90 



L. F. Nilson, 



heating with addition of carbonate of ammonium, this sulphate easily 

 afforded the calculated quantity of erbia *). 

 2) 0.79i2 gr. salt gave 0.2305 gr. selenium or 0.3239 gr. selenious acid 

 and 0.603 gr. sulphate of erbium or 0.3729 gr. erbia. 



Represented in 100 parts: 



found / calculated 



1. 2. 



Erbia 47.90 47.13 Er 2 3 389 47.91 



Selenious acid . . 42.23 40.94 3Se0 2 333 41.01 



Water (loss) ... . 9.87 11.93 5H 2 90 11.08 



100.00 100.00 812 100.00 



In consequence of the amount of water present in the salt differing 

 from that of the corresponding selenite of yttrium, the preparation of sele- 

 nite of erbium was once more undertaken, neutral sulphate being employed. 

 Then 



2. Neutral: Er 2 .O n .3SeO + 9H 2 



was obtained as an amorphous precipitate, white, with a slight inclination 

 to rosy-colour. 



Analyses: 



1) 0.5655 gr. salt gave 0.1497 gr. selenium or 0.2103 gr. selenious acid 

 and 0.249 gr. oxide of erbium, obtained by heating the sulphate to 

 whiteness, carbonate of ammonium being added. 



2) 0.5725 gr. salt gave 0.1514 gr. selenium or 0.2127 gr. selenious acid 

 and 0.2525 gr. erbia. 



In 100 parts: 



found calculated 



1. 2. 



Erbia 44.03 44.10 Er 2 3 389 44.00 



Selenious acid. . . . 37.19 37.15 3Se0 2 333 37.67 



Water (loss) 18.78 18.75 9H 2 162 18.33 



100.00 100.00 884 100.00 



') I have found this to be the case with all the sulphates of the rare earth- 

 metals; but they can as well be quantitively determined as sulphates, because these 

 salts, like those of magnesium and cobolt, by gentle heating not at all are de- 

 composed. 



