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. * * * * * 235. _Burnt Verdigris_ is what its name expresses, and is an olive-coloured oxide of copper deprived of acid. It dries remarkably well in oil, is more durable than the original verdigris, and is in other respects an improved and more eligible pigment, although not to be recommended. 236. _Olive Oxide of Chromium._ An olive oxide of this metal is obtainable, transparent, of strict stability, and altogether superior to any original or compound olive pigment as yet known. Eligible either in water or oil, it is admirably adapted for autumn foliage, where a quiet, subdued, nature-like green is required. It has not, however, been introduced, partly because of its expense, and partly because a mixture of other pigments with the ordinary chrome oxides sufficiently answers the purpose. There are more good colours in the world than are dreamt of in the palette's philosophy, but either they are not wanted, or are too costly to sell. In a great measure, both art and science are dependent on commerce. 237. _Olive Rinman's Green._ A compound analogous to cobalt green may be made, of an olive hue, with more body, and equally stable. 238. _Olive Scheele's Green._ Cupric arsenite, when heated, gives off arsenious acid and water, leaving a residue of arsenide of copper and copper arseniate. A series of olive colours is so afforded, which are as durable as their original pigment, and might with advantage be substituted for the doubtful compounds at present in use. 239. _Olive Schweinfurt Green_