2l6 



PHYSIOLOGICAL CHEMISTRY 



Residue No. i. Unite the portions of the distillate extracted as above and allow 

 the ether to volatilize spontaneously. Evaporate until crystallization begins. 

 Examine the crystals under the microscope. Ammonium chloride predominates. 

 Explain its presence. 



Ether Extract No. i. Add 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, 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 possess an alkaline reaction on cooling. Extract the whole mix- 

 ture with ether in the usual way, using care in the manipulation of the stop cock to 



FIG. 60. AMMONIUM CHLORIDE. 



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 tempera- 

 ture on a water-bath and allow the residue to evaporate spontaneously. Indole 

 and skatole should be present here. Prove the presence of these bodies. For 

 tests for indole and skatole see pages 218 and 219. 



Alkaline Solution No. 2. Make strongly acid with hydrochloric acid and ex- 

 tract 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 pressure within the vessel. The volatile fatty acids are dissolved 

 by the ether (Ether Extract No. 4). 



Ether Extract No. 3. Evaporate this ethereal solution on a water-bath. The 

 oily residue contains phenol and cresol. The cresol is present for the most part as 

 paracresol. Add some water to the oily residue and heat it in a flask. Cool and 

 prove the presence of phenol and cresol. For tests for these bodies see page 219. 



Ether Extract No. 4. Evaporate on a water-bath. The volatile fatty acids 

 remain in the residue. 



