166 Sculpture. workmen rough-out the figure or group, the artist himself adding the finishing touches. It is said that Michelangelo worked out some of his statues from the marble without any previous model or design. In making Bronze Statues similar preliminary steps are taken. Instead of plaster of Paris, loam or sand is used for making the mould, and molten metal is poured into it. To prevent a too great weight of metal, the interior of the mould is usually partly filled with cores of sand, which leave room for only a thin coating of the metal. When the cast is cold, the surface is perfected by means of a graving tool. Sometimes a bas-relief is beaten out without previous casting : in that case the form is obtained simply by beating or hammering until the proper form is required : iron and bronze are sometimes beaten when hot ; silver and gold when cold. The art of carving figures in relief on metal is called chasing : the term toreutic (from a Greek word signifying to carve) has been applied to all kinds of metal work. In modern times zinc, iron, and even tin, have been used for statues ; but they require a coating of some other substance to protect them from the action of the weather. For this purpose a thin layer of bronze has a good effect, and can easily be applied by the process of electro-plating. Wood, Stone, and Ivory Carving are performed by hand without the aid of any previous process. For Gem-engraving, splintered diamonds, fixed into iron instruments, are used ; the work is executed by the hand. A drill is employed for cutting out the larger and deeper portions of the work, which, when finished, is polished with emery powder. Gems cut in relief are
