THE BILE. 175 



CHAPTER VIII. 



THE BILE. 



THE bile is more easily obtained in a state of purity than any 

 other of the secretions which find their way into the intestinal 

 canal, owing to the existence of a gall-bladder in which it accu- 

 mulates, and from which it may be readily obtained without anv 

 other admixture than the mucus of the gall-bladder itself. Not- 

 withstanding this, its study has proved an unusually difficult one. 

 This difficulty has resulted from the peculiar nature of the biliary 

 ingredients, and the readiness with which they become altered by 

 chemical manipulation ; and it is, accordingly, only quite recently 

 that we have arrived at a correct idea of its real constitution. 



The bile, as it comes from the gall-bladder, is a somewhat viscid 

 and glutinous fluid, varying in color and specific gravity according 

 to the species of animal from which it is obtained. Human bile is 

 of a dark golden brown color, ox bile of a greenish yellow, pig'.s 

 bile of a nearly clear yellow, and dog's bile of a deep brown. We 

 have found the specific gravity of human bile to be 1018, that of 

 ox bile 1024, that of pig's bile 1030 to 1036. The reaction of the 

 bile with test-paper cannot easily be determined ; since it has only 

 a bleaching or decolorizing effect on litmus, and does not turn it 

 either blue or red. It is probably either neutral or very slightly 

 alkaline. A very characteristic physical property of the bile is 

 that of frothing up into a soap-like foam when shaken in a test- 

 tube, or when air is forcibly blown into it through a small glass 

 tube or blowpipe. The bubbles of foam, thus produced, remain 

 for a long time without breaking, and adhere closely to each other 

 and to the sides of the glass vessel. 



The following is an analysis of the bile of the ox, based on the 

 calculations of Berzelius, Frerichs, and Lehmann : 



