50 
CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. [bull. 167. 
1 and 2 precipitated from solution containing excess of alkali; 3 
and 4, from solution in which excess over 5 ISTa had been neutralized; 
5, from solution in large excess of acetic acid. 
Magnesium salt. — A. solution of the sodium salt precipitated by mag- 
nesium nitrate in the presence of acetic acid, under exactly the same 
conditions as were observed in preparing the corresponding pentameta- 
phosphimate, gave a salt which closely resembles the latter, but which 
does not approximate to any definite formula (found P : Mg — 6 : 2.43). 
The precipitation is by no means complete, much remaining in solution 
as a salt which can be precipitated by alcohol, which is not decomposed 
by boiling with alkalies, and which, in general, resembles the primary 
salt of pentametaphosphimic acid. 
Silver liexametaphosphimate, P 6 N G 12 H 6 Ag G . — The silver salt prepared 
from the sodium salt varies in composition with the relative amounts 
of the reacting bodies and with the amount of sodium. It was obtained 
of normal composition by dissolviug 1 gram sodium salt in 50 cubic cen- 
timeters water, adding enough nitric acid to produce a salt with 5.75 
atoms of sodium, and precipitating by 50 cubic centimeters one-fifth 
normal silver nitrate (analyses 3 and 4). It resembles the correspond- 
ing pentametaphosphimate, but is somewhat more gelatinous. Any 
excess of silver over 6 atoms tends to give it a yellow color. It is 
decomposed in the cold by caustic potash with separation of silver oxide. 
The analyses given in the following table of preparations dried at 100° 
show that it is derived from the true hexametaphosphimic acid, 
P G N G 12 H 12 . 
Ratio P : N : Ag. 
P. 
N. 
Ag- 
r P 6 N 6 13 H 8 .35Ag 5 .6.' 
16. 97 
7.68 
55.60 
1 
6 : 6. 08 : 5. 65 < 
Pr,N 6 12 H 6 .35Ag5.<tf 
17. 26 
7.81 
56. 53 
Found 
17.23 
16. 09 
7.89 
56.48 
57.97 
f P 6 N 6 13 H 7 . 79 Ag 6 . 21 
2 
6 : :6.21 
j P (; N ti O,,H r) . 7 ,Ag l ,., 1 
16.35 
58.89 
Found 
16.29 
16. 44 
7.44 
58.64 
57. 02 
f P 6 N (i O l:J H < x.,„Ag ; -,. 1 ,s 
3 
6 : 5. 99 : 5. 98 < 
P 6 N 6 0„Hr,„eAgr,,s 
16.71 
7. 56 
57. 95 
Found 
16.70 
16.38 
7.54 
7.41 
57. 90 
57.18 
' PeN6O13H7.9gAg8.02 
4 
6 : 6. 04 : 6. 02 • 
P fi N 6 I2 H B .. (8 Ag h .,« 
16.65 
7.54 
58. 02 
16.57 
7.54 
57. 80 
A yellow salt is obtained by precipitating the ainmoniacal solution by 
silver nitrate. 
Decomposition of hexametaphosphimic acid. — The sodium salt heated 
with acetic acid gives tetrametaphosphimic acid, which was isolated 
