&4 VINEGAR, CIDER, AND FRUIT-WINES. 



liquid flows into each generator, rims above the uppermost row. 

 Another conduit, L l common to all the generators, serves for the 

 reception of the fluid (finished vinegar) running off from the 

 lowest row, and conducts it to the collecting vessel, S. The 

 arrows indicate the course the alcoholic liquid has to traverse. 



From all appearances the arrangement of a factory according 

 to the above-described system would be most advisable, there 

 being actually nothing to do but to raise the alcoholic liquid 

 once and to remove the finished vinegar from the collecting 

 vessel. In practice, however, this so-called terrace system pre- 

 sents many difficulties not easily overcome, the greatest un- 

 doubtedly being the solution of the heating problem. Experience 

 shows that the temperature in a generator must be the higher the 

 more acetic acid the alcoholic liquid contains. According to this, 

 the highest temperature should prevail in the lowest series of 

 generators (///, Fig. 25) and the lowest in the uppermost (J). 



But in practice just the reverse is the case even with the use 

 of the best heating apparatus : the highest temperature prevails 

 in / and the lowest in JJJ, as, according to natural law, the 

 warm air being specifically lighter than the cold constantly strives 

 to ascend. 



To overcome this evil nothing can be done but to place the 

 series J, //, and III of the generators in as many different stories 

 entirely separated from each other, or, in case there is a central 

 heating apparatus in the cellar, to correctly distribute the warm 

 air in the separate stories by suitably arranged registers. The 

 solution of this problem offers no insuperable difficulties, but re- 

 quires the arrangement of the entire factory to be carefully 

 planned in accordance with the laws of physics. 



An unavoidable evil of the terrace system is the costliness of 

 the factory building, and, finally, that a disturbance occurring in 

 one of the generators must simultaneously affect two others of the 

 vertical series, which must necessarily remain idle until the dis- 

 turbance is removed. Considering all the disadvantages con- 

 nected with the terrace system, though it is seemingly so suita- 

 ble, it is but little adapted to practice, it being much preferable 

 to place all the generators on the same level and to divide them 



