31. Red is the second and intermediate of the primary colors, standing between yellow and blue, and in like intermediate relation, also, to white and black, or light and shade. It is also the second in harmonizing and contrasting with other colors, and in compounding black and all neutrals. Red is a color of double power in this respect, that, in union or connection with yellow, it becomes warm and advancing, but mixed or combined with blue, it becomes cool and retiring. Hence, it is preeminent among colors-the most positive of all-forming, with yellow, the secondary orange, and its near relatives, scarlet, etc.; and, with blue, the secondary purple, and its allies, crimson, etc. It gives some degree of warmth to all colors, but most to those which partake of yellow. It is the principal color in the tertiary russet; enters subordinately into the two other tertiaries, citrine and olive; goes largely into the composition of the various hues and shades of the semineutral, maroon, or chocolate, and its relatives, puce, murrey, morello, mordore, pompadour, etc., and, more or less, into browns, grays, and all broken colors. Tertiary and neutral colors are explained hereafter.

32. Vermilion' is a sulphuret of mercury, which, previous to its being levigated, is called cinnabar. It is an ancient pigment, found both in a native state and produced artificially. The Chinese possess a native cinnabar so pure as to require grinding only to become very perfect vermilion. The Chinese are, besides, supposed to have a process of manufacture unknown to us, whereby superior brilliancy is imparted to the color, and the beauty of the natural pigment enhanced.

Vermilion is artificially prepared by melting one part of sulphur and adding to it gradually five or six parts of mercury. The heat is maintained until the mixture swells up, and the vessel covered and removed from the heat's action. When the mixture is cold it is reduced to powder and sublimated in a closed vessel, placed in a furnace, so that the flames may play freely around it to one-half its height. The heat is gradually increased till the lower portion of the sublimating vessel becomes red hot; the cold sublimate, afterwards broken into pieces, ground in water to a fine powder, is passed through a sieve and dried.

Powder vermilion may thus be tested: Place a small quantity on a piece of paper laid on a hard surface, cover this with a card or other piece of paper, which rub with the thumb nail, the handle of a penknife, or other hard substance. If the vermilion be pure, it will, on the removal of the paper, present a smooth surface of the uniform original color, but, if adulterated with red lead, etc., it will appear orange or yellow.

33. Red lead is a very old pigment, formerly known as minium or saturnine red, confounded, by some old writers, with cinnabar. It is a deutoxide of lead, prepared by subjecting massicot to the heat of a furnace, with an expanded surface and free accession of air. It is of scarlet color and fine hue, warmer than common vermilion, bright, but not as vivid as the biodide of mercury though having the body and opacity of both pigments. It has been, even in name, confounded with vermilion, with which it was formerly the custom to mix it. When pure it is unaffected by light, but acids, white lead, or any oxide, or preparation of the metal, soon deprive it of color, while impure air will blacken and ultimately metallize it.

Red lead may be adulterated with colcothar, a sesquioxide of iron. It thus forms a powder without taste or smell, insoluble in water, alcohol, or any essential oils. Red lead is often adulterated with brick dust, whose presence is easily detected. Heat the red lead in an iron crucible and treat with nitric acid diluted, whereby the red lead will be dissolved and the brick dust remain.

34. Light red is in reality a burnt ocher of russet orange hue, principally valued for its tints, when mixed with other pigments. The crimson light red is a brown ocher burned. The principal yellow ochers afford this color best; the brighter and better the ocher from which this pigment is prepared, the brighter will be the red, and the better the flesh tints it will afford with white. It is greatly used in figure and landscape painting.