Researches on the Salts of Selenious Acid. 



39 



SELENITES OF BARIUM. 



1. Neutral: Ba.0 2 .SeO + H 2 0. 



A solution of nitrate of barium in a few moments grows turbid, on 

 adding diselenite of sodium, and, within a short time, deposits a white, vo- 

 luminous precipitate of satiny crystals. Placed under the microscope it 

 exhibits a very beautiful crystallization of small prisms, asteriatedly grouped 

 and obliquely truncated at the ends. The mother-liquor deposited, on eva- 

 porating, the diselenite, mentioned below. 



Analyses: 



1) 0.327 gr. salt, dissolved in hydrochloric acid, gave 0.2658 gr. sulphate 

 of barium or 0.1745 gr. baryta, and out of the filtrate form this 0.0884 

 gr. selenium or 0.1242 gr. selenious acid. 



2) 0.632 gr. salt gave likewise 0.5013 gr. sulphate of barium = 0.3292 gr. 

 baryta and O.179 gr. selenium or 0.2515 gr. selenious acid. 



Centesimally represented : 



found calculated 



1. 2. 



Baryta 53.36 52.09 BaO 153 54.25 



Selenious acid .... 38.00 39.79 Se 2 111 39.37 



Water (loss) _JU4 8^12 H 2 _18 _6^38 



100.00 100.00 282 100.00 



This salt, which is permanent in the air, holds consequently 1 mol. 

 crystallization water. Beezelius found it to be waterfree. It is but 

 slightly soluble in water. When heated, the waterfree salt is persistent, 

 when protected from reducing gases; otherwise it is partially reduced to 

 selenide of barium. Pettersson *), who has proved that selenite of barium 

 is able to endure even the heat in Schlosing's furnace without decomposition, 

 provided that the crucible containing it be suspended in another crucible 

 a little larger, and also found that selenate of barium, under such circum- 

 stance is converted into selenite of barium, has employed such a mode of 

 procedure in order to convert selenite of barium into selenite, for the quan- 

 titative determination of selenic acid. 



') Zeitschr. fur analyt. Ch. 1873 S. 287. 



