PREPARATION OF THE ALCOHOLIC LIQUID. 105 



vessel to the air at from 66 to 78 F., microscopical examina- 

 tion will show the development of vinegar ferment upon it and a 

 chemical analysis a constant increase, soon amounting to several 

 per cent, of acetic acid. A fluid composed of 5 to 6 per cent, of 

 alcohol, 94 to 95 per cent, of water, and a very small quantity of 

 malt extract acts in a similar manner. In many cases the vinegar 

 ferment is developed without the fluid containing acetic acid. 



The alcoholic fluid to be used may from the start contain a 

 sufficiently large percentage of alcohol to correspond to the de- 

 sired strength of the vinegar to be made ; in this case the fluid 

 has to be poured several times into the generators, it being impos- 

 sible to convert a large quantity of alcohol into acetic acid by 

 passing it through but once. By another method an alcoholic 

 liquid is first prepared containing but little alcohol, which is 

 almost completely converted into acetic acid by one passage 

 through the generators. The fluid running off from the gene- 

 rators is then further mixed with a certain quantity of alcohol 

 and being poured into a generator, in which the vinegar ferment 

 is already accustomed to larger quantities of alcohol and vinegar, 

 is also converted into acetic acid. More alcohol can then be 

 added, and so on. The last method is evidently the best as re- 

 gards the conditions of life of the vinegar ferment, and actually 

 the only one by which the strongest vinegar (with from 12 to 13 

 per cent, of acetic acid) can be obtained in generators. 



That it is advisable only gradually to increase the content of 

 alcohol in the alcoholic liquid is shown by the behavior of the 

 ferment towards alcohol and acetic acid. Both bodies, if present 

 in large quantities, are decidedly inimical to the augmentation of 

 the ferment, a fluid containing from 14 to 15 per cent, of alcohol, 

 or as much acetic acid, being capable of checking the augmenta- 

 tion of the ferment to such an extent as to disturb the process of 

 fabrication. 



Another argument against the use of the total quantity of 

 alcohol in the preparation of the alcoholic liquid to be employed 

 for the first effusion, is the fact that evidently more alcohol will 

 be lost by evaporation than by commencing with a fluid contain- 

 ing less alcohol, arid adding a corresponding quantity of the 

 latter after the fluid has once passed through the generators. 



