82 



L. F. Nilson, 



2) 0.501 g'i'. salt gave 0.155 gr. selenium or 0.2178 gr. selenious acid and 

 0.0995 gr. oxide of chromium. 



3) 0.677 gr. salt lost at 100° 0.164 gr. water. 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 



Oxide of chromium 19.62 1 C J.86 — Cr 2 3 153 20.24 



Selenious acid. . . 43.31 43.47 — 3Se0 2 333 44.05 



Water (loss) . . . 37.07 36.67 24.22 151TO 270 35.71 



100.00 TooToo 756 100.00 



Of 15 mol. of water 10 are lost at 100° (calc. 23.81); consequently 

 the salt, thus treated, contains 1 mol. of water less than the corresponding 

 salt of aluminium under the same circumstances. 



3. Va-Selenite: Cr 2 .0 6 .3SeO 4-H 2 .0 2 .Se0 + l2H 2 0. 



3 / 4 -selenite being treated with a quantity of acid requisite for the 

 formation of a diselenite, or 60.25 pr. ct. selenious anhydride, solution took 

 place neither in cold nor in heat. When the mixture, at a temperature ot 

 60°, had been brought to evaporate to dryness, there remained a green 

 powder of the same appearance as the basic salt. By treatment with water 

 there was obtained a strongly sour, slightly green-coloured liquid and a 

 microscopical crystalline, green powder, not at all soluble in water and 

 only very slowly in hydrochloric acid. The green-coloured mother-liquor, 

 on evaporating, deposited crystals of selenious acid, and only at a few 

 points a green-coloured, viscid mass was to be observed in very small 

 quantities. 



Analyses: 



1) 0.644 gr. salt gave 0.2425 gr. selenium or 0.3407 gr. selenious acid and 

 0.117 gr. oxide of chromium. 



2) 0.5025 gr. salt gave 0.1917 gr. selenium or 0.2693 gr. selenious acid 

 and 0.09 gr. oxide of chromium. 



2) 0.636 gr. salt lost at 100° 0.1155 gr. water. 



