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its degree of purity and the nature of the earths which enter into 

 its composition. It has obtained various names, derived from cer- 

 tain varieties of its appearance, nature, &c. Thus, from its pitch- 

 like colour and fracture, it has been sometimes called pitch coal ; 

 from the great degree of hardness which it sometimes possesses, 

 stone coal; from its being obtained from a mine or pit, pit coal; 

 and in London, for no better reason than its having been brought 

 hither by sea, sea coal. 



There are certain varieties of pit coal, which obtain their parti 

 cular denominations from their mode of burning, or from then 

 most obvious and predominant combinations. Hence we have 

 blind or deaf coal ; such is the Welsh and Kilkenny coal, kindling 

 slowly and burning without flame or smoke to a stony flag. Open- 

 burning coal, which does not cake, but burns with much flame and 

 smoke, and is soon reduced to ashes. Close-burning coal, which 

 kindles quickly, and melts and runs together like bitumen. Some 

 coal is termed slaty coal, from its texture ; and when it also contains 

 a larger proportion of bitumen it is called slaty Cannel coal. Culm is 

 a coal in small rough fragments, which does not melt or cake, but 

 leaves behind it a slag of the same bulk with the coal employed, 

 which yields a large portion of ashes, formed by argillaceous earth 

 impregnated with iron. 



If the translation of Sir John Hill * be admitted, and his argu- 

 ments in support of it undoubtedly appear to be forcible, fossil 

 coal was known in the time of Theophrastus. The passage is, 

 " Those fossil substances that are called coals (a^axaf), and are 

 broken for use, are earthy ; they kindle, however, and burn like 

 wood coals (avdfaxe;). These are found in Liguria, where there is 

 also amber, and in Elis, in the way to Olympias over the moun- 

 tains. These are used by the smiths/' 



* Theophrastus's History of Stones, translated by Sir John Hill, p. 63. 

 VOL. I. Y 



