Citrine, or the colour of the citron, is the first of the tertiary class of colours, or ultimate compounds of the primary triad, yellow, red, and blue; in which yellow is the archeus or predominating colour, and blue the extreme subordinate. For citrine being an immediate compound of the secondaries, orange and green, of both which yellow is a constituent, the latter colour is of double occurrence therein, while the other two primaries enter singly into its composition. The mean or middle hue comprehends eight blue, five red, and six yellow, of equal intensities.

Hence citrine, according to its name, which is that of a class of colours and used commonly for a dark yellow, partakes in a subdued degree of all the powers of its archeus yellow. In estimating, therefore, its properties and effects in painting, it is to be regarded as participating of all the relations of yellow. By some this colour is improperly called brown, as almost all broken colours are. The harmonizing contrast of citrine is a deep purple, which may be seen beautifully opposed to it in nature, when the green of summer declines. As autumn advances, citrine tends towards its orange hues, including the colours termed aurora, chamoise, and others before enumerated under the head of yellow. It is the most advancing of the tertiary colours, or nearest in relation to light; and is variously of a tender, modest, cheering character.

To understand and relish the harmonious relations and expressive powers of the tertiary colours, require a cultivation of perception and a refinement of taste for which study and practice are needed. To a great extent the colourist, like the poet, is born not made; but although he must have an innate sense of the beautiful and the true, hard work alone, with his head, his eyes, and his hands, will enable him to learn and turn to account the complex beauties and relations of tertiary colours. They are at once less definite and less generally evident, but more delightful—more frequent in nature, though rarer in common art, than the like relations of the secondaries and primaries. There is very little pure colour in the world: now and then a gleam dazzles us, like a burst of sunshine through grey mists; but as a rule, nature prefers broken colours to absolute hues. Most pure in spring, most full in summer, most mellow in autumn, most sober in winter, her tints and shades of colour are always more or less interlaced, from white and the primaries to the semi-neutral and black.

Of original citrine-coloured pigments there are only a few, unless we include several imperfect yellows which might not improperly be called citrines. The following are best entitled to this appellation:—

223. BROWN PINK,

Brown Stil de Grain, Citrine Lake, or Quercitron Lake is usually prepared from the berries of Avignon (ramnus infectorius), better known as French, Persian, or Turkey berries; but a more durable and quicker drying species is obtained from the quercitron bark. If produced from the former, it must be branded as fugitive, but if from the latter, it may be termed semi-stable. In either case it is a lake, precipitated from the alkaline decoction by means of alum, in such proportions that the alkali shall not be more than half saturated. The excess of soda or potash employed imparts a brown hue; but the lake being in general an orange broken by green, falls into the class of citrine colours, sometimes inclining to greenness, and sometimes towards the warmth of orange. It works well both in water and oil, in the latter of which it is of great depth and transparency, but its tints with white lead are very fugitive, and in thin glazing it does not stand: the berry variety dries badly. A fine rich colour, more beautiful than eligible, it is popular in landscape for foliage in foregrounds. Modified by admixture with burnt Sienna or gamboge, it yields a compound which, with the addition of a small quantity of indigo, gives a warm though not very durable green. In many of the Flemish pictures the foliage has become blue from the yellowish lake, with which the ultramarine was mixed, having faded.

It has been remarked that the alteration made by time in semi-stable pigments is not so observable when they are employed in full body. Their use generally has been deprecated, but in shadows such vegetable colours as brown pink are sometimes of advantage, as they are transparent, lose part of their richness by the action of the air, and do not become black. Moreover, if mixed with pigments which have a tendency to darken, they mitigate it very much. This last, indeed, is the most legitimate purpose to which semi-stable pigments whose colour fades on exposure can be put.

224. MARS BROWN,

or Brun de Mars, is either a natural or artificial ochre containing iron, or iron and manganese. Of much richness and strict permanence, it resembles raw umber in being a brown with a citrine cast, but is generally marked by a flush of orange which is not so observable in the latter pigment.

225. MIXED CITRINE.

What has been before remarked of the mixed secondary colours is more particularly applicable to the tertiary, it being more difficult to select three homogeneous substances of equal powers as pigments than two, that shall unite and work together cordially. Hence the mixed tertiaries are still less perfect and pure than the secondaries; and as their hues are of extensive use in painting, original pigments of these colours are proportionably estimable to the artist. Nevertheless there are two evident principles of combination, of which he may avail himself in producing these colours in the various ways of working; the one being that of combining two original secondaries; and the other, of uniting the three primaries in such a manner that the archeus shall predominate. Thus in the case of citrine, either orange and green may be directly compounded; or yellow, red, and blue be so mixed that the yellow shall be in excess.

These colours are, however, obtained in many instances with best and most permanent effect, not by the intimate combination of pigments upon the palette, but by intermingling them, in the manner of nature, on the canvas, so as to produce the appearance at a proper distance of a uniform colour. Thus composed is the citrine colour of fruit and foliage, on inspecting which we distinctly trace the stipplings of orange and green, or of yellow, red, and green. The truth and beauty resulting from such stipplings in art may be seen in the luscious fruit-pieces of the late W. Hunt, where the bloom on the plum, the down of the peach, &c., are given with wondrous fidelity to nature. In the russet hues of autumn foliage, where purple and orange have broken or superseded the summer green, this interlacing of colour appears; and also in the olive foliage of the rose-tree, formed in the individual leaf by the ramification of purple in green. Besides the durable yellows, reds, and blues, the following orange and green pigments are eligible for mixed citrines. They may likewise, however, be safely and simply compounded by slight additions, to an original brown, of that primary or secondary tone which is requisite to give it the required hue.

226. RAW UMBER,

or Umber, is a natural ochre, chiefly composed of oxide of manganese, oxide of iron, silica, and alumina. It is said to have been first brought from ancient Ombria, now Spoleto, in Italy. Found in England, and in most parts of the world, that which comes from Cyprus, under the name of Turkish or Levant umber, is the best. Of a quiet brown-citrine colour, semi-opaque, it dries rapidly, and injures no other good pigment with which it may be mixed. By time it grows darker, a disadvantage which may be obviated by compounding it with colours which pale on exposure. For light shadow tones and delicate grays it is extremely useful, and yields with blue most serviceable neutral greens. To mud walls, tints for stone, wood, gray rocks, baskets, yellow sails, and stormy seas, this citrine is suited. Some artists have painted on grounds primed with umber, but it has penetrated through the lighter parts of the work. MÉrimÉe states that there are several of Poussin's pictures so painted; that fine series, "The Seven Sacraments," being clearly among the number.

227. Cassia Fistula

is a native vegetal pigment, though it is more commonly employed as a medicinal drug. It is brought from the East and West Indies in a sort of cane, in which it is naturally produced. As a pigment it is deep, transparent, of an imperfect citrine colour, inclining to dark green, and diffusible in water without grinding, like gamboge and sap green. Once sparingly used in water as a sort of substitute for bistre, it is not now to be met with on the palette.

228. Citrine Brown.

From boiling, hot, or cold solutions of bichromate of potash and hyposulphite of soda in excess, we have obtained an agreeable citrine-brown colour, varying in hue and tint according to the mode of preparation and proportions of materials employed. It is a hydrated oxide of chromium which, when washed and carefully dried, yields a soft floury powder. Transparent, and affording clear, delicate pale washes, the oxide has not been introduced as a pigment; partly owing to certain physical objections, and partly to a tendency to greenness. This tendency is peculiar to all the brown chrome oxides of whatever hue, whether hydrated or anhydrous; and indeed distinguishes more or less nearly all the compounds of chromium. Green, in fact, is the natural colour of such compounds, the colour which they are constantly struggling to attain; and hence it is that the green oxides of chromium, being clothed in their native hue, are of such strict stability. The inclination to green which the citrine under notice possesses, may be seen by washing the precipitate with boiling water. It has been supposed that hydrated brown oxide of chromium is not a distinct compound of chromium and oxygen, but a feeble union of the green oxide with chromic acid. If this be the case, the citrine cast of the brown oxide is easily explained, as well as the gradual addition to its green by the deoxidation of the chromic acid.

In mixed tints for autumn foliage and the like, the tendency to green of this citrine brown would be comparatively unimportant; but whether the oxide be adapted to the palette or not, we believe the colour might be utilized. In dyeing, for instance, the solutions of bichromate of potash and hyposulphite of soda would be worth a trial, the liquids of course being kept separate, and the brown washed with cold water. Various patterns could be printed with the bichromate on a ground previously treated with hyposulphite.

Several other browns, and ochrous earths, partake of a citrine hue, such as Cassel Earth, Bistre, &c. But in the confusion of names, infinity of tones and tints, and variations of individual pigments, it is impossible to arrive at an unexceptionable or universally satisfactory arrangement. We have therefore followed a middle and general course in distributing pigments under their proper heads.

Of the three citrines in common use, Mars brown and raw umber are strictly stable; while brown pink, the purest original citrine the palette possesses, is either semi-stable or fugitive, according to the colouring substance used in its preparation.