ARTIFICIAL VENTILATION OF VINEGAR GENERATORS. 77 



nected with them, which will, however, decrease in the same 

 degree as the pipes cool off. Hence, in the first case, a too rapid 

 current of air accompanied by a correspondingly strong evapora- 

 tion of alcohol would pass through the generators, and in the 

 latter, ventilation would be so sluggish that the process of the 

 formation of vinegar would not proceed in a normal manner. 



Generators with constant Ventilation and Condensation. 



The object to be attained by the use of special ventilating con- 

 trivances is a double one : to conduct a constant current of air 

 through the generators, and, further, not to allow the temperature 

 to rise above a certain limit, so as to decrease by these means the 

 loss by evaporation of alcohol and acetic acid. This object can, 

 however, be attained only by the use of an apparatus which 

 allows of the most accurate regulation of the current of air pass- 

 ing through the generator, and is connected with a contrivance 

 by which the vapors of alcohol and acetic acid carried along by 

 the current of air can be condensed as much as possible. The 

 following apparatus is well adapted for the purpose ; its principal 

 parts consist of the generator, the apparatus for condensing the 

 vapors, and the ventilator. 



The construction of the lower part of the generator, Fig. 22, 

 is the same as of those previously described ; the cover fits tightly 

 upon the upper edge of the vat, the joint being made air-tight by 

 strips of paper pasted over it. In the centre of the cover is a 

 square aperture, from which rises a quadrangular pyramid, P, 

 constructed of boards, upon which sits a low prism, A. The 

 sparger D has its centre of motion upon the lath L, placed in 

 the uppermost portion of the generator, and is guided above in 

 the short lath L v which carries the sharp-edged ring described 

 on p. 64. E is the glass tube through which the alcoholic liquid 

 flows into the funnel of the sparger. On the point where the 

 pyramid passes into the prism A, is a bottom provided with a 

 circular aperture, 0, 2J to 3 inches in diameter. Upon the top 

 of the prism A is placed a nut, in which runs a wooden screw, 

 provided on the lower end with a wooden disk, S, of a somewhat 

 greater diameter than the aperture 0. By raising or lowering 



