296 GLYKOCHOLIC ACID. [BOOK II. 



This method which is the simplest, and when successful the best, 

 of all which are available, fails very frequently. Thus Marshall 1 

 found that in only 22'2 per cent, of all the trials which he made 

 with the fresh bile of oxen slaughtered in Philadelphia did the 

 separation of glykocholic acid occur. It would appear that when 

 ox bile contains a considerable quantity of taurocholic acid, in 

 addition to glykocholic acid, the former prevents the precipitation 

 of the latter by hydrochloric acid, even in the presence of ether. 



Glykocholic acid usually crystallises in the form of 



Physical and co j our i ess transparent needles. By concentrating its 

 chemical pro- , , ,. , .. r , .,. J 1 ... , , *? , 



perties. alcoholic solution at a boiling temperature, it is obtained 



in the form of thin four-sided prisms. It requires 303 

 parts of cold and 102 parts of boiling water to dissolve it. It is 

 readily soluble in alcohol, but almost insoluble in ether. It is 

 soluble in solution of the alkaline hydrates and their carbonates, and 

 displaces the carbonic acid from the latter. 



Solutions of glykocholic acid in alcohol or water possess a 

 combined bitter and sweet taste and an acid reaction. Glykocholic 

 acid is readily dissolved, without undergoing decomposition, by 

 concentrated sulphuric, hydrochloric, and acetic acids, at ordinary 

 temperatures. It is soluble in glycerin. The glykocholates of the 

 alkalies and alkaline earths are readily soluble in water and in 

 alcohol, whilst the glykocholates of the heavy metals are either 

 insoluble or only sparingly soluble in water. A watery solution of 

 an alkaline glykocholate is precipitated by neutral lead acetate, the 

 precipitate is soluble in hot alcohol and, on cooling, separates out 

 partly in a powdery condition and partly in flakes. Solutions of 

 alkaline glykocholates are able to dissolve small quantities of 

 saponifiable soaps, of lecithin, and of cholesterin. 



Free glykocholic acid and its salts are dextrogyrous. 

 ion (a)D of glykocholic acid dissolv 



May be prepared from pure glykocholic acid by 



Sodium gly- dissolving it in a solution of sodium carbonate, evapora- 

 kocholate .. , T i . , . ' 



c H NaNO ting to dryness, dissolving the residue in absolute 



alcohol and precipitating by the addition of a large 

 excess of anhydrous ether. The sodium salt soon separates out, as 

 was described in the case of crystallised bile. It is very soluble in 

 water; 100 parts of alcohol at 15C. dissolve 3'9 parts of the salt. 

 When heated, it melts and takes fire, and ultimately leaves an 

 easily fusible mass, containing much sodium cyanate. 



The specific rotation (a)D of an alcoholic solution = -f 25*7. 



1 John Marshall, 'Ueber die Hiifner'sche Eeaktion bei amerikanischer Ochsengalle.' 

 Zeitschrift f. physiol. Chemie, Vol. xi. (1887), p. 233. 



Specific rotation (a)D of glykocholic acid dissolved in alcohol 

 = + 29'0. 



