416 



sive series of slices, taken from the several varieties of coal found at 

 Newcastle and the contiguous district. 



The coal of the Newcastle district is considered by the author to be 

 of three kinds. The first, which is the greatest in quantity and the 

 best in quality, is the rich caking coal so generally esteemed ; the 

 second is Cannel or Parrot coal (Splent coal of the miners) ; and the 

 third, the slate coal of Jameson, consists of the two former, arranged 

 in thin alternate layers, and has, consequently, a slaty structure. In 

 these varieties of coal, even in samples taken indiscriminately, more 

 or less of the vegetable texture could always be discovered ; thus 

 affording the fullest evidence, if any such proof were wanting, of the 

 vegetable origin of coal. 



Each of these three kinds of coal, besides the fine distinct reticula- 

 tion of the original vegetable texture, exhibits other cells, which are 

 filled with a light wine-yellow-coloured matter, apparently of a bitu- 

 minous nature, and which is so volatile as to be entirely expelled by 

 heat before any change is effected in the other constituents of the 

 coal. The number and appearance of these cells vary with each 

 variety of coal. In caking coal, the cells are comparatively few, and 

 those which do exist are highly elongated. Their original form the 

 author believes to have been circular ; and he attributes their present 

 figure to the distention of gas confined in a somewhat yielding mate- 

 rial, subject to perpendicular pressure. In the finest portions of this 

 coal, where the crystalline structure, as indicated by the rhomboidal 

 form of its fragments, is most developed, the cells are completely 

 obliterated. In such parts the texture is uniform and compact : the 

 crystalline arrangement indicates a more perfect union of the consti- 

 tuents, and a more entire destruction of the original texture of the 

 plant. 



The slate-coal, or the third variety above mentioned, contains two 

 kinds of cells, both of which are filled with yellow bituminous matter. 

 One kind is that already noticed in caking coal; while the other kind 

 of cells constitutes groups of smaller cells of an elongated circular 

 figure. 



In those varieties which go under the name of Cannel, Parrot, and 

 Splent Coal, the crystalline structure, so conspicuous in fine caking 

 coal, is wholly wanting, the first kind of cells are rarely seen, and the 

 whole surface displays an almost uniform series of the second class 

 of cells, filled with bituminous matter, and separated from each other 

 by thin fibrous divisions. 



After describing these appearances, and illustrating them by draw- 

 ings, the author proceeds to speculate on the origin of the cells in 

 Cannel coal. He considers it highly probable that they are derived 

 from the reticular texture of the parent plant, rounded and confused 

 by the enormous pressure to which the vegetable matter has been 

 subject. 



The author next states, that though the crystalline and uncrystal- 

 line, or, in other terms, perfectly and imperfectly developed, varieties 

 of coal generally occur in distinct strata, yet it is easy to find speci- 

 mens which in the compass of a single square inch contain both va- 



