antique advertisement for a general store listing cider vinegar as being in stockVinegars have been made for thousands of years, with some of the first being made in ancient Egypt and Babylonia. Apple cider vinegar is formed from hard cider or a “must” (freshly crushed fruit that contains skins, seeds and stems of the fruit) when yeast and bacteria are present in sufficient quantities to produce a low concentration of acetic acid. 

antique recipe for making apple cider vinegar
The American Frugal Housewife,
Lydia Child, 1838

Vinegar was widely used in food preservation, recipes, and home remedies. Because of this, farmers made their own vinegar each season.  First, a wooden barrel was filled one-third to one-half full with hard cider.  The barrel was then tightly covered and turned on its side.  The bung was removed and the hole covered with a cloth.  It took three to nine months, depending on the temperature, for the naturally-occurring yeast and bacteria in the cider to be converted to acetic acid resulting in vinegar.  The process could be sped up by adding a few cupfuls of the last season’s vinegar to the new batch.