Researches on the Salts of Selenious Acid. 



67 



3. Vs-Selenite: 3Cd.0 2 .SeO + H 2 .0 2 .SeO. 



The above mentioned amorphous selenite of cadmium dissolves easily 

 in selenious acid at ordinary temperature. The solution, within a few 

 moments, affords a crystalline precipitate, which, subjected to the micro- 

 scope, proves to be composed of acicular crystals, united in radially ar- 

 ranged groups. 



Analyses: 



1) 0.588 gr. salt gave 0.2195 gr. selenium = 0.3084 gr. selenious acid 

 and 0.4245 gr. sulphate of cadmium = 0.2612 gr. oxide of cadmium. 



2) 0.5235 gr. salt gave 0.1967 gr. selenium = 0.2764 gr. selenious acid 

 and 0.3785 gr. sulphate of cadmium = 0.233 gr. oxide of cadmium. 



Centesimally represented : 



found calculated 



1. 2. 



Oxide of cadmium 44.42 44.51 3CdO 384 45.39 



Selenious acid . . 52.45 52.79 4Se0 2 444 52.48 



Water (loss). . . . 3.13 2.70 H 2 JS 2.13 



IOoToO 100.00 846 100.00 



4. Sesquiselenite : 2Cd.0 2 .SeO + H 2 .0 2 .SeO + H 2 0. 



When 1 mol. of the preceding salt was digested with 2 mol. sele- 

 nious acid and the solution evaporated to dryness, there remained, on treat- 

 ment with water, a crystalline salt insoluble in it. Under the microscope, 

 it proved to be composed of small, four-sided prisms, united in compact 

 aggregates. 



Analysis : 



1) 0.5073 gr. salt gave 0.19 gr. selenium = 0.267 gr. selenious acid and 

 0.3427 gr. sulphate of cadmium = 0.2108 gr. oxide of cadmium. 



2) 0.4868 gr. salt gave 0.1836 gr. selenium = 0.258 gr. selenious acid and 

 0.3285 gr. sulphate of cadmium = 0.2021 gr. oxide of cadmium. 



Represented in 100 parts: 



found calculated 



1. 2. 



Oxide of cadmium . . 41.55 41.52 2CdO 256 40.96 



Selenious acid 52.63 53.00 3Se0 2 333 53.28 



Water (loss) __ 5 j^l 5 ' 48 2H2 ° _^ 5 - 76 



100.00 100.00 625 100.00 



