Part I. Report of progress in 1869, by J. S. Newberry, chief geologist. Part II. Report of progress in the second district, by E. B. Andrews, assist. geologist. Part III. Report on geology of Montgomery County, by Edward Orton, assist. geologist.

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as found in the living plant. In peat and lignite we witness the first
step in the formation of coal. Peat is bitumenized vegetation, generally
mosses and other herbaceous plants, which under favorable circumstances
accumulates in marshes, hence called peat-bogs. Lignite is the product
of a similar change effected in woody tissue; and because it retains, to a
greater or less degree, the form and structure of wood, it has received
the name it bears. Peat is the product of the present period, and lignites are found in deposits of recent geological age. In the older formations these carbonaceous accumulations, still further changed, are bituminous coal. Where special and local causes have operated to carry the
change still farther, as where the beds of coal have been involved in the
upheaval of mountains, and heat has acted upon it; it is converted into
anthracite. Where this metamorphosis has been carried still further, the
result is plumbago, or black lead.
Most of the mineral fuels employed by the civilized nations of the
world belong to the class of bituminous coals, but in our own country,
up to the present time, by far the largest quantity of coal produced anl
consumed has been anthracite, because our beds of coal which lie nearest
the sea-board and have been longest worked, are of this character.
These are, however, of the same age with our Ohio coal beds, and the
peculiar phase which the coals of eastern Pennsylvania exhibit, is due to
the fact that a portion of the great Alleghany coal-field was involved in
the upheaval of the Alleghany mountains, and the coal, in common with
the associated rocks, was greatly metamorphosed-its gaseous matter
being nearly all driven off by the great heat which attended the elevation of the mountains.
The changes which vegetable tissue has'suffered in passing through
the various stages I have enumerated, are not only physical but chemical. They have been carefully studied by several eminent chemists, and
have been so fully explained, that they may be comprehended by any
intelligent person. The rationale of this process may be seen at a glance
by reference to the following formule, taken from Bischoff's Chemical
Geology:
Wood. Loss. Peat.
eCarbon........ 49.1 - 21.50 = 27.6
fHydrogen....... 6.3 - 3 50 = 2.8
(Oxygen.......... 44.6 - 29.10 = 15.5
Wood. Loss. Lignite.
Carbon......-. 49 1 18.65 30.45
Hydrogen. —....... 6 3 - 325 3 05
Oxygen..... —-. 44.6 - 24.40 20.20
Lignite. Loss. Bituminous Coal.
Carbon.....-.. 30.45 - 12.35 = 18.10
Hydrogen........ 3.05 - 1.85 = 1.20
Oxygen......... 20.20 - 1813 = 2.07