102 
CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. 
fBTJLL.167, 
corresponding to a contamination of 1.44 i>er cent barium chloride. 
After making correction for this the figures under analysis 3 were 
obtained, which approximate closely to the theoretical. 1 The excess 
of barium in analyses 1 and 2 is accounted for in the same manner. 
Possibly the difficulty is due to the presence of half dissociated barium 
ions (e. g. — Bad) in the solution. 
The substance lost but little at 100° and gave: 
Calculated for P 3 N 3 
( ;H 3 Nal5a+l|H. 2 0. 
l. 
Found. 
2. 
3. 
F 
22.09 
9. 99 
5.47 
32. 56 
1.43 
21.50 
9.91 
35.67 
21. 86 
21.99 
N 
Na 
5.56 
34.22 
5. 53 
32.86 
1.32 
Ba . ... . 
H 
1. P : N : Ba = 3 : 3.05 : 1.12. 
2. P : Na : Ba = 3 : 1.03 : 1.06. 
3. P : Na : Ba : H .= 3 : 1.02 : 1.01 : 5.58. 
Similar salts containing potassium or ammonium could not be 
obtained. A barium silver salt consisting of microscopic spherules 
was obtained by adding silver nitrate to a solution of the neutral 
barium salt in ammonium nitrate; a qualitative examination showed 
the presence of barium and silver. 
Tri-silver trimetaphosphimate, P 3 N 3 O Ag 3 . — This is the most important 
salt obtained, on account of its highly characteristic crystalline form, 
and because it is anhydrous and easily prepared pure, thereby estab- 
lishing the empirical composition of trimetaphosphimic acid. As those 
salts which contain crystal water do not lose it completely at a tem- 
perature short of decompositon, we should otherwise be unable to 
decide between the formulas P 3 N 3 O c H 6 and P 3 N 3 G 7 H H . For comparison 
the theoretical figures for a silver salt of both of these are given. 
The salt may be prepared by precipitating a cold dilute solution 
(1-50) of the sodium salt by silver nitrate, when it is thrown down at 
once in the form of colorless elongated microscopic plates, terminated 
by an angle of 78° (analyses 1-4). Much better crystals are obtained 
if the solution of the sodium salt be acidified with several equivalents of 
nitric acid and the silver nitrate added slowly, finally in large excess. I n 
this way the cry stallization is made to extend over a considerable time, but 
the precipitation is never complete (analysis 5). Thus formed the crys- 
tals are usually very well developed, though seldom over 2 millimeters 
long, and consist of thick, monoclinic plates of the forms represented 
in figs. 3 and 4, the latter resulting when the crystallization extends 
Richards has pointed out the necessity of making a similar correction in determining sulphuric 
id as barium sulphate. Zeitschr. anorg. Chem., Vol. VIII, p. 413. 
