78 



L. F. Nilson, 



SELENITES OF ALUMINIUM. 



Our knowledge of these compounds is as yet limited to what Berze- 

 LIUS and Muspratt communicate about them. The supposition of the for- 

 mer that the precipitate obtained from the solution of the neutral salt, is a 

 neutral selenite of aluminium, probably does not agree with the truth, and 

 the analytical determinations furnished by the latter to support this view, 

 will be found from the following to be little worthy of reliance. 



2. 3 /4-Selenite: Al 8 .0 21 .9SeO + 36H 2 = 3(Al 2 .0 G .3Se0) + AR0 6 .H 6 + 33H 2 0. 



Sulphate of aluminium in excess was precipitated with selenite of 

 sodium. The precipitate obtained was amorphous and very voluminous. 

 Washed and desiccated, it formed a rather heavy powder, which, on heating, 

 swells enormously and gives an extremely porous alumina of a cotton-like 

 appearance: 0.1 gr. of this alumina occupied the whole cavity of a platina- 

 crucible holding 30 cc, the cover, on heating, being lifted out of its place. 

 Though a great excess ot sulphate was employed for preparing the salt, 

 yet there were found not inconsiderable quantities of selenious acid in the 

 mother-liquor; already this circumstance proves the precipitate formed to 

 be a basic salt, 



Analyses : 



1) 0.6332 gr. salt gave 0.2175 gr. selenium, corresponding to 0.3056 gr. 

 selenious acid, and 0.124 gr. alumina. 



2) 0.5037 gr. salt gave 0.1732 gr. selenium, corresponding to 0.2433 gr. 

 selenious acid, and 0.1 gr. alumina. 



3) 0.365 gr- salt suffered at 100° a loss of 0.0525 gr. water. 



Represented in 100 parts: 



experiment theory 



1. 2. 3. 



Alumina 19.59 19.85 — 4AP0 3 412 20.05 



Selenious acid. . . 48.26 48.30 — 9Se0 2 999 48.61 



Water (loss) . . . j^J^ 31^85 14.38 36H 2 644 31.34 



lboToO TooToO 2055 100.00 



The loss the salt suffered at 100°, amounts to 16 mol. of water 

 (calc. = 13.92 pr. ct.) 



