APPENDIX. 74:5 



are certain coloring and excrementitious matters, which are also most- 

 likely distinct decomposition compounds. 



Pigments, etc. 



Bilirubin, C 9 H 9 N0 2 , is the best known of the bile pigments. It is 

 best made by extracting inspissated bile or gall stones with water (which 

 dissolves the salts, etc.), then with alcohol, which takes out cholesterin, 

 fatty, and biliary acids. Hydrochloric acid is then added, which decom- 

 poses the lime salt of bilirubin and removes the lime. After extracting 

 with alcohol and ether, the residue is dried and finally extracted with 

 chloroform. It crystallizes of a bluish-red color. It is allied in compo- 

 sition to hematin. 



Biliverdin, C 8 H 9 N0 2 , is made by passing a current of air through an 

 alkaline solution of bilirubin, and by precipitation with hydrochloric 

 acid. It is a green pigment. 



Bilifuscin, C 9 H U N0 3 , is made by treating gall stones with ether, 

 then with dilute acid, and extracting with absolute alcohol. It is a non~ 

 crystallizable brown pigment. 



Biliprasin is a pigment of a green color, which can be obtained from 

 gall stones. 



Bilihumin (Staedeler) is a dark brown earthy-looking substance, of 

 which the formula is unknown. 



Urochrome (see p. 368). 



Urobilin occurs in bile and in urine, and is probably identical with 

 stercobilin, which is found in the faeces. 



Uroef ythrin is one of the coloring matters of the urine. It is orange- 

 red and contains iron. 



Melanin is a dark brown or black material containing iron, occur- 

 ring in the lungs, bronchial glands, the skin, hair, and choroid. 



Choletelin (p. 369). 



Haematin has been fully treated of, p. 86, et seq. 



Indican is supposed to exist in the sweat and urine. It has not, how- 

 ever, been satisfactorily isolated. 



Indigo, C 8 H 5 N 9 0, is formed from indican, and gives rise to the 

 bluish color which is occasionally met with in the sweat and urine (also- 

 369). 



Indol, C 8 H 2 N, is found in the faeces, and is formed either by decom- 

 position of indigo, or of the proteid food materials. It gives the char- 

 acteristic disagreeable smell to faeces (see p. 272). 



(4.) Nitrogenous Bodies of Uncertain Nature. 



Ferments are bodies which possess the property of exciting chemical 

 change in matter with which they come in contact. They are at present 



