Starting the Fermentation.
In due course, if left alone, alcoholic fermentation, by a natural process, will be set up; but I am inclined to think, from my own experience, that it is best to add, in the first instance, a small quantity of yeast. If, as sometimes happens, the fermentative action be too slow, putrefaction of a portion is liable to take place, and the vinegar is spoilt.
The acetic fermentation is accelerated by the addition of vinegar plant, and also by the presence from the commencement of a small quantity of vinegar.
Temperature.
A suitable temperature is 70 deg. Fah., or from that to 80 deg. Summer is therefore by far the best time for vinegar making, as this temperature is then easily obtainable, especially if the vessel be exposed to the heat of the sun.
At a little over 100 deg. Fah. the development of the acetic germ ceases, while below 68 deg. it is gradually arrested.
Duration of Process.
The length of time before the completion of the process varies according to circumstances. While usually, under completely favourable conditions, in from six to eight weeks sufficient acetification has taken place, not unfrequently a longer period is required.
Racking and Clearing.