Comjjounds of Phosphoric Acid with Aniline. 11 



modifications of phosphoric acid by its amount of water of 

 hydration, giving rise to pyrophosphoric and metaphosphoric 

 acid, beautifully explained all that was enigmatical in the ob- 

 served reactions. 



Prof. Graham's excellent experiments have added a great 

 deal to our knowledge of phosphoric acid ; the study, how- 

 ever, of this acid and its salts is by no means exhausted. I 

 consequently hope that any contribution to the subject will 

 be accepted. 



The following experiments, which were instituted in the 

 laboratory of the Royal College of Chemistry, relate to the 

 combination of phosphoric acid with a large and interesting 

 group of bodies, viz. the organic alkaloids. It is curious that 

 this class of salts has not been hitherto examined ; indeed the 

 composition of scarcely any phosphate of an organic base has 

 been satisfactorily ascertained. 



It was a very interesting question, whether these bases, 

 which with monobasic acids comport themselves exactly the 

 same as mineral oxides, were capable of combining with poly- 

 basic acids in the same remarkable proportions. In the 

 absence of experiments, the only points which were known from 

 whence we might, by way of analogy, have inferred any simi- 

 larity in these compounds with the inorganic phosphates, are 

 the salts of ammonia with phosphoric acid ; ammonia being as 

 it were the type of all the organic bases. A phosphate of 

 ammonia indeed is known, containing two equivalents of the 

 volatile alkali ; but it still remained to be decided whether 

 any true organic alkaloid unites in the proportions of two or 

 more equivalents with one equivalent of phosphoric acid. 



The only analysis of a phosphate with an organic alkali is 

 published by Regnault*. This chemist determined the carbon 

 and hydrogen in phosphate of strychnine. Regnault con- 

 sidered the salt which he analysed as a compound of 1 equiv. 

 of phosphoric acid, 1 equiv. of strychnine and water, 



HO,C43H,3N,04,PO,. 



However, Rcgnault's formula of strychnine has been corrected 

 by Professor Liebigtj who showed that this base contains 

 one equivalent of carbon more, i. e. 



it is therefore evident that the composition of Regnault's phos- 

 phate is to be expressed by the formula 



* Liebig's ^«nfl/e», vol.. xxvi. p. 37. f Ibid. vol. xxvi. p. 58. 



