300 TAUROCHOLIC ACID. [BOOK II. 



the alcoholic solution possessing a bitter taste. The alkaline salts are 

 soluble in water ; the salts which it forms with the alkaline earths and the 

 heavy metals are insoluble in water but, for the most part, are soluble in 

 alcohol. The alkaline hyoglykocholates are almost completely precipitated 

 when their solutions are saturated with NaCl, NH 4 C1 and by alkaline 

 sulphates. 



When boiled with alkalies or dilute sulphuric acid, hyoglykocholic acid 

 splits up into glycocoll and hyocholalic acid C 25 H 40 O 4 . 



According to Jolin 1 , pig's bile contains, in addition to Strecker's acid, a 

 second one, also amorphous, to which the name of /3-hyoglykocholic acid 

 has been assigned. 



Taurocholic acid, C 26 H 45 NS0 7 . 



This acid occurs, though in smaller quantities than glykocholic 

 acid, in the bile of the ox, the sheep and other herbivorous animals. 

 It is the sole bile acid present in the bile of the dog ; in that of man 

 it is occasionally absent (Jacobsen), and, if present, its amount is 

 subject to great fluctuations. It occurs in the bile in combination 

 witb sodium. 



Modes of pre- 1. By Plattners process from the bile of the dog. 

 paration. Strecker found that when the bile of the dog is sub- 



jected to the process, which, when applied to the bile of the ox 

 yields the so-called crystallised bile, it likewise furnishes a crystalline 

 precipitate which, he surmised, consisted of an alkaline taurocholate. 



Hoppe-Seyler 2 not only confirmed the observation but, by de- 

 composing the salt precipitated by ether from the alcoholic extract 

 of dog's bile, obtained taurine and cholalic acid and further proved 

 that the specific rotation of the taurocholic acid of the dog agreed 

 with that of the acid in ox bile. J. Parke 3 , working under Hoppe- 

 Seyler's direction in Tubingen, repeated tbese observations. The 

 crystalline ethereal precipitate of dog's bile was dissolved in water, 

 precipitated with lead acetate and a little ammonia; the precipitate 

 was well washed, then boiled with absolute alcohol, the alcoholic 

 solution filtered hot, the filtrate treated with H 2 S as long as a 

 precipitate of PbS separated, again filtered, the filtrate concentrated 

 at a moderate temperature and then precipitated by a great excess 

 of ether. The syrupy precipitate consisting of free taurocholic acid, 

 after some time, became converted in great part into needle-shaped 

 crystals possessing a silky lustre ; even after the prolonged action 

 of ether, a portion of the precipitate refused to crystallise; on the 

 addition, however, of a drop or two of alcohol, the whole crystallised. 



1 S. Jolin, 'Ueber die Sauren der Schweinegalle. ' Zeitschrift f. physiol. Chem., 

 Vol. xi. (1887), p. 417: Vol. xn. (1888), p. 512, and Vol. xm. (1889), p. 205. 



2 Hoppe-Seyler, Journ.f. prakt. Chemie, Vol. LXXXIII. (1863), p. 83. 



3 J. Parke, ' Ueber die Taurocholsaure.' Med. Chemisch. Untersuchungen aus dem 

 Lab. fiir angewandte Chemie zit Tubingen, herausgegeben von Dr F. 0. Hoppe-Seyler. 

 Erstes Heft. Berlin, 1866. See pp. 160 and 161. 



