COAL MEASURES. 1/7 



smokeless coal, and non-caking coal. These, in different grades, 

 approach towards the anthracites, and are chiefly valued for engine 

 and smelting purposes. They contain from 70 to 85 per cent, of 

 carbon. They often exhibit, in parts of the seams at least, a 

 peculiar fibrous structure, passing into a singular toothed arrange- 

 ment of the particles, called cofte-in-cone or crystallized coal} Steam 

 coal is spoken of as semi-bituminous : it is compact and hard, and 

 is adapted for raising the largest quantity of steam. Caking coals 

 are 'bituminous' coals, which are generally used for household 

 purposes, having a tendency to cake, emitting jets of gas and 

 giving off much flame and smoke : they contain from 77 to 83 

 per cent, of carbon, while non-caking coals have from 70 to 80 per 

 cent. The ' Smalls ' have the property of fusing together in large 

 masses when duly heated, whence they are turned into coke for 

 iron-smelting and for burning in locomotives. 



Cannel {candle) coal is a hard, dull, and clean coal, containing 

 much volatile matter ; it readily ignites with a yellow flame, 

 and is much used for gas-making. It has a much larger pro- 

 portion of hydrogen and oxygen than anthracite, and leaves but 

 little ash, having from 80 to 84 per cent, of carbon. Cannel coal 

 presents no direct traces of its vegetable origin. Parrot, Splent or 

 Splint coal is a variety with a slaty structure. 



There is also a variety called ^Peacock coal^ which exhibits 

 iridescent colours. The term ' Mother CoaV is applied to the soft 

 * mineral carbon ' or ' charcoal ' occurring between brighter laminae 

 of coal. It is composed of the broken-up tissues of plants con- 

 verted into anthracite, but still retaining their external forms. 



Prof. Morris originally pointed out that the seam known as the 

 " Better-bed-coal" at Bradford, in Yorkshire (see sequel), owed its 

 peculiar chemical composition, which gave it its great value for 

 smelting purposes, to the fact that it was composed almost entirely 

 of a mass of spore-cases, which belong to a Lepidodendroid genus 

 known as Flcmingites, and to Sigillaria, etc. Prof. Huxley sub- 

 sequently observed, from specimens prepared by Mr. E. T. Newton, 

 that these spore-cases were buried in the shed spores themselves, 

 and both together make up the substance of this most remarkable 

 deposit of Coal.^ Under the microscope, coal itself appears to be 

 formed of three kinds of layers, termed by Mr. Newton the bright, 

 dull, and intermediate layers. The dull layers contain dotted tissue, 

 the intermediate layers contain macrospores and microspores, and 

 the bright layers ("mother-coal") are usually structureless, but are 

 sometimes composed of spores. Spores are abundant because they 

 resist decomposition more effectually than woody tissue.^ 



Different seams of coal are suited for different purposes — for 

 smiths, steam, gas, or the household. They vary in thickness from 

 an inch to thirty feet. 



1 See John Young, G. Mag. 1885, p. 283 ; and Prof. J. S. Newberry, Ibid. p. 559. 

 ^ Dr. H. Woodward, G. Mag. 1871, p. 497. 

 ^ See E. Wethered, Q. J. (Proc), xl. 59. 



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