GRAPES. 245 



grapes may be preserved a year, by being gathered in the 

 afternoon of a dry day, and enclosed in a dry, tight cask ; 

 being laid singly, and in layers, between alternate layers 

 of thoroughly kiln-dried bran. 



Sherbet constitutes a cooling and wholesome drink of 

 the Mohammedans. It consists of the unfermented juice 

 of the grape, mixed with water, sugar, and spices. 



The unfermented juice of the grape, which constitutes 

 the essential elements of wine, consists of, 1st, water ; 2d, 

 sugar; 3d, tartaric acid; 4th, mucilage; each in different 

 proportions. But after fermentation, wine contains, by 

 chemical analysis, 1st, water; 2d, alcohol; 3d, sugar; 4th, 

 tartaric, carbonic, and malic acids. It also contains tan- 

 nin, a coloring matter, and a volatile oil. 



Gross or watery wines are extremely difficult to pre- 

 serve and manage. It is far otherwise with those which 

 contain a suitable proportion of the essential elements ; 

 these being comparatively of very easy management. 

 Where the elementary principles are deficient, they should 

 be added at once in the beginning, and before the fer- 

 mentation has commenced. 



In modern France, sugar is now added, when its pres- 

 ence is essentially wanting ; and vineyards which before 

 would never make any thing, or but very poor wine, are 

 now, by this addition alone, rendered productive in good 

 wine ; and the sugar produced from the potato, is now, it 

 is said, much used for this purpose in that country ; and 

 for this purpose it seems to be peculiarly adapted, its taste 

 being intermediate between the sugar of the cane, and the 

 sugar which is produced from the grape. 



From a pound and a half of potato starch, one pound 

 and a quarter of crystalline brown sugar has been obtained. 

 And starch, according to Davy, is converted into sugar by 

 the very simple process of boiling in very diluted sulphuric 

 acid. One hundred parts of starch, four hundred parts of 

 water, and one part of sulphuric acid, by weight, are kept 

 boiling for forty hours ; the loss of water by evaporation 

 being supplied by new quantities. The acid is to be neu- 

 tralized by lime, precisely as the acid which is contained 

 in the juice of the sugar-cane is neutralized, and the sugar 

 is crystallized by cooling. 



The moderate use of good wine is deemed wholesome, 

 especially to convalescents recovering from malignant fe- 

 21* 



