38 



L. F. Nilson, 



2. Diselenite : Sr.O 2 .SeO + H 2 .0 2 .SeO. 



A solution, prepared from 1 mol. carbonate of strontium and 2 mol. 

 selenious acid, afforded on evaporation at the ordinary temperature no cry- 

 stallizing salt. On evaporating slowly however at 50° — 60° the salt cry- 

 stallized in pretty large — the length 5 mm. and more — shining, trans- 

 parent, monoclinic prisms with basal end-faces, in the same form, conse- 

 quently, as the diselenite of calcium 



Analyses: 



1) 0.515 gr. salt, treated in the same manner as the salts of calcium, gave 

 0.2693 gr. sulphate of strontium = 0.1519 gr. strontia and 0.24 gr. se- 

 lenium or 0.3372 gr. selenious acid. 



2) 0.5103 gr. salt gave likewise 0.2653 gr. sulphate of strontium =0.1497 

 gr. strontia and 0.2357 gr. selenium or 0.331 gr. selenious acid. 



3) 0.2903 gr. salt, fumed with sulphuric acid, gave 0.1523 gr. sulphate of 

 strontium or 0.0865 gr. strontia. 



Centesimally represented: 



experiment theory 



1. 2. 3. 



Strontia 29.50 29.35 29.80 SrO 103.5 30.13 



Selenious acid . . . 65.48 64.85 — 2Se0 2 222.0 64.63 



Water (loss) .... 5.02 5.80 — H 2 18. 5.24 



100.00 100.00 343 . 5 100.00 



This salt is permanent on exposure to the air and very easily dis- 

 solves both in cold and warm water. 



To ascertain the behaviour of the diselenite of strontium, when 

 treated with an excess of acid, an experiment was also made, by which 

 the question whether there existed any tetraselenite ot strontium, was an- 

 swered in the negative. The solution evaporating at 50 — 60°, the dise- 

 lenite crystallized unaltered in its characteristic form, and two specimens, 

 fumed with sulphuric acid, exhibited the folloving results: 

 0.569 gr. salt gave 0.2873 gr. sulphate of strontium = 0.162 gr. strontia 

 or 28.47 pr. ct. 



0.7705 gr. salt gave 0.3935 gr. sulphate = 0.222 gr. strontia or 28.81 pr. ct. 



values very nearly agreeing with the per-centage of strontia calculated by 

 the formula, assumed above. 



