HIPPURIC ACID. 197 



hippuric acid; it especially occurs in large quantity in acid febrile 

 urine, whether the fever be typhus or be associated with pneumonia 

 or any other pathological process. Before hippuric acid was dis- 

 covered in healthy human urine, I detected its presence in diabetic 

 urine,* in which it is more easily recognised than in other forms of 

 urine which abound in extractive matters. 



In diabetic urine I have found hippuric acid in every instance in 

 which I have sought for it ; Ambrosiani, Hiinefeld, and others have 

 also found it in the urine during this disease ; Bouchardat found it in 

 a case of what is called diabetes insipidus; Pettenkoferf found it in 

 large quantity in the urine of a girl with chorea. In the case of a 

 drunkard with a contracted, probably a hob-nail, liver, Birdj ob- 

 served a sediment consisting of hippuric acid, on the addition of 

 hydrochloric acid to the concentrated urine. In the strongly acid 

 urine which is sometimes passed in fevers, the acid reaction is in a 

 great degree dependent on the hippuric acid ; from the ethereal 

 extract of urine of this nature, and without the preliminary addition 

 of any acid, we often obtain the most beautiful crystals of hippuric 

 acid. Such urine is, however, by no means so common as is gene- 

 rally supposed ; for this febrile urine is much more rapidly rendered 

 acid by lactic acid, (which is not formed till after the emission of 

 the urine,) than the normal secretion, and hence, unless it be 

 examined when perfectly fresh, we usually find that febrile urine 

 is more acid than the normal fluid. 1 have not been able to 

 establish any relation between certain morbid processes or groups 

 of symptoms and the amount of the hippuric acid contained in the 

 urine. 



Hippuric acid has as yet been found nowhere but in the urine. 

 [Its recent discovery in the blood of oxen, by Verdeil and Doll- 

 fass, is noticed in the second volume, in the article on " The 

 Blood/' G. E. D.] 



Origin. Notwithstanding the many points which seem to 

 elucidate the inquiry, the formation of hippuric acid in the animal 

 body still remains unexplained. All views regarding the chemical 

 constitution of hippuric acid coincide in the belief that it contains, 

 hidden within it, a benzoyl-compound (C 14 H 5 O 2 + H or + O or + 

 H 2 N) ; it is an established fact that benzoic acid, oil of bitter 



* Journ. f. pr. Ch. Bd. 6, S. 113. 

 t Ann. d. Ch. u. Pharm. Bd. 57, S. 128. 

 London Medical Gazette, vol. 34, p. 686. 



[Compt. rend. T. 29, p. 789 ; and more fully in the Ann. d. Ch. u. Pharm, 

 Bd. 74, S 214.] 



