Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-03-12
TRADE BOARD SEES
PHYSICS MARvELS
Scientists Present Series of
Experiments at Body's
March Meeting.

About 1900 members and gsests Of
th Pshington Board of Trade last
nignt witnessed demonstrations Of ex.
plorations into the realm of physics
staged at the Willard Hotel by two re-
search specialists In this field.
The capacity attendance at the show
heard beam Of light broadcast a song
heard also the explosions of atoms, saw
large electric light bulb lighted by the
striking of a match, heard light become
audible and saw liquid air boil.
The scientists, L. A. Hawkins, execu-
tive engineer, and Ellis Manning
physicist, of the research laboratory OF
the General Electric Co., explained the
natural phenomena behind each Of the
demonstrations.
Scientists We're Guests.
The demonstrations featured the
March meeting Of the trade body. Spe-
cial guests were a number of Federal
and District officials, scientists from the
Bureau Of Standards, the National
Academy Of Sciences, National Geo.
graphic Society and a number of ply
sictans and X-ray experts.
The demonstrators last night at
tempted vainly to ring a bell made OF
lead and having a rubber clapper. They
then immersed the bell in a container
OF liquid OF highly compressed air
1roze the leaden bell and then with
easy motion made it ring out audibly
This demonstration was followed by
one showing how light could be frozen
and preserved and later brought into
existence by this same liquid air. As
Mr.. Hawkins explained this process, one
OF the effects of a cathode-ray tube Is
to cause some substances to become
brightly fuorescent, or to give of light
after the raging has been stopped. Diff
ferent colors of light are produced by
different substances, and different col
ors are also produced at different tenn
peratureS.
Became Visible in Dark.
The scientists produced a strip Of
such huorescent screen material which
had been subjected to a cathode-ray
bombardment at the Schenectady labo-
ratory and which had been brought to
Washington emersed in vacuum bottle
OF liquid air. When this screen was
removed from the bottle 1t could not
at first be seen in the hall, which had
been darkened. But as the material
warmed up toward room temperature
1t showed a variety of changing colors
As a side light show, the scientists
employed liquid air as the propellinG
force in an improvised pop-gun. Some
OF the liquid air, at temperature hun
dreds Of degrees b;low zero, was poured
into a tall metal container and a cork,
with ribbon streamers attached, was
quickly pounded into the mouth of the
bottle. In moment the liquid air con-
f9fnRF GETTING ~ Ea
room temperature, caused the frozen
air to boil, building up a gas pressure
that fired the cork far out into the
audience.
In treating the audience to the sound
OF the explosions of atoms, the scien-
lists held small metal pieces containing
uranium and radium compounds before
an apparatus containing a thin alumni
mum window. AS the uranium and
radium compounds threw Of "electrons'
and so-called alpha particles, or helium
ions, into space, the air within the
aluminium chamber was made electrical
ly conducting and the resulting "explo-
sions" were broadcast by loud speaker.
Electric Eye" Shown.
A mysterious looking contraption,
known as photo-electric tube or "elec-
trio eye" was the business part of the
demonstration of the Transformation of
light into sound.
flashed before this "eye," and it was
heard as a sound audible throughout
the room. through the loud speaker.
At the side of the room was porta-
BILE monograph. A popular song record
was set going, but no sound was audi
BILE. Instead, the record was connected
with a lamp that sent out an eerie-
looking light beam of low intensity.
When this light beam was directed
across the room to strike the electric
eye" apparatus 1t transformed the light
rays into energy that produced the
song, IN natural form, from the loud
speaker.
Then came the climax of the show,
the lighting of a large electric bulb by
the striking Of a match nearby.
Match Lights Bulb.
For this demonstration the scientists
employed tube which contains mer-
curry vapor at low "pressutes, one that
can be used with low voltages, which
can control large amounts of power.
Mr. Manning lighted a common
match in front Of the photo-electric
tube and a 1,000-watt incandescent
lamp standing nearby burst into bril-
liant light momentarily at the same
time that the bulb of the photo-electric
tube showed pale blue light. The in
candescent bulb then was moved to a
position directly in front of the electric
eye," and when the process was re-
peated the incandescent bulb continued
lighted until the scientist stepped be-
tween the two instruments to shut of
the light from the incsndescent bulb
which was operating itself through the
other tube. Mr.. Manning, however,
said that this phenomenon was not re-
garded as any basis for claim to per
petual motion"
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