344 VINOUS FERMENTATION. 



various modifications in the nature of the products 

 generated. 



Whatever opinion, however, may be held regard- 

 ing the origin of the volatile odoriferous substances 

 obtained in the fermentation of wine, it is quite cer- 

 tain that the characteristic smell of wine is owing 

 to an ether of an organic acid, resembling one of the 

 fatty acids (cenanthic ether). 



It is only in liquids which contain other very solu- 

 ble acids, that the fatty acids and cenanthic acids are 

 capable of entering into combination with the ether 

 of alcohol, and of thus producing compounds of a 

 peculiar smell. This ether is found in all wines 

 which contain free acid, and is absent from those in 

 which no acids are present. This acid, therefore, is 

 the means by which the smell is produced; since 

 without its presence cenanthic ether could not be 

 formed. 



The greatest part of the oil of brandy made from 

 corn consists of a fatty acid not converted into 

 ether ; it dissolves oxide of copper and metallic ox- 

 ides in general, and combines with the alkalies. 



The principal constituent of this oil is an acid 

 identical in composition with cenanthic acid, but 

 different in properties. (Mulder.) It is formed in 

 fermenting liquids, which, if they be acid, contain 

 only acetic acid, a body which has no influence in 

 causing other acids to form ethers. 



The oil of brandy made from potatoes is the hy- 

 drate of an organic base analogous to ether, and 

 capable, therefore, of entering into combination with 

 acids. It is formed in considerable quantity in fer- 

 menting liquids which are slightly alkaline; under 

 circumstances, consequently, in which it is incapable 

 of combining with an acid. 



The products of the fermentation and putrefaction 

 of neutral vegetable and animal matters are gener- 

 ally accompanied by substances of an oiFensive odor; 

 but the most remarkable example of the generation 

 of a true ethereal oil is seen in the fermentation of 



