510 



Dr. J. H. Gladstone on Pi/rophosphoric Acid [May 23, 



meduUares. The upper olivary bodies (which were first pointed out by 

 the author in 1857, and subsequently described by Schroeder van der 

 Kolk) and the trapezium are further investigated in a comparison 

 between those of man, the orang ontang, and different orders of mam- 

 mals. The structure of the entire medulla oblongata in the monkey 

 is likewise compared with that of man. The paper concludes with the 

 physiological and pathological application of its contents. 



II. '^''On Pyropliosplioric Acid with the Pyro- and Tetra-phos- 

 phoric Amides.'' By J. H. Gladstone, Ph.D., F.R.S. Re- 

 ceived May 9, 1867. 



Prom time to time I have communicated to the Chemical Society 

 descriptions of certain bodies which are best viewed as amides of pyro- 

 phosphoric acid ; and in pursuing the inquiry I have recently obtained 

 some fresh results, and a new class of compounds. I propose continuing 

 to send the details to the Chemical Society, but I may be permitted to 

 submit to the Royal Society a condensed account of the main facts 

 arrived at in the whole investigation, and a theory of the formation of 

 these substances. 



I'yropTiosplioriG acid is, in the notation now generally adopted, 

 P2H4 O^. In an examination of its fei'ric compounds, I found evidence 

 of the existence, in solution, of the double salt P2 Nag fe2 0^*. A more 

 remarkable fact is that the complete ferric salt, and several other pyro- 

 phosphates, can exist in an allotropic condition. Thus pure Pg fe^ O^, 

 prepared by double decomposition, dissolves readily in dilute sulphuric 

 acid ; but on heating the solution it separates in a form which is almost 

 insoluble in the acid. "When these allotropic salts are decomposed, the 

 acid produced appears to have the ordinary properties. It is a pyrO' 

 plios'pliate which is formed, when oxychloride of phosphorus is attacked 

 by a strong aqueous solution of an alkali. 



Pyropliosplioric acid exhibits a great tendency to form acid amides. 

 It is only necessary to neutralize it with ammonia to get a body which, 

 when treated with a metallic salt not in excess, gives more or less of a 

 pyropJiospliamate of the metal, thus : — 



P2 H, 0, + 4 NH3 + 3 fe CI = P2 (NH^) fe3 O, + O + 3 NH, CI. 



Fyropliospliamic acid, P^ (NH^) H3 Og, may be also prepared by 

 breaking down the higher amides. It is similar in most of its proper- 

 ties to pyrophosphoric acid, but is tribasic. Its ferric salt has also an 

 allotropic modification ; when heated with an acid it becomes far less 

 soluble in sulphuric acid, ferric chloride, or pyrophosphate of sodium. 



JPyropliospTio-diamic acid^ P^ (^112)2 H2 O., is produced in a variety of 



* In order to avoid gre^t complexity of formulse, Williainson's Ferricum, fe^l8'66, 

 has been adopted. 



