The vegetable substances principally treated in this way are—beetroot, cabbage, cauliflower, gherkins (small cucumbers), capers, French beans, onions, shallots, mushrooms, green peaches, mangoes, green walnuts, and several tropical fruits besides those mentioned. These are variously dealt with. Such as are soft-and in themselves hot and spicy require simply to have vinegar of the proper strength poured over them, after the materials have been carefully selected, washed, and, if necessary, shred. Vegetable substances of a harder and tougher character require first tobe steeped in salt brine for some time, then washed, and the vinegar poured over them hot; and yet more leathery and fibrous vegetables must be softened with boiling brine,, and then prepared with boiling vinegar. The vinegar employed may be either wood or strong malt vinegar; the. former, being free from mucilage, has no tendency to fermentation, and can be obtained of greater strength than that, prepared from malt. The vinegar is commonly flavoured with spices or aromatic herbs, flavours being chosen with special reference to the fruit or vegetable operated on. The·, flavouring materials, of which pepper, allspice, red pepper, cloves, horse-radish, garlic, and ginger are examples, are either added whole to the pickle or may be separately infused in the vinegar. For the preservation of pickles it. is necessary that the jars in which they are stored should be secured with stoppers tied over with bladder and sealed; so as to render them as far as possible air-tight. It is of the utmost consequence that in the compounding and storing of these acid preparations no vessels or fittings of copper, brass, zinc, or lead, which yield, with acetic acid, poisonous products, should be used. Contamination with copper is especially to be avoided; yet, as small quantities of acetate of copper give to pickled vegetables a fine, fresh green, natural colour, such an adulteration is not unfrequently practised; and some of the older cookery books actually recommend the use of copper vessels, and even the addition of small pieces of verdigris, to improve the colour of the pickles. As food adjuncts, pickles should be sparingly used, their chief merit being piquancy, though the acid they contain exercises a solvent influence on the more directly nutritious constituents of food, and, the added spices having a stimulating effect, they thus aid the process of digestion.