are varnishes applied upon tin, brass, and other metals, to preserve them from tarnishing, and to improve their colour. The basis of lacquers is a solution of the resinous substance called seed-lac, in spirit of wine. The spirit ought to be very strong, in order to dissolve as much as possible of the lac. For this purpose, some authors direct dry potash to be thrown into the spirit. This alkali attracts the water, with which it forms a Lactantius, liquid that subsides distinctly from the spirit at the bottom of the vessel. From this liquid the spirit may be separated by decantation; but by such a process the spirit is impregnated with part of the alkali, which depraves its colour, and communicates a property to the lacquer of imbuing moisture from the air. These inconveniences may, however, be prevented by distilling the spirit; or, if the artist has not an opportunity of performing that process, he may cleanse the spirit in a great measure from the alkali, by adding to it some calcined alum, the acid of which uniting with the alkali remaining in the spirit, forms therewith a vitriolated tartar, which, not being soluble in spirit of wine, falls to the bottom, together with the earth of the decomposed alum. To a pint of the purified spirit, about three ounces of powdered shell-lac are to be added, and the mixture digested during the same day with a moderate heat. The liquor ought then to be poured off, strained, and cleared by settling. This clear liquor is now fit to receive the required colour from certain resinous colouring substances, the principal of which are gamboge and arnotto; the former giving a yellow, and the latter an orange colour. To give a golden colour, two parts of gamboge are added to one of arnotto; but these colouring substances may be separately dissolved in the tincture of lac, and the colour required may be adjusted by mixing the two solutions in different proportions. When silver leaf or tin is to be lacquered, a larger quantity of the colouring materials is requisite than when the lacquer is intended to be laid on brass.