is likewise furnished by gentle calcination. It may be directly prepared by mixing boiling aqueous solutions of equal parts of crystallised verdigris and arsenious acid. An olive-green precipitate is immediately formed, which is apt, without due precaution, to pass into an emerald green. A durable copper colour. 240. _Olive Terre Verte._ We have obtained a very beautiful olive from terre verte by simply changing its hue. In oil, especially, the colour so produced would be found of service for autumn foliage, or richly painted foregrounds. A simple original pigment, consisting wholly of the earth, it resembles ordinary terre verte in being unaffected by strong light or impure air, and uninjured by admixture; but differs from it in not darkening by time. Semi-transparent, of sober richness and drying well in oil, it is, according to its powers, a perfectly unexceptionable colour, of strict stability. * * * * * Of the two olive colours in common use, olive lake and olive green, the first is generally semi-stable, and apt to blacken; while the second is usually fugitive, and liable to fade: both are compounds. The palette, therefore, possesses no original olive pigment, good or bad. A glance at the numbered italicised olives will show that the doubtful mixtures referred to might with advantage be superseded. It is clear that the olive pigments which the palette does not know, are better than those with which it is acquainted. CHAPTER XVII. ON THE SEMI-NEUTRAL, BROWN. As colour, according to the regular scale descending from white, ceases properly with the last of the tertiaries, olive, in theory the neutral black would here form a fitting conclusion. Practically, however, every coloured pigment, of every class or tribe, combines with black as it exists in pigments--not simply being deepened or lowered in tone thereby, but likewise defiled in colour, or changed in class. Hence there arises a new series or scale of coloured compounds, having black for their basis, which, though they differ not theoretically from the preceding order inverted, are yet in practice imperfect or impure. These broken compounds of black, or coloured blacks and greys, we have distinguished by the term, semi-neutral, and divided them into three classes: Brown, Marrone, and Gray. What tints are with respect to white, they are with regard to black, being, so to speak, black tints or shades.