120 VINEGAR, CIDER, AND FRUIT-WINES. 



acetic acid, it would, however, be necessary to acidulate all the 

 generators with vinegar of the same strength, and to use alcoholic 

 liquid very rich in alcohol. By this method the losses of alcohol 

 by evaporation, and also of acetic acid, would, however, be so great 

 as to make the product too expensive. Furthermore, the work 

 would require most careful and constant attention on account of 

 the difficulty with which oxidation takes place in alcoholic liquid 

 containing much acetic acid, and it might only too readily happen 

 that the generators suddenly worked weaker, i. e., that the content 

 of acetic acid in the vinegar running off would decrease, and the 

 quantity of alcohol remaining unchanged correspondingly increase. 



On account of these difficulties, it has become customary to 

 charge the greater number of generators with alcoholic liquid 

 yielding the so-called double vinegar with about 8 per cent, of 

 acetic acid, and to work this vinegar with the addition of the 

 required quantity of strong spirits of wine in a number of gen- 

 erators, which, of course, must be acidulated with 12 per cent, 

 vinegar. 



It will be readily understood that the employment of this 

 method is not only advantageous for the production of vinegar 

 with the highest attainable content of acetic acid, but also for 

 general purposes. Passing the alcoholic liquid but once through 

 the generators does not suffice, even for vinegar with only 5 to 

 6 per cent, of acetic acid, an examination always showing a con- 

 siderable quantity, J per cent, and more, of unconverted alcohol 

 in the vinegar running off. The conversion of alcoholic liquid 

 with a small content of alcohol into vinegar by one pouring can, 

 to be sure, be accomplished, but it necessitates the use of very 

 tall generators and a constant struggle with difficulties on account 

 of the irregular draught of air, caused by the packing together of 

 the shavings. 



Group-System. 



Theoretically, as well as practically, the group-system may be 

 considered as the perfection of the quick process. The principle 

 of the operation consists in the division of the generators into 

 two or three groups, each group preparing vinegar of determined 

 strength. In factories which do not produce vinegar of the 



