Evening star., 1936-03-07

Some day We may live in houses with
rubber windows.
Crystals OF transparent rubber, through
which the eye can see as easily as
through glass, were among the curiosities
exhibited Thursday night at the tenth
anniversary exhibition of the Division
OF Organic and Fibrous Materials of the
United States Bureau of Standards.
The substance is obtained when rub
Der. dissolved in ether, is lowered to a
temperature Of SIS degrees Fahrenheit.
AS yet this material is difficult to obtain,
even in the minutest quantities, and its
possible range of uses is unknown. The
Rubber Division of the Bureau Of Stand
ards is carrying on fundamental research
on the basic constituents of the sub
stance.
Other exhibits of this newest branch
Of the bureaus activities showed methods
used in testing for the Government the
wearing qualities of large variety of
articles from automobile tires to silk
stockings They have devised means Of
putting these experimentally through
the uses they will actually receive in
service. Auto tires are tested against
a revolving wheel, placing upon them
practically the same stresses they would
receive on the road. There Is walking
machine which determines the wearing
qualities of shoe soles by duplicating
continuously the movements of plac-
ing them against the ground.
An ingenious knee-bending machine.
designed to show up the weak points of
silk stockings, was among the exhibits
which attracted the most interest.
Throughout the exhibit stressed the ef-
forts Of the Bureau of Standards to get
at the fundamental qualities of ma
terials used in daily life and which
absorb great deal of the cost of living.
Among the gadgets on exhibition was
q rubber heat engine"
Rubber, like good many other sub
stances, contracts instead of expands on
heating. The reaction is immediate. The
"heat engine" consisted of a pendulum,
to which rubber bands were attached,
swinging in front of an electric heater
with a shield shutting off the heat at
one point. The alternate contraction and
expansion OF the bands supplies the
energy to keep the pendulum in motion
so long as the source of heat remains.
Another curiosity about rubber is that
1t loses volume when it is stretched.
When pulled to about 600 times its
normal length a rubber band occupies
2 per cent less space. The reason for
this Is not clear, but some molecular
rearrangement is suspected.
A colorful exhibit was the "electron
gun" oscillograph, in which electrons
are shot against willimite screen which
fluoreSces in lines characteristic of the
source of stimulation. This is being
used in delicate chemical analyses, and
has proven an effective means of diff
ferentiating the spores Of very similar
plant diseases which have different elec-
trical discharge rates. Bureau physicists
are working on q speedy and sure way
to diagnose white pine rust which
threatens to wreck havoc with the for
ests Of the Appalachian regions.
One Of the most interesting exhibits
was that of synthetic glasses, Of which
about 10 have been developed from cellu-
lose and from resins. The materials en-
tering the latter are the coal tar gas
ethylene, carbon dioxide and alcohols.
Such materials are as transparent as
glass. are very much lighter and much
more difhcult to break. They are, how
ever, much softer and scratch more
easily. They can be smashed on the
fioor without Injury.
Both synthetic glasses developed in
industry - basis for noli-hreakablo