56 



L. F. Nilson, 



SELENITES OF IRON - Fe. 



I have not more closely examined any salt of the bivalent iron, 

 because the difficulties, attending such a trial, would have been too great 

 without any corresponding profit. The white, amorphous precipitate, obtained 

 by the action of selenite of sodium on a solution of ammonium-ferro-sulphate, 

 has namely a strong tendency to oxidate, so that its colour changes almost 

 as speedily as that of ferro-carbonate. The precipitate grows more and 

 more yellow-coloured and is then transformed into ferric selenite. 



Berzelius remarks that ferro selenite with hydrochloric acid yields 

 selenium, chloride of iron being formed, and that it is dissolved by more 

 selenious acid to a diselenite which is but sparingly soluble. 



Ferri-selenites will be described in connexion with salts of the 

 other sesquioxides, here after mentioned. 



Chlorid of cobalt treated with neutral selenite of sodium, gives a 

 bluish-red, amorphous precipitate, Avhich, being heated, is very soon con- 

 verted into a crystalline powder of the brightest and most beautiful red- 

 violet colour. In the microscope it proves to be composed of small, pris- 

 matic crystals Insoluble in water, it easily dissolves in selenious acid to 

 a rosy-coloured fluid. 



Analyses: 



1) 0.768 gr. salt gave 2729 gr. selenium or 0.3835 gr. selenious acid and 

 0.5275 gr. sulphate of cobalt or 0.257 gr. cobaltous oxide. 



2) 0.7189 gr. salt gave 0.2552 gr. selenium or 0.3586 gr. selenious acid 

 and 0.496 gr. sulphate of cobalt or 0.2416 gr. cobaltous oxide. 



SELENITES OF COBALT. 



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



In 100 parts: 



found 



calculated 



Cobaltous oxide 

 Selenious acid . 

 Water (loss) . . 



1. 2. 



33.46 33.61 

 49.93 49.87 

 16.61 16.52 

 100.00 100.00 



CoO 76 34.08 

 SeO 2 111 49.78 

 2H 2 36 16.14 



223 100.00 



