Making Iron

Making Iron. . Ore, charcoal and rock called gabbro for flux were hauled to this site, and a drying fire was started in the furnace. Within a day or two the water wheels and bellows were set in motion, and the “blast”, once begun, would burn uninterrupted for weeks. , Workers returned from the forest, bogs, and the gabbro quarry at Nahant to toil around the clock, feeding layer upon layer of measured ingredients into the charging hole. , The 340 cubic foot furnace interior held three tons of ore, 265 bushels of charcoal and two tons of gabbro rock (fluxing agent). After three days of intense heat from the continuous blast, the ore and gabbro were reduced to liquid and the filled crucible was emptied of its molten contents. The furnace was repeatedely tapped as the layered charging continued day and night. , Captions: , Bog iron ore (the mineral limonite) was dug from stagnant ponds and swamps; each year up to 1000 tons of ore were delivered to the furnace., Gabbro, a fluxing agent and aid to smelting, was an innovative local discovery that replaced the limestone traditionally used in the 17th century ironworks of England., Charcoal, fuel for the furnace, was used in great quantities. It was produced by woodcutters and skilled colliers working in nearby forests., The weight and flow of the water in the overshot wooden wheel generated the constant horsepower needed to operate the huge bellows, key to the continuous blast of the furnace., Furnace, Water Wheel and Bellows