406 THE LIVER. 



in old blood extravasations (as hsematoidin), and in the urine and the 

 yellow-colored tissue in icterus. It is converted into hydrobilirubin, 

 C32H 40 N 4 07 (MALY), by hydrogen in a nascent state, and then shows 

 great similarity to the urinary pigment, urobilin, as well as to stercobilin 

 found in the contents of the intestine (MASIUS and VANLAin 1 ). On 

 careful oxidation bilirubin yields biliverdin and other coloring-matters 

 (see below). 



Bilirubin is derived from the blood-pigment. It has the same per- 

 centage composition as hsematoporphyrin, and like hsematin it yields 

 hsematimc-acid imide as an oxidation product (KUSTER). On reduction 

 with zinc powder or with nascent HI it yields hsemopyrrol, according to 

 ORNDOKFF and TEEPLE. 2 



Bilirubin is sometimes amorphous and sometimes crystalline. The 

 amorphous bilirubin is a reddish-yellow or reddish-brown powder; the 

 crystals have a reddish-yellow, reddish-brown, or more reddish color, 

 and sometimes they have nearly the color of crystalline chromic acid. 

 The crystals, which can easily be obtained by allowing a solution of bili- 

 rubin in chloroform to evaporate spontaneously, are reddish-yellow, 

 rhombic plates, whose obtuse angles are often rounded. On crystalliz- 

 ing from hot dimethylaniline it forms on cooling broad columns with 

 both ends sharply cut (KUSTER 3 ). On dissolving in chloroform both 

 kinds of crystals are converted into long needles or whetstones. 



Bilirubin is insoluble in water, behaves like an acid, and occurs in 

 animal fluids as soluble alkali bilirubin. It is very slightly soluble in 

 ether, benzene, carbon disulphide, amyl alcohol, fatty oils, and gly- 

 cerin. It is somewhat more soluble in alcohol. In cold chloroform it 

 dissolves with difficulty, and is much more readily soluble in warm chloro- 

 form. Its solubility varies, and supersaturated solutions are readily 

 formed (ORNDORFF and TEEPLE). The varying solubility of bilirubin 

 in chloroform depends, according to KUSTER, on the fact that in its 

 preparation derivatives which are readily soluble and contain chlorine 

 or other transformation products are formed, or perhaps the bilirubin 

 goes over into polymeric modifications having different solubilities. In 

 cold dimethylaniline it dissolves in the proportion of 1 : 100, and in hot 

 dimethylaniline much more re-adily. Its solutions show no absorption- 

 bands, but only a continuous absorption from the red to the violet end 

 of the spectrum, and they have a decided yellow color, even on diluting 

 greatly (1:500,000), in a layer 1.5 cm. thick. If a dilute solution of 



1 Maly, Wien. Sitzungsber., 57, and Annal. d. Chem., 163; Masius and Vanlair, 

 Centralbl. f. d. med. Wissensch., 1871, 369. 



2 I.e. 



3 Ber. d. d. chem. Gesellsch., 30 and 35, and Zeitschr. f . physiol. Chem., 47. 



