THEORY OF THE FORMATION OF VINEGAR. 23 



cess with the cooperation of a living organism. Alcohol and 

 oxygen alone do not suffice for this purpose, the presence of nitro- 

 genous bodies and salts, besides that of an organism, being abso- 

 lutely necessary. 



The French chemist, Pasteur, was the first to establish the 

 formation of vinegar as a peculiar process of fermentation, and 

 he maintains that a certain organism, the "vinegar ferment' 7 or 

 " vinegar yeast/' consumes the alcohol, nitrogenous substances and 

 salts, and separates acetic acid, aldehyde, etc., as products of the 

 change of matter taking place in the living organism. On the 

 other hand, the German chemist, Nageli, is of the opinion that 

 the role of the organism is to bring the particles of the substance 

 to be fermented (in this case, alcohol) lying next to it, into such 

 vibrations as to decompose them into more simple combinations 

 in this case, acetic acid, aldehyde, etc. 



The scientific dispute over these two different views is not yet 

 settled, though the majority of chemists are inclined to accept 

 Pasteur's theory. For the practical man it is of no consequence 

 which of these views will be finally accepted as the correct one ; 

 the fact that the process of the formation of vinegar is connected 

 with the living process of an organism is alone of imporauce to 

 him. 



As is well known, organisms producing fermentation are named 

 after certain products which they form in larger quantities, the 

 organism forming alcohol from sugar being, for instance, briefly 

 termed " alcoholic ferment." In this sense we may also speak 

 of a vinegar or acetous ferment, since a definite organism causing 

 the formation of larger quantities of acetic acid from alcohol is 

 known, and the cultivation of this ferment is one of the principal 

 tasks of the manufacturer of vinegar. 



Numerous observations have established the fact that the pro- 

 perties of forming large quantities of acetic acid are inherent 

 only in this ferment. Small quantities of acetic acid are, how- 

 ever, also constantly formed by other ferments, so that in examining 

 products due to the process of decomposition induced by organ- 

 isms, acetic acid will be generally found among them. In the 

 alcoholic fermentation, at least in that of wine and bread-dough, 

 acetic acid is always found. It originates in the germination of 



