194 PHENOL. 



brownish green on the addition of ammonia and finally to an emerald 

 green 1 . 



FIG. 34. CRYSTALS OF BARIUM KYNURENATE. (After Kiihne.) 



By prolonged heating to 250 260 kynurenic acid evolves carbonic 

 anhydride and is converted into kynurin, (oxychinolin) C 9 H 6 N (OH) 

 and when heated with zinc dust in a current of hydrogen it is con- 

 verted into chinolin C 9 H 6 N (OH) + H 2 = C 9 H 7 ]S" + H 2 O. These reactions 

 throw considerable light on the constitution of the acid 2 . 



The amount of kynurenic acid in the urine is increased on the 

 ingestion of isatin, a product of the oxidation of indigo 3 . Under 

 ordinary conditions its amount in this excretion is dependent upon 

 the nature of the food supplied to the animal, being greatest under 

 a proteid diet, and is not related to the occurrence or absence of 

 putrefactive processes in the alimentary canal 4 . 



5. Phenol. C 6 H 5 .OH. Oxybenzol. (Carbolic or pheny lie acid.) 

 This substance is formed, together with indol and skatol, during the 

 putrefactive decomposition of proteids, more especially in prolonged 

 putrefactive pancreatic digestions 5 . From these it may be obtained by 

 simple distillation. In accordance with this it is formed in not in- 

 considerable quantity in the alimentary canal, more especially when 

 putrefactive processes in its contents are increased either pathologically 

 or as the result of experimental interference 6 . Of the phenol thus 

 formed a small proportion is passed out in the faeces 7 , the larger 



1 Jaffe, Zt. f. physiol. Chem. Bd. vn. (18823), S. 399. 



2 Kretschy, Ber. d. d. chem. Gesell. Bd. xii. (1879), S. 1673. Monatsh. f. Chem. 

 Bd. ii. (1881), S. 57. 



3 Niggeler, Arch. f. exp. Path. u. Pharm. Bd. in. (1874), S. 67. 



4 Baumann, Zt.f. physiol. Chem. Bd. x. (1886), S. 131. But cf. Haagen, Inaug.- 

 Diss., Konigsb., 1887. (See Centralb. f. d. Med. Wiss. 1889, S. 214.) 



5 Baumann, Zt. f. physiol. Chem. Bde. i. (1877), S. 60, in. 250. Brieger, Ibid. 

 Bd. in. (1879), S. 134. Odermatt, Jn.f.prakt. Chem. Bd. xvni. (1878), S. 249. 



6 E. Salkowski, Ber. d. d. chem. Gesell. 1876, S. 1595. Ibid. 1877, S. 842. Cen- 

 tralb. f. d. Med. Wiss. 1876, S. 818. Arch. f. Physiol Jahrg. 1877, S. 476. Brieger, 

 Zt.f. physiol. Chem. Bd. n. (1878), S. 241. G. Hoppe-Seyler, Ibid. Bd. xn. (1888), S. 1. 



7 Brieger, Ber. d. d. chem. Gesell. 1877, S. 1027. Jn. f. prakt. Chem. Bd. xvn. 

 (1878), S. 134. 



