156 PHYSIOLOGICAL CHEMISTRY. 



acids, as well as by calcium, barium, and lead-salts. Biliverdin 

 gives HUPPERT'S and GMELLN^S reactions, commencing with the 

 blue color. It is converted into hydrobilirubin by nascent hydro- 

 gen. On allowing the green bile to stand, also by the action of 

 ammonium sulphide, the biliverdin may be reduced to bilirubin 

 (HAYCEAFT and SCOFIELD). 



Biliverdin is most simply prepared by allowing a thin layer of 

 an alkaline solution of bilirubin to stand exposed to the air in a 

 dish until the color is brownish green. The solution is then pre- 

 cipitated by hydrochloric acid, the precipitate washed with water 

 until no HC1 reaction is obtained, then dissolved in alcohol and 

 the pigment again separated by the addition of water. Any biliru- 

 bin present may be removed by means of chloroform. t r >ri 



Bilifuscin, so named by STADELER, is an amorphous brown pigment, 

 soluble in alcohol and alkalies, nearly insoluble in water and ether, and 

 soluble with great difficulty in chloroform (when bilirubin is not present at 

 the same time). It is found in post-mortem bile and gall-stones. Biliprasin 

 is a green pigment prepared by STADELER from gall-stones, which perhaps is 

 only a mixture of biliverdin and bilirubin. Bilihumin is the name given by 

 STADELEK to that brownish amorphous residue which is left after extracting 

 gall-stones with chloroform, alcohol, and ether. It does not give GMELIN'S 

 test. Bilicyanin is also found in human gall-stones (HEINSIUS and CAMP- 

 BELL). Cholo Iwmatin, so called by MACMUNN, is a pigment often occurring 

 in sheep- and ox-bile and characterized by four absorption- bands, and which 

 is formed from haematin by the action of sodium amalgam. In the dried con- 

 dition, obtained by the evaporation of the chloroform solution, it is green, and 

 in alcoholic solution olive-brown. 



GMELIN'S and HUPPERT'S reactions are generally used to detect 

 the presence of bile-pigments in animal fluids or tissues. The first, 

 as a rule, can be performed directly, and the presence of albumin 

 does not interfere with it, but, on the contrary, it brings out the 

 play of colors more strikingly. If blood-coloring matters are present 

 at the same time, the bile-coloring matters are first precipitated by 

 the addition of sodium phosphate and milk of lime. This precipi- 

 tate containing the bile-pigments may be used directly in HUPPERT'S 

 reaction, or may be treated with water and some hydrochloric acid, 

 and then shaken with chloroform free from alcohol, and this 

 chloroform solution used in testing for the bile-pigments. 



Besides the bile-acids and bile-pigments we also have in the 

 bile cholesterin, lecithin, palmitin, stearin, olein, and soaps of the 

 corresponding fatty acids. In some animals the bile contains a 

 diastatic enzyme. Cliolin and glycero- phosphoric acid, when 

 they are present, may be considered as decomposition products of 

 lecithin. Urea occurs, though only as traces, as a physiological 

 constituent of human, ox, and dog bile. The mineral constituents 



