Steelmaking involves the removal of iron's impurities and the addition of desirable alloying elements. Steel was first made by cementation, a process of heating bars of iron with charcoal so that the surface of the iron acquired a high carbon content. The bars were then fused together, yielding a metal harder and stronger than the individual bars but lacking uniformity in these properties. The crucible method, consisting of melting iron together with other substances in a crucible, is one of the costlier steelmaking processes, employed only for making special steels (e.g., the famous blades