ANALYTICAL EVIDENCE. 



325 



COMPOSITION OF ASPARAGINE. a 



Liebig." Calculated Ca Hs Na Oe + 2HO 



Carbon 32'351 32'35 



Hydrogen 6' 844 6' 60 



Nitrogen 18' 734 18' 73 



Oxygen 42'021 42'32 



a Ann. der Pharm., VII., 146. 



ON THE CONVERSION OF BENZOIC ACID INTO 

 HIPPURIC ACID.* 



BY WILHELM KELLER. 

 (From the Annalen der Chemie und Pharmacie.) 



So early as in the edition of Berzelius's " Lehrbuch der 

 Chemie," published in 1831, Professor Wb'hler had ex- 

 pressed the opinion, that benzoic acid, during digestion, 

 was probably converted into hippuric acid. This opinion 

 was founded on an experiment which he had made on the 

 passage of benzoic acid into the urine. He found in the 

 urine of a dog which had eaten half a drachm of benzoic 



* To the evidence produced by A. Ure, of the conversion of benzoic acid 

 into hippuric acid in the human body, M. Keller has added some very de- 

 cisive proofs, which I append to this work on account of their physiological 

 importance. The experiments of M. Keller were made hi the laboratory of 

 Professor Wohler, at Gottingen ; and they place beyond all doubt the fact 

 that a non-azotised substance taken in the food can take a share, by means 

 of its elements, in the act of transformation of the animal tissues, and in the 

 formation of a secretion. This fact throws a clear light on the mode of action 

 of the greater number of remedies ; and if the influence of caffeine on the 

 formation of urea or uric acid should admit of being demonstrated in a similar 

 way, we shall then possess the key to the action of quinine and of the other 

 vegetable alkalies. J. L. 



