246 The Minute Structure of the Vinegar Plant. 



vats are fitted up "with, perforated shelves, on which a quantity 

 of beech or deal shavings, first dried and soaked in strong vinegar, 

 is placed. A mixture, consisting of one part of alcohol, sp. gr. 

 0*850, of six of water, and 1000th of honey, yeast, or wort, is 

 allowed to trickle slowly through the shavings, while the tem- 

 perature is raised to about 80° F. The acetification does not 

 proceed rapidly until the process has been in operation for some 

 days,* that is to say, until the vinegar plant has had plenty of 

 time to grow. Spongy platina will oxydize alcohol and gene- 

 rate vinegar as the vinegar plant does, although probably 

 not precisely in the same way ; but, however, alcohol becomes 

 changed into acetic acid, Professor Miller considers that the 

 formation of aldehyd always precedes the production of vinegar 

 by an oxydizing process, and he gives the following formula as- 

 expressing what takes place when alcohol is thus transformed : — - 

 Alcohol. Aldehyd. 



04 He O? + 2 O = 0* IL a + 2 HO; and 

 Aldehyd. Acetic acid. 



cTaa + 20 = So, C4H3O3 



When vinegar is obtained from a saccharine solution, the 

 changes are more complicated ; the cane-sugar is converted 

 into grape-sugar, the grape-sugar into alcohol, and the alcohol 

 into vinegar. Thus the vinegar plant appears to perform the 

 double function of first alcoholizing and then acetifying the 

 solution. Do the yeast-like cells accomplish one portion of this- 

 task, and the bacterium bodies the other ? 



The mycoderm of wine does not in its ordinary state give 

 rise to vinegar. Its own vital processes merely supply the 

 means by which the changes incidental to vinous fermentation 

 take place, but it occasionally happens that brewers are greatly 

 teased by the acetous fermentation of their beer occuring after 

 the alcoholic change has finished. I have heard of several 

 instances this summer in which great annoyance has been 

 experienced from this cause, and it would seem either that 

 spores of the vinegar plant were diffused to a greater extent 

 than usual, or that portions of yeast remaining in the beer had 

 developed into the vinegar plant form. M. Pasteur's view of 

 fermentation does not coincide with the common statement 

 that the yeast plant merely separates sugar into carbonic acid 

 and alcohol — at any rate he does not represent that as the 

 entire process, because he tells us that when experiments were 

 performed in close vessels containing, besides the fermenting 

 liquid, a known quantity of air, it was found that the vinegar 

 plant took oxygen from the air, and therewith converted the 

 * Miller's Chemistry > vol. ii. p. 135. 



