The Egyptian bronze consisted, according to Bessari, of two-thirds brass and one-third copper. Pliny says, that the Grecian bronze was formed by adding one-tenth lead and one-twentieth silver to the two-thirds of brass, and the one-third of copper of the Egyptian bronze; and that this was the proportion afterwards made use of by the Roman statuaries. The modern bronze is commonly made of two-thirds copper, fused with one-third of brass; and recently, owing to the great demand for ornaments and decorative furniture of this alloy, lead and zinc in small proportions have been added to the copper and brass. These additions, it is said, increase the fusibility of the alloy, and facilitate the process of casting. Bronze casting is employed in forming equestrian statues, colossal and other figures in alto relievo, to adorn public places, its peculiar tint finely contrasting with the stone or marble of architecture, especially when the artist displays taste in his design and skill in his execution.

The casting in bronze is performed in the following manner: first, the figure or pattern to be cast must have a mould, and this is prepared and laid on a plaster cast, previously wrought and finished by the sculptor.

The mould is made of plaster of Paris, moistened with water, to which is added brick-dust in the proportion of one-third of the former to two-thirds of the latter. This is carefully laid on the mould, with strength in proportion to the weight of metal intended to be used in the founding. In its joints should be cut small channels tending upwards and from different parts of the internal hollow, to allow of vent for the air to escape, as the heated metal runs in upon the mould. A thin layer of clay should be spread over the inside of it, and of the thickness which it is intended the bronze should be. Withinside of the clay a filling-up of plaster and brick-dust, in the proportions as before described, will be required to compose the core; but if the work to be cast be large, before the plaster and brick-dust are poured into the mould to form the core, a skeleton, composed of iron bars, as a support for the figure, should be prepared and fixed; after which the filling up of the core may be proceeded in.

When this is done the mould must be opened again, the layer of clay taken out of it, and the core thoroughly dried, and even burned, with a charcoal fire, or with straw; for if the least damp remain the cast will be blown to pieces when the hot metal comes in contact with it, in running it into the mould, and the workmen employed about the work be maimed or killed by the dispersion of the heated bronze. After the core, etc. has been properly dried and is deemed ready for the work, it should be laid in the mould, and supported in its place by short rods of bronze, which should run through the mould into the core. All being so far advanced, the mould should be clad and bound round with iron, of strength proportionate to the size of the work to be cast; after which the mould should be laid in a situation for running in the metals, and must be supported for that purpose by bricks, etc. Great care should be taken that every part be perfectly dried before any metal be run into the mould, or, as has been before observed, the most fatal consequences will arise to those who may be about the work. A channel must be made from the furnace in which the melted metal is, in order to its running to the principal jet of the mould, and with a descent to promote its flowing rapidly.

The jets, furnace, etc. etc. are all contrived, as has been before described, for casting figures in brass.