514 Di*. J. H. Gladstone on Pyropliosphoric Acid [May 23, 



acid, when we start not with the oxychloride, but with the amidated 

 oxychloride of phosphorus. The two stages, analogous to those given 

 above for the formation of pyrophosphoric acid, Avill be 



2P (N CI, 0+ g } 0=2H C\+l g JjJ ^ } 0, 



P (N H,) CI 1 Q H I P (n£) (H 0) O 1 o 



P (N H,) CI O J "^'^H J ^^P (N H,) (H 0) J ' 



which is (N II^)^ Og, pyrcypJiospTio-diamic acid. 



The symmetry of this reaction would be lost were pyrophosphamic 

 acid produced, and, indeed, it seems never to occur among the sub- 

 stances actually formed. 



But the pyro-diamic acid may be equally produced, if we start with 

 the higher amidated oxychloride formed at a low temperature. In this 

 case it is necessary to suppose that while two molecules of the phos- 

 phorus compound attack one molecule of water, two other molecules of 

 water give rise to the usual replacement of H O for IN" H^. The two 

 stages are precisely analogous to those given above, but are probably 

 simultaneous, the reaction being favoured by the affinity of the hydro- 

 chloric acid for the ammonia, 



2P (N H,), CI O + J } 0=2H CI + J g J^j^^ J } O, 



P(NHJ,0J "+^h|^-^^-^=+P(NH,) (HO)o1"' 



which, as before, is (N ^.^^ O pyropTiosplio-diamic acid. 



The formation of pyropliospJio-triamic acid is dependent on some 

 alteration in the amidated oxychloride, when produced at a high tempe- 

 rature. As the nature of this change is unknown, it may be better not 

 to speculate on the intermediate stages, but the result of the action on 



water would seem to be ^ ^5" ^ 1 O, or P (JST H,)3 H 0,. 



P(NH,)^0 J ' ^ 



If this be the true explanation of the manner in which the pyrophos- 

 phoric amides are formed, it wall equally explain the formation of the 

 tetrapho spheric compounds. It does not follow that when two mole- 

 cules of the amidated oxychloride have attacked one of water to form 



P (N H ) CI O } ^' ^^^^ remaining chlorine 



should be replaced by H O. The process of attacking both atoms of 

 hydrogen in water may be repeated, thus — 



2P, (N HJ3 CI, O3+ JJ } 0=2H C1+ jJJ ^{ ^3 1 o, 



which, when acted on by water in the usual way, gives 



P, (N H,), CI O3 10+2^1 0-2H Cl + ^^ ^^^^ ^) ^3 1 q 

 P, (N HJ, CI O3 J ^ H J """^ ^'^P, (N H,), (H 0) O3 J 



which is P^ (jST H^)^ Og, tetrapJiospho-tetramic acid. And this com- 



