ON THE SUGAR OF GRAPES. 347 



The muscovadoes I have examined were extracted from Black grapes 



the Avhite grape, called alvilla. and the black, called the ^5'*'''^^^."^^''^ . 

 ^ ^ 7 ' / than white, and 



Arragon grape. The first afforded twenty-six per cent, scarcely darker 

 the second thirty. The latter is not perceptibly higher co- <:oio"''cd. 

 loured than the other, as the skin of the grape alone is co- 

 loured, if care be taken not to mix with the must the juice 

 extracted by pressing. It will perhaps excite surprise, that 

 the must, after being freed from its acids, affords a quantity 

 of muscovado equal in weight to the rob: but the reason of 

 this is, that the tartar, the only acid that precipitates with 

 the lime, and a few particles of calcareous citrate and sul- 

 phate, are found in it but in very small quantity. Of this Very little tar- 

 we may judge by the following result, though we may pre- ^^"^ ^" ^^^ *'^P^* 

 sume there is a little more in the common grape than in the 

 muscadine. A pound of the latter duly treated with spirit 

 of wine does not afford more than 48 grains of tartar. 



It is not the tartarous acid, but the malic, that gives Their acid the 

 grapes their sharpness : and this too is but in small quantity, ™^"*^* 

 since a pound of the juice of the muscadine grape does not 

 afford above 40 or 45 grains of malate of lime. Novr if 

 we reckon, that this salt contains one third of its weight 

 of earth, it will follow, that a pound of the fruit does not 

 contain much above 30 grains of acid. 



Hence we may conclude, that the juice of the grape freed Grape juke 

 from its tartar, an effect that may be obtained by simply Jq^v^^q one 

 boiling it down to one third, is already a muscovado little th'i'd almost 

 different from that of the cane, which equally contains ma- 

 lic acid, if no lime have been employed in its preparation. 

 As the sugar of the grape approaches so near that of the transparent 

 cane in its qualities, we may understand why the rob of the'"^^"Se from 

 muscadine^ dried and poured on a marble, affords a trans- 

 parent lozenge, without colour, pleasant to the taste, ahd 

 appearing like barley sugar: but it has the defect of soon 

 growing moist, as the malic acid and liquid sugar occasioa 

 it io deliquesce in a short time. 



It is remarkable, that the common people have already The art of su- 



approached very near the art of making grape sugar, in the^^^"" "^^«^"^g 



preparation of their rob; but the last step, that remained proachcd by 



for them to take, required a kind of reflection, for which ''^^ common 

 ■^ people. 



their education is seldom adapted. At Arganda^ near Ma- 



drid. 



