Researches on the Salts of Selenious Acid. 



95 



As to the composition this salt agrees completely with a ferric sele- 

 nite, obtained from a neutral solution of chloride of iron with selenite of 

 sodium : 



Fe' ; .0 ,7 .8SeO + 28H 2 0. 



As, however none of the already mentioned earth-metals, except 

 cerium, by decomposition of the sulphate with excess of selenite of sodium, 

 has given any basic salts, I was induced to repeat the preparation of sele- 

 nite of lanthanum. The appearance of the obtained precipitate was the 

 same as in the preceding - case A considerable excess of selenite of so- 

 dium was employed. 



Analyses: 



1) 0.5097 gr. salt gave 0.1288 gr. selenium or 0.181 gr. selenious acid 

 and 0.3312 gr. sulphate of lanthanum, containing 0.1908 gr. oxide of 

 lanthanum. 



2) 0.4683 gr. salt gave 0.12 gr. selenium or 0.1686 gr. selenious acid 

 and 0.3095 gr. sulphate of lanthanum, containing 0.1782 gr. oxide of 

 lanthanum. 



With these values, which calculated on 100 parts may be thus re- 

 presented: 



1. 2. 

 Oxide of lanthanum . 37.43 38.05 



Selenious acid 35.51 3G.01 



Water (loss) 27. 06 25.94 



100.00 100.00 



the following formula exhibits a tolerably close correspondence, 



2. Neutral: La 2 .0 G .3SeO + 12H 2 0. 



La 2 3 326 37.26 

 3Se0 2 333 38.05 

 12H 2 216 24.69 

 875 100.00 



although the great deficiency of selenious acid, amounting to 2 — 2 . 5 pr. 

 ct, sufficiently proves that the precipitate was mixed with a basic salt, 

 and that lanthanum, on mixing neutral solutions, has a great tendency to 

 fall Out as a basic selenite. 



