THE BILE. 273 



Bile is a reddish yellow (especially in carnivorous animals) 

 or green (in herbivora) fluid, with faint alkaline reaction and 

 bitter taste. That found in the gall bladder is more concen- 

 trated than that obtained directly from the liver. Bile contains 

 sodium and potassium salts of the so-called bile acids, mucin, 

 or other albumin (to which its viscidity is due), bile pigments, 

 lecithin, cholesterin, fats, soaps, and mineral matter. 



The bile acids are chiefly glycockolic acid, C 2G H 48 NO (i , and 

 taitrocholic acid, C 2(i H 45 N0 7 S. These are both monobasic 

 acids and give with strong sulphuric acid and cane sugar (or 

 better with a minute trace of furfurol) characteristic colour 

 reactions (Pettenkofer's reaction). The liquid becomes suc- 

 cessively cherry red, dark red, and finally purple violet. The 

 acids and their alkaline salts have a strong bitter taste. Solu- 

 tions of sodium or potassium salts of both acids have solvent 

 powers for soaps, lecithin, and cholesterin. 



The acids undergo hydrolysis, taurocholic acid the more 

 readily, yielding, in the one case, (jlycocoll and cholalic acid, and 

 in the other, taurine and cholalic acid, thus : 



C 2(i H 43 N O fl + H a O = CH 2 (NH 2 )COOH + C 24 H 40 5 

 and C 2(i H 45 N0 7 S + H 2 O = CH 2 (NH 2 ).CH 2 .S0 2 .OH + C 24 H 40 5 . 



Glycocoll glycocine amido-acetic acid ''sugar of glue," 

 CH 2 (NH 2 ).COOH, is a crystalline body, of sweet taste, very 

 soluble in water, and of acid reaction. It is also produced by 

 the decomposition of hippuric acid, C r> H G .CO.NH.CH 2 .COOH, 

 and in the pancreatic digestion of gelatine 



Taurine, amido-ethyl sulphonic acid, NH 2 .CH 2 .CH 2 .SO 2 .OH, 

 is a crystalline, tasteless body, soluble in water, insoluble in 

 alcohol, and of neutral reaction. 



Cholalic acid, C 24 H 40 O, 5 , a monobasic acid, is very slightly 

 soluble in cold water. It has the characteristic bitter taste of 

 the bile acids. 



The bile pigments are chiefly bilimbin and biliverdin. 



These pigments appear to be formed from haemoglobin, or 

 rather hsematin, but contain no iron. 



Bilirubin, C 1(i H 18 N 2 O 8 , is a reddish yellow substance, in- 

 soluble in water but soluble in alcohol or chloroform. It is 

 also soluble in alkalies. It is found in bile, especially in that 



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