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. [Sidenote: 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. [Sidenote: 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. [Sidenote: Racking and Clearing.] When the proper degree of acetification is reached, the liquor should be strained, or, if in a cask, be racked into a fresh one, without tilting. Then fined with isinglass, or allowed to settle for a week or two, when it may be drawn off clear and bottled. It may subsequently require decanting and re-bottling. The membrane or plant is useful for restarting the action, but it must not be allowed to remain for any length of time out of the liquor, or be exposed to a low temperature, or it will be injured. [Sidenote: Colour.] The colour will at first be found to be quite light, but in course of time it will assume an amber shade and gradually darken with age. That this colouration may proceed as rapidly as possible, the vinegar should be bottled in light glass bottles, and exposed to the light. * * * * * Dilute acetic acid has been in general use from remote times. The ancient Hebrews used it, as we know from the several allusions to it in the Old Testament. It is mentioned also in the New Testament. The Greeks and Romans, too, made use of it. It is frequently spoken of by classical writers, as Pliny, Livy, and others. In our own times it is almost universally employed for culinary and preservative purposes, besides being largely used medicinally. Vinegar is anti-scorbutic and anti-bilious. Largely diluted it forms a very refreshing beverage. It has been in past ages and in modern times so used by soldiers on long marches, and by others employed on hard and exhausting labour, with beneficial results. The vapour of vinegar inhaled greatly relieves hoarseness, and, diluted as a gargle, is useful in throat complaints.