286 VINOUS FERMENTATION. 



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 gluten, but 

 are remarkable for the large quantity of hydrogen 

 which enters into their composition. 



(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 proportion of 

 oxygen. The oil of potatoes contains much more 

 hydrogen. 



Although it cannot be doubted that these volatile 

 liquids are formed by a mutual interchange of the 

 elements of gluten and sugar, in consequence, 

 therefore, of a true process of putrefaction, still it 

 is certain, that other causes exercise an influence 

 upon their production and peculiarities. 



The substances in wine to which its taste and 

 smell are owing are generated during the fermen- 

 tation of the juice of such grapes as contain a certain 

 quantity of tartaric acid ; they are not found in 

 wines which are free from all acid, or which con- 

 tain a different organic acid, such as acetic acid. 



The wines of warm climates possess no odour ; 

 wines grown in France have it in a marked degree, 

 but in the wines from the Rhine the perfume is 

 most intense. The kinds of grapes on the Rhine, 

 which ripen very late, and scarcely ever completely, 



