OILY AND ETHEREAL PRODUCTS. 313 



The fermentation of pure sugar in contact with yeast must evi- 

 dently be a very different process from the fermentation of wort 

 or of must* 



In the former case, the yeast disappears during the decompo- 

 sition of sugar ; but in the latter, a transformation of gluten 

 is effected at the same time, by which ferment is generated. 

 Thus yeast is destroyed in the one case, but is formed in the 

 other. 



Now, since no free hydrogen gas can be detected during the 

 fermentation of beer and wine, it is evident that, since the oxida- 

 tion of the gluten, that is, its conversion into ferment, must take 

 place at the cost either of the oxygen of the water, or of that of 

 the sugar; either the hydrogen liberated must enter into new 

 combinations, or by the dooxidation of the sugar, new compounds 

 containing a large proportion of hydrogen, and small quantity of 

 oxygen, together with the carbon of the sugar, must be formed. 



It is well known that wine and fermented liquors generally 

 contain, in addition to the alcohol, other substances which could 

 not be detected before their fermentation, and which must have 

 been formed, therefore, during that process, in a manner similar 

 to the production of mannite. The smell and taste distinguishing 

 wine from all other fermented liquids are known to depend upon 

 an ether of a volatile and highly combustible acid ; the ether is 

 of an oily nature, and has received the name (Enanthic ether. 

 It is also ascertained that the smell and taste of brandy from corn 

 and potatoe are owing to a peculiar oil, the oil of potatoe spirit 

 This oil is more closely allied to alcohol in its properties, than to 

 any other organic substance. 



These bodies are products of the deoxidation of the substances 

 dissolved in the fermenting liquids; they contain less oxygen 

 than sugar or gh.'en. but are remarkable for their large propor- 

 tion of hydrogen. 



(Enanthic acid contains an equal number of equivalents of 

 carbon and hydrogen, exactly the same proportions of these 

 elements, therefore, as sugar, but by no means the same pro- 

 portion of oxygen. The oil of potatoes contains much more 

 hydrogen. 



* The liquid expressed from grapes when fully ripe is called must 

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