166 



PHYSIOLOGICAL CHEMISTRY. 



Ether Extract No. r. Add an equal volume of water, render the 

 mixture alkaline with potassium hydroxide and shake thoroughly 

 by means of a separatory funnel as before. The volatile fatty acids, 



FIG. 45- 



AMMONIUM CHLORIDE. 



contained among the putrefaction products, would be dissolved by 

 the alkaline solution (No. i) whereas any indole or skatole would 

 remain in the ethereal solution (No. 2). 



Alkaline Solution No. I. Acidify with hydrochloric acid and add 

 sodium carbonate solution until the fluid is neutral or slightly acid 

 from the presence of carbonic acid. At this point a portion 

 of the solution, after being heated for a few moments, should pos- 

 sess an alkaline reaction on cooling. Extract the whole mixture 

 with ether in the usual way, using care in the manipulation of the 

 stop cock to relieve the pressure due to the evolution of carbon 

 dioxide. The ether (Ether Extract No. 3) removes any phenol 

 or cresol which may be present while the volatile fatty acids will 

 remain in the alkaline solution (No. 2) as alkali salts. 



Ether Extract No. 2. Drive off the major portion of the ether 

 at a low temperature on a water-bath and allow the residue to evap- 

 orate spontaneously. Indole and skatole should be present here. 

 Prove the presence of these bodies. For tests for indole and 

 skatole see pp. 168 and 170. 



Alkaline Solution No. 2. Make strongly acid with hydrochloric 

 acid and extract with a small amount of ether, using a separatory 

 funnel. As carbon dioxide is liberated here, care must be used in 

 the manipulation of the stop cock of the funnel in relieving the 



