QUICK PROCESS OF FABRICATION OF VINEGAR. 



57 



in the interior is too great, it can be at once diminished by closing 

 a number of these holes, it being even possible to direct it to- 

 wards a certain portion of the filling. This arrangement is, 

 however, only available when the false bottom to be described 



Fig. 4. 



Cover of a Generator provided with Draught Apertures. 



later on is either not used or provided with a number of short 

 vertical tubes which permit the passage of the air. 



Many generators are provided with a number of obliquely 

 bored apertures below the false bottom through which the air can 

 escape. This is, however, attended with the disadvantage that 

 a regular draught of air only takes place in the outer layers of 

 filling next to the walls, while it is not sufficiently strong in the 

 centre of the apparatus. It is also incorrect to have but one air 

 aperture in the cover, which can be enlarged or diminished by 

 means of a slide. In a generator thus arranged the current of 

 air entering below will naturally pass chiefly through the conical 

 portion of the filling, the basis of which is formed by the lower 

 lath-bottom and the apex by the draught aperture in the cover. 

 The lower portion of the filling, which embraces this cone, re- 

 mains without sufficient ventilation and is ineffective as regards 

 the oxidation of alcohol. 



In Figs. 5 and 6 the hatched surfaces terminated by the dotted 



