AMOUNT OF ALCOHOL IN WINE. 141 



much is injurious. Besides this, tannic acid appears 

 to check fermentation. If the quantity of these acids 

 be too great, the albuminous matter will be too much 

 checked to allow of its conversion into ferment, and 

 a proportionate quantity of sugar will remain unde- 

 composed. 



Lastly, we mast not overlook the fact that even 

 when the composition of the grape juice is such 

 as favours the formation of alcohol, its amount, 

 which depends upon the maintenance of satis- 

 factory fermentation, must be considerably affected by 

 the weather, as also by the temperature and other 

 external circumstances. 



There are many interesting circumstances con- 

 nected with these facts with which we would gladly 

 be acquainted, but which must be the subject of 

 future investigation. It is well known, for example, 

 that fermentation takes place as well during the forma- 

 tion as during the decomposition of ferment, and that 

 consequently during the fermentation of grape juice 

 and the production of alcohol, the two points must be 

 kept distinct, namely fermentation during formation, 

 and during decomposition of yeast. But, although 

 we know that such a difference does exist, the condi- 

 tions which govern it have never yet been made the 

 subject of research. The influences which might 

 check the formation of yeast differ, at least partially, 

 from those which hinder its decomposition. The 

 formation of ferment is in every case affected by the 



