416 URINE. 



It appears from the investigations of Wohler, that most of the 

 organic acids pass unchanged into the urine, when they are intro- 

 duced into the system in a free state; he experimented with oxalic, 

 citric, malic, tartaric, succinic, gallic, and salicylous acids. 



Tannic acid is converted, in its passage through the animal 

 organism, into gallic acid. 



The observation made by Wohler, that benzoic acid is separated 

 from the animal body by the urine in the form of hippuric acid, 

 has been confirmed by Ure,* Keller,t and many other observers. 



The organ from whence the benzoic acid in this case obtains the 

 elements of fumaramide (see vol. i., p. 198) cannot at present be 

 decided with certainty ; Ure believes that after the use of benzoic 

 acid, the hippuric acid is increased in the urine at the expense of 

 the uric acid, and that it consequently assimilates a nitrogenous 

 group of atoms, which in its absence would have been applied to 

 the formation of uric acid : hence he recommends physicians to 

 employ benzoic acid against the uric acid diathesis. Unfortunately, 

 however, Wohler and Keller could not detect any diminution of 

 the uric acid after the use of benzoic acid; and Booth and Boye^ 

 arrived at the same conclusion. Garrod, on the other hand, believes 

 that he has constantly found a diminution in the quantity of urea 

 in the urine after the administration of benzoic acid ; but neither 

 Simon^s investigations nor my own confirm this view. In four 

 observations in which I examined the twenty- four hours' urine 

 after the administration of large doses (two drachms) of benzoic 

 acid, I failed in any case to detect a marked diminution of any of 

 the nitrogenous constituents ; experiments of this nature are, how- 

 ever, so difficult to execute, and the daily sum of the individual 

 nitrogenous constituents is so fluctuating, that no conclusions 

 should be drawn from such investigations ; thus, for instance, it 

 would be extremely rash to conclude, from the apparently negative 

 result of the examination of the urine, that the benzoic acid ab- 

 stracted nitrogenous matter from the substances designed for cell- 

 formation. 



If the close affinity that exists between benzoic and hippuric 

 acids in some degree elucidates the production of the latter from 

 the former in the metamorphosis of the animal tissues, the result 

 obtained by Erdmann and Marchand is the more striking, namely, 



* Pharm. Trans. Vol. 1, No. 1. 



t Ann. de Ch. u. Pharm. Ed. 43, S. 103. 



Medical Times, November, 1845. 



Journ. f. pr. Ch. Bd. 35, S. 307-309. 



