FERMENTATION. 53 



addition of that portion which has been exposed to 

 evaporation. 



It follows of course that, since the must necessarily 

 loses by evaporation, the wine suffers diminution in 

 quantity. 



One or other of these adulterations may however be 

 considered certain after an unfavourable summer. 



Let us now pass to the consideration of the liquid 

 as it flows from the wine-press. 



Shortly after pressing, the liquid appears to be in 

 motion, and little air bubbles rise to the surface ; fer- 

 mentation has begun ; the juice, not quite clear at first, 

 becomes more turbid, the motion of the liquid in- 

 creases, and froth is formed on the surface ; the gas 

 bubbles become larger, the consistency of the liquid 

 decreases, as do also its saccharine contents. In place 

 of these more and more alcohol is engendered, and 

 the liquid, originally watery, and now enriched with 

 alcohol to a greater or less degree, can no longer 

 retain in a state of perfect solution various matters 

 which it previously held in that condition. Fermen- 

 tation reaches its highest point with greater or less 

 rapidity according to the temperature ; in a moderate 

 climate it generally occurs in from three to four days. 



When the fermentation is diminishing, and before 

 it is completely finished, the whole mass of liquid is 

 stirred up, in order to bring its elements into contact 

 with each other afresh. I know not whether the 

 practice still exists ; but till within a few years, in 



