XIII. ALCOHOLIC FERMENTATION 



A. The development of heat by alcoholic fermentation: 



1. In these experiments fresh compressed yeast may 

 be used, and, for a fermenting substance, either 

 commercial molasses (20 c.c.) in water (100 c.c.), 

 or Pasteur's solution, made up as follows: 



Pasteur's Fermentation Solution 



Grape sugar 150 c.c. 



Ammonium tartrate. 10 c.c. 



Magnesium sulphate 2 grams 



Calcium phosphate 2 grams 



Potassium phosphate 2 grams 



Distilled water 838 c.c. 



Experiment 33. To ascertain what temperature change 

 accompanies alcoholic fermentation. 



2. Place about 5 grams of compressed yeast in 250 

 c.c. of the Pasteur's solution, shake well, and pour 

 into a Dewar flask. 



3. Place a similar amount of distilled (or tap) water 

 in a second flask. 



4. Record the temperatures of both liquids at once, 

 using two thermometers which should remain in 

 the liquids until the experiment is over. 1 The 

 experiment will work best if the liquids are at 

 about 25C. 



1 The instructor will, of course, understand the necessity of carefully 

 comparing the initial readings of the thermometers, where two or more are 

 used, and of making necessary corrections in subsequent readings. 



So 



