72 On the Resinous Nature of Coal. : 
From what cause, then, can arise the difference in various 
coals? At present only three characters of diversity are ap- 
parent: specific gravity, quantity of carbon, and quantity of 
hydrogen. ‘To show this the following descending scale may 4 
Hydrogen. Carbon. Specific gravity. ! 
sphaltum, 9 percent. 78°10 1:0 Fs 
Hillsboro’ Coal, eiceaeeeee | <<: peaieninemba 1:09 to 1:12 | 
Cannel, a 5°66 to 6-00 =—81-00 1:28 ‘S 
Bituminous “ various, 4:80 to 5-60 81 to 86 1:29 to 1:32 
Anthracite, “ 2°40 to 4:20 89 to 92 1:34 to 1:47 
Graphite, none 99 2 to 2:27 
accomplished in the study of the internal structure and contents 
of coal*, and that the vast and varied coal formations of this im 
a continent, are chiefly to be relied on as the fields of this 
Stay. 
-he consequences to geology, should the truth of my views 
be finally sustained, are obviously of importance, with respect t0 
the present opinion on central heat, on the atmospheric state of 
these early periods, and on other points, on which this is not the 
proper time to enlarge. . 
Juicielanea 
pin 3 
of 
doubi, with the ashes of recent plants, particularly of Coniferee and Equisita, 
_be very interesting, ‘ 
