274 HAND-BOOK OF PHYSIOLOGY. 



lowing manner: mix bile which has been evaporated to a quarter of its 

 bulk with -animal charcoal, and evaporate to perfect dryness in a water 

 bath. Next extract the mass whilst still warm with absolute alcohol. 

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

 drous 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 gly- 

 cocholate 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 taurocho- 

 late 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 purple 

 color is developed. 



The re-action 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 

 the fourth near D. 



The yellow coloring matter of the bile of man and the Carnivora is 

 termed Bilinibin or Bilifulvin (c J6 H J8 N 2 o 3 ) crystallizable and insoluble in 

 water, soluble in chloroform or carbon disulphate; a green coloring matter, 

 Biliverdin (c 16 H 20 N 2 o 6 ), which always exists in large amount in the bile of 

 Herbivora, being formed from bilirubin on exposure to the air, or by sub- 

 jecting the bile to any other oxidizing agency, as by adding nitric acid. 

 When the bile has been long in the gall-bladder, a third pigment, Bilipra- 

 sin, 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 characteristic 

 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 



