270 THE URINE. 



distillation with hydrochloric acid is quite considerable. According 

 to Giinther, Chalmot, and Tollens, it yields 46 per cent., and its 

 derivatives, euxanthinic acid and urochloralic acid, 12.5 and 17 per 

 cent, respectively. 



The demonstration of the presence of glucuronic acid in the urine 

 and other fluids of the body directly is most conveniently conducted 

 by decomposing the conjugate glucuronates with 1 per cent, sul- 

 phuric acid in the autoclave, and preparing its p-bromphenyl- 

 hydrazin compound (COH.(CH.OH) 4 .COOH.NH 2 .NH.C 6 H 4 Br). 

 This is characterized by its high melting-point, 236C. (200-216C.) 

 in impure form) its insolubility in absolute acohol, and its high degree 

 of laevorotation in a pyridin-alcoholic solution, viz., 725 / . The 

 same method may be used for its quantitative estimation ( Zeit. f. 

 phys. Chem.j 1900, vol. xxix., p. 256). 



For the clinical recognition of glucuronic acid compounds the fol- 

 lowing data suffice : laevorotation of the urine after fermentation, 

 which diminishes on boiling with acids or changes to dextrorotation ; 

 an increased reduction after boiling with dilute sulphuric acid, and 

 a positive orcin reaction (see Pentoses), which was negative before 

 boiling. 



The Compound Glycocolls. 



As has been pointed out, phenyl-propionic acid and phenyl-acetic 

 acid, which are both formed from albuminous material during the 

 process of intestinal putrefaction, are in part absorbed in the intestinal 

 tract, and are eliminated in the urine in combination with glycocoll 

 as hippuric acid and phenaceturic acid, respectively. But while 

 phenyl-acetic acid unites with glycocoll directly, phenyl-propionic 

 acid is usually first oxidized to ben zoic acid (see page 95). 



Hippuric Acid. While a certain amount of the benzoic acid 

 which enters into the construction of the hippuric acid molecule is 

 derived from the phenyl-propionic acid which results during the 

 process of intestinal putrefaction, another portion is ingested as 

 such, or in the form of other aromatic substances which can be 

 transformed into benzoic acid in the animal body. We can thus 

 understand why larger amounts of hippuric acid are encountered 

 in the urine of herbivorous animals than in that of the carnivora, as 

 the food of the former always contains very considerable amounts of 

 toluol, cinnamic acid, quinic acid, etc., all of which may give rise to 

 benzoic acid. In man the daily elimination corresponds to about 

 0.7 gramme, but may be increased by the ingestion of such articles 

 of food as cranberries, prunes, reine-claudes, etc. 



In a few instances the substance has been found in urinary 

 sediments. 



While the source of the aromatic component of hippuric acid 

 is thus quite well understood, we know but little of the origin of 

 glycocoll. To a certain extent this may also be formed during the 

 process of pancreatic digestion, as we know th at all albumins con- 



