Evening star. [volume] (Washington, D.C.) 1854-1972, 1902-12-06
HOW WAS COAL FoRMEDp
Consideration of One of the Great Pro-
cesses Of Nature.
From the Literary Digest.

From the Literary Digest
Some interesting and mysterious points in
the history of coal formation are discussed
by DIR. J. F. Hoffman, of Berlin in the
Zeitschrlft fur Angewandte Chemie. AL
though authorities are agreed that coal Is
fossiized vegetation. the details OF the pro-
cess by which 1t came to be what 1t Is are
by no means clear. DIR. Hoffman, believes
that spontaneous combustion was an i'm
portant factor. According to contributor
to London Engineering. 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 first leaves. and sink in their
turn. The weighted-down residue decom-
pose through the influence Of microbes,
with the generation of methane and car
bonic acid and when the decomposed mass
is afterward exposed to high pressure we
find. according to the age of the deposit,
peat, Ignite. coal or anthracite; graphite
does not appear to have the same genesis
as coal. He goes to say:
Some weak points of the popular view
are pretty apparent. If time and pressure
be the main factors which decide the char
acter Of the coal. then we should find an
thraCite in the oldest geological formations
and peat in the most recent. But Ignite &C.
ours in the Devonian. and We know histOri-
Caliy of the Chdnge or mine TIMBER INTO llS-
mite. while we have examples of peat
passing into coal. Further, anthracite
forming the bottom layer should contain
most ashes. and. go far as actual expert
ments can teach us. the very highest pres
sures of 10000 atmospheres do not cause
vegetable fiber to become COAL
DR.. Hoffman, raises some other points.
He would distinguish three periods in the
formation OF coal. First, a period of mi
crobe activity a fermentation. to say:
then period of decay, and finally, the car
bonization period proper. Mere heat does
rot change wood into coal, though we can
finally obtain substance like anthracite
when we gradually raise the temperature
above 400 degrees Centigrade. Hoffman,
draws attention to the spontaneous heating
and ignition often observed in vegetable
products and he studies the problem Their
incidentally. 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 80 are oiled
rags.
A mill containing grain and flower was
burned down In Berlin some years ago; the
fire was ascrfbed to spontaneous combus-
ton, and in some big Jumps of smolder-
ing grain which had been thrown into the
river Hoffman discovered layers resembling
Ignite. coal and anthracite In this Sc
quence. In all these cases moisture favors
the combustion or the fungous growth
starting 1t. With coal this Is not so, be-
cause there is no organized fiber and no
gunSuS growth Inc WRITER IN Eng1neer-
ing says in concluding his review of the
German article:
"GeologicalIy 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 CO.
acted By spontaneous combus-
ton some seam would become charred: the
heat would be communicated to another
seam. and so on. so that coal beds Of con-
siderable extent would be produced But
himself n
derstand on these lines how it Is that coal
beds consist of fairly uniform coaI-coal
anyhow, not lignfte-a1l through down to
their extreme veins. We do not arrive at
any final conclusions as to the genesis of
coal. therefore. and the chief interest of
DR.. Hoffmann's paper lies in the fact that
he draws attention to the influence of spon-
famous combustion.