248 CHYMISTRY APPLIED TO AGRICULTURE. 



in sweet wine, as there still exists in that a portion of sugar 

 which renders it incapable of undergoing any other than the 

 vinous fermentation ; but when this principle is entirely de- 

 composed, a sufficient degree of heat, the contact of the at- 

 mosphere, and the presence of a little mucilage will cause 

 the acidification of the greater number of wines. 



The acid degeneration generally takes place when the 

 grapes do not contain sugar enough to decompose all the 

 vegeto-animal part : it occurs necessarily in wine which 

 holds in solution mucilage and extract ; and this is always 

 the case when the sugar contained in the grapes is not 

 sufficient to develope much alcohol, and precipitate these 

 substances. 



It appears, from well-confirmed experiments, that the con- 

 tact of the air and the existence of mucilage and extract in 

 wine containing but a small quantity of alcohol, will produce 

 spontaneous acidification. 



Stahl states, that if the flowers of the rose-tree, or the lily 

 of the valley be moistened with alcohol, and the vase con- 

 taining them shaken occasionally, vinegar will be formed. 

 He likewise informs us that when the acid of lemon is satu- 

 rated with lime, if alcohol be thrown upon the remaining 

 portions of the lemon juice, the mixture, when exposed to a 

 gentle heat, produces vinegar. 



The best wine may be converted into vinegar by soaking 

 or steeping green wood in it : the process described by Boer- 

 haave is founded entirely upon this principle : he employed 

 for the purpose the branches of the vine and the stalks of 

 grapes. 



The mash of grapes, the lees of wine, and the residuum 

 of distillation well dried and moistened with a little alcohol 

 and water, undergoes the acetous fermentation. The juices 

 of most other fruits, as well as of grapes, may be made, by 

 fermentation, to produce a spirituous liquor to be used either 

 as drink, or to furnish alcohol by distillation. 



The practice of fermenting various kinds of bread corn, 

 particularly rye and barley, has existed for a long time, 

 and from them are produced, by distillation, the liquors 

 that are most used in those countries where the vine is not 

 cultivated. 



Since the culture of the potato has been so astonishing- 

 ly extended in Europe, the uses of it have been multiplied, 

 and it is now fermented for the purpose of obtaining alco- 

 hol by distillation. The first process which was followed 



