View of molten iron being poured from a blast furnace ladle into an apparatus for the purification of pig iron, intermediate product of smelting iron ore, at an unknown manufacturing plant. Blast furnaces are used to chemically reduce and physically convert iron oxides into liquid iron or "hot metal," a step in the process of converting iron into steel. This photograph is one of a set of fourteen stereographs detailing the production of iron and steel by various processes.