280 HANDBOOK OF PHYSIOLOGY. 



Separate the alcoholic extract by filtration, and to it add perfectly an- 

 hydrous ether as long as a precipitate is thrown down. The solution and 

 precipitate should be set aside in a closely stoppered bottle for some days, 

 when crystals of the bile salts or bilin will have separated out. The 

 glycocholate may be separated from the taurocholate by dissolving bilin 

 in water, and adding to it a solution of neutral lead acetate, and then a 

 little basic lead acetate, when lead glycocholate separates out. Filter 

 and add to the filtrate lead acetate and ammonia, a precipitate of lead 

 taurocholate will be formed, which may be filtered off. In both cases, 

 the lead may be got rid of by suspending or dissolving in hot alcohol, 

 adding hydrogen sulphate, filtering and allowing the acids to separate 

 out by the addition of water. 



The Test for bile salts is known as Pettenkofer's. If to an aqueous 

 solution of the salts strong sulphuric acid be added, the bile acids are 

 first of all precipitated, but on the further addition of the acid are re- 

 dissolved. If to the solution a drop of solution of cane sugar be added ? 

 a fine deep cherry red to purple color is developed. 



The reaction will also occur on the addition of grape or fruit sugar 

 instead of cane sugar, slowly with the first, quickly with the last; and a 

 color similar to the above is produced by the action of sulphuric acid and 

 sugar on albumen, the crystalline lens, nerve tissue, oleic acid, pure 

 ether, cholesterin, morphia, codeia and amylic alcohol. 



The spectrum of Pettenkofer's reaction, when the fluid is moderately 

 diluted, shows four bands the most marked and largest at E; and a 

 little to the left; another at F; a third between D and E, nearer to D; 

 and a fourth near D. 



(b) The yellow coloring matter of the bile of man and the Carnivora 

 is termed Biliriibin or Bilifulvin (C 16 H 18 N 2 3 ) crystallizable and insolu- 

 ble in water, soluble in chloroform or carbon disulphide; a green color- 

 ing matter, Biliverdin (0 16 H 20 N 2 5 ), which always exists in large 

 amount in the bile of Herbivora, being formed from bilirubin on expo- 

 sure to the air, or by subjecting the bile to any other oxydizing agency, 

 as by adding nitric acid. When the bile has been long in the gall- 

 bladder, a third pigment, Biliprasin, may be also found in small 

 amount. 



In cases of biliary obstruction, the coloring matter of the bile is re- 

 absorbed, and circulates with the blood, giving to the tissues the yellow 

 tint characteristic of jaundice. 



The coloring matters of human bile do not appear to give character- 

 istic absorption spectra; but the bile of the guinea pig, rabbit, mouse, 

 sheep, ox, and crow do so, the most constant of which appears to be a 

 band at F. The bile of the sheep and ox give three bands in a thick 

 layer, and four or five bands with a thinner layer, one on each side of D, 

 one near E, and a faint line at F. (McMunn.) 



