58 



L. F. Nilson, 



2) 0.493 gr. salt gave 0.2712 gr. selenium = 0.3811 gr. selenious acid and 

 0.1702 gr. sulphate of cobalt = 0.0829 gr. cobaltous oxide. 



In 100 parts: 



found calculated 



1. 2. 



Cobaltous oxide. . 16.93 16.82 CoO 76 17.80 

 Selenious acid . . 77.25 77.30 3SeO a 333 77.98 

 Water (loss) .... 5. 82 5.88 H 2 18 _4.22 



loo.oo ioo.oo 427 TobToo 



Consequently cobalt, as has been before shown to be the case with 

 magnesium and glucinum, when circumstances are such that a tetraselenite 

 might be formed, does not give any salt more acid than the triselenite just 

 mentioned. In order to try whether the formation of a more acid salt would 

 be caused by adding still more selenious acid, this triselenite was acted 

 upon with as much selenious acid as it already contained and then placed 

 to digest at 60° with a little water. Then a salt was obtained in very 

 small, microscopical crystals, which by means of analytical determinations 

 was proved to be the above-mentioned waterfree diselenite, for 



0.529 gr. gave 0.2805 gr. selenium, corresponding 0.3941 gr. or 74.50 pr. ct. 

 selenious acid and 0.2765 gr. sulphate of cobalt = 0.1338 gr. or 25.29 

 pr. ct. cobaltous oxide, numbers very closely agreeing with calculation. 



SELENITES OF NICKEL. 



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



By treating carbonate of nickel with selenious acid at the ordinary 

 temperature there was obtained a siskin-green deposit of microscopic, glo- 

 bular, insoluble crystal-aggregates. 



Analysis : 



0.6173 gr. salt gave 0.2162 gr. selenium = 0.3038 gr. selenious acid and 

 0.2045 gr. oxide of nickel, precipitated as carbonate. 



