84 TiMEHRI. 



Yeast develops best in a slightly acid medium — this 

 acidity should not exceed i per cent. — and at a temper- 

 ature of 92 deg. F. If the temperature rises higher, its 

 power is weakened, while that of its enemy, the Ia6lic 

 acid ferment, is increased. The Ia6lic acid ferment 

 developes best in a neutral medium at a temperature of 

 112 deg. F., but if the acid amounts to 2 per cent, its 

 a6lion is stopped. But, on the other hand, if the acid is 

 allowed to accumulate, mouldiness is set up. 



The only means of escape then is to start such a 

 vigorous fermentation that the predominance of the 

 yeast will entirely obscure the harm done by the other 

 ferments or kill them to a great extent ; for in fermen- 

 tation, as well as in everything else, it is only that 

 which is adapted to the environment that flourishes. 



As it is in the beginning of the fermentation that the 

 la6tic acid ferment is likely to get a hold, the necessity 

 for quick starting of the alcoholic fermentation is 

 obvious. Towards the end both the alcohol and the acid 

 developed keeps it in check, but neither of these (the 

 alcohol and acid) restrain much the aftion of the acetic 

 acid ferment which begins to be very evident towards 

 the end of the alcoholic fermentation. The appearance 

 of a peculiar film on the surface of the wash indicates 

 the presence of a species of Saccharomvces that is busy 

 changing the spirit into acetic acid. It should be beaten 

 down under the surface where it cannot obtain the oxygen 

 necessary to destroy the spirit. 



This is not the Acetic Acid ferment proper. It 

 developes throughout the whole wash and is quite a 

 different organism. It flourishes best at the same tem- 

 perature as yeast and is thus difficult to restrain, 



