38 VINEGAR, CIDER, AND FRUIT-WINES. 



4. Besides the substances mentioned in 2, the vinegar ferment 



requires for its vigorous development free oxygen and a 

 temperature lying between 68 and 95 F. 



5. In the acetous fermentation the greater portion of the alcohol 



is converted into acetic acid and water ; besides these small 

 quantities of other products are formed which are partially, 

 not yet thoroughly, known. In the conversion of wine, 

 beer, etc., other combinations contained in the fluids, 

 besides alcohol, are also essentially changed. 



CHAPTER IV. 



PRODUCTS OF ACETOUS FERMENTATION. 



THE formation of vinegar by fermentation being a chemico- 

 physiological process, many and complicated chemical processes 

 must take place in the fluid to be converted into vinegar in order 

 to produce all the combinations required for the augmentation of 

 the ferment. Attention cannot be too frequently called to the 

 fact that from the standpoint of the manufacturer, the regular 

 augmentation of the ferment is the main point of the entire fab- 

 rication, the quick conversion of the alcohol contained in the fluid 

 being a necessary consequence of it. 



The body of the ferment, however, contains cellulose, albu- 

 minous substances, very likely fat and other combinations not yet 

 known, all of which must be formed from the nourishing sub- 

 stances (sugar, dextrine, albuminous substances, etc.), present. 

 It being very probable that a portion of the alcohol contained in 

 the fluid is consumed for this purpose, a small but nevertheless per- 

 ceptible loss of alcohol will occur in the fabrication. It would 

 be erroneous to suppose that the conversion of alcohol into acetic 

 acid and water is effected according to the Formula given on p. 21 ; 

 a certain portion of it is always converted into other combinations, 

 the nature and formation of which can only be, to a certain extent, 

 explained. 



In the vinous fermentation, which of all fermenting processes 



