THE CHEMISTRY OF THE ANIMAL BODY. 1013 



Cynurenic Acid, C 9 H 5 N.OH.COOH. This is oxychinolin carbonic acid ; it is found 

 normally in dog's urine, being derived from proteid metabolism. This form of the chinolin 

 group is therefore not burned in the body. 



Indol, or Benzopyrol, C 8 H 7 N. The source of iudol is surely from 

 proteid putrefaction ; it may also be obtained by melting proteid with potash. 



H H 



C C 



// \ /\ // \ /\ 



HC C CH HO C COH 



I II II I II II 



HC C CH HC C CH 



\ /\/ % /\/ 



C N C N 



H H H H 



Indol. Indoxyl. 



After its absorption it receives an oxy- group just as benzol does, and like 

 benzol pairs with sulphuric acid with the loss of a molecule of water, and 

 appears as ethereal sulphate in the urine. In preparing indol from feces the 

 fecal odor clings to it. Pure indol, however, has no smell. An alcoholic 

 solution of indol mixed with hydrochloric acid colors fir-wood cherry-red. 

 If urine be mixed with an equal volume of hydrochloric acid, chloroform 

 added, and then gradually an oxidizing agent (chloride of lime), any indoxyl- 

 sulphuric acid present will be oxidized to indigo-blue, which gives a blue color 

 to the chloroform in which it dissolves. 



Skatol, or /3-Methyl Indol, C 8 H 5 CH 3 NH. The history of skatol, 



H 

 C 



// \ /\ 

 HC C CCH 3 



I II II , 

 HC C CH 



* /\/ 



C N 

 H H 



Skatol. 



is the same as that of indol. Its source is from proteid putrefaction ; after ab- 

 sorption it unites with an oxy- group, and the skatoxyl thus produced pairs with 

 sulphuric acid, and appears in the urine as ethereal skatoxyl-sulphuric acid. 



AROMATIC BODIES IN THE URINE. There have been named above as 

 appearing in normal human urine the ethereal sulphates of phenol, >-cresol, 

 pyrocatechin, indoxyl, skatoxyl, hydroparacumaric acid, and oxyphenyl-acetic 

 acid, of which, however, the last two appear likewise as their salts without 

 being combined with sulphuric acid. 1 These are derived from proteid putre- 

 factive products formed almost entirely in the large intestine (see p. 988), 

 which are partially absorbed and partially pass into the feces. The amount 

 1 Baumann : Zeitschrifi fur physiologische Chemie, 1886, Bd. 10, p. 125. 



