The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1902-11-23
HOW WAS COAL FORMED.
Consideration OF one of the Great
Processes of Nature.
Literary Digest.

Literary Digest.
in. the history Of coal formation are dis
cussed by Or: j. F: Hoffman,, of Berlin.
IN the Zeitsehrift fur Angewandts
that coal Is fossiliZed vegetation, the de-
tails of the process by which it came to
be what 1t is are by no means clear. DR..
HOFFMAN, believes that spontaneous COM
bustion was an important factor. Accord
ing TO 2 contributor to London Engineer
Ing who discusses Dr. Hoffmann's paper.
the popular view of the formation of coal
may be summarized as follows: Certain
plants or trees grow in morasseS; they
decay and sink; more plants grow on the
nrst layer, and sink in their turn. The
weighted-down residue decompose through
the influence of microbes, with the genera
ton of methane and carbonic acid; and
when the decomposed mass is afterward
exposed to high pressure we find, according
10 the age OF the deposit, peat, Ignite.
coal or anthracite. Graphite does not APP
pear 10 have the same genesis as coal. He
goes on to say:
Some weak points in the popular view
are pretty apparent. II time and pressure
be the main factors which decide the
character of the coal, then we should
find anthracite in the oldest geological
formations and peat in the most recent
But Ignite occurs in the Devonian, and
we know historically OF the change of
mine timber into ignite. while we have
no examples of peat passing into coal.
Further, anthracite forming the bottom
layer. should contain most ashes, and, so
far as actual experiments can teach us,
the very highest pressures OF 10000 atmos-
pheres do not cause vegetable fibre to be-
come coal
DR.. Hoffmann raises some other points.
He would distinguish three periods In the
formation of coal. First, a period of mi
crobe activity, fermentation, so to say:
then a period of decay. and. finally, the
carbonization period proper. Mere heat
does not change wood into coal. though we
can finally obtain substance like anthra-
cite when We gradually raise the tempera-
ture above 400 degrees G. Hoffman, draws
attention to the spontaneous heating and
ignition often observed in vegetable prod
ucts, and he studies the problem thermo-
chemically. Hay is very apt to heat In a
warm. damp condition and to burst into
flames when air gains access. Wet fax is
VIGOROUSLY dangerous, and so are oiled
rags.
A mill containing grain and flour was
burned down in Berlin some years ago: the
IRE was ascribed to spontaneous combus-
ton, and in some big Jumps of smoldering
grain which had been thrown into the river
Hoffman, discovered layers resembling lig-
mite. coal and anthracite in this sequence
In all these cases moisture favors the COM
bustion or the fungous growth starting
Il. With coal this is not so, because there
IS no organized fiber and no fungous
growth. The writer in Engineering SAYS in
concluding his review of the German ar
ticle:
''Geologically we have reason to believe
that the formation of the coal beds was
followed by violent titanic commissions, dur
ing which heat and pressure may have
coaeted- BY spontaneous combus-
fion some seam would become charred; the
heat would be communicated to another
seam and so on, that coal beds of con-
siderable extent would be produced. But
Hoffman, himself sees that we do not un-
derstand, on these lines, how 1T is that coal
beds consist of fairly uniform coal-coal.
anyhow, not hgnite-all through down TO
their extreme veins. We do not arrive at
any final conclusion as 10 the genesis OF
coal. therefore. and the chief interest OF
DR.. HOffmanns paper lies in the fact that
ne draws attention to the influence OF spon-
famous combustion"