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, or cerus; yellow and red ochres; several kinds of earth, umbre, orpiment, lamp-black, burnt ivory, black lead, cinnabar or vermilion, gamboge, lacca, blue and green ashes, verdigris, bistre, bicce, smalt, carmine, ultra marine: each of which, with their uses, &c. are to be found under their proper articles.
Of these colours some are used tempered with gum-water, some ground with oil, others only in fresco, and others for miniature.
Painters reduce all the colours they use under these two classes, of dark and light colours: dark colours are black, and all others that are obscure and earthy, as umbre, bistre, &c.
Under light colours are comprehended white, and all that approach nearest to it.
Painters also distinguish colours into simple and mineral.
Under simple colours they rank all those which are extracted from vegetables, and which will not bear the fire; as the yellow, made of saffron, French berries, lacca, and other tinctures extracted from flowers, used by limners, illuminers, &c.
The mineral colours are those which being drawn from metals, &c. are able to bear the fire, and therefore used by enamellers. Changeable and permanent colours is another division, which, by some, is made of colours.
Changeable colours are such as depend on the situation of the objects with respect to the eye, as that of a pigeon's neck, taffeties, &c. the first however being attentively viewed by the microscope, each fibre of the feathers appears composed of several little squares, alternately red and green, so that they are fixed colours.