VERMILION. A beautiful scarlet-red pigment. It is usually obtained from mercury, being the red sulphuret of that metal. It is said, by some authors, that the Mimeos vermilion is a sulphuret of arseek : others, on the contrary, assert that it is prepared from the cinnabar of the East, which being an ore of mercury, already combined with sulphur, renders it an obvious and an easily conducted process. Large quantities of vermilion are manufactured Dutch. Their consists in grinding together 150 pounds of sul ur, and 1000 of quicksilver, and then beating the Łthiops mineral thus pro in a two feet and a half in diameter, and one foot deep. If proper precaution is taken, the Ethiops does not take fire, but merely dots together, and requires to be ground. Thirty or forty pots, capable of holding twenty-four ounces of water each, are then filled in readiness with this 21E.thiops.
The sublimary vessels are earthen bolt heads, coated two-thirds of their height with common fire-lute, and hung in the iron rings, at the top of three pot &r oams, built in a stack under • hood or chimney, so that the fire has free access to the coated part; each sublimer has a flat iron plate, which covers the mouth of it occasionally. The fire being lighted in the evening, the sublimers are heated gradually to redness. A pot of JEthiope is then flung into each sub limer; the Ethiops instantly takes fire, and the flame rises from four to six feet high; when the tame begins to diminish, the sublimer is covered for some time. By degrees, and in the course of thirty-four hours, the whole of the lEthiops is put into the sublimate, being 410 pounds into each. The sublimer. being thus discharged, the fire is kept up, so that on takingoff the covers every quarter or half-hour, to stir the mass with an iron flame rises about three or four inches above the mouth of the sublimer. The sublimation usually takes thirty-six hours, and when the sublimer! are taken out of the furnace, cooled, and broken, 400 pounds of vermilion are obtained from each.
Kirchoff first showed, that by commingling and triturating mercury, sulphur, and potash together, and applying heat, cinnabar might be obtained; but the process was uncertain, and gave variable quantities of vermilion. The follow mg is a process recommended by M. Bruner:— The mercury and sulphur are first triturated together, from three hours to a whole dap according to the quantities used. When the mixture is homogeneous, the solution of potash is added, the trituration continued, ancl the mixture heated in an earthen vessel or porcelain, or, if on a large scale, of iron. At first, the stirring must be constant, afterwards, from time to time. The heat should be sustained 1130; it should never pass The liquid should not be allowed to diminish by evaporation, but be made up. After some hours, the mixture will acquire a reddish brown colour, and then great care is required : the mix ture must not pass 113*. If it becomes globose., a little water should be added; the mixture of sulphur and mercury should always be in a polverent form in the liquid. The colOur becomes more and more brilliant, and at time increases with astonishing rapidity : when it has attained ,its highest intensity, the vessel is to be taken off the fire, but still to be retained warm for several hours. The time necessary for the application of beat, appear. to be directed as the upon. If the proportion above be in grammes, (about 151 grains each, the red colour will appear in about eight hours, and the ope ration be finith in about twelve hours.
The cinnabar is then to be washed, and the small quantity of metallic mer cury that may be present, separated; from 328 to 330 parts of vermilion will be obtained, of a colour, equalling that of the native cinnabar, and fir surpass ing that of cinnabar obtained by sublimation. The mercury and the should be quite pure.