22 



L. F. Nilson, 



Represented in 100 parts: 



found calculated 



1. 2. 



Oxide of ammonium. 23.50 23.18 2Am 2 104 22.86 



Selenious acid .... 71.41 72.34 3Se 2 333 73.18 



Water (loss) 5. 09 4.48 H 2 18 3.96 



100.00 100.00 455 100.00 



Over sulphuric acid, the salt diminishes in weight and becomes 

 milk-white; the loss, in one experiment, was 15 pr. ct., or the whole amount 

 of water and half the amount of oxide of ammonium, so that the residue was 

 possibly an anhydrous salt of the formula Am 2 .0 2 .SeO + 2Se0 2 ; I am, 

 however, able to furnish no other quantitative determination, to confirm the 

 truth of this supposition. 



3. Diselenite: AmH.0 2 .SeO. 



Was obtained from a syrupy solution, prepared by acting upon the 

 neutral salt with an appropriate quantity of anhydride of selenious acid, and 

 crystallized in four-sided, probably monoclinic prisms with basal end -faces; 

 the acute edges between these and the prism-faces were very often trun- 

 cated. They are generally united into larger aggregates and deliquesce 

 speedily on exposure to the air. 



Analyses: 



1) 0.5694 gr. salt gave 0.213 gr. sal-ammoniac or 0.1035 gr. oxide of 

 ammonium and 0.3082 gr. selenium or 0.4331 gr. selenious anhydride. 



2) 1.1434 gr. salt gave 0.4156 gr. sal-ammoniac or 0.202 gr. oxide of 

 ammonium. 



Centesimally represented : 



found calculated 



1. 2. 



Oxide of ammonium . . 18.18 17.67 V 2 Am 2 26 17.81 



Selenious acid 76.07 — SeO 2 111 76.03 



Water (loss) 5.77 — V 2 H 2 9 6.16 



100.00 146 100.00 



It has already been remarked that this salt is prepared from the 

 neutral selenite, by means of spontaneous decomposition in contact with the air. 



