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QUICK PROCESS OF FABRICATION OF VINEGAR. 65 



place in a perfectly uniform manner. A number of apertures in 

 the cover of the generator serve also here for the regulation of 

 the current of air. 



A thermometer is an indispensable adjunct to a generator, and 

 should be so placed that the temperature prevailing in the appa- 

 ratus, and especially in the centre, can be readily read off. This 

 is best effected by introducing at about half the height of the 

 apparatus, through an obliquely bored hole in one of the staves, 

 a glass tube closed at the lower end and reaching to the centre of 

 the filling. This tube serves for the reception of a thermometer 

 fastened to the lower end of a stick of wood. The latter pro- 

 jects from the glass tube, so that the thermometer can be quickly 

 drawn out and the temperature read off. 



Fitting of the Generators. 



For filling the space between the upper disk and lower lath 

 bottom, material offering a large surface for the distribution of 

 the alcoholic liquid is used. Pieces of charcoal and of pumice 

 stone, washed in hydrochloric acid and well rinsed in water to 

 remove empyreumatic substances, which would render induction 

 of acetous fermentation impossible, have been used for the pur- 

 pose, as well as old corks or waste of cork. Pumice stone 

 especially has the advantage of being easily cleansed by water 

 and by fire when the liquors, such as those from fruits, contain a 

 great deal of mucilaginous and albuminous substances, which 

 will rapidly accumulate and prevent the proper working of 

 shavings. Grape-stalks, which actually present a very large 

 surface, were formerly much used for filling the generators, but, 

 independently of the fact that they cannot be everywhere obtained 

 in sufficient quantities, they have the disadvantage of becoming 

 in a short time so strongly compressed as to prevent the free pas- 

 sage of air. 



J3ut beechwood shavings are now nearly everywhere employed 

 for filling the generators. Indeed, beechwood presents many ad- 

 vantages; it can be had easily and cheap; it curls well and 

 stands without breaking for a length of time. White woods will 

 curl as well, but they will hot stand so well as beech ; resinous 

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