STOKES.] 
TRIMETAPHOSPHIMIC ACID. 
103 
over several hours. No other faces are ever observed, and the angle a 
(between the edges) measured under the microscope is very nearly 78 . 
Fig. 3. Fig. 4. 
A=o>P66. B = Poo. C = ooPoo. 
The air-dried salt lost nothiug at 100° and gave: 
Calculated for 
P 3 N 3 6 H 3 Ag 3 . 
Calculated for 
P 3 N 3 7 H 5 Ag 3 . 
Found. 
1. 
2. 
3. 
4. 
5. 
(;. 
p 
N 
Ag 
11 
16.68 
7.55 
58. 04 
0.54 
16.16 
7.31 
56.20 
0.87 
16.50 
57.75 
16. 70 
7.53 
57. 90 
0.62 
16. 74 
7.67 
57. 77 
16.64 
57.93 
7.72 
57.80 
15.71 
60.08 
1. P 
Ag = 3 
3.02. 
2. P 
N : Ag 
: H = 3 : 2.99 : 2.99 
3. P 
N : Ag= 
= 3 : 2.98 : 3.04. 
4. P 
Ag-3 
3. 
5. N 
Ag = 3 
3. 
6. P 
Ag=3 
3.3 
3.47. 
The salt is insoluble in water, easily soluble in ammonia, and some- 
what difficultly in dilute nitric acid. It is not affected by light, but on 
boiling under water it becomes somewhat yellow, owing to the forma- 
tion of a superficial coating of the 6 atom salt and the liberation of 
free acid, the decomposition products of which can be detected in the 
liquid, if free from silver nitrate, caustic soda does not discolor it, even 
on boiling. On heating it swells up, gives off ammonia, and fuses to a 
mass which contains metallic silver. In order to ascertain if it is 
actually precipitated in the anhydrous form, or if it contains water 
which is given off on standing, a freshly precipitated sample was 
washed with alcohol and ether, pressed out, and at once weighed: it 
lost nothing at 100°, indicating that even at the moment of formation 
it is anhydrous. Precipitation from boiling solution seems to have no 
influence on its composition ; if, however, the solution of the sodium salt 
