108 



PHYSIOLOGICAL CHEMISTRY. 



5. Sodium Glycocholate, C 26 H 42 NO 6 Na. 



This and the following substance are the characteristic ingredients 

 of the bile. Like the two coloring matters of this secretion, they are 

 mingled in various proportions, either the one or the other preponder- 

 ating in different specimens, or in the bile of different animals. 

 Together they are designated as the " biliary salts." 



Sodium glycocholate is a saline body, consisting of a nitrogenous 

 organic acid, glycocholic acid (CaeH^NOg) in combination with sodium. 

 Glycocholic acid is so called because by boiling with potassium hydrate 

 or baryta-water, or by continued boiling with dilute hydrochloric or 

 sulphuric acids, it is decomposed with the production of two new 

 bodies, namely, glycine (CaHfiNO*), a nitrogenous neutral substance, 

 and cholic acid (C. 2 4H W O 5 ), a non-nitrogenous organic acid, so called 

 because peculiar to the bile. This change takes place with the assump- 

 tion of the elements of water, as follows : 



Glycocholic acid. Glycine. Cholic acid. 



CsJIaXO. + H 2 = CiHftNO, + 24 H 40 6 . 



Sodium glycocholate is a neutral crystallizable substance, very 

 soluble in water and in alcohol, insoluble in ether. It is extracted 

 from the bile as follows : The bile is evaporated to dryness over the 

 water-bath, the dry residue extracted with absolute alcohol, the 

 alcoholic solution decolorized with animal charcoal, and then mixed 



with from 8 to 10 times its vol- 



Fl - 16 - ume of ether. A whitish pre- 



cipitate is thrown down, which 

 collects in drops and masses, of 

 a consistency like that of Canada 

 balsam, whence the biliary salts 

 are sometimes termed the " res- 

 inous " matters of the bile. In 

 the course of 24 hours, some- 

 times only after four or five 

 days, the sodium glycocholate 

 crystallizes in hemispherical or 

 star-shaped masses of fine radi- 

 ating needles. The crystals 

 may be preserved indefinitely 

 in the mixture of alcohol and 

 ether ; but if the liquid be poured 



.# .\. _ nr AA nvnrtnnarl V^ mmr, 

 ott , tne colcl produced by CVap- 



oration causes a condensation 

 of atmospheric moisture and a 

 rapid solution of the crystals, which liquefy into transparent, rounded, 

 oleaginous-looking drops. The solubility of these drops in water and 

 their insolubility in ether will distinguish them from oil globules, 

 which they closely resemble in their optical properties. Sodium gly- 

 cocholate may be precipitated from its watery solution by both the 



SODIUM GLYCOOHOLATE FROM OX-BILK, after two 

 days' crystallization. At the lower part of the fig- 

 ure the crystals are melting into drops, from evap- 

 oration of the ether and absorption of moisture. 



