Terra-cotta was chosen by many sculptors to preserve the spirit and freedom of the original. Although some shrinking under the action of the fire must be allowed for, yet what is well baked is certain to possess the excellence of the fresh clay. It escapes the chances of over-finish, which too often befalls marble and bronze. Another form of sculpture to be noticed is called _chryselephantine_, on account of the combined use of gold and ivory; the nude parts of the figure being of ivory, probably with color applied to the features and the drapery of gold. The statue was substantially but roughly made in marble, with wood, perhaps, upon it; the ivory being laid on in thick pieces. Statues of wood, of various kinds, were made by the most ancient sculptors. Many small figures in wood, the work of the Egyptian carvers, are to be seen in the museums, and the mummy cases show the practice of carving the head, while the trunk is left only partly shaped out of the block. Bronze was one of the most important forms of ancient statuary. It must be remembered that bronze is an entirely different alloy from brass, the former being an alloy of copper and tin, while brass is of copper and zinc. Small proportions of gold, silver, lead, and iron, were mixed with the bronze by ancient metal-workers to give various colors to their work; thus a blush of shame was produced by allowing the iron in the bronze to rust. Plutarch mentions a face which was pale, the sculptor having mixed silver with the bronze. The primitive bronze-workers, before they arrived at the knowledge of casting, began by hammering solid metals into shapes. The _toreutic_ art, although not definitely known at present, was probably that of hammering, punching, and chiseling plates of metal, either separately or with a view of fixing them upon stone or wood. Both the solid hammered work and the hollow-plate work is mentioned by the authorities. The hollow statues were built up in pieces, fastened together with nails, rivets, and dove-tails, and it is not improbable that some system of welding was practiced. The casting of metals in moulds must have followed the discovery that they could be melted. As the sculptor improved in his art of modeling he would be able to make better moulds. He would soon observe that the solid statue was not only very costly, but so very heavy that the whole figure would collapse from sheer weight. This trouble was corrected by the discovery of a contrivance for casting metals in a hollow mould. It was done pretty much as it is at the present day, by fixing within the mould a _core_, which did not touch the sides, except at certain small points necessary for support. The space between this and the surface of the mould was to be filled by the molten metal.