Hard Silver
An alloy of 5 parts silver and 1 part copper forms the hardest alloy of these metals.
How to silver a mirror, brew ginger beer, kill moths, make fireworks, tan a hide, bronze iron, cure a ham and clean a straw hat: William B. Dick's numbered encyclopedia answered the questions a nineteenth-century household actually had.
An alloy of 5 parts silver and 1 part copper forms the hardest alloy of these metals.