may be compounded in several ways; directly, by mixing green and purple; or indirectly, by adding to blue a smaller proportion of yellow and red, or by breaking much blue with little orange. Cool black pigments, combined with yellow ochre, afford eligible olives; hues which are called green in landscape, and invisible green in mechanic painting. It is to be noted that in producing these and other compound colours on the palette or canvass, those mixtures will most conduce to the harmony of the performance which are formed of pigments otherwise generally employed in the picture. Thus, presuming aureolin to be the principal yellow used, the same yellow should be chosen for compounding orange and green, or for obtaining indirectly citrine, russet, and olive.
| PERMANENT GREEN. | PERMANENT PURPLE. |
|---|---|
| Oxide of Chromium, opaque. | Mars Violet, true. |
| Oxide of Chromium, transparent. | Purple Madder. |
| Veronese Green. | |
| Viridian. | |
| Emerald Green. | |
| Scheele's Green. | |
| Terre Green. |
As in the case of russet, there may be added to the two original purples, mixtures composed of durable reds and blues. There are so many ways of producing the tertiaries, that no difficulty can be found in compounding them with stable pigments. Each tertiary may be represented as follows:—
From the above equations, and by consulting the lists given of permanent primary and secondary colours, the artist will at once see how easily and safely he may vary his mode of compounding the tertiaries.
233. OLIVE GREEN,
sometimes called Dewint's Green, is an arbitrary compound, or mixed green, of a fine deep olive colour and sober richness. Advisedly or not, it is used in landscape, sketching, &c.; but only in water, olive lake supplying its place in oil. Like many other compound pigments, it is either permanent, semi-stable, or fugitive, according to the constituents of which it is composed. Generally speaking, it is more beautiful than durable, and is often decidedly fugacious, fading on exposure. It is impossible for a writer to pronounce an absolute opinion on the stability of all mixtures sold in a separate form, inasmuch as the compounds of one firm may differ from those of another. We have before expressed our dislike to such pigments, and this uncertainty with regard to their composition serves to strengthen it. Nevertheless, as there are exceptions to every rule, it must be admitted that the palette possesses compounds always to be relied upon.
234. OLIVE LAKE
is in commerce exclusively an oil colour. When true, it is a lake prepared from the green ebony, or laburnum, and is of considerable permanence, transparency, and depth, both in water and oil; in which latter vehicle it dries well. This variety, however, may be said to be obsolete; having given way to a mixture, usually semi-stable, and liable to blacken.