Fur·nace n.
 1. An inclosed place in which heat is produced by the combustion of fuel, as for reducing ores or melting metals, for warming a house, for baking pottery, etc.; as, an iron furnace; a hot-air furnace; a glass furnace; a boiler furnace, etc.
 Note: ☞ Furnaces are classified as wind or air. furnaces when the fire is urged only by the natural draught; as blast furnaces, when the fire is urged by the injection artificially of a forcible current of air; and as reverberatory furnaces, when the flame, in passing to the chimney, is thrown down by a low arched roof upon the materials operated upon.
 2. A place or time of punishment, affiction, or great trial; severe experience or discipline.
 Bustamente furnace, a shaft furnace for roasting quicksilver ores.
 Furnace bridge, Same as Bridge wall. See Bridge, n., 5.
 Furnace cadmiam or Furnace cadmia, the oxide of zinc which accumulates in the chimneys of furnaces smelting zinciferous ores. --Raymond.
 Furnace hoist Iron Manuf., a lift for raising ore, coal, etc., to the mouth of a blast furnace.