



