ANALYTICAL EVIDENCE. 315 



COMPOSITION OF ASPARAGINE. a 



Liebig.* Calculated C8 Hs N 2 O 6 + 2 HO. 



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. 



NOTE XLIII. P. 143, 167. 



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 Wohler 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 decisive proofs, which 1 append to this work on account of their 

 physiological importance. The experiments of M. Keller were, made 

 in the laboratory of Professor Wohler, at Gottingen ; and they place 

 beyond all doubt the fact that a non-azotized substance taken in the 

 food can take a share, by means of its elements, in the act of trans- 

 formation 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. /. L. 



