34 VIXEGAR, CIDER, AND FRUIT-WINES. 



and to form acetic acid after melting and heating the fluid to 59 

 F. It should, however, be expressly stated that while vinegar 

 ferment in a state of development keeps up a slow growth when 

 the fluid is reduced to a low temperature, it is very difficult to 

 rear it upon a cold fluid. This is very likely the reason why 

 acetous degeneration is not known in cold wine cellars, while in 

 those having a temperature of over 59 F. this dreaded process 

 can only be guarded against by the greatest care. . 



Since the augmentation of the ferment and its fermenting 

 activity increase with a higher temperature, it would appear most 

 suitable to keep the temperature of the fluid to be converted into 

 vinegar as near the uppermost limit of 95 F. as possible. Ex- 

 perience, however, has shown that at this temperature disturb- 

 ances are of frequent occurrence in the generators, and for this 

 reason one of 86 to 89 F. is generally preferred. The process 

 of the formation of vinegar itself explains why disturbances may 

 easily occur at a high temperature. It is a chemical (oxidizing) 

 process in which a certain quantity of heat depending on the 

 quantity of alcohol to be oxidized within a certain time is always 

 liberated. If now by the use of a temperature close to 95 F. 

 the activity of the ferment is strained to the utmost, a large quan- 

 tity of alcohol is in a short time converted into acetic acid, and 

 consequently so much heat is liberated that the temperature in the 

 generator rises above the permissible maximum and the ferment 

 immediately ceases its activity. Thus it may happen that in a 

 generator which has satisfactorily worked for some time, the for- 

 mation of vinegar ceases all at once, and on examining the ther- 

 mometer placed on the apparatus the cause will be generally found 

 to be due to too high a temperature. 



Mother of Vinegar. 



In connection with the description of the conditions of life of 

 the vinegar bacteria, a peculiar formation, playing in many cases 

 a role in the practice of the fabrication of vinegar, has to be 

 mentioned. This is the so-called mother of vinegar, the term 

 having very likely been applied to it on account of its causing 



