CHEMICAL SCIENCE. 313 



It is not strange that the grapes which grow on the sunny side of the 

 Johannisberg should be very superior, as far as the flavor and fragrance of 

 their juice is concerned, to those produced on the opposite side of the moun- 

 tain ; nor that, in general, a hotter and stronger wine is produced in warm 

 regions than in such as are cold or temperate. If we add to this, that the 

 peculiar nature of the soil, its constituent?, the influx and drainage of water, 

 the lightness or stiffness of the ground in which the roots spread ; that, 

 further, the dry ness or dampness of the air, and the change or equality of 

 temperature, exercise a well known influence upon plants and the fruits pro- 

 duced by them, we shall at least have a general idea of the varieties of 

 the juice which constitute the principal element of these berry-bearing 

 fruits. 



It is, moreover, sufficiently known that there is a general difference in the 

 color of grapes, between black, purple or red, and white ; the juice of both 

 is colorless, and colorless wine can therefore be obtained from both. If the 

 black, purple, or red grapes are pressed, and the skins thrown aside, a color- 

 less wine, which in substance equals that procured from the juice of the 

 white grape, is obtained by fermentation. I say substantially, for the variety 

 in the juices, which even a slight difference in the external influences occa- 

 sions, would effectually prevent the one fermented liquid from equalling the 

 other in flavor and aroma. Or is it, perhaps, that the heat of the sun pene- 

 trates more thoroughly the purple grape, wliile its dark skin partially pre- 

 serves it from the action of light 1 



Is then, the same chemical action possible to the juice of the purple grape 

 (inclosed, as it were, in a small bladder) as that which is produced in the 

 juice of the white grape by the difference between these two powerful influ- 

 ences, heat and light 1 TTe know that in our regions the white grapes are 

 much sweeter than the purple, and ascribe this peculiarity to the difference 

 of the plants, Irit forget that in the easier passage of the light through the 

 colorless skin of the white grape we possess a sufficient explanation of a 

 more powerful chemical action, the result of which may be a larger forma- 

 tion of sugar. And if we generally find the purple grapes inferior in flavor 

 and smell, we must ascribe this circumstance to heat, which in this case 

 penetrates more easily the skin of the grape, and which in all living things 

 is a powerful means of exciting chemical action. 



The opinion that wine which has grown old iu bottles has therefore become 

 richer in alcohol, is thoroughly f'ul-c. I do not deny that the alcoholic con- 

 tents of many old wines is considerable, but I d.-ny that the wine being kept 

 in bottles increases it. Evaporation is very much hindered by the cork, even 

 when it is not covered with resin and scaling wax. Th s wir which exists, 

 for example, in red wine, is in too insignificant a quantity to evolve alcohol 

 by means of fermentation ; and in old wine, the opening of tae bottle causes 

 no escape of carbonic acid. Therefore, the formation of alcohol in the bot- 

 tles is impossible. The simple explanation of our finding old wine rich in 

 alcohol is, that only the stronger wines can be preserved, and the weaker 

 ones cannot resist the effects of time. The color of wine is materially 

 affected by another change which it undergoes when ceii;:r ! (I am sup- 



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