1048 FLUIDS SECRETED SUBSERVIENT TO DIGESTION. 



After being washed and dried, fellinic acid forms a white, 

 . earthy, inodorous and bitter mass which fuses without decom- 

 position at 212. In boiling water it undergoes fusion and 

 dissolves to a small extent ; in alcohol it dissolves easily and 

 the solution has the bitter taste of bile; in ether it is also 

 soluble. Its salts of alkaline bases are soluble both in water 

 and alcohol, but insoluble in an excess of alkali, and then pre- 

 cipitated as a plastic plaster-like substance. The salts of lead 

 and barytes, which are insoluble, have the same appearance. It 

 enters into combination with bilin, and forms in union with it 

 a compound acid, which should be named bilifellinic acid. 



Cholinic acid is separated from its salt of ammonia lately 

 mentioned, by hydrochloric acid, in the form of white flocks, 

 and becomes by aggregation, on drying, an easily pulverised 

 mass. It is readily fused by the heat of hot water, in which it 

 is wholly insoluble ; it dissolves easily in alcohol. 



Biliverdin is separated from its compound with barytes, men- 

 tioned under bilin, by digestion in dilute hydrochloric acid 

 which dissolves the barytes: The residue of biliverdin is 

 purified by solution in alcohol and precipitation from the latter 

 by water. It forms a brilliant, greenish brown tasteless mass, 

 insoluble in water, dissolving easily in an alkali, and precipitated 

 from that solution in green flocks by an acid. It dissolves of 

 a fine green colour in hydrochloric acid, and of a red tint in 

 acetic acid. This principle of bile contains no nitrogen. The 

 biliverdin of the bile of the ox appears to be identical with the 

 chlorophyl of plants. That of carnivorous animals is different, 

 although it may contain the same matter in combination with 

 another substance. Such a substance appears to be the prin- 

 cipal constituent of the yellow matter forming the concretions, 

 found in the ox, which from the beauty and permanence of its 

 tint is much prized by painters. These gall stones dissolve in 

 caustic potash of a greenish brown colour, giving a solution 

 which when over- saturated with nitric acid, becomes first green, 

 and rapidly in succession blue, violet and red, and finally 

 yellow. 



Cholesterin, C 37 H 32 O. This is a crystallizable substance 

 which may be dissolved out of inspissated bile, by ether ; it is 

 also a constituent of the brain and nerves. It is contained in 

 largest proportion by the gall stones of the human subject, 



