Crucible

Webster's Dictionary of the English Language

·noun A hollow place at the bottom of a furnace, to receive the melted metal.

II. Crucible ·noun A test of the most decisive kind; a severe trial; as, the crucible of affliction.

III. Crucible ·noun A vessel or melting pot, composed of some very refractory substance, as clay, graphite, platinum, and used for melting and calcining substances which require a strong degree of heat, as metals, ores, ·etc.