ANALYTICAL EVIDENCE. 317 



bile by the action of the atmosphere, or of chemical re- 

 agents, may be of importance in reference to certain pa- 

 thological conditions ; but except as concerns the general 

 character of the bile, the knowledge of these products 

 is of no value to the physiologist ; it is only a burthen 

 which impedes his progress. It cannot be maintained of 

 any one of the 38 or 40 substances, into which the bile 

 has been divided or split up, that it exists ready formed 

 in the healthy secretion ; on the contrary, we know with 

 certainty that most of them are mere products of the ac- 

 tion of the re-agents which are made to act on the bile. 



The bile contains soda; but it is a most remarkable 

 and singular compound of soda. When we cause that 

 part of the bile which dissolves in alcohol (which contains 

 nearly all the organic part) to combine with oxide of lead, 

 thus separating the soda, and then remove the oxide of 

 lead, we obtain a substance, choleic acid, which, when 

 placed in contact with soda, forms a compound similar to 

 bile in its taste ; but it is no longer bile ; for bile may be 

 mixed with organic acids, nay, even with dilute mineral 

 acids, without becoming turbid or yielding a precipitate ; 

 while the new compound, choleate of soda, is decomposed 

 by the feeblest acids, the whole of the choleic acid being 

 separated. Hence, bile cannot be considered, in any 

 sense, as choleate of soda. Further, it may be asked, in 

 what form are the cholesterine, and stearic, and margaric 

 acids, which are found in bile, contained in that fluid? 

 Cholesterine is insoluble in water, and not saponifiable by 

 alkalies ; and if the two fatty acids just named were 

 really present in the bile as soaps of soda, they would be 

 instantly separated by other acids. Yet diluted acids cause 

 no such separation of stearic and margaric acids in bile. 



It is possible that, in the course of new and repeated 

 investigations, the composition of the substances obtained 



