Cāse'-hārd'en, v. t.

(-här'dn), v. t. To harden the surface of, as iron, by converting it into steel, while the interior retains the toughness of malleable iron. This may be done by putting the iron into an iron box, with a cement of animal or vegetable charcoal, and exposing it, for some hours, to a red heat. Ure.