60 



L. F. Nilson, 



ned a salt in oblique, four-sided tablets, which are dissolved with difficulty 

 in cold, more easily in warm water. At 100° it very slowly diminishes in 

 weight, giving off the water. 



Analyses: 



1) 0.4995 gr. salt gave 0.2925 gr. selenium = 0.4109 gr. selenious acid and 

 0.0688 gr. oxide of nickel. 



2) 0.608 gr. salt gave 0.356 gr. selenium = 0.5002 gr. selenious acid and 

 0.086 gr. oxide of nickel. 



3) 0.4785 gr- salt did not diminish in weight, when kept over sulphuric 

 acid, but, on very long heating at 100°, lost 0.0182 gr. 



Centesimally represented : 





e 



xperiment 





theory 









1. 



2. 3. 











Oxide of nickel. 



. 13.77 



14.14 — 



NiO 



75 



13, 



.96 



Selenious acid. . 



. 82.27 



82.27 — 



4Se0 2 



444 



82, 



■ 68 





. 3.96 



3.59 3.80 



H 2 



18 



3 



.36 





100.00 



100.00 





537 



Too - , 



■ 00 



SELENITES OF COPPER. 



l. Neutral: Cu.0 2 .SeO + 2H 2 0. 



When diselenite of potassium is added to a solution of sulphate of 

 copper a greenish-yellow precipitate falls down; the amorphous precipitate 

 is, however, in a few moments considerably diminished and converted into 

 small, but even to the naked eye, distinct, beautifully blue-coloured four- 

 sided, prismatic crystals, combined with pyramid-faces. The salt, when 

 gently heated, gave off water and became yellow; at a higher temperature 

 it fused, selenious acid sublimed and finally oxide of copper remained as a 

 black, glazed mass, in appearance most resembling charred sugar. The 

 salt seems to be wholly insoluble both in cold and boiling water; when 

 the heating had lasted for some time, the water was filtered away, but no 

 traces of copper could be detected in it with ferro-cyanide of potassium. 

 Also in free selenious acid it proved equally insoluble. 



