112 
CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY^ [bull. 161 
The salt is practicably insoluble in water, easily in ammonia, an( 
rather difficultly in dilute nitric acid. When pure it is not discolorec 
by light or by caustic soda. It contains no crystal water. Analysii 
gave 
Calculated for 
P 3 N 2 8 H 4 Ag 3 . 
Found. 
1. 
2. 
p 
16.14 
4.87 
56.10 
16. 39 
4.76 
55.94 
16.29 
N 
Ag '■ 
56. 36 
1. P : N : Ag = 3 : 2.01 : 2.94. Direct from decomposed solution of trimeta- 
phosphimic acid. 
2. P : Ag = 3 : 2.99. From sodium salt. 
Penta-silver (lUmidotriphosphate, V^^^O^iA^. — One moleculai 
weight tertiary sodium salt is dissolved with addition of not less than 
1J nor more than 4 molecular weights ammouia, and added to an excess 
of a solution of silver nitrate ; the pure white amorphous voluminous 
precipitate is washed, sucked out, and dried in vacuo. When fresh it 
is colorless, but on drying it assumes a yellowish tint, and after staud- 
iug for some time it is partially converted into crystals, the nature oi 
which was not determined. On boiling with water it also becomes 
yellowish, and in each case the change of color is accompanied by 
decomposition, as its ammoniacal solution is partially precipitated in 
amorphous form by magnesia mixture, an effect which is not observed 
in the perfectly fresh white salt. Warming with ammonium nitrate 
destroys the yellow color, which is consequently not due to silver i>hos- 
phate. The fact that it remains white on boiling with ammonium 
nitrate serves to distinguish it from the trimetaphosphimates, the more 
basic silver salts of which, as pointed out, become orange-red under 
these conditions. The salt is very difficultly, yet perceptibly, soluble in 
water, and is reprecipitated by adding considerable silver nitrate; it is 
easily soluble in ammonia, and nitric acid converts it partly into the 
tertiary salt before dissolving it. 
Dried at 100° it gave : 
Calculated for 
P 3 N 2 8 H 2 A 6 . 
Found . 
1 
2 
3 
p 
N 
Ag 
11.77 
3. 55 
68.23 
12.05 
3.66 
68.96 
11.96 
3. 65 
68.92 
11.75 
69. 24 
1. P :N : Ag = 3 : 2.02 : 4.94. 
2. P: N : Ag = 3 : 2.02 : 4.97. 
3. P : Ag- = 3 : 5.08. 
