Prof. Johnson’s Report on the Bradford Coal Field. 139 
One circumstance worthy of remark in connection with the 
position of the lower coal bed in the formation, is that in the 
central portion of the basin, this bed reposes not on a conglom- 
erate rock nor is it underlaid at all by such material, but rests on 
a fine grained gritstone five or six feet thick, distinguished from 
the underlying sand rocks chiefly by its superior compactness and 
white color. On the borders of the coal basin on the contrary, 
the underlying rock is a massive conglomerate of coarse pebbles 
many feet in thickness, capping the otherwise denuded ridges and 
serving by its great durability to defend the softer rocks below 
from the action of water and the disintegrating power of growing 
and decaying vegetables. 
The materials collected from the several parts of the Bradford 
coal field have been submitted to assay aie Prof. Johnson, and. 
yielded the following results. 
* Analyses of Coal.—Eight samples of the coal of this region have 
bees examined 
No. 1. This specimen is from the fifth ply of coal in the lower bed, 
opened near the head of Fall creek. a of the ply, 5} inches. 
Its specific gravity is 1.5155. 
At a temp. of 300°, it loses of. moisture, - 
By distillation at a red heat of water, = - - 
1.3 per cent. 
os. 
Uncondensable gaseous matter, - . - he ae 
It contains of carbon, - - - a - Sage * 
And of earthy matter, - - - * a S 
100.0 
“‘The ashes are almost —_— white, and of moderate density. “This 
as well as the two following specimens, is from parts of the bed so near 
the outcrop as to yield, as in all similar cases, a higher proportion of 
earthy matter than would be found to exist in the coal when not exposed 
to any of the decomposing influences of the a re. 
“No. 2. This specimen was from the third ply of coal in the same 
opening as the preceding. The thickness of this ply is9} inches. Its - 
specific gravity is 1.4485. 
At 260° it loses of moisture - 1.9 per cent. 
62 ce 
_ * a bright — heat it gives of Dee wai 
of gas, - . OS 32% 
= | . 17.4 
It contains of carbon, - ~ - - 70.0 ‘“ 
nes 2 aertiaad 
And of earthy matter, - - - 
