GOLD-BEATING. The gold is prepared for leaves by melting it in a blacklead crucible, with some borax, in a wind furnace; and as soon as it is in perfect fusion, it is poured out into an iron ingot mould, then forged and passed between steel rollers, until they become long ribbons, as thin as writing paper: each of these ribbons is then cut into 150 pieces, and each of these pieces is next forged upon an anvil, till it is about an inch square. These squares, which weigh 64 grains each, and are about „ part of an inch thick, are now well annealed, preparatory to the next operation, which consists in interlaying the plates of gold alternately with pieces of very fine vellum, about four inches square, and about twenty vellum leaves are placed on the outsides; the whole is then put into a case of parchment, over which is drawn another similar case, so that the packet is kept tight and close on all sides. It is now laid on a smooth block of marble or metal, of great weight, and the workman begins the beating with a roundfaced hammer, weighing sixteen pounds ; the packet is turned occasionally upside down, and beaten till the gold is extended nearly to an equality with the vellum leaves. The packet is then taken to pieces, and each leaf of gold is divided into four, with a steel knife, having a smooth but not very acute edge. The 600 pieces thus produced are interiaid with pieces of animal membrane, (see Suir,) from the intestines of the ox, of the same dimensions and in the same manner as the vellum. The beating is continued, but with a hammer weighing only twelve pounds, till the gold is brought to the same dimensions as the interposed mem brane. It is now again divided into four, by means of a piece of cane, cut to an
edge, the leaves being by this time bo thin, that any accidental moisture conden sing on an iron blade, would cause them to adhere to it. The 2400 leaves hence resulting areinto three packets, with interposed membrane as before, and beaten with hammer, weighing about ten pounds, till they acquire an extent equal to the former. The packets are now taken to pieces, and the gold leaves, by means of a cane instrument and the breath, are laid flat on • cushion of leather, and cut one by one to an even square, by a little square frame, made of cane ; they are lastly laid in books of twenty-five leaves each, the paper of which is previously smoothed, and rubbed with red bole, to keep the gold from adhering. By the weight and measure of the best wrought leaf-gold, it is found that one grain is made to cover 561 square inches; and from the specific gravity of the metal, together with this admeasurement, it follows that the leaf itself is part of an inch thick. This, however, is not the limit of the extensibilitf of the metal ; for by computing the surface covered in silver gilt wire, and the quantity of gold used, it is found to be only one-twelfth that of the gold leaf, or part of an inch thick ; nevertheless it is so perfect as to exhibit no cracks when viewed by a microscope.