20 



L. F. Nilson, 



An alyses: 



1) 0.4678 gr. salt gave 0.26G3 gr. sal-ammoniac or 0.1295 gr. oxide of 

 ammonium. 



2) 0.8428 gr- salt gave 0.472 gr. sal-ammoniac or 0.2296 gr. oxide of 

 ammonium. 



3) 0.794 gr. salt gave 0.3625 gr. selenium or 0.5093 gr. selenious acid.' 



4) 0.4415 gr. salt gave 0.199 gr. selenium or 0.2796 gr. selenious anhydride. 



Calculated on 100 parts: 



1. 2. 3. 4. 



Oxide of amonium 27.69 27.24 — — 



Selenious acid . . : — — 64.15 63.34 



numbers very closely corresponding to the formula above, which requires: 



Am 2 52 28.73 

 SeO 2 111 61.32 



H 2 18 9.95 



181 100.00 



Though the salt was prepared for analysis with the greatest speed 

 and care, yet the result exhibits a less close correspondence with the cal- 

 culated values, the compound very speedily giving off considerable quantities 

 of ammonia, of which more here after. 



Muspratt, who has obtained a salt of ammonium in the way here 

 mentioned, found it to contain 32.49 per cent oxide of ammonium. Con- 

 sidering, however, the great tendency of this salt to give off ammonia, it 

 seems rather unaccountable, how he has been able to obtain this high per- 

 centage of oxide, not only amounting to, but even, on using the atomic 

 weights here employed, exceeding by 0.6 per cent what is required by the 

 formula for a waterfree salt Am 2 .0 2 .SeO. 



When the neutral salt now described was left in a vessel, covered 

 with a glass-plate, under the mother-liquor in which it had been formed, 

 the milk-white, fine needles were changed into comparatively much larger, 

 short, thick, transparent, colourless crystals, the form of which it was im- 

 possible more closely to determine. Like the foregoing salt, it smelled of 

 ammonia and soon liquefied in contact with the air. In spite of its changed 

 appearance, it proved to be completely unaltered in composition. 



Analyses: 



1) 0.5085 gr. salt gave 0.22 gr. selenium or 0.3091 gr. selenious acid. 



