Anthracite iron as an ingredient into a reverberatory furnace (and in later years, a Bessemer converter). Anthracite, also known as stone coal or rock coal, is very difficult to ignite, mine, clean, and break into smaller chunks and requires correct conditions to build heat or hold temperature and sustain burning—which oft depend upon the size and uniformity of the coal particles. Yet American cities were cramped for fuels, woodlands were exhausted near bigger towns and Philadelphia, largest city in America needed fuels for mills and foundries as well to sustain manufacturing. Inventor and industrialist Josiah White (owner of a wire mill, foundry
Anthracite difficulty of igniting it. This was a particular concern in smelting iron using a blast furnace. With the invention of hot blast in 1828, which used waste heat to preheat combustion air, anthracite became a preferred fuel, accounting for 45% of US pig iron production within 15 years. Anthracite for iron smelting was later displaced by coke. From the late 19th century until the 1950s, anthracite was the most popular fuel for heating homes and other buildings in the northern US, until it was supplanted by oil-burning systems and more recently natural gas systems. Many large public buildings, such as