GEOLOGICAL SOCIETY OF PENNSYLVANIA. 



283 



mineral., I have been inducedj in the sections fig. 4 and 5, 

 to exhibit these coal seams at their maximum thickness, 

 rather than the ordinary average. 



Quality. 



The coals of this region are of the white ash kind. 

 In the purest beds its structure is imperfectly crystalline ; 

 having the conically radiated arrangement so frequently 

 observable in the anthracite coals. Being highly bitu- 

 minous, they of course burn to a coke and form a hollow 

 fire. For domestic purposes this coal is very agree- 

 able ; burning with a yellow flame and forming a du- 

 rable or lasting Are without the frequent necessity of 

 renewal, as is the case in some descriptions of the fatter 

 bituminous kinds. The quality of the coal is understood 

 to vary in most of the deep veins. That of Black Heath 

 has long commanded the highest price in the market ; 

 being esteemed superior to the Nova Scotia coal. But 

 in all the mines there are portions of the beds, particu- 

 larly towards the bottom, where the quality is inferior 

 and sulphury ; the introduction of which has injured the 

 general estimation of the Richmond coal.* 



The specific gravity of Richmond coal has been de- 

 termined to be 1.246, and the weight of one bushel is 

 66| lbs., according to Mr Bull. 



* The upper beds of the Richmond coal are, as before observed, of the best 

 quality. 



Graham's or Anderson's, fig. 1, and adjoining pits : 



Upper vein of excellent quality and decidedly superior to the lower. Has a 

 striated crystalline texture, entirely without sulphur. 



Lower vein contains sulphuret of iron, and does not make, for some pur- 

 poses, so strong a fire. Somewhat slaty, but the coal itself is lighter than the 

 top vein. It forms an excellent fuel for grates. 



Willis's. Good coal, the u.pp©r vein rather superior. 



Crouch's. Said to be of better quality than Willis's ; the highest coal is 

 the best. 



Brown's. Upper vein eight feet, good ; lower vein three and three quarter 

 feet, inferior. 



Hill's. Top vein of the best description. 



These mines are not mentioned with a view to selection asTjeing the best, 

 fcut rather to show a certain conformity in qnality at remote positions. 



