This is also an alloy of copper and tin, in the proportions of 8 or 9 parts of the former to 1 of the latter. It is a very tenacious metal, easily forged, and possesses a considerable amount of resistance; it is the metal of which large guns were formerly cast, whence the name. In order to make a perfectly uniform alloy, the melted metals should be cooled in the moulds as rapidly as possible. Gun-metal of the above composition has a specific gravity of 8.462; the weight of a cub. in. is 0.304 lb., and its tensile strength 15.2 tons to the sq. in.

The composition employed by the Kellers is-100 of copper, 9 of tin, and 6 of zinc. Fesquet states the proportions adopted by the chief European armouries as follows:-

Copper.

Tin.

England......

100

12.5

• •

„ • • • •

90

10

..........

88-92

12-8

Austria, Bavaria,) Prussia, Russia, Saxony.. ..

100

10

Spain ...............

100

11