THE PREPARATION OF FARM PRODUCTS. 283 



species of the vinegar plant to produce acetic acid under varied 

 conditions. 



A second process of vinegar- making, known as the "quick 

 process," does not at first sight appear to be caused by micro- 

 organisms. This process, used mostly in Germany, consists 

 simply in an intimate mixture of alcohol with air, by means of 

 beechwood shavings. A mass of such shavings is placed in 

 tall vessels and thoroughly moistened with an alcoholic solution. 

 Then the whole is inoculated with a little warm vinegar. The 

 vinegar thus added starts the process and, in a few hours, 

 vinegar makes its appearance in quantity. Such a process 

 seems at first to be more like a chemical phenomenon than a 

 fermentation induced by microorganisms. But here also a 

 vital process is concerned. In the first place, the process does 

 not start until a little warm vinegar has been added to the 

 mixture, and such vinegar will be sure to contain bacteria. 

 This of course suggests that the microorganisms, thus added, 

 spread through the shavings, grow rapidly and soon induce 

 the oxidation. Indeed, Pasteur and others were easily able to 

 prove that, if the growth of the fungi is prevented in such a 

 mixture, no vinegar is formed. Hence the quick vinegar proc- 

 ess is also dependent upon the presence and active growth of 

 the vinegar plants. 



These are not the only methods adopted in vinegar-making, 

 for this industry, which is a very large one and increasing in 

 importance, has demanded numerous devices. Different de- 

 tails are followed by different manufacturers and different kinds 

 of vinegar are made in different ways. But whatever be the 

 process it is always fundamentally dependent upon the growth 

 of some of the vinegar organisms which are either naturally 

 or artificially inoculated into the alcoholic solution. 



THE VINEGAR ORGANISMS. 



What are these organisms which bring about this oxidation 

 of alcohol into acetic acid ? While Pasteur's investigations 



