32 VINEGAR, CIDER, AND FRUIT-WINES. 



employed as carbohydrates. These fluids further contain nitro- 

 genous combinations which may serve as nutriment for the 

 ferment, and also considerable quantities of phosphates. Hence 

 by an addition of wine (or must), malt extract, beer, or any fruit 

 wine (apple or pear cider) to a mixture of alcohol and water, a 

 fluid can be prepared, which contains all the substances essential 

 to the nourishment of the ferment. 



The quantity of these nourishing substances, as compared with 

 that of alcohol, is very small, the quantity by weight of vinegar 

 ferment required for the conversion of a very large amount of 

 alcohol into vinegar being only a few fractions of one per cent, of 

 weight of alcohol used. Hence the manufacturer may be very 

 economical with the addition of nourishing substances to the fluid 

 to l>e converted into vinegar without having to fear that the fer- 

 ment will be stinted. 



The vinegar ferment is very sensitive to sudden changes in the 

 composition of the fluids upon which it lives and suffers injury 

 by such changes which is recognized by diminished propagation 

 and decreased conversion of alcohol into acetic acid. 



By bringing, for instance, vinegar ferment which vegetated in 

 an entirely normal manner upon a fluid containing only 4 to 5 

 per cent, of alcohol, upon one with a content of 10 to 11 per 

 cent., its augmentation, as well as fermenting energy, decreases 

 rapidly and remains sluggish until a few new generations of cells 

 have been formed which are better accustomed to the changed 

 conditions. By bringing, on the other hand, a ferment from a 

 fluid rich in alcohol upon one containing a smaller percentage the 

 disturbances in the conditions of the ferment can also be observed, 

 but they exert a less injurious influence upon the process of the 

 formation of vinegar than in the former instance. 



The process of nourishment of the vinegar ferment must, how- 

 ever, not be understood to consist simply in the consumption of 

 sugar, albuminates, and salts. It differs according to the compo- 

 sition of the nourishing fluid, and is so complicated as to require 

 a very thorough study for its explanation. If, for instance, wine 

 is converted into vinegar, and the composition of the latter com- 

 pared with that of the original wine, it will be found that not 

 only the alcohol has been converted into acetic acid and the fluid 



