Tar kiln

Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. Production and trade in pine-derived tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden sailing vessels against rot. The largest user was the Royal Navy. Demand for tar declined with the advent of iron and steel ships.

Tar-like products can also be produced from other forms of organic matter, such as peat. Mineral products resembling tar can be produced from fossil hydrocarbons, such as petroleum. Coal tar is produced from coal as a byproduct of coke production. Bitumen is a term used for natural deposits of oil "tar", such as at the La Brea Tar Pits.

"Tar" and "pitch" can be used interchangeably; asphalt (naturally occurring pitch) may also be called either "mineral tar" or "mineral pitch". There is a tendency to use "tar" of more liquid substances and "pitch" of more solid (viscoelastic) substances. Both "tar" and "pitch" are applied to viscous forms of petroleum or heavy crude oil, technically better described as asphalt or bitumen, such as the asphalt found in naturally occurring "tar pits" (e.g., the La Brea Tar Pits in Los Angeles) and oil sands deposits (sometimes called "tar sands") (e.g., the Tar Tunnel in Shropshire). "Rangoon tar", also known as "Burmese Oil" or "Burmese Naphtha", is also a form of petroleum.

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Wikipedia