96 



L. F. Nilson, 



3. 6 / 3 -Seieilite: La 2 .0^3SeO + 2H 2 .0 2 .SeO-f 4H 2 0. 



When the next-preceding salt was acted upon with an aqueous solu- 

 tion of 40 pr. ct. its weight of selenious anhydride, there was, already at 

 the ordinary temperature, within a few moments obtained a crystalline com- 

 pound. When subjected to the microscope, the crystals seemed to be four- 

 sided oblique tablets; they did not alter in appearance on evaporating the 

 solution to dryness at a moderate heat, but remained unchanged, when the 

 residue was treated with water. 



Analysis: 



0.6948 gr. salt gave 0.272 gr. selenium or 0.3822 gr. selenious acid and 

 0.404 gr. sulphate of lanthanum, corresponding to 0.2327 gr. oxide of 

 lanthanum. 



Represented in 100 parts: 



found calculated 



Oxide of lanthanum . . . 33.49 La 2 3 326 32.96 



Selenious acid 55.01 5Se0 2 555 56.12 



Water (loss) 6H 2 1_08 10.92 



100.00 989 100.00 



The correspondence between this salt and the selenite of chromium 

 formed under the same circumstances, 



Cr 2 .0 ,; .3SeO + 2H 2 .0 2 :SeO -f 7H 2 0, 



is evident. It is surprising that lanthanum has not, under the above cir- 

 cumstances, afforded any 4 /3- se l e,1 i te > that being the case with all the other 

 rare earth-metals. 



5. Diseleilite: La 2 .0 6 .3SeO + 3H 2 .0 2 .SeO + 4H 2 0. 



This compound was obtained, when the salt mentioned under 2 was 

 digested with 120 pr. ct. its weight of anhydride of selenious acid, the 

 solution allowed to evaporate to dryness at a gentle heat and the residue 

 treated with water; the excess of acid was then extracted, leaving an 

 insoluble crystal-powder, which under the microscope seemed to consist of 

 four- sided prisms. 



