CHAP. IV.] PHYSICAL PROPERTIES OF THE BILE. 289 



the spectrum, but before it has come in contact with air presents no 

 definite absorption bands ; in other words, at the time of death the 

 bile does not contain any body possessing the optical properties of 

 the cholohaematin of MacMunn, but a chromogen from which cholo- 

 haematin is rapidly developed (Gamgee). The main colouring 

 matter on which the green colour depends exhibits no absorption 

 bands. 



The brown tint which human bile, collected in the gall-bladder 

 mortem, usually possesses, and which frequently is exhibited 



the bile obtained from biliary fistulse, when, through septic 

 invasion, catarrh of the gall-bladder has been set up, is due to a 

 change which the normal pigment has undergone. 



When exposed to the air, bile which when fresh had a reddish- 

 yellow colour, may assume a grass-green tint similar to that of the 

 herbivora. Conversely, the green bile of the ox when decomposing 

 in the absence of air, loses its green colour and becomes brown. 

 The causes of these changes in colour will be treated of in discussing 

 the colouring matters of the bile. 



Taste. The bile possesses at first a characteristic sweet-bitter, 



almost immediately followed by a purely bitter, taste, which is 

 imparted to it by the bile acids which it contains. 



Odour. The fresh bile is usually destitute of smell. The bile 



of the ox and sheep when concentrated on the water bath often 

 exhales a faint musk-like odour. 



Density. The density of the bile which is flowing freely from a 

 fistula is much lower than that of bile obtained from the gall- 

 bladders of animals post mortem. 



According to Frerichs, the specific gravity of human (gall-bladder) 

 bile varies between 1*03 and 1*04. According to v. Gorup-Besanez, 

 the specific gravity of human bile varies between 1*0105 and 1*032. 

 On the other hand, the most reliable determinations of the density 

 of bile from biliary fistulse in man give results which never approached 

 the higher limit assigned by Gorup-Besanez. O. Jacobsen 1 , in his 

 examination of the bile of a man with biliary fistula, found the 

 density to vary between 1*0105 and 1*0107 (t. 17'5 C.). Copeman 

 and Winston 2 found it to range between 1*0085 and I'OlOo. Yeo 

 and Herroun 3 found the density to vary between 1*008 and 1*0082. 

 In Mayo Robson's case, Fairley found it to vary between 1'0085 

 and 1*0090. Noel Paton and Balfour observed variations between 

 1*0054 and 1*008. 



1 Osc. Jacobsen, ' Untersucbung menschlicber Galle.' Ber. d. deutsch. Chem. 

 Gesellschaft. Vol. vi. (1873), p. 1026. 



2 Copeman and Winston, loc. cit., p. 221. 



3 Yeo arid Herroun, ' A note on tbe composition of Human Bile obtained from a 

 fistula.' Journal of Physiology, Vol. v. (188384), p. 118. 



G, 19 



