96 ANIMAL BASES, 



sidered the bile to be composed. Gmelin's method of obtaining 

 it was the following : 



Ox bile was mixed with muriatic acid, and filtered to separate 

 a mucous or albuminous matter which had precipitated ; the filter- 

 ed liquor being left for some dd^ in repose, some stearic acid 

 was deposited. The filtered liquor was then concentrated by eva- 

 poration till only a small quantity remained. This residue con- 

 sisted of a resinous matter and an acid liquor. The liquor being 

 separated from the resin and still farther concentrated, more of 

 the resin fell, and finally crystals of taurin and of common salt 

 were deposited. The taurin was picked out and purified by a 

 second crystallization. When the resin is dissolved in absolute 

 alcohol and the solution filtered, taurin in small crystals remains 

 on the filter. It may be purified by washing it in absolute alco- 

 hol, dissolving it in water and crystallizing. 



Thus purified taurin consists of transparent colourless crystals. 

 The primitive form is a right rhombic prism with angles of 111 

 44', and 68 16'. But it is usually in six or eight-sided prisms, 

 terminated by four or six-sided pyramids. These crystals crackle 

 under the teeth, and have a sharp taste, neither sweetish nor sa- 

 line. Taurin neither reacts as an acid nor an alkali, and is not 

 altered by exposure to the air, even when heated to 212. 

 When strongly heated taurin melts into a thick liquid, becomes 

 brown, swells, and exhales an agreeable but empyreumatic odour, 

 similar to that of burning indigo. It leaves a charcoal which is 

 easily consumed. When distilled per se it gives a thick brown 

 oil with a little yellow coloured and acidulous water, which con- 

 tains an ammoniacal salt in solution, and reddens a solution of 

 perchloride of iron. 



Taurin dissolves in 15 J times its weight of water at the tem- 

 perature of 54. It is much more soluble in boiling water, and 

 the surplus crystallizes as the solution cools. Boiling alcohol of 

 0*835 dissolves only ji^th part of its weight of taurin, and in ab- 

 solute alcohol it is almost insoluble. 



Concentrated sulphuric acid dissolves it without the assistance 

 of heat, forming a transparent brown liquor from which the tau- 

 rin is not precipitated by water. When this solution is raised 

 to the boiling point its colour becomes darker, but no sulphurous 

 acid is disengaged. Cold nitric acid dissolves taurin readily, and 

 when the acid is evaporated away the taurin remains unaltered. 



The aqueous solution of taurin is not sensibly acted on by 

 muriatic acid, potash, ammonia, alum, chloride of tin, chloride 



