ON THE SUGAR OF GRAPE?. 341 



IV. 



All Essay on the Sugar of Grapes ; Bij Professor Proust. 



Concluded from page 316. 



jTaFTER observing, that sugar is become an indispensable ^f^ the Importa- 

 articJe of consumption, Professor Proust expatiates on the were'^sto^pped 

 necessity of finding a substitute for that of the West Indies, that of the 

 should their intercourse with Spain, France, and other con- fubsdt'uted. 

 tinental countries be cutoff; and for this purpose he recom- 

 mends the sugar from grapes. This he confesses is not 

 precisely the same with that of the cane, but may very well 

 supply its place. Without being refined it will answer 

 every purpose, in which colour is no object, as for sweet- 

 ening coffee, chocolate, or dishes made of milk, in phar- 

 maceutical preparations, &c. 



When refined, says Professor Proust, it is perfectly white, its qualities, 

 but will not acquire the solidity of that of the cane, on 

 account of its granular and porous crystallization ; so that 

 it cannot be made into loaf sugar, unless the art of the 

 sugar-baker furnish him with resources, Avhich I have 

 no room to expect from the trials I have made. 



Its sweetness is evidently inferior to that of the sugar 

 from the cane, so that it must be used in larger quantity ; ' 



and it is not so readily soluble. It dissolves entirely in 

 spirit of wine; but it separates from it much sooner than 

 that of the cane, and always in tuberculous, granular 

 crystals, in which no determinate arrangement of parts can 

 be perceived. 



Presuming, that a comparison of the juice of green Contents of the 

 grapes with that of the perfectly ripe fruit will not be un- """^° J"''^^' 

 interesting, I shall first give a sketch of the results I 

 obtained by analysing it. In it are found, 1, tartar; 2, 

 sulphate of potash ; 3, sulphate of lime ; 4, citric acid in 

 abundance; 5, malic acid a very little ; 6, extractive matter; 

 and, 7, water. 



The citric acid is the chief base of this juice. It con- Would fumi'-h 

 tains neither gum nor saccharine matter : and in those years ^^^ ° lemon=!. 

 when the dearness of lemons does not allow us to extract 



their 



