Source : Webster's Revised Unabridged Dictionary (1913)

Casehardening \Case"hard`en*ing\, n.
   The act or process of converting the surface of iron into
   steel. --Ure.

   Note: Casehardening is now commonly effected by cementation
         with charcoal or other carbonizing material, the depth
         and degree of hardening (carbonization) depending on
         the time during which the iron is exposed to the heat.
         See {Cementation}.