Creosote mixed with coal-tar creosote, or fortified with pentachlorophenol. Water-gas-tar creosote is also derived from petroleum oil or shale oil, but by a different process; its distilled during the production of water gas. The tar is a by-product resulting from enrichment of water gas with gases produced by thermal decomposition of petroleum. Of the creosotes derived from oil, it is practically the only one used for wood preservation. It has the same degree of solubility as coal-tar creosote and is easy to impregnate into wood. Like standard oil-tar creosote, it has a low amount of tar acids and tar bases, and
Coal oil Coal oil Coal oil is a shale oil obtained from the destructive distillation of cannel coal, mineral wax, or bituminous shale, once used widely for illumination. Chemically similar to the more refined, petroleum-derived kerosene, it consists mainly of several hydrocarbons of the alkane series, with 10 to 16 carbon atoms in each molecule and a higher boiling point (175–325 °C) than gasoline or the petroleum ethers and lower than the oils. Because kerosene was first derived from cannel coal, classified as terrestrial type of oil shale, it continued to be popularly referred to as "coal oil" even after production shifted