CONSTITUENTS OF WINE. 135 



lates, and is precipitated. By drying the grapes, or 

 evaporating a portion of the must, sweet wines may 

 be prepared from all kinds of grapes, and a richness 

 in alcoholic or saccharine contents may be imparted to 

 them, which they did not derive from the grapes. For 

 this purpose grape juice ought to contain 50 per cent, 

 sugar, and this it does not (p. 31). 



As a general rule, harsh wines have most bouquet, 

 that is, supposing them to be good, and not poor 

 in alcohol and sugar. Spirituous wines, more espe- 

 cially heavy, loaded red wines, are apt to undergo in 

 the course of time a considerable change in colour 

 and flavour. 



Such as contain tannic acid are also considerably 

 affected by time, and lose their flavour. 



Effervescing wines generally remain good only for a 

 short time, since they are saturated with carbonic acid 

 condensed in the wine. Since the preparation of effer- 

 vescing wines needs scarcely any chemical explanation, 

 we have not dwelt particularly upon it. The sweet fresh 

 wine still in a state of fermentation is drawn off from 

 the casks in which it would continue to ferment, and 

 at once bottled. Fermentation still continues, and 

 ferment is deposited, and in order to ensure its being 

 deposited against the cork, the bottles are placed with 

 the necks down. The corks are withdrawn and re- 

 placed by others, and this proceeding is continued till 

 the wine remains clear. But fermentation has not 

 yet quite ceased, on the contrary, sufficient carbonic 



