180 THE BILE. 



considerably in size, clear, transparent, strongly refractive, and 

 bounded by a dark, well-defined outline. These drops are not to be 

 distinguished, by any of their optical properties, from oil- globules, as 

 they usually appear under the microscope. They have the same 

 refractive power, the same dark outline and bright centre, and the 

 same degree of consistency. They would consequently be liable at 

 all times to be mistaken for oil-globules, were it not for the complete 

 dissimilarity of their chemical properties. 



Both the glyko-cholate and tauro-cholate of soda are very freely 

 soluble in water. If the mixture of alcohol and ether be poured 

 off and distilled water added, the deposit dissolves rapidly and 

 completely, with a more or less distinct yellowish color, according 

 to the proportion of coloring matter originally present in the bile. 

 The two biliary substances present in the watery solution may be 

 separated from each other by the following means. On the addi- 

 tion of acetate of lead, the glyko-cholate of soda is decomposed, 

 and precipitates as a glyko-cholate of lead. The precipitate, sepa- 

 rated by nitration from the remaining fluid, is then decomposed in 

 turn by carbonate of soda, and the original glyko-cholate of soda 

 reproduced. The filtered fluid which remains, and which contains 

 the tauro-cholate of soda, is then treated with subacetate of lead, 

 which precipitates a tauro-cholate of lead. This is separated by 

 filtration, washed, and decomposed again by carbonate of soda, as 

 in the former case. 



The two biliary substances in ox bile may, therefore, be dis- 

 tinguished by their reactions with the salts of lead. Both are 

 precipitable by the subacetate; but the glyko-cholate of soda is 

 precipitable .also by the acetate, while the tauro-cholate is not so. 

 If subacetate of lead, therefore, be added to the mixed watery solu- 

 tion of the two substances, and the whole filtered, the subsequent 

 addition of acetate of lead to the filtered fluid will produce no pre- 

 cipitate, because both the biliary matters have been entirely thrown 

 down with the deposit ; but if the acetate of lead be first added, it 

 will precipitate the glyko-cholate alone, and the tauro-cholate may 

 afterward be thrown down separately by the subacetate. 

 - These two substances, examined separately, have been found to 

 possess the following properties : 



G-lyko-cholateof soda(N&0,G 52 TI 42 ~NO u ) crystallizes, when precipi- 

 tated by ether from its alcoholic solution, in radiating bundles of 

 fine white silky needles, as above described. It is composed of 

 soda, united with a peculiar acid of organic origin, viz., glyko-cholic 



