THE BILE. 181 



CK/ t (G 52 H 42 NO ll ,HO). This acid is crystallizable and contains nitro- 

 gen, as shown by the above formula, which is that given by Leh- 

 mann. If boiled for a long time with a dilute solution of potassa, 

 glyko-cholic acid is decomposed with the production of two new 

 substances; the first a non-nitrogenous acid body, ckolic add 

 (C 48 H 3g O 9 ,HO) ; the second a nitrogenous neutral body, glycine 

 (C 4 H 5 NO 4 ). Hence the name- glyko-cholic acid, given to the 

 original substance, as if it were a combination of cholic acid with 

 glycine. In reality, however, these two substances do not exist 

 originally in the glyko-cholic acid, but are rather new combinations 

 of its elements, produced by long boiling, in contact with potassa 

 and water. They are not, therefore, to be regarded as, in any way, 

 natural ingredients of the bile, and do not throw any light on the 

 real constitution of glyko-cholic acid. 



Tauro-cholate of soda (NaO,C 52 H 45 NS 2 14 ) is also a very abundant 

 ingredient of the bile. It is said by Eobin and Yerdeil 1 that it is 

 not crystallizable, owing probably to its not having been separated 

 as yet in a perfectly pure condition. Lehmann states, on the con- 

 trary, that it may crystallize, 2 when kept for a long time in contact 

 with ether. We have not been able to obtain this substance, how- 

 ever, in a crystalline form. Its acid constituent, tauro-cholic acid, 

 is a nitrogenous body, like glyko-cholic acid, but differs from the 

 latter by containing in addition two equivalents of sulphur. By 

 long boiling in a dilute solution of potassa, it is decomposed with 

 the production of two other substances ; the first of them the same 

 acid body mentioned above as derived from the glyko-cholic, viz., 

 cholic acid; and the second a new nitrogenous neutral body, viz., 

 taurine (C 4 H 7 NS 3 O fl ). The same remark holds good with regard to 

 these two bodies, that we have already made in respect to the sup- 

 posed constituents of glyko-cholic acid. Neither cholic acid nor 

 taurine can be properly regarded as really ingredients of tauro- 

 cholic acid, but only as artificial products resulting from its altera- 

 tion and decomposition. 



The glyko-cholates and tauro-cholates are formed, so far as we 

 know, exclusively in the liver ; since they have not been found in 

 the blood, nor in any other part of the body, in healthy animals : 

 nor even, in the experiments of Kunde, Moleschott, and Lehmann 

 on frogs, 3 after the entire extirpation of the liver, and consequent 



t ' Chimie Anatoraique et Physiologique, vol. ii. p. 473. 



2 Physiological Chemistry, Phil, ed., vol. i. p. 209. 



3 Lehmann's Physiological Chemistry, Phil, ed., vol. i. p. 476. 



