Researches on the Salts of Selenious Acid. 



13 



2. Diselenite: KH.CHSeO. 



This salt was obtained by treating 1 mo], carbonate with 2 mol. 

 anhydride of selenious acid, and crystallized from this solution, after strong' 

 concentration over sulphuric acid, as laminar, four-sided, probably rhombic 

 prisms, the ends of which were obliquely truncated on both sides. The 

 salt is very deliquescent on exposure to the air. On account of this, it 

 was, before the analysis, desiccated between folds of bibulous paper and 

 dried over vitriol oil. 



Analyses: 



1) 0.9765 gr. salt gave 0.4563 gr. selenium or 0.6411 gr. selenious acid 

 and 0.5068 gr. sulphate of potassium, containing 0.2741 gr. potash. 



2) 0.9285 gr. salt gave 0.434 gr. selenium or 0.6098 gr. selenious acid 

 and 0.4795 gr. sulphate of potassium, containing 0.2593 gr. potash. 



3) 0.7845 gr. salt, when heated for several days at 100°, lost 0.042 gr. 

 of its weight. 



Centesimally represented : 



experiment theory 



1. 2. 3. 



Potash 28.07 27.93 — V 2 K 2 47.1 28.19 



Selenious acid . . 65.65 65.68 — SeO 2 111.0 66.42 



Water 6^28 6.39 5.35 V 2 H 2 • 9.Q 5.39 



100.00 100.00 167.1 100.00 



Consequently the salt at 100° completely, though very slowly, loses its 

 hydrogen in form of water, and becomes an anhydrous salt without fusing; 

 at a higher temperature, half the selenious acid passing off, it is converted 

 to a neutral salt. 



Muspratt communicates a potash determination on diselenite of po- 

 tassium, closely agreeing with the formula above. 



3. Tetraselenite: KH.0 2 .SeO + H 2 .0 2 .SeO, 



crystallizes from a solution, containing 1 mol. carbonate to 4 mol. selenious 

 acid, in form of glass-shining prisms, permanent on exposure to the air and 

 generally exhibiting a great number of combination-faces. There is seldom 

 observed a rhombic prism, combined only with predominant macrodiagonal 

 end-faces and pyramid-faces of the same order, but generally also 



