_White lead_ is the most valuable of all the colouring bodies, since it enters into the composition of almost every other. It is made by exposing sheet-lead to the action of vinegar, by which a white substance is procured. _Bougival white_, and _Spanish white_, are mineral substances procured from abroad. _Chrome yellow_, _Turner’s yellow_, _Massicot_, _Naples yellow_, _King’s yellow_, _Orpiment_, and _Ochres_, are various bodies of a yellow colour, some derived from earths, others from ores, and others from chemical treatment of metals. _Vermilion_, _Carmine_, _Cochineal lake_, _Madder lake_, _Red lead_, _Indian red_, _Venetian red_, &c., produce various tints of red and crimson; but the materials themselves are derived from very different sources. Vermilion is a compound of sulphur and mercury; Carmine and Cochineal lake are prepared from an animal substance; Madder lake from a vegetable; Red lead is an oxide of that metal; while the others are derived from various kinds of earth. For a _blue_ colour, the painter employs _Prussian blue_, which is a compound of prussic acid and iron; _Indigo_, derived from a plant growing in the East Indies; _Blue Verditer_, a nitrate of copper; and some other substances. Most _green_ paints are made of salts of copper, such as _Verdigris_, which is an acetate of copper; _Scheele’s green_, an arseniate of copper; _Green Verditer_, a nitrate of copper, and _Brunswick green_, a muriate of copper; together with two or three earths, such as _Italian green_, _Saxon green_, &c. _Browns_ are generally produced by a mixture of _black_ and _red_; but there are several earths which yield a brown colour. These are the principal colouring materials employed by the house-painter, for almost every intermediate tint or grade of colour can be produced by mixtures of two or more of the above-mentioned materials, in certain proportions.