104 
CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. [roll. 167. 
be added to a large excess of a solution of silver nitrate, the resulting 
precipitate, though white, is amorphous and contains much too high a 
percentage of silver (analysis 6), probably indicating an admixture of a 
more basic salt. 
If tri silver trimetaphosphimate be heated in a current of dry air at 
a temperature rising gradually from 200° to 260°, very nearly one-third 
of the nitrogen is given off as ammonia: 
Calculated 
for NH 3 . 
Found. 
Loss 
3.05 
2.86 
The product is no longer completely soluble in dilute acid. Alter- 
nate treatment with sodium chloride and ammonia extracts the silver 
and an acid which gives an amorphous precipitate with magnesium 
nitrate mixture. A considerable white residue remains in the form of 
pseudomorphs of the original substance, which is insoluble in ammonia, 
and soluble in hydrochloric acid only on boiling. 
Salt with 4 atoms of silver, P 3 N 3 6 H2Ag 4 or P r{ N~ 3 Q 7 H 4 Ag4. — If silver' 
nitrate be added slowly to a solution of the 4- atom sodium salt (sodium 
amidodiimidotriphosphate), each drop produces a white precipitate, 
which, on stirring, turns yellowish, in presence of an excess of sodium 
salt; when the latter is used up and an excess of silver nitrate has been 
added, it again becomes white. If, on the contrary, the sodium salt be 
added to the silver nitrate, each drop gives a yellow precipitate, turn- 
ing white on^ stirring, and remaining so as long as an excess of silver is 
present. This white amorphous salt is decomposed by washing with 
pure water, turning yellow, while trimetaphosphimic acid goes into 
solution. The change may be represented thus: 
3P 3 N 3 7 H 4 Ag 1 = 2P :3 N 30 7 H,Ag, ; -f P 3 N 3 0«H 6 + H,0. 
Silver nitrate prevents this change; the precipitate must therefore 
be washed with 1 per cent aqueous solution of silver nitrate, then with 
1 per cent alcoholic solution of the same, and finally with ether. On 
pressing and drying, it then remains colorless. Preparations made in 
this manner gave the following results after drying at 100°, at which 
temperature the salt remains white: 
Calculated for 
Calculated for 
Found. 
P 3 N 3 6 H a Ag 4 . 
P 3 N 3 7 H 4 Ag 4 . 
1. 
2. 
3. 
p 
14.01 
64.92 
13.63 
63.22 
13.32 
65.79 
13.70 
64.71 
13. 29 
A«; 
65.89 
1. P:Ag = 3:4.26. 
2. P:Ag = 3:4.07. 
3. P:Aff=3:4.28. 
