either roasted calcine or raw copper sulfide concentrate. While they have been supplanted in this role, first by flash furnaces and more recently also by the Ausmelt and ISASMELT furnaces, as they are very effective at producing slags with low copper losses. History The first reverberatory furnaces were perhaps in the medieval period, and were used for melting bronze for casting bells. They were first applied to smelting metals in the late 17th century. Sir Clement Clerke and his son Talbot built cupolas or reverberatory furnaces in the Avon Gorge below Bristol in about 1678. In 1687, while obstructed from smelting lead (by litigation), they moved on to copper. In the following decades, reverberatory furnaces were widely adopted for smelting these metals and also tin. They had the advantage over older methods that the fuel was mineral coal, not charcoal or 'white coal' (chopped dried wood). In the 1690s, they (or associates) applied the reverberatory furnace (in this case known as an air furnace) to melting pig iron for foundry purposes. This was used at Coalbrookdale and various other places, but became obsolete at the end of the 18th century with the introduction of the foundry cupola, which was a kind of small blast furnace, and a quite different species from the reverberatory furnace. The puddling furnace, introduced by Henry Cort in the 1780s to replace the older finery process, was also a variety of reverberatory furnace. Aluminium melting Today, reverberatory furnaces are widely used to melt secondary aluminium scrap for eventual use by die-casting industries. The simplest reverberatory furnace is nothing more than a steel box lined with alumina refractory brick with a flue at one end and a vertically lifting door at the other. Conventional oil or gas burners are placed usually on either side of the furnace to heat the brick and the eventual bath of molten metal is then poured into a casting machine to produce ingots. See also Open-hearth furnace Puddling furnace References Bibliography Encyclopædia Britannica, 14th ed. J. Day & R. F. Tylecote (eds.), The Industrial Revolution in Metals (1991) P. W. King, "The Cupola at Bristol", Somerset Araeology and Natural History 140 (for 1997), 37–52. P. W. King, "Sir Clement Clerke and the Adoption of coal in metallurgy", Transactions of the Newcomen Society 73(1) (2001–2), 33–53. External links Industrial furnaces