APP.] CHEMICAL BASIS OF THE AXIMAL BODY. 761 



small bulk ; the hippuric acid is then precipitated by adding an excess of 

 hydrochloric acid ; the acid is then purified by several crystallisations 

 from boiling water. 



When heated in a small tube, hippuric acid gives a sublimate of 

 benzoic acid and ammonic benzoate, accompanied by an odour like that 

 of new hay, while oily, red drops are observed in the tube. This is very 

 characteristic, and distinguishes it from benzoic acid. 



Phenylic (Carbolic) acid or Phenol. C 6 H 6 O. 



This body is undoubtedly obtained as the result of the putrefactive 

 decomposition of proteids, notably in putrefactive pancreatic digestions \ 

 It may be obtained from the distillate of such digestive mixtures. It 

 is also found in the contents of the alimentary canal under the same 

 conditions which give rise to indol. When so occurring a portion of it 

 may be obtained from the fseces while the rest reappears in the urine 2 . 



Buliginsky 3 says the urine of many animals, of cows and horses always, contains 

 a substance insoluble in alcohol, and not precipitated by lead acetate and ammonia^ 

 which by the action of dilute mineral acids gives carbolic acid. The same acid 

 applied to the body externally or internally also passes into the urine 4 . Similarly 

 benzol (C 6 H 6 ) when taken into the stomach appears as carbolic acid in the urine 5 . 



The pure acid crystallises in long, colourless prismatic needles; they 

 melt at 35 C., and boil at 180C. It is readily soluble in alcohol and 

 aether, slightly soluble in water (1 part in 20). In most cases it acts as 

 a weak acid, forming crystalline salts with the alkalis. With nitric acid 

 it yields picric acid. Its solutions reduce silver and mercury salts. 



Preparation. By the dry distillation of salicylic acid, also from the 

 acid products of the distillation of coal. It is obtained in the last 

 portions of the distillate when preparing indol, and is separated by 

 forming a compound with bromine C 6 H 3 Br 3 O. 



THE BILE SERIES. 



Cholalic (or dtolic) acid. H . C 24 H^ O 5 + H 2 O. 



Occurs in traces in the small intestine, in larger quantities in the 

 contents of the large intestine, and the fseces of men, cows and dogs. 



1 Baumann, Zeitsch. f. physiol. Chem. Bd. i. (1877), S. 60. 



2 Salkowski, Ber. d. deutsch. Chem. Gesell. ix. (1876), S. 1595. Centralb. f. d. 

 med. Wiss. 1876, S. 818. Ber. d. deutsch. Chem. Gesell. x. (1877), S. 842. Virchow's 

 Arch. Bd. LXXII. (1878), S. 409. See also Centralb. f. d. med. Wiss. 1878, Nos. 30, 

 31, 34, 42, and Zeitsch. f. physiol. Chem. Bd. n. (1878), S. 241. 



3 Hoppe-Seyler, Med. chem. Untersuch. Heft 2 (1867), S. 234. 



4 Alme'n, Neues Jahrb. d. Pliarm. Bd. 34, S. 111. Salkowski, Pfluger's Archiv, 

 Bd. v. (1871-72), S. 335. 



6 Schultzen and Naunyn, Reichert u. Du-Bois Keymond's Archiv, 1867, Heft 3, 

 S. 349. 



