METHODS OF FABRICATION OF VINEGAR. 51 



a certain quantity of alcohol can thus be directly converted into 

 vinegar. 



Alcohol furnishing ultimately the material for the fabrication 

 of vinegar, the direct use of dilute alcohol or spirit of wine for the 

 manufacture of vinegar became obvious. By the employment of 

 a suitable process, i. e., one corresponding to the 1 laws of acetous 

 fermentation, it was found that the conversion of dilute alcohol 

 into acetic acid could be effected in a much shorter time than by 

 the old method, and upon this process is based the quick method 

 of fabrication now in general use. A distinction may, therefore, 

 be made between two principal methods of fabrication, viz., the 

 older or slow process, which requires more time, and the more 

 modern or quick process. 



In the old process many modifications are found, which are 

 partially based upon old usage and partially upon the difference 

 in the chemical composition of the raw material used. Beer, for 

 instance, which contains only about 4 per cent, of alcohol and 

 a large quantity of extractive substances (sugar, dextrin, salts, 

 etc.), requires a different treatment from wine, which contains on 

 an average 10 per cent, of alcohol, but scarcely 2 per cent, of 

 extractive substances. Fruit-wines (cider, etc.), with only 5 to ft 

 per cent, of alcohol but a large quantity of extractive substances, 

 again require different treatment from grape wine, etc., so that, 

 in a certain sense, it may be said there are as many different 

 methods of fabricating vinegar as there are fundamental materials, 

 and by taking into consideration the difference in the chemical 

 composition of the latter, it is evident that there must be just as 

 many varieties of vinegar. Besides acetic acid and a certain 

 amount of water, every vinegar contains other substances, which, 

 though frequently only present in very minute quantities, never- 

 theless exert considerable influence upon its properties. 



Even vinegar obtained from dilute alcohol shows differences in 

 odor, which depend on the material used in the preparation of 

 the specific alcohol. Potato alcohol always contains traces of 

 potato fusel oil (amyl alcohol), while certain fusel oils are found 

 in alcohol prepared from grain or molasses. In the oxidation of 

 the alcohol by the vinegar ferment these fusel oils are also oxi- 



