THE PIGMENTS USED coloured liquids which cause lowering of tone and stain through. Vermilion. This is one of the oldest pigments in the Originally the native sulphide of artist's palette.
mercury or cinnabar was used, but even
in the time of Pliny the preparation of vermilion by the subliming together of sulphur and mercury was kno^vn. This is the method used to-day in China, but has been replaced in Europe by wet methods of manufacture. Vermilion under ordinary conditions in the light of a room or gallery is permanent, as can be seen by examining some of the old pictures in which vermilion has been used, such as " The Rape of Helen," National Gallery, No. 591. When exposed to sunlight the sulphide of mercury is converted from the red to the black variety, thus going brown. This is a molecular change and cannot be prevented by protection with varnishes. It is somewhat capricious, some samples standing exposure without change, but it is evident that vermilion cannot be safely used for outside painting. Sometimes the vermilions made in this country contain residue of alkaline sulphide, in which case they are not safe to mix with white lead. The Chinese vermilion is almost chemically pure, containing less than one part in a thousand of a harmless neutral ash. Pure vermilion can be safely mixed with pure white lead without any change. The opacity of vermilion is about the same as chrome yellow, and it is almost to be regarded as an opaque pigment its place in the table will be found in the chapter on Oil Painting. Red lead is an oxide of lead obtained by roasting massicot gently. It is occasionally found in mediaeval manuscripts, and when it has not turned black, has stood well. Modern tests have shown that it is not permanent ;
either in oil or water colour.
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