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Glaze without Lead

Common earthenware is glazed with a composition con- and carbonate of lead especially, must be conand carbonate of lead especially, must be taining lead, on which account it is unfit for entirely free from oxide of tin, as the smallest many purposes. The following glaze has been particle of this imparts milkiness to the paste. proposed, among others, as a substitute: 100 All the ingredients must be separately resubstitute: 100 All the ingredients must be separately reparts washed sand, 80 parts purified potash, duced to powder; and, after being mixed, 10 of nitre, and 20 of slacked lime, all well sifted through lawn. For the finer kinds of mixed, and heated in a black-lead crucible, in a reverberatory furnace, till the mass flows into a clear glass. It is then to be reduced to powder. The goods to be slightly burnt, slightly burnt, dipped in water, and sprinkled with the powwith the powder. mock diamonds, rock crystal should alone be employed; when sand is used, the purest , the purest white variety should be selected, and be washed thoroughly, first with muriatic acid and then with water, to remove any traces of earthy matter. Much of the minute detail in making artificial gems can only be acquired