The anti-monopolist. [volume] (Saint Paul, Minn.) 1874-1878, 1878-01-17
SCIENCE.
THE GEOLOGICAL RELATIONS OF THE

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ATMOSPHERE.
The gaseous envelope which sur
rounds our globe plays very con-
siderable part in the chemical changes
ever going on in rock formation,
whether actually at the surface-as in
what is called the '.weathering of
rocks or in the less apparent, but
perhaps more powerful, action carried
on below the surface. In late
number of the Quarterly Journal Of
Science, Edward L. Hardman, F.C.S.,
has very exhaustive paper on 1.-the
Atmosphere Considered in its Geologi-
cal Relations" from which we extract
the following interesting facts:
Perfectly pure water has very
appreciate solvent effect on rocks,
which is immensely augmented when
it is chemically charged with carbonic
acid, oxygen, nitric acid. and other
matters derived directly or indirectly
from the atmosphere. But while on
the one hand the influence of the
atmosphere disintegrates and destroys
rock masses, on the other it is mighty
in building them up. Without the
small percentage of carbOnic acid
contained in the air there could be no
vegetation. and there wOnld be none
of the coal beds which form such
important members of our rock
formations. The immense masses of
limestone found everywhere, and the
coral reef Of the present day, must
owe their being indirectly to the
carbonic acid of former atmospheres.
\ drop of rain water absorbs IA trace
of carbOnic acid from the atmosphere,
falls on rock containing lime in some
form. dissolves the lime as bicarbonate
carries it down to the ocean. and
finally gives it up to become part of
the skeleton of a coral or mollusc.
which in its turn may form portion
of an immense mass of limestone
rock.
The bulk Of the atmosphere is made
Of oxygen and nitrogen, but these do
not take so active shares in geological
matters as the almost infinite.,imal
trace of carbonic acid present. The
amount ranges from to 10 volumes
in 10000 volumes Of air. The princi-
and other subterranean exhalatiOns;
respiration of animals; combustion Of
fuel and vegetable decay.
The series of rock lmetamorphisms
due to the simple absorption of car.
bonic acid.by a plant is very interest
ing. The carbon is assimilated by the
plant. and it dies and becomes thus a
part of coal bed or lies embedded in
sediment of some kind. Decomposi-
ton sets in; and if there be REDUCE
bic compound near it, chemical
changes result. If the strata contains
snlphate of iron. it is reduced TO sui
phide, commonly known rs iron py-
rites or false gold. The reduction is
effected by the carbon of the plant alb
stracting the oxygen from the sui
phate. The resulting carbonic acid
either is taken up by percolating
water and penetrates farther into the
heart Of the rock, affecting new
changes. or it finds its way to the
surface through some crevice, or by
aid of mineral spring, and once more
mingles with the atmosphere. to be
perhaps again absorbed by vegetation
and pass through q similar round Of
changes afresh. In many cases the
action of the carbonic acid changes a
metallic ore from an insoluble to a
soluble compound. thus reducing the
ancient crystalline rocks. The metals
carried away by streams were
deposited along their beds. and
valuable beds of ore were formed.
The atmosphere in the carbonifer-
ons age contained much larger
portion of carbonic acid. This has
been gradually absorbed into the
earth. until the amount stored in the
earth is estimated at G.52o times as
much as there is in the atmosphere.
although the latter contains / 80. 00c.-
100000 tons Of carbon. All animal
carbon is derived from the atmos-