The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, 1884-09-10

of the passage by which 1t comes up. A
good practical example of connected IL
guilds not standing at the same level is seen
in our artesian wells in the neighborhood
of Honolulu, where the water will always
flow ont literally at a height of about 40
feet above the sea level while there is no
doubt whatever that the same stratum of
water is connected with the ocean and
runs off into it at some depth beneath the
surface. but there is column of salt wa
ter at specific gravity of LOB against
that of the fresh water at l. Besides
which there is the extra length of pas
sage to force itself through between the
spot where the artesian bore strikes it and
the point where it reaches the sea. In
fine, connected liquids even at the same
density do not under all circumstances
stand at the same level, and when the
density varies they may stand steadily at
very different levels. What Is of still
more importance in this question to re-
member. is, that when two connected col
umns of lava change their heights by diff
ferences occurring in their density, not
the slightest symptom of sympathy be-
tween them is to be expected from such a
change.
ANY one may make some interesting ex-
periments illustrative of the action of
molten layas in tubes connected with a
general molten mass, by constructing a
closed metal box in the top of which are
inserted glass tubes of different diameters
say inches to ] inch, and then nearly
filling the whole with molten stearine.
Apply lamps underneath SO as to heat the
stearine equally, but keeping the temper
AZURE under the boiling point. 1t will
then be found that the liquid stands stead
lily highest in the largest tubes while in
the smallest ones it will stand the lowest.
By connecting narrow tube with the side
of the box, by an elbow slanting down
wards, the stearine will often freeze low
down in the tube 1t is evident that the
wider the tubes are. the less the contained
liquid Is cooled by radiation and conduc
ton in proportion to its mass. Besides
which the convection currents act freely
in the wider tubes, while they are almost
destroyed in the narrow ones. The re-
suit is a considerable relative excess of
temperature and consequent expansion in
the wider tubes so that longer column
of liquid is balanced by shorter column
in the narrow tubes, while in the case
where the convection currents are de-
stroyed the liquid cools so rapidly
as to set solid low down in the tube.
These convection currents, be it observed,
have no connection with steam or expand
ing gases, but are the simple results Of
expansion by heat. In this experiment
we can see before us how liquid mass of
one temperature and density below, may
stand steadily at different heights in col
umns connected with it. The application
to columns of lava connected with one uni
yersal subsratum standing at different
heights in those columns is obvious Mol
ten stearine seems to behave in many re
spects as molten lava does when exposed
to cooling. A variety of interesting anal
ogles may be exhibited by the apparatus
just described. By reducing the heat, or
increasing the cold, crust will form on
the surface of the stearine. Allowing the
whole apparatus to cool little, the molten
stearine will contract in the tubes, some
times retreating from the crust and leaY-
ing a space between. A second crust will
occasionally form below, illustrating what
is often seen in the crater of Kilauea. On
slightly heating up the apparatus again
and breaking up the crust it will be seen
to descend with the convection currents
and re melt, just as the lava crUsts appear
to do in the lakes of Kilauea.
In fine, while the behavior of the molten
and solid stearine exhibits what most other
experiments with molten substances do,
that differences of temperature may pro
duce a reversal of the relative densities in
the solid and molten states, there is no diff
Guilty about the formation of solid crust
on a molten substratum, while it suggests
the possibility of even denser crust re-
manning supported by less dense liquid
beneath it, especially when there is an OPP
portunity offered for building up tubes
or cones above the crust, in which higher
column of the less dense liquid acting on
the mass below becomes the substitute for
its smaller density and the crust becomes
Enthusiastically balanced. Volcanoes such
as Kilauea and Moluaweoweo with their
cones and conduits containing liquid lava.
built up far above the earth's surface, thus
appear as portions of a system of self-act
ing machinery by which the comparatively
| cold crust of the earth is sustained upon
its less dense, and white hot, molten sub
stratum.
As many BIOLOGISTS refer volcanic action
mainly to the occlusion of water or steam
in the lavas, rising from great depths, it is
Almost important point to ascertain whether
or not the Hawaiian lavas do, as a rule
occlude water or steam. Captain button
though he does not attribute the main
| action to this cause-seems to have no
doubt of it, and refers to any fragment OF
Hawaiian patoeh0e as a proof. He might
have added "a, for both are constantly
crowded with vescicles. But what is the
proof that these vescicles are caused by
steam or vapor of water? In my view there
| is no such proof. Ihave always looked upon
these vescicles-wherever found, except in
certain very exceptional cases as simply
| air bubbles The most notable instance
of this vescicular structure is to be OBJ.
served at all our great lava fountains The
lava spouts up under head of liquid and
forms fountain, and at the same time a
lake or pool of molten lava is formed
around it. A fountain of any liquid thus
thrown into the air and falling into the
same liquid below produces mass of foam
or air bubbles which are again thrown up
into the air. Lava foam when thus thrown
up is instantly converted into glass-foam
which is the simple origin of our so-called
pumice, it being congeries of glass air
cells so light as to float in water
When the light frothy mass of molten
glass runs away on the river of molten
lava which proceeds from these fountains
it cools rapidly and forms the clinkery sur
face of our al streams The interior of an
al stream, when it has had time to settle
and quietly cool, is often quite compact
without vescicles. But even the interior
portion which pours in little cataracts over
the uneven surface of the ground, must be
constantly enclosing air bubbles which get
frozen in. Let any one watch even gen,
tie stream of water pouring from small
height into a reservoir, he will find the
water in the track of the entering stream
to be full of air bubbles, fountain or cat
aract produces d mass of foam.
am well aware that the freezing pro
cess tends toexclude air bubbles and even
solids in solution, and this effect is com
monty seen in our pdhoehoC lavas. The
outer thin crust is often composed of a
compact glass without vescicles; the freez-
ing process, however, which of course
commences from the outside has frozen the
bubbles in, for just inside the compact
CLASSY coating, perhaps half an inch OF
more thick, the air bubbles are closely com.
pacted.
AT the lava lakes of Kilauea other pro-
cesses are constantly going on to fill the
molten lavas with air bubbles which get
frozen in in the same manner For in
stance, as / interpret the facts-which
SLIGHTLY differs from (tapfaiu Tuffo1,-e nv