Chemistry / [Michael Donovan].

  • Donovan, Michael, -1876
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry / [Michael Donovan]. Source: Wellcome Collection.

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    the formation of vinegar during the acetous ferment- ation, founded on the belief that the absorption of oxygen from the atmosphere is indispensable : and the agency of the oxygen has been supposed to be the removal of carbon and hydrogen from the alcohol, by the formation of carbonic acid and water; for it is known that acetic acid contains less carbon and hydro- gen than alcohol. <A theory of this kind, however, has to contend with the fact, that although oxygen is absorbed during the acetous fermentation, and carbonic acid is formed, this absorption seems to be effected by some other carbonaceous matter present in the liquor, and not by the carbon of the alcohol; for vinegar may be formed perfectly, and with ease, even though the access of air be totally prevented. This fact is proved by many instances. Beccher included wine in a glass bottle, which it filled : he hermetically sealed the mouth, and exposed it to a digesting heat ; after some time the wine was converted into very strong vinegar. (Physica Subterranea, Lipsie, p.184.) Fourcroy and Vauquelin obtained vinegar from a solution of sugar contained in elose vessels. Homberg included good wine in a bottle, and having closed it accurately, he fastened it to the sail of a windmill: in three days it was very good vinegar. It is a fact well known to every one, that a bottle filled with weak beer, and closely corked, will in some time be converted into vinegar. It may be said that air was absorbed through the cork: but this could scarcely happen: for, after a cubic inch or two of oxy- gen would thus be absorbed, the neck of the bottle would be filled with azote; and there being now no longer the aid of a partial vacuum, it is hard to con- ceive how air could enter. But the experiment of Beccher seems to me irrefragable ; and, I think, we are bound. to admit that the absorption of oxygen during the formation of vinegar is incidental, not necessary. According to Gay-Lussac and Thenard, 100 parts of acetic acid consist of 50°224 carbon, 44°147 oxygen, and 5°629 hydrogen. If we alter these numbers very