424 THE LIVER 



namely from cholic acid, choleic acid and desoxycholic acid, and these 

 three acids are identically constructed in regard to their 19 carbon atoms. 



The choloidanic acid is interesting in several respects. PANZER X has obtained 

 from it by distillation with soda-lime, a hydrocarbon, CnHie, a homologue of 

 benzene, and on the oxidation of the cholic acid he has obtained an acid with the 

 formula, C 8 0i 2 6 , which he considers as an oxyhexahydro-benzene-l-4-dicarboxylic 

 acid and from which he obtained paraoxybenzaldehyde. PREGL has obtained 

 from choloidanic acid, by heating, pyrocholoidanic acid, Ci 6 H 2 o0 4 which he con- 

 siders as parabenzoic acid d-methyl-n-capric acid, and is produced from the 

 hexahydrobenzene derivative by total dehydrogenation of a benzene derivative. 



v. FURTH and collaborators have investigated the products obtained on the 

 dry distillation of cholic acid at ordinary pressure, and WIELAND and WEIL 2 on 

 such distillation in vacuum. In the first case chiefly hydrocarbons with 12 to 

 17 carbon atoms were obtained, and in the second instance chiefly an unsaturated 

 acid, C 24 H3 4 O2, was obtained, and in both cases these products and their double 

 bindings have been carefully investigated. We must wait for further developments 

 in these investigations before we attempt to draw any positive conclusions from 

 them. 



From the investigations on the cholic acids carried out thus far we 

 are not able to draw any positive conclusions on their constitution, but 

 that they are derivatives of hexahydrobenzene, is very probable for sev- 

 eral reasons. 



Cholic acid crystallizes partly in rhombic plates or prisms with one 

 molecule of water, and partly in larger rhombic tetrahedra or octahedra 

 with one molecule of alcohol of crystallization (MTLIUS). These crystals 

 quickly become opaque and porcelain-white in the air. They are quite 

 insoluble in water (in 4000 parts cold and 750 parts boiling), rather 

 soluble in alcohol, but soluble with difficulty in ether. The amorphous 

 cholic acid is less insoluble. The solutions have a bitter-sweetish taste. 

 The crystals lose their alcohol of crystallization only after a lengthy 

 heating to 100-120 C. The acid free from water and alcohol melts at 

 195-196 C. According to BONDI and MULLER the melting-point of the 

 perfectly pure acid is 198 C. It forms a characteristic blue compound 

 with iodine (MYLIUS). If finely powdered cholic acid is added to 25 

 per cent hydrochloric acid at the ordinary temperature, a beautiful violet- 

 blue coloration gradually appears, and this color is permanent for some 

 time and then becomes gradually green and yellow. The blue solution 

 shows an absorption band in the neighborhood of the D line (HAMMAR- 



STEN 3 ) . 



The alkali salts are readUy soluble in water, but when treated with a 

 concentrated caustic or carbonated alkali solution, they may then be 



1 Panzer, Zeitschr. f. physiol. Chem., 48 and 60. 



2 v. Fiirth with Link, Bioch. Zeitschr., 26, with Ishihara, ibid., 43; Wieland and 

 Weil, Zeitschr. f. physiol. Chem., 80. 



3 Zeitschr. f. physiol. Chem., 61. 



