SPECIAL CHOLIC ACIDS. 427 



stances various conjugate bile-acids. In some cases the bile-salts of 

 human bile are precipitated by BaCb and in others not. According to 

 the statements of LASSAR-COHN l three cholic acids may be prepared 

 from human bile, namely, ordinary CHOLIC ACID, CHOLEIC ACID, and 



FELLIC ACID. 



Lithofellic Acid, C2oH 3 60 4 , is the acid related to cholic acid which occurs in 

 the oriental bezoar stones, which is insoluble in water, comparatively easily solu- 

 ble in alcohol, but only slightly soluble in ether. 2 



Lithocholic Acid, C^HUOs, is a cholic acid found by H. FISCHER 3 in gall- 

 stones. It melts at 184-186 and is tasteless. 



The hyo-glycocholic and cheno-taurocholic acids, as well as the 

 glycocholic acid of the bile of rodents, yield corresponding 'cholic acids. 

 This also seems to be the case with the glycocholic acid of the hippopota- 

 mus-bile, which stands very close to the pig-bile (HAMMARSTEN 4 ). In the 

 polar bear a third cholic acid exists besides cholic and choleic acids. 

 It ite called ursocholeic add, CigHsoCU or CigH^gCU (HAMMARSTEN 5 ). 

 Also in the bile of other animals (walrus,, seal) HAMMARSTEN 6 has found 

 special cholic acids, phoccecholic acids, of which one, the a-acid crystallizes 

 from benzene or petroleum ether in six-sided thin plates which melt at 

 152-154 C. Its formula seems to be C22H3e05. The other, fl-phocse- 

 cholic acid has the formula C24H4o05 and is isomeric with cholic acid. 

 The isocholic acid melts at 220-222 C. 



On boiling with acids, on putrefaction in the intestine, or on heating, 

 cholic acids lose water and are converted into anhydrides, the so-called 

 dyslysins. The dyslysin, C24H3eO3, corresponding to ordinary cholic 

 acid, which occurs in fseces, is amorphous, insoluble in water and alkalies. 

 Choloidic acid, 24^304, is called the first anhydride or an intermediary 

 product in the formation of dyslysin. On boiling dyslysins with caustic 

 alkali they are reconverted into the corresponding cholic acids. 



THE DETECTION OF BILE-ACIDS IN ANIMAL FLUIDS. To obtain the 

 bile-acids pure so that PETTENKOFER'S test can be applied to them, the 

 protein and fatt must first be removed. The protein is removed by 

 making the liquid first neutral and then adding a great excess of alcohol, 

 so that the mixture contains at least 85 vols. per cent of water-free alcohol. 

 Now filter, extract the precipitated protein with fresh alcohol, unite all 

 filtrates, distil the alcohol, and evaporate to dryness. The residue is 



'Schotten, Zeitschr. f. physiol. Chem., 11; Lassar-Cohn, Ber. d. deutsch. chem. 

 Gesellsch., 27. 



2 See Jiinger and Klages, Ber. d. deutsch. chem. Gesellsch. 28 (older literature). 



3 Zeitschr. f. physiol. Chem., 73. 



4 Ibid., 74. 

 * Ibid., 36. 



6 Ibid., 61 and 68. 



