Cannel coal orcandle coal is a type ofbituminous coal,[1] also classified as terrestrial typeoil shale.[2][3][4] Due to its physical morphology and low mineral content cannel coal is considered to be coal but by its texture and composition of the organic matter it is considered to be oil shale.[5] Although historically the term cannel coal has been used interchangeably withboghead coal, a more recent classification system restricts cannel coal to terrestrial origin, and boghead coal tolacustrine environments.[2]
Cannel coal is brown to black oil shale.[3] It comes from resins, spores, waxes, and cutaneous and corky materialsof terrestrial vascular plants, in part fromLycopsid (scale tree).[4][6] Cannel coal was accumulated in ponds and shallow lakes inpeat-forming swamps and bogs of theCarboniferous age under oxygen-deficient conditions.[6] Thus cannel coal seams are shallow and often found above other deposits, while the coal itself, being rich in oils, burns long, with a bright yellow flame and little ash. The modernLycopodiopsida relatives of these lycopsids (scale trees), with their similar high oil content, high surface area spores, are the source of highly flammablelycopodium powder.
Cannel coal is also lower in fixed carbon than typical bituminous coal. It includes various amounts ofvitrinite andinertinite. Analytically, cannel coal consists ofmicrinite, andmaceral of theexinite group, and certain inorganic materials.
Cannel coal has been used as jewellery since theNeolithic, with pieces appearing in Scotland (often alongsidejet) dating from the centuries before 3500BC.[7]
In England a member of theBradshaigh family discovered a plentiful shallow seam of smooth, hard, cannel coal on his estate, inHaigh,Lancashire in the 16th century.[8][9] The shallow depth at which it was found meant it was suitable for the simple surface mining methods available at that time. It could be worked and carved, and was prized for fireplaces as an excellent fuel that burned with a bright flame, was easily lit, and left virtually no ash.
Cannel coal commanded a premium price as a grate fuel for use in home fireplaces. It burned longer than wood, and had a clean, bright flame.[10] It is more compact and duller thanordinary coal[citation needed], and can be worked in thelathe and polished.[11] In theDurham coalfield and elsewhere carving cannel coal into ornaments was a popular pastime amongst the miners.
The excess ofhydrogen in a coal, above the amount necessary to combine with itsoxygen to form water, is known as disposable hydrogen, and is a measure of the fitness of the coal for use in the manufacture ofcoal gas. Such coal, although of very small value as fuel, commands a specially high price for gas-making.[11] Cannel coal was used as a major feedstock for the historicalmanufactured gas industry, as the gas produced from it was valuable for lighting due to the luminosity of the flame it produced. Cannel gas was widely used for domestic lighting throughout the 19th century before the invention of the incandescentgas mantle byCarl Auer von Welsbach in the 1880s. Following the introduction of the gas mantle, cannel coal lost favour as a manufactured gas feedstock as the gas mantle could produce large quantities of light without regard for the flame luminosity of the gas burnt.
On October 17, 1850,James Young, ofGlasgow, Scotland, patented a method for the extraction ofparaffin (kerosene) fromtorbanite, a very pure cannel coal. It was widely used from 1850 to 1860 in the manufacture ofcoal oil, which today would be called shale oil. The principal consumer product was the illuminating oil kerosene. In 1860, there were 55 companies in the United States making coal oil from cannel coal, most of them near the cannel coal mines, in New York, Pennsylvania, Ohio, Kentucky, and western Virginia (now West Virginia). The discovery of petroleum deposits in the US, starting with theDrake Oil Well in 1859, made petroleum a cheaper raw material for making kerosene and drove the American oil shale industry out of business.[12]
In June 1857, a large gathering to celebrate the laying of a foundation stone of a pedestal on which to raise the retired Locomotion No 1 outside the Stockton and Darlington Railway Station (now North Road Station and Darlington Railway Museum -Head of Steam) witnessed that inside a special cavity in the pedestal were laid many items as a time capsule, and a cannel coal box made by a driver of the locomotive, Robert Murray, as a tribute toEdward Pease (often known as the "Father of the Railways").[13]
This article incorporates text from a publication now in thepublic domain: Bauerman, Hilary (1911). "Coal". InChisholm, Hugh (ed.).Encyclopædia Britannica. Vol. 6 (11th ed.). Cambridge University Press. pp. 574–585.| Coal types by grade (lowest to highest) |  | |
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Note: [1] Peat is considered a precursor to coal. Graphite is only technically considered a coal type. | ||