122 
CONTRIBUTIONS TO CHEMISTRY AND MINEKALOGY. 
[BULL. 167. 
Di-ammonium tetrametaphosphima te, P 4 1ST 4 O 8 H c ( N II 4 ) 2 . — This salt 
forms whenever a solution of the neutral salt is strongly acidified, and 
was at first mistaken for the free acid, which it somewhat resembles. 
It forms 4- and 6-sided prisms with base (tetragonal?), closely resem- 
bling the acid potassium salt, and, like this, is very difficultly solu- 
ble even in boiling water. It separates on heating a solution of the 
neutral salt with acetic acid in excess (analyses 1 and 2), or with a 
stronger acid, in which case it may be slightly contaminated with free 
acid. The preparation under analysis 3 was crystallized from a large 
excess of hot 5 per cent nitric acid. It contains no crystal water. 
Analysis gave: 
Calculn ted for 
P4N 4 8 n,(XH 4 )2. 
Found. 
1. 
2. 
3. 
P 
N 
35. 42 
24.04 
34.41 
24.32 
35. 10 
24.33 
"35. 20 
23. 17 
1. P:N = 4:6.26. 
2. P:N = 4:6.15. 
3. P:N = 4:5.82. 
Barium tetrametaphosphimate, PJ^OsILiBas + 2H 2 0. — A solution of 
the di- or tetra-ammonium salt in 500 parts cold or, better, boiling water, 
is precipitated by an excess of barium chloride. The salt forms a 
voluminous precipitate consisting of microscopic needles, branched or 
forked, insoluble in water, and undecomposed by acetic acid. These 
have approximately the composition of neutral salt, with a slight defi- 
ciency of barium. 
The air-dried salt lost nothing at 100° and gave: 
Calculated for 
P 4 N 4 O s H 4 Ba 2 
+2H 2 0. 
Found. 
1. 
2. 
p 
20.28 
44.83 
t 
20.17 
42.91 
20. 18 
42. 39 
Ba 
1. P:Ba = 4:1.93. 
2. P:Ba = 4:1.90. 
From acid ammonium salt. 
Prom neutral ammonium salt. 
Basic barium salts of indefinite properties seem to exist, but no indi- 
cation of an acid salt could be obtained. 
No satisfactory results were obtained with magnesium salts, a large 
variety of crystalline and amorphous precipitates being obtained under 
different conditions. 
Manganese salts give with free tetrametaphosphimic acid a liocculent 
