13G CONTRIBUTIONS TO CHEMISTRY AND MINERALOGY. [bull 167. 
in gasoline and in ether. Toward water it is nearly as stable as hexa- 
phosphonitrilic chloride, but is slowly attacked when exposed to atmos- 
pheric moisture. Hot dilute ammonia dissolves it very slowly, but 
more rapidly when alcohol is added. 
This body is obviously a secondary product of the reaction of phos- 
phorus pentachloride and ammonium chloride, as it is never found 
when a pure phosphonitrilic chloride is polymerized and depoiymerized. 
It is noteworthy that no indication of other bodies of a similar nature 
has been observed, although no reason appears why they should not 
be formed at the same time. Whether it is in reality hexaphosphoni- 
trilic chloride in which 3 chlorine atoms are replaced by one of nitrogen 
or not can not be decided at present. 
5. THE HIGHER METAPHOSPHIMIC ACIDS. 
In the preceding sections on the metaphosphimic acids it was shown 
that the two lower phosphonitrilic chlorides, P 3 N 3 C1 G and P 4 N 4 C1 8 , 
give on saponification two well-defiued acids, trimetaphosphimic acid, 
P 3 N 3 (i H 6 and tetrametaphosphic acid, P 4 N 4 8 H 8 . In a later section 
the existence of the higher phosphonitrilic chlorides P 5 N 5 C1 ]() , P 6 K 6 01i 2 , 
and P 7 N 7 Cli 4 was shown, and it was further demonstrated that the 
series does not end here, but is continued through a number of mem- 
bers, which are incapable of separation by existing methods, and 
terminates with a rubber like polymer of high molecular weight. 
The work outlined in the present section was begun with the expecta- 
tion of finding that each of the new phosphonitrilic chlorides would 
give on saponification the corresponding metaphosphimic acid of the 
general formula (PN0 2 H 2 ) n . The result, however, has not justified this 
anticipation. It has been found that penta- and hexaphosphonitrilic 
chlorides give true penta- and hexametaphosphimic acids, (PNQ 2 H 2 ) 5 
and (PN0 2 H 2 ),;, but that heptaphosphonitrilic chloride gives, not 
(PJS"0 2 H>) 7 , but an acid (PN0 2 H 2 ) 7 + H 2 0. The metaphosphimic series, 
therefore, appears to be limited by the acid (PN0 2 H 2 ),;. 
The metaphosphimic acids are the lactams of the imidophosphoric 
amides, 1 and it is therefore not surprising that there should be a certain 
similarity of behavior between these and certain organic oxy- and ainido- 
acids. The y and S oxy- and amido acids, while existing as salts in 
alkaline solution, pass more or less readily in the free state into the inner 
anhydrides, the lactones and lactams, a behavior which is not observed 
when the hydroxyl or amido-group is still further removed from the 
carboxyl. Joh. Wislicenus has shown 2 that the geometric configuration 
of the lactone-giving acids is such as to bring the reacting groups into 
1 The imidophosphoric acids consist of chains of alternate NH and PO groups, the first being imido- 
diphosphoric acid, PO(OH) 2 .NH.PO(OH) 2 . This and diimidotriphosphoric acid are described in the 
section on trinietaphosphimic acid, and triimidotetraphosphorie acid in the present section. The 
amides, of which the metaphosphimic acids are the lactams, may be regarded as imidophosphoric acids 
having one terminal hydroxyl replaced by an amido group. 
2 Kaumliche Anordnung der Atome, p. 07. 
