40 



L. F. Nilson, 



2. Diselenite: Ba.0 2 .SeO + SeO. 



By dissolving- 1 mol. carbonate of barium in 2 mol. boiling selenious 

 acid this salt was obtained. The solution evaporating at 40 — 50°, it was 

 deposited in satiny, small, four-sided prisms, truncated in the ends. The 

 crystals are commonly arranged in aggregates, the individuals radiating 

 from a common point. The salt is but slightly soluble in cold, more so 

 in warm water. 



Analyses : 



1) 0.5253 gr. salt gave 0.3228 gr. sulphate of barium from the solution, 

 acidulated with hydrochloric acid, or 0.212 gr. baryta, and from the 

 nitrate 0.218 gr. selenium or 0.3063 gr. selenious acid. 



2) 0.686 gr. salt gave 0.4235 gr. sulphate of barium = 0.2781 gr. baryta 

 and 0.2846 gr. selenium or 0.3999 gr. selenious acid. 



3) 0.31 gr. salt, obtained by the treatment of the diselenite with 2 mol. of 

 selenious acid, gave, when fumed with sulphuric acid, 0.19 gr. sulphate 

 of barium or 0.1248 gr. baryta. 



In 100 parts: 



found calculated 



1. 2. 3. 



Baryta 40.36 40.54 40.26 BaO 153 40.80 



Selenious acid . . . 58.31 58.30 — 2Se0 2 222 59.20 



98.67 98~.~84 375 100.00 



It has been already observed that this anhydrous salt was obtained 

 from the mother-liquor of the above neutral salt; the analysis 3) shows that 

 it is deposited from a solution, containing 4 mol. ot acid to 1 mol. of ba- 

 ryta, from which it seems to follow that no salt of barium, more acid than 

 diselenite, can be obtained. 



Neutral waterfree selenite and diselenite of barium Avere employed 

 by Berzelius to ascertain the capacity of saturation of selenious acid, of 

 which, for this purpose, he undertook quantitative baryta determinations, 

 showing a proportion of 57.93 in the neutral (calc. 57.96), and 40.54 in 

 the acid salt (calc. 40.80). 



