Many of these, such as the ochres and umbers, are from natural earths; others are artificially made. They may generally be purchased either as dry powder or ground in oil.

Blacks

"Lampblack" is the soot produced by burning oil, rosin, small coal, resinous woods, coal-tar, or tallow; is in the state of very fine powder, works smoothly, is of a dense black colour, and durable; but dries badly in oil. "Vegetable black " is a better kind of lampblack made from oil; is very light, free from grit, and of a good colour; should be used with boiled oil, driers, and a little varnish; linseed oil or turps keeps it from drying. " Ivory Black " is obtained by calcining waste ivory in close vessels, and then grinding; is intensely black when properly burnt. "Bone Black" is inferior to ivory black, and prepared in a similar manner from bones. "Blue Black" and "Frankfort Black" of the best quality are made from vine twigs; inferior qualities from other woods, charred and reduced to powder. "Grant's Black," or "Bideford Black," is a mineral substance found near Bideford; it contains a large proportion of silicious matter, is denser than lampblack, but has not so much colouring power.