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
Picoline its unpleasant smell. In 1849, the Scottish chemist Thomas Anderson (1819 – 1874) prepared picoline in pure form, from coal tar and via the pyrolysis of bones. Anderson also named picoline by combining the Latin words "pix" (tar) and "oleum" (oil) because coal tar oil was a source of picoline. By 1870, the German chemist Adolf von Baeyer had synthesized picoline in two ways: by the dry distillation of "acroleïnammoniak" (CH=CH-CH=N-CHOH-CH=CH) and by heating "tribromallyl" (1,2,3-tribromopropane) with ammonia in ethanol. In 1871, the English chemist and physicist James Dewar speculated that picoline was methylpyridine. If the structure of pyridine that