Researches on the Salts of Selenious Acid. 



57 



2. Diselenite: Co.0 2 .SeO + SeO 2 . 



The neutral selenite is easily dissolved in warm, concentrated sele- 

 nious acid; such a solution allowed to evaporate over sulphuric acid, affords 

 a beautifully red, completely amorphous, glassy mass; but on slowly eva- 

 porating at 60° in a vessel covered with a watch-glass, the concentrated 

 solution soon yields a salt in dark-violet crusts, showing a very beautiful 

 crystallization under the microscope. The crystals consist of rhombic prisms 

 in combination with very developed brachydiagonal end-faces and macrodia- 

 gonal dome, on account of which they assume the form of rhombic tablets, 

 the acute angles only little truncated by the slightly developed prism-faces. 



Analyses: 



1) 0.504 gr. salt gave 0.265 gr. selenium or 0.3724 gr. selenious acid and 

 0.2608 gr. sulphate of cobalt or 0.1271 gr. cobaltous oxide. 



2) 0.4847 gr. salt gave 0.2558 gr. selenium or 0.3594 gr. selenious acid 

 and 0.251 gr. sulphate of cobalt or 0.1223 gr. cobaltous oxide. 



In 100 parts: 



Cobaltous oxide . . 

 Selenious acid . . . 



This anhydrous salt is not at all soluble in cold, and only with 

 difficulty in warm water. 



3. Triselenite: Co.O'.SeO + 2Se0 2 +H 2 0. 



One mol. of neutral selenite and 3 mol. of anhydride of selenious 

 acid with some water being allowed slowly to evaporate at 60°, there was 

 obtained a red-violet salt in microscopic, oblique, four-sided tablets, though 

 complete solution never took place. To water it behaved as the preceding 

 compound. 



Analyses: 



1) 0.577 gr. salt gave 0.3172 gr. selenium = 0.4457 gr. selenious acid and 

 0.2005 gr. sulphate of cobalt = 0.0077 gr. cobaltous oxide. 



Nova Acta Reg. Soc. Sc. Ups. Ser. HI. 8 



found 



1. 2. 



25.22 25.23 



73.89 74.15 



¥9.11 99.38 



calculated 



CoO 76 25.50 

 2Se0 2 2J!2 74.50 

 298" 100.00 



