Anthracite iron charcoal — long the fuel of preference for smelting and glass making, creating a decades long search for alternative fuels. By mid-1792 prominent Philadelphians had formed the Lehigh Coal Mine Company (LHCM Co.) to bring Anthracite to cities reachable via the Delaware River Valley, especially Philadelphia — the nation's largest and most industrialized city, though no one fully understood how to use anthracite as a sole fuel—just that "it 'could' burn 'some' of the time" with a hot enough base fire, so could augment furnace fuels. The LHCM Co. had great difficulty getting many ark-loads of coal to the docks
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