Being the most positive of colours, and holding the middle station of the primaries, red contrasts and harmonizes with black and white, which are the negative powers or neutrals of colours, and the extremes of the scale. Moreover, as red is less nearly allied to black or shade than to white or light, this harmony is most remarkable in the union or opposition of white and red, and this contrast most powerful in black and red.
As a primary and simple colour, red cannot be composed by mixture of other colours. So much is it the instrument of beauty in nature and art in flesh, flowers, &c., that good pigments of this genus are most indispensable. On the whole, the palette cannot be considered so well furnished with reds as with yellows. Especially is there wanting a permanent transparent scarlet, a colour for which a prize of £500 has for many years been offered by the Society of Arts.
68. CADMIUM RED.
The deep, pale, and lemon yellows which cadmium at first afforded, were followed by an orange, which has quite recently been succeeded by a red. This is a most vivid orange-scarlet, the red predominating, of exceeding depth, and intense fire. It is a simple original pigment, containing no base but cadmium, and possessing a large amount of latent colour. It is more orange in hue than vermilion, and has the advantages of flowing and drying well, of greater brilliancy, of retaining that brilliancy when dry, and of considerable transparency. Hence this red is preferably employed where opacity is to be avoided—in sunset clouds for instance. As day declines or by artificial light, the colour approaches very nearly to a deep pure scarlet; and the best substitute for a permanent transparent scarlet which has yet been obtained is furnished by admixture of cadmium red with madder carmine, or by using the latter as a glaze. Compounded with white, the red yields a series of fine flesh tints; and it mixes readily and safely with other colours. Without harshness or rankness, neither injured by an impure atmosphere nor exposure to light and air, cadmium red is eligible in every department of art, enamel painting only excepted. In illumination, the red contrasted by viridian will be found most beautiful and effective. Seeing that previous to its introduction the number of bright reds, not being crimson, nor of a crimson cast, was limited to vermilions, pure scarlet, red chrome, and red lead, of which the first alone were permanent, there was room on the palette for a strictly durable and somewhat transparent pigment like cadmium red, with its many distinctive properties.
COCHINEAL LAKES.
Lake, a term derived from the lac or lacca of India, is the name of a number of transparent red and other coloured pigments of great beauty, prepared for the most part by precipitating coloured tinctures of dyeing drugs upon aluminous bases. Consequently, the lakes form a numerous class, both with respect to the variety of their appellations, and the substances whence they are produced. Those under notice are known as Carmine, Crimson Lake, Scarlet Lake, Purple Lake, Chinese Lake, Florentine Lake, Hamburgh Lake, Roman Lake, Venetian Lake, &c., and are obtained from the "coccus cacti," an insect found on a species of cactus, from the juice of which it extracts its nourishment. This coccus is a native of Mexico, where two kinds are recognised, under names which signify wild cochineal and fine cochineal. The latter may be considered a cultivated product, its food and wants being carefully attended to, while the former is left in a natural state, and is less valuable. Wild cochineal is distinguished by having a woolly downy coat, which is not the case with the fine cochineal. The females, of which there are from one hundred and fifty to two hundred for each male, are marked by the absence of wings, and constitute the commercial article. They are generally killed by immersion in boiling water, which causes them to swell to twice their natural size, and are then dried and packed for market. The insects shrivel in drying, and assume the form of irregular grains, fluted and concave. The best sorts have a silvery-grey colour, with a purplish reflection, and seem to be dusted with a white powder. This appearance is often given by means of heavy spar, carbonate of lead, Venice talc, &c. A good lens, however, will mostly expose the fraud; or it may be detected by macerating the insect in water, and allowing the loosened pulverised particles to settle.
Cochineal is a very rich colouring substance, yielding about half its weight of real colouring matter, which may be easily extracted by boiling in water. Dr. Warren De La Rue, who examined the living animal, states that on piercing the side of the insect a purplish-red fluid exuded, containing the colouring matter in minute granules. This colouring matter he succeeded in obtaining pure, in the form of a purple-brown friable mass, pulverizable to a fine red powder, transparent when viewed by the microscope, and soluble both in water and alcohol in all proportions. At temperatures above 136° it decomposed, and by alkalies its colour was turned to purple. These facts account for the care required in drying cochineal lakes, and for their liability to change of hue when in contact with alkaline substances, as in mural decoration.
The lakes of cochineal may be known from those of the dye-woods by their solubility in ammonia, a liquid which purples but does not dissolve the colours produced from the latter.
69. CARMINE.
A name once given only to the fine feculences of kermes and cochineal tinctures, now denotes generally any pigment which resembles them in beauty, richness of hue, and powdery texture. We have, therefore, blue and other coloured carmines, though the term is usually confined to the crimson and scarlet lakes of cochineal. As at present commonly understood, carmine is that preparation of cochineal which contains the most colouring matter and the least aluminous base. Hence it is the richest, deepest, most intense, and most permanent. Although not to be classed as durable, yet by reason of its extreme depth, carmine is more stable than the weaker crimson, scarlet, and purple lakes. When well-made, pure, and employed alone and in body, it has been known to retain its colour for years, especially if protected by oil or varnish. In tint with white lead, however, it has no stability; and though little affected by impure air, in glazing it is soon discoloured and destroyed by the action of light. Of great power in its full touches, it possesses considerable clearness in the pale washes, and works admirably. In landscape, carmine is seldom used, the colour being chiefly valued in flower painting and illumination.