Researches on the Salts of Selenious Acid. 



87 



Analyses: 



1) 0.5555 gr. salt gave 0.2286 gr. selenium or 0.3212 gr. selenious acid 

 and . 1085 gr. oxide of iron. 



2) 0.4495 gr. salt gave 0.1858 gr. selenium or 0.2611 gr. selenious acid 

 and 0.0885 gr. oxide of iron. 



Centesimally represented: 



found calculated 

 1. 2. 



Oxide of iron 19.53 19.69 Fe 2 3 160 20.41 



Selenious acid 57.82 58.09 4Se0 2 444 56.63 



Water (loss). ..... 22.65 22.22 10H 2 O 180 22.96 



100.00 100.00 784 100.00 



That the oxide of iron in the circumstances, under which the two 

 last mentioned compounds have been obtained, does not form any salts 

 more acid than those, is, in a theoretical point of view, of great interest. 

 Two of the earth-metals, yttrium and erbium, have namely, under the same 

 circumstances also not been able to unite with more selenious acid than 

 to form a 4 / 3 -selenite, as will be seen in the following. It is also to be 

 remarked that the salt has taken up more water of crystallization, when a 

 larger quantity of acid has been present. 



SELENITES OF YTTRIUM 1 ). 



l. Neutral: Y 2 .0 6 .3SeO + i2H 2 0. 



From a solution of sulphate of yttrium an excess of selenite of so- 

 dium precipitated a white, heavy matter which a microscopical exami- 

 nation proved to consist of globular, transparent aggregates. The yttrium 

 had so completely fallen, that a solution of oxalate only caused a scarcely 

 perceptible precipitate in the mother-liquor. It is consequently nearly inso- 

 luble in water; a solution of selenious acid does not affect the salt, either 



') For the material of the rare earths that have been employed for this in- 

 vestigation, I am under obligation to Professor Cleve, who has generously placed 

 at my disposal more than sufficient quantities of the same chemically pure, spectro- 

 scopically tested material that he has himself used for his researches. 



