62 PHYSIOGRAPHY. CLASS ill. 



Stiria ; = 1-271, black coal from Newcastle; 



= 1 -288, bituminous wood ; 1 -329, common brown 



coal from Leoben in Sdria ; 1-423, cannel coal 



from Wigan in Lancashire. 



Compound Varieties. Massive: composition la- 

 mellar, faces of composition smooth and even, dif- 

 ferent gradations ; granular texture, often impal- 

 pable, and then fracture is uneven, even, or flat 

 conchoidal. Ligniform shapes, the structure of 

 which resembles that of wood, sometimes very dis- 

 tinct, but often obliterated, with the exception of some 

 slight traces. Fracture then becomes conchoidal, 

 particularly across the fibres. There are some 

 earthy varieties of a loose friable texture. 



OBSERVATIONS. 



I. In the present species of bituminous Mineral-coal are 

 comprised the Drown Coal and the Black Coal of WERNER, 

 excepting the columnar coal, which must be referred to 

 the following species. These two kinds, however, and 

 still more so the varieties which they contain, are very 

 difficult to be ascertained. Colour, structure, and the kind 

 of lustre which depends upon the latter, are almost all that 

 remain for their distinction. The colour of Brown Coal, 

 as the name imports, is brown ; it possesses a ligneous 

 structure, or consists of earthy particles ; the colour of Black 

 Coal is black, not inclining to brown, and it does not possess 

 the structure of wood. The varieties of Brown Coal are 

 the following : Bituminous Wood, which presents a ligneous 

 texture, and very seldom any thing like conchoidal frac- 

 ture, imperfect, and without lustre ; Earthy Coal, consist- 

 ing of loose friable particles ; Moor Coal, or Trapezoidal 

 Brown Coal, distinguished by the want of ligneous struc- 

 ture, by the property of bursting and splitting into angular 



