48 ORGANIC CONSTITUENTS. 



forms a white, earthy, inodorous aud bitter mass, which fuses 

 at 212° without decomposition. In boiling water it undergoes 

 fusion, and dissolves to a small extent ; in this respect it differs 

 from cholinic acid, which fuses but is wholly insoluble in hot 

 water. It is soluble in ether, and its baryta salt dissolves 

 freely in alcohol. 



Fellinic and cholinic acids possess the property' of combining 

 and forming acid compounds with undecomposed bilin, to 

 which Berzelius has given the names of biUfellinic and bilicho- 

 linic acids. 



Bilifellimc acid apparently exists as such in fresh bile : it 

 may be obtained either from bile after the removal of mucus, 

 colouring matters, and other acids, by neutral acetate of lead, 

 or from pure bilin. 



In either case we add a solution of basic acetate of lead, 

 which throws down a flocculent precipitate which soon collects 

 into a soft, tenacious, plastery mass. The salt of lead must be 

 decomposed by carbonate of soda, and the soda-salt in its turn, 

 by sulphui'ic acid : we thus obtain a very soft, almost oily, 

 yellow mass, from which the free sulphuric acid must be 

 removed bv carbonate of lead, and free fellinic and cholinic 

 acids, by ether. We then obtain bilifeUinic acid in the form 

 of a thick syrupy fluid soluble in every proportion of water, 

 and possessing a bitter taste. If this acid be digested with 

 oxide of lead, or decomposed by basic acetate of lead, a plastery 

 bilifellinate of lead is again precipitated, while at the same 

 time piire bilin is found in the supernatant fluid. Hence it 

 appears that bilin combines with fellinic acid in more than one 

 proportion. Bilicholinic acid appears to resemble bilifeUinic 

 acid in almost every respect. 



A mixture of these two bilin-containing acids constitutes 

 Demar9ay^s choleic acid,^ and forms the principal part of 

 Thenard's biliary resin. (Berzelius.) 



On cooling bilin in a solution of caustic potash till ammonia 

 ceases to be developed, we obtain, on evaporation, a clotty 

 matter, Avhich, when dissolved in water and treated with 

 acetic acid, precipitates a peculiar acid, the choUc acid of 

 Gmelin. It forms fine silky acicular crystals, of which the taste 



' This substance is described in the chapter on the Bile. 



