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In 1709 Darby moved his foundry enterprise to Coalbrookdale, a village along the Severn River, about eighty miles north of Bristol, near Dudley. There he began developing a method of preparing coal for iron smelting by coking it—baking it in a kiln under low-oxygen conditions to drive out the sulfur and other impurities that would otherwise embrittle the iron. Writing about the invention later, his son’s widow, Abiah Darby, would compare it to drying malt.47 As they mastered the technology, Darby and his descendants gradually substituted coke for charcoal. Smelting iron with coked coal then enabled British industry to bypass the bottleneck of wood scarcity, Abiah Darby noted in 1763: “Had not these discoveries been made, the Iron trade . . . would have dwindled away, for woods for charcoal became very scarce, and landed gentlemen [who owned the forests] rose the prices of Cord Wood exceeding high—indeed it would not have been to be got. But from pit coal being introduced in its stead, the demand for wood charcoal is much lessened and in a few years I apprehend will set the use of that article aside.”48 By the beginning of the nineteenth century, iron had largely replaced wood in manufacture and construction.49
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