Tar: Encyclopedia - Tar

Tar

Tar is a viscous black liquid derived from the destructive distillation of organic matter. Most tar is produced from coal as a byproduct of coke production, but it can also be produced from petroleum, peat or wood. Naturally occurring "tar pits" (e.g. the La Brea Tar Pits in Los Angeles) actually contain asphalt, not tar, and are more accurately known as asphalt pits. In English and French, "tar" means primarily the coal derivative, but in northern Europe, it refers primarily to the wood distillate, which is used in the flavoring of candy (among other things).

Tar was a vital component of the first sealed, or "tarmac", roads. It was also used as seal for roofing shingles and to seal the hulls of ships and boats. It was also used to waterproof sails, but today sails made from naturally waterproof synthetic substances have negated the need for sail sealing. Tar, of which surprisingly petroleum tar is the most effective, is used in treatment of psoriasis. Tar is a disinfectant substance, and used as such.

Rangoon tar is a natural oil obtained at Rangoon by sinking wells about 60 feet deep in the soil. These wells yield annually about 412,000 hogsheads of liquid.

Wood tar is still used to seal traditional wooden boats and the roofs of historical shingle-roofed churches. Wood tar is also available diluted as tar water, which has numerous uses:

• Flavoring for candies (e.g. Terva Leijona) and alcohol (Terva Viina)
• Scent for saunas
• Anti-dandruff agent in shampoo
• As a component of cosmetics

See also

• Bitumen
• Pitch (resin)
• Pitch drop experiment

Tar - Sources

• The Popular Encyclopedia or Conversation Lexicon’ Blackie & Son c 1890

Categories: Materials | Food additives

Adapted from the Wikipedia article "Tar", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki