STOKES. ] 
TRIMETAPHOSPHIMIC ACID. 
89 
forms. The free acid far surpasses the metaphosphoric acids in stability, 
and may be boiled for hours with nitric acid or aqua regia without 
much decomposition. 
Tetraphosphonitrilic chloride is readily extracted from its ethereal 
solution by aqueous ammonia, the ammoniacal solution giving tetra 
metaphosphimic acid on warming with hydrochloric acid. No clear 
evidence of the formation of chloramides lias yet been observed. 
Oily phosphonitrilic chloride. — This substance, obtained from the resi- 
dues as above stated, is possibly a mixture. It is scarcely volatile 
without decomposition, not volatile with steam, and not acted on by 
water, except in ethereal solution, when a moderately soluble phos- 
phimic acid is slowly formed, which crystallizes in needles, and decom- 
poses on warming with water into tetrametaphosphimic acid and 
ammonium phosphate. The analysis gave: 
Calculated for 
(PNC1 2 ) X . 
Found. 
p 
26.77 
12.11 
61.12 
26.73 
12.09 
61.89 
N 
CI 
P: N: Cl=l: 1:2.03. 
2. ON TRIMETAPHOSPHIMIC ACID AND ITS DECOMPOSITION 
PRODUCTS. 
In the preceding section of this paper I mentioned, by way of pre 
liminary notice, that Liebig's chloronitride, P 3 N 3 C1 6 , by appropriate 
treatment gives an acid, P 3 N 3 6 H G , to which I gave the name trimeta- 
phosphimic acid. The object of the present section is to describe in 
detail the properties and decomposition products of this, the third 
member of the metaphosphimic-acid series. 
In the preliminary notice a metaphosphimic acid was defined as a 
metaphosphoric acid (P0 3 H) n , in which one-third of the oxygen is 
replaced by an equivalent of imide groups, KH, i. e., (PN0 2 Il2)„. It was 
further pointed out that for each acid of this formula, with the excep- 
tion of the simplest, at least four forms are theoretically possible, two 
of which are direct substitution products of the corresponding meta- 
phosphoric acid, containing a nucleus consisting of phosphorus atoms 
united by oxygen, the other two belonging to a different type, in which 
the phosphorus atoms are united by nitrogen. This was illustrated by 
the acid, P 2 N 2 6 H G , none of the forms of which, it is true, are as yet 
known with certainty: 
PO.NH 2 
0< >0 
PO.NH 2 
(a) 
Dimetaphosphory] 
amide. 
P(NH).OH 
0<>0 
P(NH).OH 
PO.OH 
NH< >NII 
PO.OH 
(c) 
Dimetaphosphimic 
acid. 
P(OH) 2 
N<>N 
P(OII); 
id) 
Diphosphonitrili 
acid. 
