PHENACETURIC ACID. BENZOIC ACID. 723 



filtrate by hydrochloric acid. The crystals are purified by recrystalliza- 

 tion and decolorized, when necessary, by animal charcoal. 



The quantitative estimation of hippuric acid in the urine may be 

 performed by the following method (BUNGE and SCHMIEDEBERG): 

 The urine is first made faintly alkaline with soda, evaporated nearly to 

 dryness, and the residue thoroughly extracted with strong alcohol. 

 After the evaporation of the alcohol the residue is dissolved in water, 

 the solution acidified with sulphuric acid, and completely extracted by 

 agitating (at least five times) with fresh portions of acetic ether. The 

 acetic ether is then repeatedly washed with water, which is removed by 

 means of a separatory funnel, then evaporated at a medium temperature 

 and the dry residue treated repeated!}' with petroleum-ether, which 

 dissolves the benzoic acid, oxyacids, fats, and phenols, while the hippuric 

 acid remains undissolved. This residue is now dissolved in a little warm 

 water and evaporated at 50-60 C. to crystallization. The crystals are 

 collected on a small weighed filter. According to HENRIQUES and 

 SORENSEN the acidified urine can be directly shaken out with acetic ether, 

 the residue after evaporation of the acetic ether boiled with hydrochloric 

 acid in order to split the hippuric acid into benzoic acid and glycocoll 

 and the quantity of nitrogen in the latter determined by a formol titra- 

 tion. Other methods have recently been suggested by FOLIN and 

 FLANDERS, by STEENBOCK and by HRYNTSCHAK. 1 



Phenaceturic Acid, C 1 oHnN03=C 6 H 5 .CH 2 .CO.NH.CH 2 .COOH. This acid, 

 which is produced in the animal body by a combination of glycocoll with the phenyl- 

 acetic acid, C 6 H 6 .CH 2 .COOH, formed in the putrefaction of the proteins, has 

 been prepared from horse's urine by SALKOWSKi, 2 but it probably also occurs in 

 human urine. According to VASILIU 3 it is just as important a constituent of the 

 urine of herbivora as hippuric acid is. 



Benzoic Acid, C 7 H 6 2 or C 6 H 5 .COOH, is found in rabbit's urine and sometimes, 

 though in small amounts, in dog's urine (WEYL and v. ANREP). According to 

 JAARSVELD and STOKVIS and to KRONECKER it is also found in human urine in 

 diseases of the kidneys. The occurrence of benzoic acid in the urine seems to 

 be due to a fermentative decomposition of hippuric acid. Such a decomposi- 

 tion may very easily occur in an alkaline urine or in one containing proteid(VAN 

 DE VELDE and STOKVIS). In certain animals pigs and dogs the kidneys, 

 according to SCHMIEDEBERG and MiNKOwsKi, 4 contain a special enzyme, SCHMIEDE- 

 BERG'S histozym, which splits the hippuric acid with the separation of benzoic 

 acid. 



Ethereal Sulphuric Acids. In the putrefaction of proteins in the 

 intestine, phenols whose mother-substance is considered to be tyrosine 

 and also indol and skatol are produced. These phenols directly, and the 

 two last-named bodies after they have been oxidized respectively into 



1 Bunge and Schmiedeberg, Arch. f. exp. Path. u. Pharm., 6; Henriques and 

 Sorensen, Zeitschr. f. physiol. Chem., 64; Folin and Flanders, Journ. of biol. Chem., 11; 

 Steenbock, ibid., 11; Hryntschak, Bioch. Zeitschr., 43. 



2 Zeitschr. f. physiol. Chem., 9. 



3 Mitteil. d. landw. Inst., Breslau, 4. 



4 Weyl and v. Anrep, Zeitschr. f. physiol. Chem., 4; Jaarsveld and Stokvis, Arch, 

 f. exp. Path. u. Pharm., 10; Kronecker, ibid., 16; Van de Velde and Stokvis, ibid., 

 17; Schmiedeberg, ibid., 14, 379; Minkowski, ibid., 17. 



