COLORING MATTERS OF BILE. 481 



C 26 H 37 C1 7 0, insoluble in water, fusing at 60. It unites 

 directly with one molecule of bromine, when the latter 

 is added to its solution in carbonbisulphide, as long 

 as the color of the bromine disappears. The resulting 

 compound, cholesterindibromide, C 26 H 44 Br 2 0, crystallizes 

 in small needles, insoluble in water, difficultly soluble 

 in alcohol, easily soluble in ether ; fusing point, 147 ; 

 reconverted into cholesterin by nascent hydrogen. 



Cholesterin is a monatomic alcohol. When treated 

 with hydrochloric acid or phosphorus chloride, it yields 

 cholesterol chloride, C 26 H 43 C1, which, when in a pure 

 state, forms colorless, acicular crystals, soluble in 

 alcohol. Cholesterin combines with acids, forming 

 ethers. The stearic ether, C 26 H 43 .O.C 18 H 35 0, is produced 

 by heating cholesterin with stearic acid to 200 in 

 sealed tubes. Small, white, needles; fusing at 65. 

 The benzoic ether, C 26 H 43 .O.C 7 H 5 0, prepared in the same 

 manner, forms small, crystalline plates, which melt be- 

 tween 125 and 130. 



Dehydrating substances, concentrated sulphuric or 

 phosphoric acid, convert cholesterin into various crys- 

 tallizing, isomeric, or polymeric hydrocarbons, C 26 H 42 . 



5. Coloring matters of bile. Biliary calculi 

 from the human being, which contain a great deal of 

 pigment, are pulverized, freed of cholesterin and fat 

 by treatment with ether, and then freed of other 

 bodies by successive extraction with hot water and 

 chloroform. The residue, which contains earthy phos- 

 phates and carbonates and compounds of the coloring 

 matters with lime and magnesia, is treated with hydro- 

 chloric acid, and the coloring matters, which remain 

 after drying, extracted with chloroform. This solu- 

 tion, on being evaporated to dry ness, leaves a dark, 

 crystalline residue behind, from which absolute alco- 

 hol extracts bilifuscin, while bilirubin remains behind, 

 which can be purified by repeatedly dissolving in 

 chloroform and precipitating with alcohol. The por- 

 tion that remains undissolved by chloroform in the 

 first place, still contains a great deal of bilirubin, 

 41 



