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**Creosote Types and Discovery:**

Creosote is a category of carbonaceous chemicals formed by distillation of tars and pyrolysis of plant-derived material.
– Two main types in industry are coal-tar creosote and wood-tar creosote, with other varieties made from oil shale, petroleum, lignite, and peat.
Creosote was first discovered in wood-tar form in 1832 by Carl Reichenbach and carbolic acid (phenol) in coal-tar in 1834 by Friedrich Ferdinand Runge.
– Early chemists believed creosote, carbolic acid, and phenylhydrate were identical substances, but investigations revealed differences between them.

**Creosote Use in Preservation and Industrial Applications:**

– Historically, creosote was used for wood preservation, meat preservation, ship treatment, and medical purposes.
Creosote was used for seagoing and outdoor wood structures to prevent rot, as well as in chimney flues for smoked meat flavor.
– Industrial uses of creosote include wood preservation, as a primary ingredient in liquid smoke for flavoring and preservation, and as a preservative in various products.

**Creosote Oils and Composition:**

Creosote is considered a pesticide for wood preservation meeting AWPA Standards P1/P13 and P2.
Creosote for wood products must be pure coal tar derived from bituminous coal, manufactured through a pressure process under licensed supervision.
– The constituency of distillations of creosote from different woods at different temperatures and the composition of typical beech-tar creosote are detailed.

**Environmental Regulations and Historical Uses:**

Creosote for wood preservation must meet EPA and AWPA Standards, with only pressure processes supervised by licensed applicators allowed.
– Mixing with other creosote types is not permitted except for blending with high-boiling petroleum oil.
– Historical uses of creosote in both industrial and medical applications are outlined, including its use as a replacement for meat smoking and in medicinal remedies.

**Medical Applications and Current Uses of Creosote:**

Creosote has been historically used in medical applications, with components like guaifenesin developed for expectorant and cough medicines.
– Current uses of creosote include over-the-counter expectorants, anti-diarrheals, and cough medicines containing beechwood creosote, as well as in liquid smoke for flavoring and preservation.

Creosote (Wikipedia)

Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood, or fossil fuel. They are typically used as preservatives or antiseptics.

Wood railroad ties before (right) and after (left) infusion with creosote, being transported by railcar at a facility of the Santa Fe Railroad, in Albuquerque, New Mexico, in March 1943. This U.S. wartime governmental photo reports that "The steaming black ties in the [left of photo]... have just come from the retort where they have been infused with creosote for eight hours." Ties are "made of pine and fir... seasoned for eight months" [as seen in the untreated railcar load at right].

Some creosote types were used historically as a treatment for components of seagoing and outdoor wood structures to prevent rot (e.g., bridgework and railroad ties, see image). Samples may be found commonly inside chimney flues, where the coal or wood burns under variable conditions, producing soot and tarry smoke. Creosotes are the principal chemicals responsible for the stability, scent, and flavor characteristic of smoked meat; the name is derived from Greek κρέας (kreas) 'meat', and σωτήρ (sōtēr) 'preserver'.

The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood; coal-tar creosote was also formerly used as an escharotic, to burn malignant skin tissue, and in dentistry, to prevent necrosis, before its carcinogenic properties became known. The wood-tar variety has been used for meat preservation, ship treatment, and such medical purposes as an anaesthetic, antiseptic, astringent, expectorant, and laxative, though these have mostly been replaced by modern formulations.[citation needed]

Varieties of creosote have also been made from both oil shale and petroleum, and are known as oil-tar creosote when derived from oil tar, and as water-gas-tar creosote when derived from the tar of water gas.[citation needed] Creosote also has been made from pre-coal formations such as lignite, yielding lignite-tar creosote, and peat, yielding peat-tar creosote.[citation needed]

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