Evening star., 1937-05-04
STARS, MEN AND ATOMS
Notebook of Science Progress in Field.
Laboratory and Study.
BY THOMAS r. HENRY

What is water?
Perhaps the most familiar, abundant
and indispensable substance on earth,
its peculiar properties long have mystl-
fed physicists and chemists, but recent
studies with new technique at the geo.
physical laboratory of the Carnegie In
stitution of Washington are beginning to
throw light on its internal structure.
BY means of the Raman spectrum of
water DR.. James H. Hibben of the geo.
physical laboratory staff has been able
to look inside the familiar H2O molecule
and watch its constituent atoms at their
work and play The inside of this mole
cule is busy and exciting place, he finds,
with complex pullings and shovings going
on which hitherto have not been sus-
pected.
DR.. Hibben sends beams of light, of
known wave length, through the water
molecules. When a particle of light hits
an atom in the molecule it is bounced
off and loses some of its energy from the
impact. 1t comes out different wave
length-consequentl a different color
than when it went in. BY studying the
changes which have taken place in the
light DR.. Hibben is able to deduce where
an atom was when 1t was hit and what 1t
was doing. Thus he is able to construct a
hypothetical picture of actual events in
the invisible world
The picture changes markedly as the
H2O combination passes from one to
another of its three familiar states
steam, water and ice. But the changes,
DR.. Hibben finds are quite different from
those which ordinarily accompany a
transition from the gaseous to the liquid
and the liquid to the solid state. The
findings have just been published in
detail in the Journal of Chemical Physics.
Here is DR.. Hibben's picture of water
in its vapor form, as reconstructed from
It's Raman spectrum:
The atoms in its molecule are arranged
in the form of an equilateral triangle.
At the apex of the triangle is the rela-
lively heavy atom of oxygen. Forming
the base are the two much lighter atoms
of hydrogen.
These three atoms are never at rest,
but are continually oscillating toward and
away from each other. Thus the tri-
angle pattern is always distorted. 1t is
like a three -cornered tug g-of-war which
goes on forever
This oscillation is apparently the only
movement of the oxygen atom as whole.
The two hydrogen atoms, however, are
continually rotating at increasing speeds
as the temperature Of the vapor is in
creased.
The vapor is cooled down until it be-
comes liquid. Then, DR.. Hibben finds,
comes the rare phenomenon Of blocked
rotation" This may be unique prop
erty of water, although there is some
evidence that it might be found in vari-
GUS complex alcohols. The molecules
are closer together and appear to exert
such an influence on each other that the
hydrogen atoms cannot make complete
rotations but are restricted to half or
quarter rotations, the arc traversed be-
coming smaller with decreasing tenn
perature until, with the final crystalliza-
ton of water into ice, the rotating move
ment is inhibited altogether.
Now water has always been looked
upon as liquid, perhaps the typical
liquid. But in liquid presumably tho
molecules have no arrangement In def
mite patterns-that Is, In crystals-which