702 URINE. 



a case of alcaptonuria studied by them. It melts at 130-133 C. Otherwise, 

 in regard to its behavior with alkalies, with access of air, and also with alkaline 

 copper solutions and ammoniacal silver solutions, and also MILLON'S reagent, 

 it is similar to homogentisic acid. 



NEUBAUER and FLATOW, who have prepared dioxyphenyl-a-lactic acid syn- 

 thetically, find that this acid has entirely different properties from the so-called 

 uroleucic acid. GARROD and HURTLEY * have also shown that an impure homo- 

 gentisic acid with a low melting-point is easily obtained, and they suggest the 

 possibility that the earlier reports in regard to uroleucic acid are due to an 

 error. 



Oxymandelic acid, C 8 H 8 O 4 , paraoxyphenylglycolic acid, HO.C 6 H 4 .CH(OH)COOH 

 is, as above stated, found in the urine in acute atrophy of the liver. The acid 

 crystallizes in silky needles. It melts at 162 C., dissolves readily in hot water, 

 less in cold water, and readily in alcohol and ether, but not in hot benzene. It 

 is precipitated by basic lead acetate, but not by lead acetate. 



CH COTI 



HC C C.COOH 

 Kynurenic acid (^-oxy-/?-quiriolincarboxylic acid) , C 10 H 7 NO 3 , | 



' HC C CH 



has only been found thus far in dogs' urine, but not always ; its quantity is increased 

 by meat feeding. It does not occur in the urine of cats. According to the obser- 

 vations of GLAESSNER and LANGSTEIN the mother-substance seems to be con- 

 tained among the products of pancreatic digestion which are soluble in alcohol 

 and precipitable by acetone. ELLINGER 2 has been able to show positively that 

 tryptophane is the mother-substance of this acid. By the introduction of tryp- 

 tophane in the organism he has shown the formation of a l<ynurenic acid not only 

 in dogs but also in rabbits. 



The acid is crystalline, does not dissolve in cold water, rather well in hot alcohol, 

 and yields a barium salt which crystallizes in triangular, colorless plates. On 

 heating it melts and decomposes into CO 2 and kynurin. On evaporation to dry- 

 ness on the water-bath with hydrochloric acid and potassium chlorate a reddish 

 residue is obtained which on adding ammonia becomes first brownish green and 

 then emerald green (JAFFE'S reaction 3 ). 



Urinary Pigments and Chromogens. The yellow color of normal 

 urine depends perhaps upon several pigments, but in greatest part upon 

 urochrome. Besides this the urine seems to contain a very small quantity 

 of hcematoporphyrin as a regular constituent. Uroerythrin is also of 

 frequent occurrence in normal urine, but not always. Finally, the 

 excreted urine when exposed to the action of light regularly contains a 

 yellow pigment, urobilin, which is derived from a chromogen, urobilinogen, 



1 Journ. of Physiol., 36. 



2 Glaessner and Langstein, Hofmeister's Beitrage, 1; Ellinger, Ber. d. cl. chem. 

 Gesellsch., 37, 1804, and Zeitschr. f. physiol. Chem., 43. The older literature on 

 kynurenic acid may be found in Josephsohn, Beitrage zur Kenntnis der Kynurensaure 

 ausscheidung beim Hunde, Inaug.-Dissert., Konigsberg, 1898. 



3 Zeitschr. f. physiol. Chem., 7. In regard to kynurenic acid, see also Huppert- 

 Neubauer, 10. AuflL, and Mendel and Jackson, Amer. Journ. of Physiol., 2; Mendel 

 and Schneider, ibid., 5; Camps, Zeitschr. f. physiol. Chem., 33. 



