Researches on the Salts of Selenious Acid. 



81 



SELENITES OF CHROMIUM. 



1. 8 / 4 -Selenite: Cr 8 .0 21 .9SeO+64H 2 = 3[Cr 2 .0 6 .3Se0 3 ]^Cr 2 .0 6 .H 6 +6lH 2 0. 



On adding selenite of sodium to a solution of chrome-alum there is 

 obtained a green, voluminous, amorphous precipitate. The solution of alum 

 was employed in excess, and yet selenious acid was to be found in the 

 mother-liquor. 



Analyses: 



1) 0.5293 gr. salt gave 0.136 gr. selenium or 0.1911 gr. selenious acid 

 and 0.1134 gr. oxide of chromium. 



2) 0.6183 gr. salt gave 0.1602 gr. selenium or 0.2251 gr. selenious acid 

 and 0.1325 gr. oxide of chromium. 



3) 0.51 gr. salt gave off 0.1317 gr- water at 100° 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 



Oxide of chromium 21.43 21.43 — 4Cr 2 3 612 22. 15 



Selenious acid ... 36. 11 36.41 — 9Se0 2 999 36.15 



Water (loss) .... 42.46 42.16 25.83 64H 2 1152 41.70 



100.00 100.00 2763 100.00 



At 100° the salt loses 40 mol. of water (calculated 26.06 pr. ct); 

 the rest then has the composition 



Cr 8 .0 21 .9Se0 2 + 24H 2 0, 



whereas the corresponding compound of aluminium, obtained in an analogous 

 way, then retains 20 mol. of water. 



2. Neutral: Cr 2 .0 6 .3SeO + 15H 2 0. 



The preceding salt was treated at the ordinary temperature with 

 12.05 pr- ct. selenious anhydride in an aqueous solution. This was coloured 

 green, the green salt was microscopically crystalline and consequently not 

 wholly insoluble in water. 



Analyses: 



1) 0.7365 gr. salt gave 0.227 gr. selenium or O.319 gr. selenious acid and 

 . 1445 gr. oxide of chromium. 



Nova Acta Reg. Soc. Sc. Ups. Ser. III. 11 



