BILE. 69 



The temperature must never rise above 70 C; to avoid 

 this, cool the tube under the tap. Upon careful mixing 

 and cooling as described above, the whole solution finally 

 becomes cherry-red or reddish purple. Such a solution 

 shows a definite and characteristic spectrum which distin- 

 guishes it from other substances, giving the same reaction, 

 such as phenol, petroleum, fusel-oils, pyrocatechinol, choles- 

 terol, and proteins. 



Crystallization of the Bile Salts (Phttner's}. 



Mix 20 c.c. of the bile with sufficient animal charcoal 

 to form a thick paste and allow the mass to evaporate on 

 the water-bath to dryness. Grind up the dry residue and 

 extract it in a flask with 25 c.c. of absolute alcohol on the 

 water-bath for 15-20 minutes. Filter and to the filtrate add 

 ether until a slight precipitate is visible. Cover the vessel and 

 set it away for a few days. Examine the crystals. Dissolve 

 some in alcohol and try Pettenkofer's Test. 



BILE PIGMENTS. 



The differences in color which were noticed in the various 

 samples of bile are dependent upon the presence in pre- 

 dominating amounts of certain pigments of which the two 

 most important are bilirubin and biliverdin. The former 

 is chiefly present in the bile of carnivora, while that of the 

 herbivora contains biliverdin in greater quantities. The 

 bile pigments are closely connected generically and probably 

 chemically with the blood and urinary pigments. 



Bilirubin is insoluble in water, somewhat soluble in alcohol 

 and ether, and dissolves readily in chloroform, benzene, and 

 acids and alkalies. It oxidizes in the air to biliverdin. 



Biliverdin is soluble in alcohol, partly soluble in ether, 

 and insoluble in chloroform and water. 



