The Indianapolis times. [volume] (Indianapolis [Ind.]) 1922-1965, 1934-01-02
-Dietz on Science
ice HEATED AS
STOVE is FREAK
OF LABORATORY
Harvard Professor Uses
Molecular Theory to
Attain Result.
BY DAVID DIETZ
scripps- Howard Science Editor

Ice hot as a stove in full blast.
That is one of the curiosities which
DR.. P w. Bridgman, professor Of
mathematics and natural philos-
ophy at Harvard university, is able
to produce in his laboratory.
High pressure is the magic which
Professor Bridgman employs. He
has developed apparatus by which
he can obtain a pressure Of 30
tons to the square inch. When he
has obtained that pressure, he gets
many strange results. Many gases,
for example, turn to thick hqulds
and can be poured like warm mo-
laSSeS.
Ice kept under this high pres
sure can be heated to a tempera-
ture Of 100 degrees without melting.
Water, it will De recalled, boils at
ordinary pressures at a tempera-
ture Of 212 degrees.
Professor Bridgnlan describes his
experiments in report to the
Engineering Foundation of New
York City.
M0lecule Theory Involved
Professor Bridgman's paradoXical
experiments can be understood if
we reflect for a moment upon the
nature Of solids, liquids and gases
and the meaning Of boiling and
freezing.
All substances are composed OF
minute particles called molecules.
These particles are continuously
subjected to two forces. One is the
force of their own vibration or mo-
ton. This force tends to separate
them and drive them away from
each other The other force is the
electromagnetic attraction which
exists between molecules. This force
tends to draw them together.
Whether a substance exists as a
gas, liquid or solid depends upon
which force has the upper hand.
In gas, the vibration or motion
SO overbalances the attractive force
that all the molecules are continu-
ouSly flying about in all directions.
In a liquid, the two forces are
more nearly equal. The attractive
force is strong enough to draw mole
cules together but almost immedi-
ately the force of vibration causes
them to separate.
Likened to Dance
The molecular condition of a IL
quid, therefore, might be likened to
a dance in which the dancers are
continuously changing partners
sort Of supercircle two-step.
In solid, the force of attraction
or cohesion has the upper hand and
the molecules are bolted into place.
They are still in vibr&t ton but their
motions are confined to a limited
area-like chained dogs which run
back and forth within the limits of
their leaShes.
Whether substance exists as
gas, liquid or solid at ordinary
temperatures and pressures depends
upon how strong the two opposing
forces are under those conditions.
Temperature is really a measure
Of molecular vibration When we
heat an object We give energy to its
1IlO4CCu1ES anu UIlUS increase Uf1e
rate Of vibration That is why iron
turns to a liquid if it is heated
enough.
When we cool an object we take
energy away from it. That is why
water freezes or turns to a solid
AS we take energy away from the
molecules, their rate of vibration
becomes SO slow that the force of
cohesion gains the ascendency. AS
a result, the molecules are chained
to their position and the liquid,
water, becomes a solid, ice.
What Professor Bridgman does is
to subject the ice to tremendous
pressure. This aids the cohesive
force and pushes the molecules clos
er together than they normally
exist.
Now when heat is applied, the
molecules do not get enough energy
to break their chains. Consequent
ly the ice remains a solid though
it is heated almost to the ordinary
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