Fermentation separates the particles of bodies, and from liquids throws off the gross parts from the finer, which, without it, could not be effected. There is what is called a _fret_, which is only a partial fermentation, that nature is strong enough in some liquors to bring on, without the assistance of art; but this _fret_, or partial fermentation, is never strong enough to discharge the liquor of its foul parts; and if they should ever happen to subside, the least alteration in weather, as well as a hundred other accidents, will occasion their commixing, and render the liquor almost, or altogether as foul as ever; to prevent which we call in the assistance of art, and which our method will effectually prevent. In brewing beer, yest is apply'd to it, in order to ferment it, without which it would never be beer. This opens the body of the liquor, and renders it spirity and fine. The reason that cyder is not often fine, is owing to its not being fermented. After it is got into the hogshead, the generality of people think they have acquitted themselves very well, and done all the necessary business, except racking it. But I can assure them, the more any liquor is rack'd, the more it is weaken'd. By often racking, it loseth its body, and so becomes acid for want of strength to support it. Another gross error many people are guilty of, in keeping the bungs out of the casks. Nothing is more pernicious to fermented liquors, than their being exposed to the open air, whereby they lose their strength and flavour. Take a bottle of wine, draw the cork, and let it stand exposed to the open air for twenty-four hours only, and you will then find it dead, flat, and insipid; for the spirit is volatile, and has been carried off by the air, and what remains is the gross, elementary part chiefly. A cyder-cask should never be kept open more than fourteen or fifteen days, that is, 'till the ferment is stopt; but so contrary is the practice, that I have known them very commonly kept open three or four months. It hath been objected to me by cyder and sweet-makers, that stopping up the cask so soon will endanger the head being blown out or bursted; but their fears are groundless, provided the ferment is stopt. The bottoms are quite confined, and it is impossible they should rise, unless a forcing be added to raise them. The best time for bottling your cyder, is in the winter, or cool weather, when it is _down_, otherwise you will hazard breaking most of the bottles. The best method of keeping it, is to put it up in dry saw-dust, which will keep it in a due temperature of heat, without the colour's subsiding, unless you have laid a high colour on it, which, by long keeping, will subside in the same manner port-wine doth in bottles. For 'tis impossible to set a colour on cyder so strong, as to have it stand the bottle more than twelve or eighteen months, at farthest. The natural colour will change but little in a much longer time.