Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1889-10-24
LIQUIDS IN CRYSTALS.
Results Obtained from the Study of Mi
mute Cavities In Rocks.

results obtained from the Study OF MI.
mute Cavities in Rocks.
Various delicate and beautiful
methods of analysis have been devised
for the determination of the micro
scopic quantities of this liquid. Let
US note briefly some of the theoretical
results obtained from the study of
these cavities in the rocks. 1t is to be
inferred, then. that the rocks contain
ing them, if they have cooled down
from igneous fusion. must have done
so under great pressure. in fact, must
have been great enough to keep the
contents of the cavities liquid at a
temperature which, under atmospheric
pressure, would have converted them
into vapor. OF course, this argument
could not apply to lavas which have
cooled at the surface; but it has been
observed that in these the crystals con-
tanning cavities bear evidence of being
derived. It is supposed that crystals
from the granite mass below fioated
on the molten lava before it
was elected from the vol
cano without being fused. When
the lava was poured out the granite
crystals came with it. This seems to
indicate that granite and lava are
formed from the same subterranean
reservoir, and thus the study of the
cavities adds d fresh link to the
chain of evidence which now leads
biologists to consider GRANTEES. basalts
and lavas as produced from the same
molten mass by diverse circumstances
of cooling. The theory held by the
older biologists, not so very many
years ago, that granite was the orig
inal first-formed rock of the globe,
from which all others have been de-
rived. is now exploded. GRANTEES are
known to be of all ages. With regard
to GRANTEES, it is inferred that igne-
Gus fusion alone will not account for
their formations; water has been pres
ent and played it's part in the process.
differences have also been drawn from
the quantity of liquid in the cavities
as to the approximate depth at which
certain GRANTEES have been formed.
The expansion of the contained
liquid at different temperatures being
known, it can be calculated how great
a pressure would be required to keep
certain quantity in the liquid state at
given temperature. This involves a
careful estimation OF the amount of
liquid in cavity. When their minute
size is remembered-1,O 00 900. 900 to
10, O0O, 600, 900 per cubic inch-the diff
ficulties to be surmounted in obtaining
the necessary data may be conceived.
First of all. the size of the cavity must
be measured as accurately as possible;
then, that of the bubble must be as
certained. The difference of these
gives the amount of liquid. If, now,
it is known, or can be estimated at
what temperature the rock was fused,
it can be calculated what pressure was
required to keep the liquid within the
limits of the cavity. Such measure
ments and calculations have actually
been made by Mr.. Sorby. The result
thus arrived at is that many GRANTEES
have been formed at depths of from
five and half to fifteen
miles. Since many of the same
rocks now appear at the surface.
We are here furnished with fresh
evidence showing that strata many
miles in thickness have been removed
by denudation from the surface of the
land. Applying the tests to the gran
ties of the Highlands and of Cornwall,
it has been inferred that the former
have originated at greater depth
than the latter. Considering the large
possibilities of error in estimating the
size of the microscopic cavities and
bubbles, we shall probably be inclined
to consider the results, as but shadowy
approximations; yet they may be ac-
copied as pointing at least in the right
direction. Prof. Judd says: The
grand conclusion that granite rocks
could only have been formed under
such great pressures as exist at great
depths beneath the surface appears to
be one not open to reasonable doubt"
Chambers Journal