BRONZE AND BRASS ORNAMENTAL WORK. The use of bronze dates from remote antiquity. This important metal is an alloy composed of copper and tin, in proportions which vary slightly, but may be normally considered as nine parts of copper to one of tin. Other ingredients which are oc casionally found are more or less accidental. The result is a metal of a rich golden brown colour, capable of being worked by casting—a process little applicable to its component parts, but peculiarly successful with bronze, the density and hardness of the metal allowing it to take any impression of a mould, however delicate.
This process is known as tire perdue, and is the most primitive and most commonly employed through the centuries, having been described by the monk Theophilus, and also by Benvenuto Cellini. Briefly, it is as follows : A core, roughly representing the size and form of the object to be produced, is made of pounded brick, plaster or other similar substance and thoroughly dried. Upon this the artist overlays his wax, which he models to the degree required in his finished work. Passing from the core through the wax and projecting beyond are metal rods. The modelling being completed, the outer covering which will form the mould has to be applied ; this is a liquid formed of clay and plaster sufficiently thin to find its way into every detail of the wax model. Further coatings of liquid are applied, so that there is, when dry, a solid outer coating and a solid inner core held together by the metal rods, with the work of art modelled in wax between. Heat is applied and the wax melts and runs out, and the molten metal is poured in and occupies every detail which the wax had filled. When cool, the outer casing is carefully broken away, the core raked out as far as possible, the projecting rods are removed and the object modelled in wax appears in bronze. If further finish is required it is obtained by tooling. (W. W. W.) Copper came into use in the Aegean area towards the end of the predynastic age of Egypt about 3500 B.c. The earliest known implement is a flat celt, which was found on a neolithic house-floor in the central court of the palace of Knossos in Crete, and is regarded as an Egyptian product. Bronze was not generally used until a thousand years or more later. Its first appearance is probably in the celts and dagger-blades of the Second City of Troy, where it is already the standard alloy of tin. It was not established in Crete until the beginning of the Middle Minoan age (M.M.I., c. 200o B.c.) . The Copper age began in northern Greece and Italy c. 2500 B.C., much later than in Crete and Anatolia, and the mature Italian Bronze age of Terremare culture coincided in time with the Late Aegean (Mycenaean) civilization (1600-100o B.c.). The original sources both of tin and copper in these regions are unknown.