Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-01-25
TEMPERATURE NEAR
TO ABSOLUTE ZERO
OBJECT OF BUREAU
Test Expected to Produce
Cold of 453 Degrees Minus,
Declare Federal Experts.
LIQUIFIED HELIUM GAS
EXPECTED TO SET RECORD
Apparatus Now Being Assembled
for Effort in United States
Standards Laboratory.
BY THOMAS R. HENRY.

Apparatus is being set up at the Blu
reau of Standards which is expected to
produce some of the lowest tempera-
lures ever attained.
This will be done by liquifying helium
gas. a feat which has not yet been ac-
complished in the United States. 1T
will be necessary to reach tempera-
ture of 453 degrees below zero, Fahren-
heit only about six degrees above the
lowest possible attainable temperature
This would be reached at 459 below
zero. q point which probably Is ,i impoS,
Sible for science to attain, although
scientists in European laboratories have
been within two degrees Of 1t.
Helium, the strange gas flrst dis
covered in the sun and now OF immense
practical value in filling airshipS be-
cause it is on-combuStible, is the hard
est substance on earth to nquify and
freeze. Hydrogen, which is also used TO
initiate dirigibles, liquifles at higher
temperature than helium.
The first step in making liquid helium
is to produce liquid hydrogen, which
is accomplished by subjecting the gas
to q pressure of 1000 pounds to the
square inch, after which it is cooled
BY LIQUID air to a temperature OF $40
degrees below zero. Then a supply OF
helium as pure as can be obtained by
refining processes will be compressed
to a pressure of 200 pounds to the
square inch, after which the COM
pressed gas will be cooled with liquid
air and liquid hydrogen to the tenn
perature of the latter, 423 degrees be-
low zero.
will Stin Be Gas.
The helium will still be a gas even
at this low temperature. The next step
will be to allow it to expand, thereby
producing additional refrigeration and
lowering the temperature OF the hel1um
to 453 degrees. at which 1t will hqu1ty.
In making liquid helium it is first neces-
Sary to insure a plentiful supply OF
liquid hydrogen, which is to be pro-
duced in the same laboratory.
The liquid nelium will be used for
scientific purposes to study the nature
of matter at such low temperatures.
Some weird effects have been observed
which science is unable to explain. For
instance, certain materials at extremely
low temperatures lose their resistance
to an electric current which, once start
ed through them, would flow forever If
the low temperature could be main
tanned. Actually matter is not kept in
such condition very long. The ma
terialS which thus become perfect con-
ductors at such low temperatures are
the poorer conductors at ordinary tenn
peratures Good conductors do not be-
come approximation by such treat
ment.
Conclusion Declared Sound.
While man never has experienced a
temperature of --45s Fahrenheit, ac-
cording to DR.. F. O. Brickwedde, in
charge of the low temperature labora-
tory, It is far from a mere speculation
to say that it IS impossible to go any
lower. Cold, according to the laws Of
physics, cannot be infinite. If 1t were
possible to attain lower temperatures
one might build an engine, similar to a
steam engine, capable OF operating at
such low temperatures, which would
give out more energy in work than
was put into it to operate 1t. This, like
perpetual motion, would be contrary TO
the established principle of the conser-
walton Of energy. Although the con-
struction Of such an engine would be
impossible, DR.. Brickwedde says, the
conclusion Is sound.
An important activity of the low
Temperature laboratory at present Is the
celebration Of platinum resistance ther-
nometers whereby temperatures can
be determined to one-thousanth OF
degree centigrade by the change Of the
resistance offered by platinum wire
TO an electric current which responds
correspondingly to the temperature OF
the metal Changes even smaller can
be detected by this method.
Important sources of rrors are i'm
purities in the platinum, and 1t Is ex-
pected to obtain exact information on
the effect Of these. The platinum IesiS-
lance scale of temperatures IS based on
the "gas thermometer" with the ala
of which true or thermodynamic tenn
peratures are determined by measuring
the pressure change of constant VOL
ume Of gas at different temperatures.
More Reliable instrument.
The platinum resistance thermometer,
Or. Brickvedde said, is not necessarily
the instrument most sensitive to tenn
perature changes, but it is the most
reliable for scientific use where accurate
measurements are necessary. MorS
sensitive are some thermocoupleS made
by joining together diSsimilar metals.
When the temperature of one junction
Of q thermocouple changes ever so
Glightly from that of the other junction
an electric current is started which
varies with the degree of temper ATTIRE
difference. So sensitive is this iHstru-
ment that It has been possible to meas
TIRE with it the temperature Of planets
millions Of miles in space. For ac-
rurate measures of temperature, how
ever, it Is not so reliable.
A work which may prove to be OF
great practical Importance undertaken
in the low temperature laboratory is
the measurement of the specific heats
Of organic substances at low tempera-
lures. This consists in determining
how much energy must be added to
the substance to change its temperature
degree centigrade. The results are
expected to prove significant in the
work Of the fixed nitrogen research
laboratory of the Department Of Agri-
culture, which is trying to find how
nitrogen can be attached to an organic
compound. This never has been ac-
complished by man, although plants do
It all the time. With tables of specific
heats the research workers will be able
TO determine the ways most likely to
succeed and concentrate upon them.
The results of this investigation may
point the way to new and better uses
for such waste farm products as corn
ltalks, straw, waste lumber, etc.