History and What It Became

The earliest European blast furnaces are dated archaeologically to the twelfth and thirteenth centuries, with carbon-dated remains at Lapphyttan in Sweden among the oldest known, and the technology spread through the Bergslagen mining region, the Bergamasque area of Lombardy, and the iron districts of Champagne across the thirteenth to fifteenth centuries as part of what historians of technology call the late medieval steel revolution. The decisive step was mechanical rather than chemical: fitting a furnace's bellows to a water wheel let ironworkers scale up the draft far beyond what hand or foot power could sustain, and it was that stronger, steadier forced blast, more than any change in ore or fuel, that pushed furnace temperatures high enough to produce liquid iron continuously rather than the spongy, semi-solid "bloom" earlier bloomery furnaces produced in batches. Where nearly every other instrument in this category shrank down into laboratory glassware as chemistry separated from alchemy, the blast furnace went the other way entirely, growing continuously larger and more mechanized from the medieval water-wheel furnace through the coke-fired furnaces of the industrial revolution to the enormous computer-controlled furnaces of a modern steelworks, which still bear the name "blast furnace" and still work on the same forced-draft principle.