Blue. Of all blues in use none can equal ultra-marine—its wonderful brilliancy and permanency excelling all others. But it is often adulterated after reaching this country, and the genuine is not common. Put a small quantity on a case knife, and hold it over a candle, keep the smoke from touching it; if adulterated it will appear in grey spots, and if genuine it will remain brilliant as at first. It was formerly made from lazulite, the beautiful variegated blue mineral, worth at one time in Italy twenty-five dollars an ounce. A greater part of that used now is composed of carbonate of soda, sulphur and kaolin, colored with cobalt.
Prussian Blue is a good color, it is a ferrocyanuret of iron, produced in different ways. There is no substitute for Prussian blue for miniature painting on account of its strength of effect and transparency. The best and purest is that which is dark color.
Indigo is beautiful on account of its extreme depth of color, nearly approaching to black; the best is called the rock indigo.
Cobalt is another fine blue, much used in sky grounds, and in the delicate parts of faces and necks.
French Ultra. A beautiful bright blue; it is adapted for ladies’ drapery—rather too powerful for pearly tints or flesh.
Permanent Blue, Cerulean. Useful in draperies and backgrounds; also in landscape and flower painting. Not good for flesh tints.
Sap Green is the juice of buckthorn berries, and has proven to be a highly useful color when judiciously mixed with other colors, producing warm fleshy tints which cannot be made without it.
Copper is the base of most blues, though some are formed from iron and cobalt.
Reds. Carmine is a fine bright crimson, inclining to scarlet, and rather an opaque color. From it a variety of fine tints may be made, but it being a very high red, renders it unfit for delicate subjects; in this case use rose madder. There are various kinds of it prepared of other reds, but the deep kind is the best, the lighter being made so by adulteration, commonly made of alum and cream tartar, colored with cochineal, but it fades rapidly by out door exposure. The genuine is made from kaolin, or China clay, colored with cochineal, prepared with much difficulty, which makes it expensive.
Crimson Lake is a beautiful crimson color, inclining toward the purple, making it useful for the carnation tints in painting delicate subjects.