the general character of yellow ochres, of which it is one of the best.
Stone ochre has been confounded with the preceding, which it frequently resembles, as does also Roman ochre. True stone ochres are found in balls or globular masses of various sizes in the solid body of stones lying near the surface of rocks among the quarries in Gloucestershire, England, and elsewhere. These balls are of a smooth compact texture, in general free from grit, and of a powdery fracture; they vary exceedingly in color, from yellow to brown murrey and gray, but do not differ in other respects from the preceding, and may be safely used in oil or water in the several modes of painting. Varieties of ochreous colors are produced by burning and compounding with lighter, brighter and darker colors, but often very injuriously and adversely to a certainty of operation, effect and durability.
Raw sienna is a ferruginous, or impregnated with iron, native pigment, and appears to be an iron ore which may be considered as a crude, natural yellow lake, firm in substance, of a glossy fracture, and very absorbent. It is in many respects a valuable pigment, of rather an impure yellow color, but has more body and transparency than the ochres, and being little liable to change by the action of either light, time, or impure air, it may be safely used, according to its powers, either in oil or water, and in all the modes of practice. By burning, it becomes more transparent and drying, and changes color to a red brown. Raw sienna is a valuable color in graining.
There are several pigments called yellow lake, varying in color and appearance according to the coloring substances used, and modes of preparation; they are usually in the form of drops, and their colors are in general of a bright yellow, very transparent, and not liable to change in an impure atmosphere, qualities which would render them very valuable pigments were they not soon discolored and even destroyed by the opposite influences of oxygen
