Evening star., 1936-03-14
STARS, MEN AND ATOMS
k of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

Springs lush vitality and natures
melancholy WEAKNESS in Autumn may
be due, in part. to a hitherto unsus-
pected phenomenon-variations in the
thickness of the ozone screen 20 miles
or more above the earths surface.
This hypothesis was advanced before
meeting of the Washington section of
the American Chemical Society Thurs
day evening by DR.. Oliver r. Wulf, De-
partment of Agriculture chemist, who
has been making extensive studies Of the
concentration and effects Of rare gases
in the atmosphere.
Ozone is gas whose molecule consists
of three atoms Of oxygen. It is formed
by the passage through atmospheric
oxygen of certain radiation or of elec-
trical discharges. Its pungent odor some
times can be detected after lightning
stroke. It long has been regarded as
especially stimulating.
This ozone forms, at the utmost, only
about a millionth part Of the earth'S
atmosphere. It appears to be concen-
trated, DR.. Wulf has found, in thin
belt starting at an elevation of about 20
miles and entirely surrounding the earth.
If it were not for this belt, DR.. Wulf
stresses, it hardly could have evolved in
its present form and probably could not
continue to exist.
There is a very narrow band of ultra
violet radiation from the sun which is
absorbed by the great majority Of or
ganic molecules which make up the SUBJ
stance of living things. 1t appears to
be strongly inhibitive or poisonous.
This ultraviolet band, lying between
3,l00 and 1850 Angstrom units and con-
stitutes only a very minute part of the
total ultra violet radiation received from
the sun and most of which does not
appear to have any organic photo-chen1-
ical effect. It is radiation within this
band which causes severe sunburn and
which kills bacteria and other one-celled
organisms exposed to it. These waves
also are absorbed by ergosterol to pro-
duce vitamin d, the essential element in
diet which prevents rickets in children.
Hence it is, in limited quantities, essen
tial to human and animal life. II there
were much more Of it, producing an in
hibiting action on the living cells, the
results might be unpredictably bad.
The wave lengths in this ultraviolet
band are absorbed by the ozone molecule,
which is itself destroyed in the process.
These molecules stand like an outer
guard of the domain Of terrestrial life
forever destined to sacrifice their own
existence for the safety Of the unique
phase of nature below them. Propor-
tionately to their abundance in the solar
spectrum, very few of the death-dealing
waves get through. It doesn't make any
difference how many of the ozone mole
cules are sacrificed, because there Is q
continuous replenishment Of the supply
by the action of radiation in the upper
atmosphere.
But the thickness Of this ozone screen
varies enormously with the seasons. Be-
cause of this, DR.. Wulf points out, at
some times tenfold more violet
radiation in the forbidden band is reach
ing the surface of the earth than at
other times. It should have far-reach-
ing effects.
All Winter long, said DR.. Wulf, the
ozone content Of the atmosphere is piling
up. It is greatest at Just about the time
when the great annual fehirth OF nature