Home-Made Cider Vinegar 
9 
twenty-four hours to permit settling, after which it should be trans¬ 
ferred to barrels. The bung should be left out and a loose stopper 
of cotton batting inserted in the hole to decrease evaporation and 
prevent dirt from falling in. The barrels should not be tightly 
stoppered until the vinegar contains at least 4.5 to 5.0 per cent, of 
acetic acid, at which time they should be filled entirely full and 
securely bunged. Throughout the entire period of vinegar making, 
the casks should be placed on their side and not on the end. This 
gives the cider a larger free surface exposed to the air, which is 
quite essential to rapid vinegar formation. It may be of some ad¬ 
vantage in admitting air to bore a one and one-half inch hole in 
each end of the barrel along the upper edge. If this is done, the 
holes should be covered with fine wire gauze or two thicknesses 
of cheese cloth to exclude small vinegar flies. 
The Alcoholic Fermentation. 
A few days after the cider is put into the barrels, the charac¬ 
teristic frothing appears at the bung-hole. To use a common ex¬ 
pression, “It is beginning to work.” This indicates that the alco¬ 
holic fermentation, the first step in the vinegar making process, has 
begun, and the sugar of the apple juice is being converted into 
alcohol and carbon dioxide gas. 
The first of these substances is too well known to need any 
further comment other than to state that it is this element of “hard” 
cider that gives it its intoxicating property. With carbon dioxide, 
many of us are not as well acquainted. It is this gas escaping 
from the fermenting cider that causes the frothing and likewise 
the foamy appearance of the bread sponge. It is this gas dissolved 
in the cider or in the carbonated drinks at the soda-water foun¬ 
tains that imparts to them the characteristic bite or tingle, and 
upon escaping from the stomach produces that peculiar sensation 
in the head and nose. Strangely enough, this same gas is the 
active principle of practically all chemical fire extinguishers. 
Now, what is the exciting agent which starts up the fermenta¬ 
tion in the bread sponge and in the sweet cider? In both cases it 
is the same: a microscopic organism, the yeast plant. In the one 
instance we add a yeast cake to the bread mixture; in the other 
we either trust to the wild yeasts of the air and the skin of the 
apples or following the more recent, approved method, we add a 
yeast cake or a pure culture of a yeast selected especially for this 
purpose. 
To depend upon the wild yeasts of the air to accomplish the 
fermentation is too uncertain since many of them are able to con- 
