326 ON PLANTS WHICH PRODUCE 



CONVERSATION XXIX. 



ON THE CULTIVATION OF PLANTS WHICH PRODUCE FER- 

 MENTED LIQUORS. 



Mrs. B. There exists in all vegetables, though in 

 very different proportions, a saccharine substance from 

 which sugar is obtained ; and this substance is suscepti- 

 ble of being converted into alcohol, or spirit of wine. For 

 this purpose it is not necessary to resort to the laborato- 

 ry of the chemist : when placed under favorable circum- 

 stances, the transformation takes place spontaneously by 

 a process called fermentation. 



Emily. It is a process with which we are already tol- 

 erably well acquainted, as you explained the different 

 fermentations to us in our Conversations on Chemistry. 



Mrs. B. You will then recollect that the juice of all 

 fruits when expressed, will, (like that of the grape) fer- 

 ment; and that during this process a general disorgani- 

 sation of the parts takes place, and a new arrangement 

 is established, in consequence of which the sugar or sac- 

 charine matter contained in the liquor will be converted 

 into spirit. But fermentation is not confined to the juice 

 of fruits : spirit may be obtained from any part of a plant 

 containing the saccharine principle ; thus the sap of the 

 palm-tree, when fermented, produces palm wine. 



Caroline. It is to be regretted that we have no trees 

 whose sap can be fermented : it would be so much more 

 easily obtained than fruit. 



Mrs. B. The sap of the birch is sometimes fermented. 

 But you may recollect that the vinous fermentation is fre- 

 quently followed by another of a very different nature, 

 called the acetous fermentation, which reduces the wine 

 or spirit to vinegar : this occurs in some measure with 

 the fermented sap of the birch ; it becomes slightly acid, 

 and may therefore be considered rather as a refreshing 

 than a spirituous beverage, AH sap would yield spirit; 

 but, independently of its susceptibility of turning acid, 



1759. What substance in vegetables may be converted into alcohol's 

 1760. By what process may it be done 1 ? 1761. What changes take 

 place in this process 1 1762. How is palm wine produced 7 ? 1763. 

 -'By what process and from what is vinegar produced 1 ? 



