Evening star., 1940-12-14
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Laboratory. Field
And Study
By Thomas r. Henri.

~ 4ftOHtuc ~. 44OfGI.
One of the chief theoretical obstacles
to atomic power by splitting the nuclei
Of uranium atoms-a problem upon
which which Adolf Hitler is reported on
good authority to have set the foremost
scientific brains in Germany to work
has been removed in a report to the
trustees of the Carnegie Institution of
Washington from its atomic physics
laboratory.
When struck by slow neutron under
the right circumstances, an atom of
Uranium 235, rare form of an element
abundant in the earth's crust from
which radium Is derived, splits in two
with the release of energy approximating
hitherto achieved by man and ap-
preached only by the energies in the
interior of the sun.
When only a few atoms are involved,
however, the actual power obtained Is
almost imperceptible. In order to make
the process practical source of heat and
energy, it is necessary to set up a chain
reaction-that is, the explosion Of one
atom must cause the explosion of another
and so on until, in an inflnitesimal
fraction of second, countless billions
of the particles are exploded From the
first this has been theoretically possible
the great difficulty being to separate the
Uranium 235 from ordinary uranium in
which it occurs in an abundance of about
one part to 100. There is no known
chemical method of making the separa-
ton and this is the supposed object of
Hitler's scientists.
Solving the problem might mean an
easy conquest of the world and be, per Sc,
the most momentous single event in
human history. Laboratories all over the
earth are working on it. Up to about
eight months ago all results obtained,
except in Germany, were published freely
to the world in scientific journals. Since
then all progress has been one of the
most zealously guarded military secrets
and the findings reported in skeleton
form today by the Carnegie workers were
actually attained before the ban of
secrecy was imposed by the War De-
Dartment.
Nearly everywhere there has been un-
restrained enthusiasm Among the few
skeptics have been Dr. Merle A. Tuve
and his assistants on the Carnegie staff,
the first in this country to produce the
primary reaction of uranium splitting
The U-235 atom not only splits into two
roughly equal halves when hit by a
neutron but simultaneously it shoots out
other neutrons in all directions. These
were depended upon to hit the neigh
boring atoms and continue the splitting
process
Early in their investigation, however.
DR.. Tuve and his associates found that
some of these neutrons were being
"eaten" by a mysterious process which
might prove an insuperable obstacle to
mans ancient dream of tapping the vast
power which holds the universe together.
They found in their preparations after
bombardment some radioactive material
which was not one of the splitting prod
ucts and half of which exploded in %
days They were unable to indentify
this substance by any method of chem
ical analysis and feared-or hoped, con-
sidering the possible terrible conse-
quences of solution of the problem at
this time-that it arose from combina-
ton of neutrons with atoms of the criti-
cal U-235 which did not cause splitting.
If this were true it was likely that
chain reaction could not be set up.
They reported today, however, that DR..
Philip H. Abelson of the Carnegie staff
and DR.. Edwin Mcmillan of the Univer-
sity of California, working with the
more powerful equipment at the latter
institution, at last had identified the
product as element 93-one step above
uranium in the atomic table-which can
be shown to arise directly from U-238,
the more abundant form of the element
which long has been abandoned as q
possible source of atomic power. Ele-
ment SO does not exist on earth in its
natural state and in ordinary times its
discovery would be physical event Of
the first magnitude. 1t now becomes,
however, merely subsidiary step in the
major problem, the solution Of which
may affect the life of every human being
on earth.
When element SO explodes, it was
found, it becomes another isotope of
uranium, U-239. There has been some
discussion of the possibility of deliber-
ately making 239 in the expectation that
it would explode rapidly and become the
elusive 235 The tests of Drs. Abelson and
Mcmillan indicate, however, that it is
extremely stable. If 1t explodes auto
matically it must have half-life of
close to a million years-that is, half the
atoms in any particular mass of it will
break up in that period.
With this obstacle removed, however,
physicists seemingly are as far away as
ever from finding a reasonably cheap
and quick way of getting pure concen-
trations of U-235. Any progress that has
been made is strict military secret in
the United States, but the subject is so
vital that it has even been proposed, it
is understood, that the Nations reserve
gold supply be used to make gold-lined
tubes to be used in one possible process.