Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/66

58 mixture of sulphur and mercury. Genuine vermilion is very durable, but when mixed with red lead, as it is sometimes, it will not stand the weather. It can be tested by heating in a test tube; if genuine it will entirely volatilize, German vermilion is the tersulphide of antimony, and is of an orange-red color.

Indian red is a ground hematite ore brought from Bengal; it is sometimes made artificially by calcining sulphate of iron. The tints vary, but a rosy hue is considered the best. It may be used with turpentine and a little varnish to produce a dull surface, drying rapidly, or with bulled oil and a little drier to produce a glossy surface.

Tuscan red is essentially a mixture of Indian red with some sort of lake color. The cheapest article is made from a reduced Indian red and rose pink. The richness of such article is very fleeting, particularly if the rose pink be simply whiting colored with a coal tar dye. It is apparent that the real value of a Tuscan red lies in the permanency of the lake coloring material employed to give it richness. Orange is a chromate of lead, brighter than vermilion, but less durable.

Orange ochre is a bright yellow ochre burnt to give it warmth of tint; it dries and works well in water or oil, and is very durable. It is known also as Spanish ochre. Orange red is produced by a further oxidation