tar


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tar:

see tar and pitchtar and pitch,
viscous, dark-brown to black substances obtained by the destructive distillation of coal, wood, petroleum, peat, and certain other organic materials. The heating or partial burning of wood to make charcoal yields tar as a byproduct and is an ancient method for the
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Tar

 

a black viscous substance obtained after distilling the fuel and oil fractions from petroleum. The yield of tar from various petroleums is 15–30 percent based on the petroleum. The main components of tar are oil not distilled during the fractionation of petroleum, petroleum resins, solid asphaltic substances (asphaltenes. carbenes, and carboids), and substances of an acidic nature (asphaltogenic acids and their anhydrides). Tar has a density of 0.95–1.0g/cm3 and a viscosity of 18°-45° of conventional viscosity at 100° C.

Tar containing a considerable amount of oil fractions is called semitar; its viscosity is 18°-25° of conventional viscosity and its flash point, 140° C. Tar is also the name for concentrated residues of petroleum oil (petroleum tar) that undergo multistage refining processes to obtain high-quality motor oils. The residues obtained after the sulfuric acid refining of petroleum products are called acid tars.

Tar is used to prepare petroleum bitumens and in road construction. Semitar is used to lubricate coarse mechanisms. Oil tars are used as plasticizers in the rubber industry and in construction. Cracking and destructive hydrogenation can be used to convert very viscous tars into gasoline, diesel fuel, and other substances.

REFERENCES

Nametkin, S. S. Khimiia nefti [3rd ed.]. Moscow. 1955.
Nefteprodukty: Svoislva, kacheslvo, primennie. Spravochnik. Moscow, 1966.

Tar

 

a liquid product of the dry distillation of solid fuels, such as coal and lignite, shales, wood, and peat. The consistency of tar varies from a readily mobile liquid to a mass that flows with difficulty; it is usually dark brown, but it can be almost black. Tar is a complex mixture of organic compounds; its composition depends on the initial material and the method of treatment. The low-temperature (500°-600°C) dry distillation of coal or peat—that is, semicoking—yields so-called primary tar. The coking of coal yields coal tar. The tar formed by heat treating wood is called wood tar.


Tar

 

(1) A plucked stringed instrument used in the Caucasus. The tar has an overall length of approximately 900–1,000 mm. It has three pairs of melody strings (or three pairs and one single string) and two pairs of drone strings.

(2) In Arab countries, a small tambourine.

tar

[tär]
(materials)
A viscous material composed of complex, high-molecular-weight compounds derived from the distillation of petroleum or the destructive distillation of wood or coal.

coal-tar pitch, tar

A dark brown to black hydrocarbon obtained by the distillation of coke-oven tar; softening point near 150°F (65°C); used in built-up roofing as a waterproofing agent.

tar

1. any of various dark viscid substances obtained by the destructive distillation of organic matter such as coal, wood, or peat
2. another name for coal tar

tar

(file format)
("Tape ARchive", following ar) Unix's general purpose archive utility and the file format it uses. Tar was originally intended for use with magnetic tape but, though it has several command line options related to tape, it is now used more often for packaging files together on other media, e.g. for distribution via the Internet.

The resulting archive, a "tar file" (humourously, "tarball") is often compressed, using gzip or some other form of compression (see tar and feather).

There is a GNU version of tar called gnutar with several improvements over the standard versions.

Filename extension: .tar

MIME type: unregistered, but commonly application/x-tar

Unix manual page: tar(1).

Compare shar, zip.

tar

(Tape ARchive) A Unix utility that is used to archive files by combining several files into one. It is often used in conjunction with the "compress" or "gzip" commands to compress the data. The name came from the days when magnetic tape was the predominant storage medium rather than disk. Tar archives are often called "tarballs." See archive formats.
References in periodicals archive ?
JPMorgan Chases CEO has said he disagrees with Trump on this issue, and yet, the bank has increased its financing for tar sands this year, banking on major companies as they acquire new tar sands assets, said Alison Kirsch, Rainforest Action Networks Climate and Energy Program Research Coordinator.
The researchers have proposed three tar production methods that could have been developed by Neanderthals.
Some tiny carbon particles and inorganic substances enter into coal tar because of mass transfer process such as gas flow and adhesion in the process of coal carbonization.
Caption: "Polish Landscape II (Auschwitz)," latex and tar on tile over Masonite (Jan, 5, 1990).
They were likely drawn to the area because they wanted to eat animals that were stuck in the tar.
Coal tar pitch is a complex mixture of the residue from the distillation of high temperature coal tar with an approximate softening point of 90 to 180 degree C.
Tonawanda Mayor Rick Davis keeps a sample of the coal tar in a jar on his desk at City Hall, "In this whole area, we have evidence of coal tar contamination from the old gasworks site.
The direct and indirect impacts to birds from tar sands development are immense," states the report.
Tar burns usually are occupational in nature and are observed mostly in male patients.
Newcastle City Council has drawn up PS2m plans to stop tar leeching off the site.
Accelerated urbanization and economic growth is leading to growing obese and elderly populations, triggering the TAR patient population in emerging nations to increase at a faster rate than elsewhere.
However, among paving contractors, even in the same city, there can be diametrically opposing views about the performance, cost, health, and environmental pros and cons of coal tar - and asphalt-based sealers.