[Pg 4]

These conditions require that the liquid shall contain alcohol, nitrogenous matter, and alkaline salts in certain proportions, and that it shall be in contact with the air, at a suitable temperature, for a sufficient length of time.

The researches of Pasteur showed the process of oxidation to be due to a microscopical fungus (mycoderma aceti), possessing the power of condensing oxygen and conveying it to the fermentable substance. This organism, which is a true bacterium, as the fermentation proceeds, forms a leathery membrane (slightly differing according to the substance fermenting) on the surface of the liquor, which constitutes the so-called mother of vinegar, or vinegar plant.

The oxidation of alcohol into acetic acid can also be performed independently of the organic agent. Finely divided platinum, for instance, is capable of effecting disintegration of the alcohol, and of placing it in immediate contact with the oxygen of the atmosphere, thus accomplishing the acetification.[Pg 5]

Vinegar, on the continent, is prepared from weak or sour wine, hence its name (vin aigre.) In this country it is, to a large extent, produced from an infusion of malt, but considerable quantities of inferior quality are made from sour beer, etc.

The vinegars thus produced, if properly purified, and providing no injurious adulterants are resorted to, are, for many purposes, almost all that can be desired; but for table use, for sauces and salads, where delicacy of flavour is appreciated, and for medicinal purposes where pureness and whol