Vermilion (sulphide of mercury, Hg, 87; S, 13) exists in the native state as Cinnabar (q.v.), from which this beautiful red pigment is obtained by selecting pure pieces and simply grinding them.
It is, however, generally made artificially. By one dry process the first step is to prepare an intimate mixture of 100 parts of mercury and 18 parts of sulphur, which are agitated together in revolving vessels until they have combined. The powder so obtained is afterwards sublimed in specially constructed retorts, and the purest portion condensed on the heads of the retorts is then treated with a little caustic potash, and washed with warm water. One of several wet processes in use for making vermilion consists in combining mercury and sulphur by grinding them together in the presence of water, caustic potash being afterwards added, and the mixture triturated for some hours at a temperature of 113° F. The product is afterwards thoroughly washed. The Chinese have long made beautiful vermilion. See PIGMENTS, and RED.