Crucible furnaces are among the oldest and simplest furnaces used in the foundry industry. They are primarily used to melt smaller amounts of nonferrous metals but can also be used for ferrous metals. They are mostly used by smaller foundries or for specialty alloy lines. The crucible or refractory container is heated in a furnace, typically fired with natural gas or liquid propane, although coke, oil or electricity have been used. There are three common crucible furnaces: bale-out furnaces, where molten metal is ladled from the crucible; tilting furnaces, where the metal is poured directly from the furnace; and lift-out furnaces, where the crucible can be removed from the furnace and used as a ladle.