454 



MICROBIOLOGY OF SPECIAL INDUSTRIES. 



passes, furnished at its lower end with a glass or rubber tube extending 

 to within a few inches of the bottom of the cask. By means of this funnel 

 new liquid can be added without disturbing the surface film. The 

 lower bung-hole is closed with a cork, through which passes an L-shaped 

 glass tube which serves as an indicator of level and which also can be used 

 to draw off the vinegar. 



When this apparatus is working well, from one-fifth to one-quarter 

 of the contents may be taken off every three or four weeks. This depends 



FIG. 89. Vinegar barrel. L, surface of liquid; O, O, openings for entrance of air; 

 t, tube for introducing new supplies of wine without disturbing surface films; E, glass 

 tube to show level of liquid and for drawing off vinegar. (Original.) 



on the temperature, which should be between 10 and 18. The vinegar 

 drawn off is immediately replaced with wine or cider which, if added 

 slowly, will, owing to its lower specific gravity, remain at the surface in 

 contact with the bacterial film. 



ORLEANS METHOD. This is practically the same as the method just 

 described with slight modifications to adapt it to large scale operations. 

 It is the oldest commercial method and produces vinegar of the highest 

 quality. 



Barrels of about two hectoliters are usually employed, fitted essentially 

 like that already described but with the omission of the funnel and draw- 

 ing-off tubes. 



The wine is first cleared in a vinegar filter. This consists of a wooden 

 vat filled with beech chips which have been extracted by soaking for several 



