COLOUR, in Painting, is applied both to the drugs and to the tints produced by those drugs, variously mixed and applied. The principal colours used by painters are red and white lead, yellow and red ochres, several kinds of earth, umber, orpiment, lamp black, ivory black, black lead, vermilion, gamboge, lacca or lake, blue and green ashes, verdigris, bistre, raw and burnt sienna, bice, smalt, carmine, ultramarine. For much interesting information regarding the pigments employed by the Greeks and Romans, the reader may consult Vitruvius, vii.; Pliny, xxxiii., xxxiv., xxxv.; Dioscorides, v.; and Theophrastus, De Lapidibus. See also Philosoph. Trans. of Royal Soc., 1815, for the experiments and observations of Sir Humphry Davy on some ancient colours and paintings in the baths of Titus and of Livia, &c.