a compound of copper and tin, to which sometimes other metallic substances, particularly zinc, are added. This metal is brittle, hard, and sonorous. It is employed for various uses, as for making of bells, cannon, and statues; and the proportions of the component metals are varied to suit the several purposes to which it is applied. This compound, like some others, is specifically heavier than either of the metals taken separately. A metallic mass, composed of four-fifths of copper and one-fifth part of tin, weighs in water 7\(\frac{1}{2}\) grains more than the same quantities of these two metals would together weigh in water, if not alloyed. This proves, that in the union of copper and tin there is a penetration of parts, the one metal entering into the pores of the other; and this is further confirmed by an observation of Mr Tillet, member of the royal academy of sciences. In his memoir concerning the ductility of metals, he takes notice, that when the mixture of copper and tin is made in the proportions above mentioned, the colour of the copper is entirely annulled and covered by that of the tin, although the quantity of the first be four times greater; and this singular effect cannot be understood without admitting a total change in the size and disposition of the pores of the compound metal.

Tin being less subject to rust than copper, bronze is also found to be less liable to be covered with verdigris than pure copper is; and this is one reason why it is used for cannons, statues, and works exposed to the air and weather. The greater fusibility of bronze than copper is also an advantageous property, and much facilitates the casting of large works. The operation for casting bronze is sufficiently simple. For this purpose a brick furnace is used, nearly of the shape of an oven for baking bread. The floor of this furnace is concave, and consists of a composition of sand and clay. In this hollow floor the metals to be fused are put. The furnace has three openings. The first is a lateral mouth, at which enters the flame of the wood placed in a second furnace, on one side of the first: the second opening is a chimney placed on a side opposite to the mouth, by means of which the flame is drawn over the metal. The third is a hole which is opened and shut at pleasure; through which the inner part of the furnace may be occasionally inspected, that the state of the metal may be observed. When the metal is in the state required, a fourth opening is then unclosed, communicating with the hollow floor, and through which the melted metal flows by channels into the moulds prepared to receive it.

BRONZE also denotes a colour prepared by the colourmen of Paris, wherewith to imitate bronze. There are two sorts, the red bronze, and the yellow or golden. The latter is made solely of copper-dust, the finest and brightest that can be got: the former is made of the same, with the addition of a little quantity of red ochre well pulverized. They are both applied with varnish. To prevent their turning greenish, the work must be dried over a chafing-dish as soon as bronzed.