426 THE LIVER. 



that desoxycholic acid, like choleic acid, yields dehydrocholeic acid and 

 cholanic acid as oxidation products, makes the formation of desoxycholic 

 acid from cholic acid by reduction very improbable. The conclusion 

 of LATSCHINOFF that both choleic and desoxycholic acids are identi- 

 cal, is not to be accepted on account of the different properties of the 

 two acids, and as shown by LANGHELD and also found by HAMMARSTEN/ 

 both acids can be detected in the same perfectly fresh ox-bile. PREGL 2 

 has given important proofs that we are here dealing with two different, 

 probably, isomeric acids. He found that the two acids yielded dehydro- 

 choleic acid on oxidation but that the dehydro-acid was not the same 

 in both cases. The choleic acid yielded a dehydro-acid with a lower 

 melting-point and a weaker specific rotation than the desoxycholic acid. 

 The desoxycholic acid crystallizes from glacial acetic acid in needles 

 with 1 molecule acetic acid, having a melting-point of 144-145. The 

 melting-point of the acid crystallized from alcohol-ether is 153-155, 

 and for the anhydrous acid or crystallized from acetone it is 172-173. 

 It is soluble with difficulty in water, more readily soluble in alcohol, but 

 somewhat less soluble in glacial acetic acid than choleic acid. It has an 

 intensely bitter taste. The acid does not give a blue iodine compound, 

 and no color reaction with hydrochloric acid. Its barium salt is soluble 

 with difficulty in cold water, but dissolves in boiling alcohol and crys- 

 tallizes on cooling. 



The cholic acids are best prepared from ox-bile, which is boiled for 

 24 hours with 5-10 per cent caustic soda. The crude acid is precipitated 

 by hydrochloric acid, dissolved in ammoniacal water and precipitated 

 by BaCl2. The precipitate contains essentially choleic and desoxy- 

 cholic acids, while the nitrate contains a part of these and the chief part 

 of the cholic acid. In regard to the further rather complicated method 

 of separating the various acids, as also in regard to the many methods 

 suggested for the preparation of the pure cholic acids, we must refer to 

 more extensive hand-books. 3 



Fellic Acid, CtMwO* is a cholic acid, so called. by SCHOTTEN, which he obtained 

 from human bile, along with the ordinary acid. This acid is crystalline, is insolu- 

 ble in water, and yields barium and magnesium salts, which are very insoluble. 

 It does not respond to PETTENKOFER'S reaction easily and gives a more reddish- 

 blue color. The existence of this acid is still doubtful. 



The conjugate acids of human bile have not been sufficiently investi- 

 gated. To all appearances human bile contains under different circum- 



1 Ekbom, Zeitschr. f. physiol. Chem., 50; Pregl, Wien. Sitz-Ber. Bd., Ill, Math. 

 Naturw. Kl., 1902; Latschinoff, Ber. d. d. Chem. Gesellsch., 20; Langheld, ibid., 

 41; Hammarsten in Abderhalden's Handbuch d. bioch. Arbeitsmethoden Bd. 2, 2. 



2 Zeitschr f. physiol. Chem., 65. 



3 Abderhalden's Handbuch d. bioch. Arbeitsmethoden Bd. II. 2; also Pregl and 

 Buchtala, Zeitschr. f. physiol. Chem., 74 and Schryver, Journ. of Physiol., 44. 



