1888.] Compounds of Ammonia with Selenium Dioxide. 113 



of one part in 116 at 12°. Heated with the alcoholic ammonia it 

 dissolves freely, but on cooling, the solution remains long super- 

 saturated, crystals continuing to deposit for several days. It is very 

 slightly volatile at ordinary temperatures, both in a vacuum and in a 

 current of air. As might be expected, potash at once liberates 

 ammonia from it. Sulphurous acid and stannous chloride reduce it 

 with separation of selenium. It is only slightly affected by hydro- 

 chloric or nitric acid in the cold, but strong sulphuric acid reacts 

 violently upon it, a portion of the salt being sublimed by the heat 

 evolved. Chlorine passed through its aqueous solution converts it 

 completely into ammonium selenate, — a reaction which was taken 

 advantage of for its analysis. 0*7820 gram was dissolved in water, 

 saturated with chlorine, and barium chloride added. The resulting 

 barium selenate weighed 1*5150 gram, equivalent to a percentage of 

 76*84 of selenium dioxide. The ammonia was estimated by Kjel- 

 dahl's process, slightly modified on account of the volatility of the 

 substance. 0*5651 gram was mixed roughly with potassium perman- 

 ganate in a small strong flask by means of a glass rod, after which a 

 thin tube containing 10 c.c. of sulphuric acid mixture was lowered 

 into it, and broken by shaking the flask after it had been well secured 

 with an india-rubber cork. It was then heated to 150° for one hour 

 in a paraffin bath. The contents of the flask distilled with potash 

 yielded 0*13175 gram of ammonia, equivalent to a percentage of 

 23*32. The results obtained agree with the composition — 



2NH 3 ,Se0 2 = NH 4 ,Se0 2 (NH 2 ). 



Calculated. Found. 



SeG 2 76*53 76*84 



NH 3 " 23*47 23*32 



100*00 100*16 



The original alcoholic solution from which the .crystals had depo- 

 sited, was found to contain selenium. In order to ascertain in what 

 form it existed, a portion of the solution was evaporated to dryness 

 in a vacuum. The residue weighing- 0*666 gram, treated as before, 

 yielded 1*285 gram of barium selenate, equivalent to 76*53 per cent, 

 of selenium dioxide, the theoretical amount in the above compound, 

 showing that a portion remained in solution after the crystals had 

 deposited. It was considered a matter of interest to ascertain how 

 much of the nitrogen in this salt would be precipitated by platinum 

 chloride. 0*5772 gram was accordingly taken, platinum chloride 

 poured upon it, alcohol added, and the mixture allowed to stand in 

 the cold. The double chloride obtained weighed 1*5502 gram, equiva- 

 lent to a percentage of 20*59 of ammonia. A second estimation in 



i 2 



