Anthracite iron were their principle businesses. The Franklin Institute, in 1830, offered a gold medal to the manufacturer of the greatest quantity of anthracite iron, and Nicholas Biddle and his associates offered a prize of $5,000 to the first individual to smelt a certain quantity of iron ore within a given time, using anthracite. The Lehigh Coal & Navigation, by then an industrial giant of the times, also offered free water power and discount rates on coal and shipping to encourage the development of the process. The first key breakthrough occurred in 1828-29, when Scotsman James Beaumont Neilson patented the hot blast
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