88 
changing the bituminous to the above-mentioned kinds. If 
so, we should naturally expect the coal near breaks to be 
more altered, whereas we know there is no difference. When 
the water has been off for a few years, the admission of air 
through the interstices changes the colour of the iron 
pyrites from white to yellow. Now as we always find the 
pyrites to be white in fresh cuttings, it is demonstrative 
evidence that the metalliferous deposit has never been 
exposed to the action of the atmosphere. 
Mr. H. D. Rogers,* says, " The striking fact that we 
" nowhere, not even in the most dislocated and disturbed 
" districts of the anthracite coal field, find any traces of true 
" igneous rocks, that by their contiguity to the coal could 
" have caused the loss of its bitumen, is a circumstance in their 
" geology which goes far to confirm the truth of the hypothesis." 
We know from experience that cannel or stone coal is 
preferred for our domestic gas manufactories, because it 
contains more pure carbon and hydrogen than bituminous 
coal does. If then it had been changed by heat, the 
hydrogen would have been driven off at this early period, 
which we know is not the fact. 
Where trap dykes have been known to come up through 
or near the coal, it has either converted it into coke, cinder, 
or smudge coal ; and where it has only disturbed and broken 
up the coal strata into small patches, and then mixed it up 
with other materials, allowing steam and water to pass 
through, there is no anthracitic tendency. I do not think, 
therefore, from my observations and a careful consideration 
of the subject, that when once bituminous coal is deposited, 
and a subsequent strata laid upon it, that it can be con- 
verted into cannel coal by any process in nature with which we 
are conversant, but that it is a distinct and original deposit 
from water. 
* Geology of Pennsylvania, vol. 2, p. 809. 
