STUDIES ON FERMENTATION. 331 



commission to be appointed by our opponent, any quantity of 

 ferment that lie might require, and to effect the fermentation 

 of any weight of sugar whatsoever. 



Our knowledge of the facts detailed in the preceding chap- 

 ters concerning pure ferments and their manipulation in the 

 presence of pure air, enables us to completely disregard those 

 causes of embarrassment that result from the fortuitous occur- 

 rence of the germs of organisms, different in character from the 

 ferments, introduced by the air or from the sides of vessels, or 

 even by the ferment itself. 



Let us once more take one of our double-necked flasks (Fig. 

 22, p. 110), which we will suppose is capable of containing 

 three or four litres (six to eight pints). 



Let us put into it the following : — 

 Pure distilled water. 



Sugar candy . . . . 200 grammes. 



Bitartrate of potassium . . 1*0 ,, 



,, ,, ammonia . . 0'5 „ 



Sulphate of ammonia .. 1*5 ,, 



Ash of yeast .. .. 1-5 ,, 



[1 gramme — 15'43 grains.] 



Let us boil the mixture, to destroy all germs of organisms 

 that may exist in the air or liquid or on the sides of the flask, 

 and then permit it to cool, after having placed, by way of 

 extra precaution, a small quantity of asbestos in the end of the 

 fine, curved tube. Let us next introduce a trace of ferment 

 into the liquid, through the other neck, which, as we described, 

 is terminated by a small piece of india-rubber tube closed with 

 a glass stopper. 



Here are the details of such an experiment : — 



On December 9, 1873, we sowed some pure ferment — 

 saccharomyces j^astoriamts. From December 11, that is, within 

 so short a time as forty-eight hours after impregnation, we saw 

 a multitude of extremely minute bubbles rising almost con- 

 tinuously from the bottom, indicating that at this point the 

 fermentation had commenced. On the following davs, several 



