WORK IN A VINEGAR FACTORY. 117 



spending quantity of strong spirits of wine to every fresh affu- 

 sion. 



As soon as all the alcohol is converted into acetic acid, the 

 vinegar ferment, as previously mentioned, commences with great 

 energy to oxidize the latter to carbonic acid and water, and hence 

 the amount of spirits of wine added to the alcoholic liquid must 

 be so large that the vinegar running off always contains a minute 

 quantity of it. 



Much has been written about this gradual strengthening of the 

 alcoholic liquid with alcohol, and explicit directions are given 

 as to the original composition of the alcoholic liquid as well as to 

 how much, how often, and when the alcohol is to be added. 

 These directions may have proved useful in many cases, but local 

 conditions exert too great an influence upon the process of fabri- 

 cation for them to be of general value. Besides the content of 

 alcohol in the alcoholic liquid, the size of the generators, the 

 strength of the draught in them, the temperature prevailing in 

 the workroom and in the interior of the generators, are factors 

 which must be taken into consideration in determining on a plan 

 of operation actually adapted to existing conditions. 



The size of the generators is, of course, fixed once for all ; in 

 a proper state of working the strength of the current of air must 

 be so regulated that the temperature in the interior of the gene- 

 rators is only about 45 F. higher than that of the workroom, which 

 is readily accomplished with a suitable central heating apparatus. 

 There still remains the determination of the most favorable pro- 

 portion of the content of alcohol in the alcoholic liquid to be first 

 used and its gradual strengthening by the addition of spirits of 

 wine, which can only be effected by a chemical examination of 

 the fluid running off from the generators. 



This chemical examination is restricted to the accurate deter- 

 mination of the quantity of acetic acid in the fluid and to that of 

 the alcohol to 0.1 per cent. The determination of the acetic acid 

 is effected by volumetric analysis, and with some experience re- 

 quires four to five minutes for its execution ; for the determina- 

 tion of the alcohol an examination with the ebullioscope suffices, 

 which can also be accomplished in four to five minutes.* These 



* The manner of executing these determinations will be described later on. 



