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166 FERMENTATION OF WINE. 



concentrate the must by boiling, because, in the latter 

 case, a portion of the azotized matter necessary to its 

 subsequent fermentation, is rendered insoluble and 

 useless. Care must, however, be taken not to add too 

 much sugar, as, when this is done, fermentation pro- 

 ceeds very slowly ; the proportion of sugar should in 

 no case be greater than one-eleventh of the weight of 

 the must. 



389. During the two stages of fermentation through 

 which the must passes, the greater part of the azo- 

 tized matter undergoes decomposition, becomes inso- 

 luble, and falls down, constituting, together with the 

 other insoluble matters, the lees of the wine. The 

 sugar disappears, carbonic acid gas is given off, and 

 alcohol formed. A small quantity of certain peculiar 

 volatile oils is also formed, to the formation of which 

 the wine owes its flavor, or bouquet. A considerable 

 quantity of tartar or bitartrate of potassa likewise is 

 thrown down during the fermentation of the wine. 

 This salt, which is soluble in water, but almost inso- 

 luble in a mixture of water with spirit of wine, exists 

 naturally in the juice of the grape; as the ferment- 

 ation proceeds, and alcohol is formed, the tartar 

 being consequently no longer soluble in the liquid, is 

 deposited in the form of crystals on the side and 

 bottom of the cask (498). 



390. The fermentation and ripening of wine con- 

 tinues for a long time in the wood ; a small quantity 

 of undecomposed azotized matter remains in the wine; 

 this acts as a very slow ferment, and hence the wine 



