BILE. Syn. Gall. (Gr. xoNo); Lat. bilis ; Fr. bile ; Ger. die Galle ; Ital.jiele.)—This im portant secretion has been laboriously examined by several modern chemists of eminence, among whom we may especially enumerate Tlienard, Berzelius,t Tiedemann and Gmelin,X and Frommlierz and Gugert.§ Their results, how ever, are so much at variance, that it is impos sible to draw any general conclusions from them respecting the real nature and chemical components of the bile ; these discrepancies seem partly to arise from the extreme facility with which chemical agents react upon this secretion, so that many of the supposed educts or component parts which have been enume rated, are probably products of the different operations to which has been submitted, or at all events modifications of its true proximate elements : it has been therefore well observed by Berzelius, that our present chemical know ledge of the nature of bile can only be consi dered as a foundation for the more extended and satisfactory researches of future experimen talists. We shall here endeavour to select some of the least disputable and most import ant facts respecting the chemical properties of the bile, remarking at the outset to those who may be inclined to repeat the experiments which we shall cite, that the indications of re agents upon different specimens of bile are apt to vary, and that their action is often much modified by temperature, quantity, and the mode in which they are used.
There always appears to be mixed with bile a variable proportion of mucus, probably deri ved from the gall-bladder and its ducts, and not, therefore, a true component of the secre tion : this gives the bile its viscidity, and often seems in some way to modify its other charac ters: in general, however, (ox-gall,) it is a green liquid, varying much in tint, of a pecu liar odour, a bitter and nauseous taste, and a specific gravity fluctuating between 1.020 and 1.030. It does not coagulate when heated, and although it may possibly contain albumen, or something very like it, it is not immediately coa gulated by alcohol or by dilute acids. The rela ti ye proportion of solid matter obtained by evapo ration is between eight and ten per cent. By means of acetic acid, the mucus which is mixed with the bile may to a great extent be separated. In the mammalia, generally, the bile exhibits nearly the same characters; and in birds and fishes its components seem to be the same, but rather more dilute in the former and more con centrated in the latter: it is always alcaline, from the presence of soda, apparently in the same state of combination as it exists in the serum of the blood. When bile is evaporated very care
fully to about half its bulk, and alcohol added, (in the proportion of about four parts to one of the evaporated bile,) a coagulated matter is thrown down, which has some of the proper ties of albumen ; yet neither solution of corro sive sublimate, nor of ferroeyanate of potassa, which are such delicate tests of that proximate animal principle in other cases, enables us to detect it in the original bile. When alcohol is added to bile which has been evaporated nearly to dryness, it acquires, when filtered off, a brownish green colour and bitter taste ; when evaporated, it leaves a residue which is almost totally soluble in water; and in this aqueous solution, dilute sulphuric acid slowly throws down a grey substance, which appears to be a compound of the acid and the bitter principle of the bile; when it has been washed with water (in which it is not soluble), it dissolves in alcohol, and if the sulphuric acid be then separated from it by carbonate of baryta and filtration, the filtered solution leaves on evapo ration a green, transparent, bitter residue, which appears to be the characteristic princi ple of the bile, and which Berzelius calls Gal lenstolf. As thus obtained, it is not quite free from foreign matters, and ether digested upon it takes up a little fatty matter ; indeed when bile, concentrated by evaporation, is agitated with ether, and the latter, after having separated upon the surface, is poured off and evaporated, it always leaves traces of a fatty substance, probably identical with cholesterine. The pu rified bitter residue, to which we have just adverted, is apparently the picromel of Thenard; it has a bitter, pungent, and sweetish taste, is inflammable, deliquescent, soluble in water and alcohol, but insoluble in ether ; its solu tion is precipitated by many acids, (not by acetic or phosphoric,) and the precipitate is nearly insoluble in water, of a greenish colour, resinous appearance, and fusible at This precipitate (consisting of picromel combined with the acid used to throw it down) dissolves in alcohol, and is again thrown down by water : it dissolves in solution of acetate of potash, the alcali of which combines with the acid of the precipitate, whilst the acetic acid unites to the picromel to form a soluble acetate. Picromel dissolves in weak alcaline solutions apparently without decomposition.