is a superficial conversion of that metal into steel, by the ordinary method of conversion, namely by cementation with vegetable or animal coals. This operation is generally practiced upon small pieces of iron wrought into tools and instruments to which a superficial conversion is sufficient; and it may be performed conveniently by putting the pieces of iron to be case-hardened, together with the cement, in an iron box, which is to be closely shut and exposed to a red heat during some hours. By this cementation a certain thickness from the surface of the iron will be converted into steel, and a proper hardness may be afterwards given by sudden extinction of the heated pieces of converted iron in a cold-fluid. See STEEL.

CASE-SHOT, in the military art, musket-balls, stones, old iron, &c., put into cases, and shot out of great guns.