THE AROMATIC CONSTITUENTS OF THE URINE. 259 



acidified with hydrochloric acid, and allowed to stand. In this 

 manner the hippnric acid is obtained in fairly pure form, and can be 

 further purified, if desired, by recrystallization from hot water. 



Isolation of Glycocoll and Benzole Acid from Hippuric Acid. As 

 stated before, glycocoll is most conveniently obtained from hippnric 

 acid. To effect the decomposition, this is boiled for ten to twelve 

 hours with four parts of diluted sulphuric acid. On cooling, the 

 benzoic acid which has separated out is filtered off. The filtrate is 

 concentrated and extracted with ether, which takes up the remain- 

 ing benzoic acid. The sulphuric acid is now removed by means of 

 barium hydrate and the excess of barium precipitated with carbon 

 dioxide. The filtrate is concentrated, when on cooling the glycocoll 

 is obtained in crystalline form. 



Isolation and Quantitative Estimation. Five hundred to one thou- 

 sand c.c. of urine are rendered slightly alkaline with sodium car- 

 bonate, and are evaporated to a thick syrup, taking care that the 

 reaction remains alkaline. It is then extracted with cold strong 

 alcohol (90 to 95 per cent.) by adding about one-half the volume of 

 the original solution, and allowing the mixture to stand for twenty- 

 four hours. It is then filtered and the alcohol distilled off. The 

 remaining aqueous solution is acidified with dilute sulphuric acid, 

 and the liberated hippuric acid extracted with several portions of 

 acetic ether The ethereal solution is evaporated to dry ness, when 

 the remaining impurities, such as phenols, aromatic oxy-acids, 

 benzoic acid, and fat, are removed by washing with cold petroleum- 

 ether, in which hippuric acid is insoluble. It is then dissolved in 

 warm water, and the solution evaporated at a temperature of from 

 50 to 60 G. until crystallization occurs. On cooling, the crystals 

 are filtered off and weighed. The mother-liquor is extracted with 

 acetic ether, the ethereal solution is evaporated to dryness, and the 

 weight of the residue added to that of the crystals. 



Phenaceturic Acid. In small amounts phenaceturic acid has 

 been repeatedly obtained from the urine of man, but is principally 

 met with in that of herbivorous animals, in which the putrefactive 

 processes, owing jbo the greater length of the intestinal tract and the 

 character of the food, are more extensive. On boiling with dilute 

 mineral acids it is decomposed into its components, as shown in the 

 equation : 



CH 2 .NH(CH 2 C 6 H 5 .CO).COOH + H 2 O = CH 2 (C 6 H 5 ).COOH + CH 2 (XH 2 ).COOH 

 Phenaceturic acid. Phenyl-acetic acid. Glycocoll. 



Properties. Phenaceturic acid crystallizes in small rhombic plates 

 with rounded angles, which are very similar to the corresponding 

 crystals of uric acid. 



Isolation. Phenaceturic acid may be isolated from the urine of 

 the horse after separation of the hippuric acid, as shown above. 

 The mother-liquor is then extracted with acetic ether, which takes 

 up the acid. On evaporation the residue is dissolved in a dilute 



