For the rapid progress of the acetous fermentation, a high temperature is requisite, even as great as about eighty-six degrees, and free exposure to air is essential. The best vinegar is that made from weak wine, at Orleans; the plan followed is to introduce a portion of vinegar into the vessels, adding the wine at intervals, and never quite emptying them. In this country, a weak beer is brewed, without hops, for the purpose of making vinegar, and a small quantity of diluted oil of vitriol is added, after the vinegar is formed, to destroy the mouldiness that is otherwise apt to be present. Vinegar may be formed from any weak spirituous liquid; but it should be borne in mind that two circumstances are essential to success, namely, a high summer temperature, either natural or artificial, and free exposure to air. The process of distillation is one which is used for separating liquids from each other which boil at different degrees of heat. In domestic economy, it is most frequently employed to obtain spirit, more or less flavoured, or scented, with some volatile essential oil. The apparatus commonly used is the still, for boiling the liquid to generate the vapour, and a long spirally-twisted tube termed the worm, which is placed in a tub of cold water, and through which the steam passes to be condensed. The worm is the most objectionable part of the modern still; its great evil is the difficulty with which it is cleaned, so as to prevent one strong-flavoured substance spoiling those which are distilled afterwards. If the coils of the worm are not very numerous, a bullet, with a string attached, may be passed through it, and a sponge or small bottle-brush, fastened to the string, may be worked backwards and forwards; but if there are several coils, it will be found impossible to do this, from the resistance caused by friction. In this case, the only plan is to close one end of the worm with a cork, and fill it with a solution of caustic alkali, allowing it to remain for some hours, and repeating the application with fresh liquid, if it be required. [Illustration: _Fig. 1._] In Germany, the worm is being superseded by an excellent condenser, which is so superior that we are induced to give a sketch of it, hoping that it may lead to its adoption in this country. The vapours from the still pass into the tube A (_Fig. 1_), by which they are conducted into B, a hollow globe, made to unscrew at its centre. The vapours, passing along the tube C, are condensed, and the distilled liquid drops from D. The pipe E should convey a constant stream of cold water to the bottom of the tub, and this, rising as it is warmed by extracting heat from the tubes and globe, should escape by F. All the tubes being straight, it is obvious that they can be readily cleaned from their ends.