By Carina Magyar in Fuel — Dec 23, 2022

III: Tar

Four tall tales about tar

An asphalt road surface. Photo by Fran Soza / Unsplash

Good morning. Today is tridi, the 3rd of Nivôse, Year CCXXXI. We celebrate le bitume, the sticky stuff we use to make roads.

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You have to dig up coal, but bitumen will ooze right up to the surface. Cracks in the earth combine with heat pressures to create everything from small tar balls that cool and wash up on the shore to massive tar pits like the ones in La Brea, California or pitch lakes like the one in Trinidad. As a result, bitumen is the fossil fuel with the oldest track record of use in human history, although it wasn't used to burn, but to glue and waterproof.

First, let's get a thing straight: yes, there is a difference between bitumen, tar, and asphalt. Without getting into geology or chemistry too deeply, "bitumen" is naturally occurring oil sludge, "asphalt" is man-mixed oil sludge, and "tar" is coal sludge. The difference between oil and coal is whether the fossil fuel was made of just plant stuff (coal) or plant and animal stuff (oil). So you can turn bitumen into tar through distillation, but not the other way around.

Does any of this matter? Not for what we're about to discuss, no. But here's a video on why people give a crap about the distinction:

III: Tar

II: Coal

IV: Sulfur

II: Coal

IV: Sulfur

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