FERMENTATION OF WINE. 165 



385. The must, as the expressed juice of the grape 

 is called, being left undisturbed in the fermenting 

 tun, soon passes into a state of active fermentation; 

 the azotized matter decomposes, causing at the same 

 time the decomposition of the sugar; the liquid be- 

 comes turbid and froths up from the escape of carbo- 

 nic acid. After a time these appearances cease, the 

 liquid clears, and fermentation becomes very feeble. 



386. The fermentation of the wine, however, is 

 not yet completed; the half- formed wine is racked 

 off into casks, and allowed to continue slowly ferment- 

 ing for some time, the casks being kept quite full, so 

 that the froth and ferment which rises to the open 

 bunghole, easily escapes as fast as it rises. When 

 it is judged that this second fermentation has con- 

 tinued long enough, the casks are closed and left for 

 some time. 



387. As the quantity of alcohol which is thus pro- 

 duced depends wholly on the proportion of sugar 

 which existed in the must, so, when the grapes are not 

 sweet, and the quantity of sugar is small, the wine 

 formed will be very weak. In such cases, therefore, 

 either the must is concentrated by evaporation, or a 

 portion of sugar is added to augment the proportion 

 of fermentable matter in the must. Much better 

 wine is formed by thus increasing the sugar in the 

 must previous to its being fermented, than by the 

 addition of spirit to the wine when its fermentation 

 is complete. 



388. It is generally better to add sugar than to 



