CHOLIC ACID. 125 



In healthy solid excrements Pettenkofer* found no substance 

 yielding this biliary reaction ; the dejections in cases of diarrhoea, on 

 the other hand, always contained a substance yielding this reaction. 

 I have, however, always been able to detect a little cholic acid in 

 perfectly normal excrements. 



The alcoholic extract of previously dried solid excrement pre- 

 sented no reaction with sulphuric acid and sugar ; but on further 

 treating this extract with ether, and on purifying the residue of the 

 ethereal solution, by means of water, from the fatty acids which 

 are always mixed with it, I found that the somewhat concentrated 

 aqueous solution (of this ethereal extract) presented the biliary 

 reaction most beautifully. On using a larger quantity of material, 

 the acid was obtained in a crystalline state; as it yielded no am- 

 monia when treated with potash, and as its baryta-salt was soluble, 

 it could hardly have been any other than cholic acid. 



In the intestinal canal we can detect the presence of bile in the 

 contents of the whole of the small intestine, by the addition of 

 sulphuric acid to the alcoholic extract, in the manner above 

 described. 



If I rightly recollect, Pettenkofer informed me, in a private 

 communication, that he had already made this observation. I 

 have repeatedly convinced myself of its accuracy in animals; in 

 the case of an intestinal fistula, where it could not be determined 

 with certainty whether the perforation was in the small or large 

 intestine, and where no conclusion could be drawn from the absence 

 of villi, the diagnosis was established by the bile- test. It was sub- 

 sequently proved that the fistula occurred in the small intestine. 



That substances containing or yielding cholic acid sometimes 

 occur in exudations, requires no proof, as the blood is frequently 

 overloaded with such matters. 



I will here only mention that in the dropsical exudations occur- 

 ring in a case of granular liver, and in another case of insufficiency 

 of the mitral valves with stoppage of the biliary ducts, I found a 

 considerable quantity of biliary matter. This subject is more fully 

 noticed in the chapter on " Exudations." 



The presence of biliary matters in morbid saliva and expectora- 

 tion, is asserted by Wright, f but has not been proved. 



Origin. As we must return, in a future page, to the different 

 opinions which are maintained regarding the origin of the essential 

 constituents of the bile, we shall here only notice such points as 



* Ann. d. Ch. u. Pharm. Bd. 53, S. 90-96. 

 f The Lancet, 1842-3. Vol. 1, p. 559. 



