50 FEEMENTATION. 



water; therefore, for such grape juice, or rather for 

 the wine to be produced from it, the alcoholic contents 

 must be under 15 per cent, as maximum, and 7 per 

 cent, as minimum. 



The knowledge that 92 parts alcohol in wine pre- 

 supposes 198 parts grape sugar in the juice, enables 

 us to arrive pretty accurately at the saccharine con- 

 tents originally contained in the grapes. For ex- 

 ample, a port wine containing 16 per cent, (by weight) 

 alcohol, if it has not been mixed with alcohol must 

 have been produced from grape juice containing 34 

 per cent, grape sugar. 



Sugar is found in all wine, though in certain kinds 

 but little exists ; while in Muscadel and others we 

 have 9 per cent, alcohol by weight, and from 22 

 to 24 per cent, residue after evaporation, of which 

 more that 20 per cent, is sugar. Let us suppose 

 20 per cent, sugar in the wine; 19 per cent, sugar 

 is necessary to the production of 9 per cent, alco- 

 hol by weight. 39 per cent, sugar must have been 

 contained in the grape juice before the formation of 

 such a wine was possible. If, therefore, sugar or 

 alcohol has not been purposely added, the composition 

 of such wines leads us to conclude that they were 

 prepared from dried grapes. 



Pew examples are needed to show how close the 

 connexion is between the saccharine contents of the 

 grape juice and the excellence of the wine to be 

 prepared from it. 



