3 7 8 CHEMISTR Y OF THE DIGESTIVE PR O CESSES. 
from the others by two bands, one between the solar lines D and E 
near to E, the other at F. 1 
The bile salts produce great slowing of the heart's beat, which may be used 
as a physiological test for them in confirmation of Pettenkofer's reaction. In 
a curarised frog the heart is exposed, the pericardium removed, and the action 
of the vagus paralysed by atropine ; on now adding a drop of a solution of a 
bile salt, the rhythm of the heart is greatly slowed." 2 
Cleavage products of the bile acids. — All the bile acids, under the 
action of hydrating agents, split up into two components, of which one 
is always either glycocoll or taurin, and the other a non-nitrogenous 
monobasic acid which may be cholalic acid or one of several allied acids. 
Glycocoll and taurin are nitrogenous bodies, belonging to that class 
of substances called amido-acids, i.e. organic acids, in which one or more 
hydrogen atoms are replaced by the group amidogen (XH,). Both these 
amido-acids are probably formed by the breaking up of proteids, or 
their allies the albuminoids. 
The process of hydration can be carried out directly from bile, by heating 
with hydrochloric acid, in a flask attached to a reversed condenser. Taurin 
and hj drochlorate of glycocoll are formed, and the free cholalic acids, which 
slowly lose water and pass into the form of their anhydrides (the dyslysius, 
p. 382); these being insoluble are precipitated. As soon as the reaction is 
completed, as shown by the failure of Pettenkofer's test, the flask is allowed 
to cool and the dyslysius filtered off. The filtrate', which contains the 
amido-acids, is strongly concentrated, and, while still warm, decanted from the 
sodium chloride which has crystallised out. It is next evaporated to com- 
plete dryness and treated with absolute alcohol, which takes up the glycocoll 
hydrochlorate and leaves the taurin behind. The residue is dissolved in as 
small a quantity as possible of warm water, and filtered while warm; to 
this filtrate a little alcohol is added, and, on slowly cooling, crystals of taurin 
are formed. 
The alcohol is evaporated from the alcoholic extract containing the glycocoll 
hydrochlorate, and water is added ; to the watery solution, hydrate of lead is 
added, when insoluble lead chloride and a soluble lead compound of glycocoll 
are formed. The latter is separated in solution by filtration ; into the solution 
a stream of sulphuretted hydrogen is passed, the lead sulphide is filtered off, 
and the filtrate is concentrated, until, on cooling, free glycocoll crystallises out. 
The free cholalic acids 3 can be recovered from the dyslysius formed in 
the first step of the above process. The dyslysins are removed from the 
filter, and boiled with dilute alkali, when they take up water, and, combining 
with some of the alkali, are converted into soluble alkaline cholalates. On 
acidifying with hydrochloric acid, and evaporating to dryness, the cholalic 
acids can be extracted with a small quantity of hot alcohol, from which they 
crystallise on cooling, or on the addition of excess of ether. 
Glycocoll, glycocine, or glycine, is amido-acetic acid (NH 2 .CH 2 .COOH). 
Besides occurring combined with cholalic acid, as glycocholic acid in the 
bile, it is found in the urine of certain animals and occasionally in man, 
combined with benzoic acid, to form hippuric acid, and is formed as an 
end hydration product from gelatine and similar substances. 
1 Koschlakoff and Bogomololf, CentraZbl. f. d. med. Wissenseh., Berlin, 1S68, Bd. vi. ' 
S. 529. In this paper four bands are described. Bogomoloff, ibid., 18G9, Bd. vii. S. 529 ; 
Schenck, Jahresb. it. d. Fortschr. d. ThMr-Chem., Wiesbaden, 1872, Bd. ii. S. 232. 
2 Mackay, Arch. f. exper. Path. u. Pharmacol., Leipzig, 1885, Bd. xix. S. 279. 
3 The term "cholalic acids" is used to signify cholalic acid and its allies. 
