Colours for enamels.—Vitreous masses a.re em ployed by the minakar, or enameller on silver, etc. The colours are principally green and blue, salts of iron and copper diffused through vitreous matter ; a yellowish colour also is produced by litharge. The manufacture consists in taking a silver or metal vase, having the pattern of leaves or flowers worked on it in relief, and filling the hollows with enamel in a melted state. The colours wed are blue, green, and red. The art of making this material is known in Lahore, Multan, and other places.
Chinese red colour is made from Taow-fau, or copperas. Their mode of preparation is by putting a pound of copperas into a crucible, over which another crucible is luted, having a small hole in it, which is lightly covered over ; around these they pile charcoal, and enclose the whole within bricks, when they fire the charcoal, and as soon as the fumes issuing from the aperture in the crucible become of a light colour, a small quan tity of the copperas is taken therefrom, laid upon fir-wood, and moistened. with water ; if the colour then prove to be a bright red, they remove the fire ; if not, they allow the copperas to remain subjected to the heat until it assuines that colour, and then remove the fire. When the crucibles are cool, a cake is found in the lower one, but the finest colour is encrusted on its sides and on the bottom of the upper crucible, which is kept separate from the cake ; the pound of copperas produces about four ounces of colour.
Chinese white colour is made from calcined translucent flint, to an ounce of the powder of which they add an equal quantity of white lead.
Chinese green is beautiful. It is prepared with one part of powdered calcined flint, two parts of white lead, and six parts of the scales of well hammered copper.
Chinese violet is produced by adding an addi tional quantity of the prepared white to the green.
Chinese yellow is made by combining equal portions of prepared white and red.
Liu is the powder blue of Chinese commerce. It is the Pien-t'sing stone, au azure mineral, pro bably arseniuret of cobalt, roasted and powdered.
All these various colours are used by the china ware painters having been previously dissolved in gum-water, t'° which they occasionally add salt petre, copperas, or white lead. The colours are laid on after the first baking and varnishing of the china-ware, but the beauty and depth of the colouring is imperceptible until after the second baking.
Black. china-ware, the Ow-mi-ew, ornamented with gold, is very much prized in China. To make it, they mix three ounces of azure and seven of the oil of stones ; this is laid on the ware, and Fhen perfectly dry it is baked, after which the gold is laid on and the vessel is re-baked.
Crac'ked porcelain, the To-wi-kie, is a porcelain prepared simply by varnishing the vessels With a. whitish ash-coloured varnish, made from calcined translucent white pebbles ; this has the of marbling and veining the ware, and giving ft' an appearance as if it had been fractured into many pieces, which had been carefully reunited. .21/. M. C. ; Jameson's Journal, 1853 ; • Williams' Middle Kingdom,- Powell's Handbook ; Sires Chinese • Madras Ex. Jur. .Rep.