Evening star., 1901-07-03
POINT OF ABSOLUTE ZERO
THAT TEMPERATURES AT WHICH ALL
LIFE AND MOTION CEASE.
Experiment in the Reduction of Hy-
drOgen to q SOlid-Interest in
Dewar's Achievement.

matter OF interest in scientific circles
is the experiment recently made by Prof.
James Dewar before the Royal Society Of
London, the result of which was the reduc-
ton of hydrogen to solid, by which the
celebrated chemist reached the lowest tenn
perature ever attained in a laboratory. In
other words, Prof. Dewar has reached a
point considerably nearer what is termed
the absolute zero than has ever been
achieved by science. This absolute zero
is to chemists what the pole is to geogra-
piers and naturalists. and while we are get
ting nearer and nearer to both the real sig
nifcance Of reaching the goal seems even
now to be purely matter Of speculation in
the case of the absolute zero" as well as
in that of the north pole.
By the absolute zero is meant the low
est temperature compatible with heat-that
point of temperature, in fact, at which
body would be wholly deprived Of heat and
at which the particles whose motion constl-
tutes heat would be at rest. This tempera-
ture is supposed to be about IA degrees
centigrade or-461 degrees Fahrenheit. The
term heat Is here used in Its scientific
sense, for men use the word in every
day language its significance depends on
the temperature of the human body. Men
call warm everything with a temperature
higher than their own and cold all those
objects which have less heat than they. In
reality, however, the coldest body known to
man Is far from being utterly without heat.
Ice, for example. has heat. only in a degree
so much below mans temperature that one
can scarcely imagine 1t to be anything but
"cold"-a term which actually implies
comparatively low degree Of heat. Accord
ingly the zero of thermometers is only
conventional point marking a certain de-
gree Of heat. There seems to be point,
however, where heat ceases absolutely
r. ior },H, io Lr1nx Oh
istry as the absolute zero"
The progress made in the direction of
this absolute zero is associated with the
work of Transforming highly volatile gas
like hydrogen into a liquid and from
liquid into a solid, because the process OF
liquefying or solidifying gases is practically
process of lowering their temperature.
To convert gaseous hydrogen for example.
into liquid we place bulb Of this gas in
a vessel containing liquid air. Then by ex-
hausting the air so as to make it evaporate
we lower the temperature of the bulb until
it's contents pass from a gaseous into
liquid state. When We put some alcohol on
the palm Of the hand the evaporation Of
the alcohol makes our hand cold. This Is
due to the fact that in evaporating the al
cohol needs heat to separate it's particles
and to reduce it from liquid to gas, and
this heat is drawn from our hand In
like manner the evaporation of the liquid
air in the vessels robs the hydrogen of the
bulb of considerable quantity Of it's heat,
lowering it's temperature until 1t becomes a
liquid, just vapOr assumes the form Of
water when the surrounding temperature
is considerably lowered.
Helium IS the name of newly discovered
chemical element which is even more vola-
tile than hydrogen. and Prof. Dewar says
that by using hydrogen. In liquid solid
form. as cooling agent we ought to be
able to 1iquefy this gas in the same manner
as hydrogen is liquefied by means Of liquid
air. This would bring us to a boiling point
about four or five degrees above absolute
zero.
Thus, even liquid helium (were the pro-
duction of such a substance within our
means) would not be enough to reach The
absolute zero" Another gas would have
to be found, still more volatile than helium,
in order that the liquefyng Of that gas,
with liquid helium for cooling agent,
might Dring us to the desideratum of scien-
tific chemists.
This subject was discussed recently in an
interview by DR.. Robert Huebner, a WELL
known chemist and bacteriologist. "If the
whole world were at absolute zero the
whole world would be dead" he said. Life
and AM all the forces and manifestations of
life mean motion. Can you imagine exist
ence without motion? But then why give
so much latitude to ones magination? Prof
Dewar Is no dreamer. He Is a scientist
and he likes to have hard ground to tread
upon. The nearer we get to the absolute
zero the more we know of the nature of
things. There is no telling what sort Of
chemical combinations. impossible now,
would become matter Of course, should
we chemists be able to reduce the tenn
perature-not of the whole world, but of
some liquid at least-to It's lowest limit
But 1t can be reduced to powder already,
and, perhaps. when we go a few degrees
further We may be able to make sugar, for
instance, by combining carbon. hydrogen
and oxygen In certain proportions. Oh. we
might be able to do lots of things. but let
us imagine as little as possible and stick
to realities as much possible.
Professor Dewar's experiment can
scarcely be regarded as a discovery, how
ever" DR.. Huebner added. Professor
Raoul Pierre Pictet of Geneva reduced
hydrogen to a liquid and then to a solid
as far back as 1877 At the same time he
liquefied oxygen and nitrogen both of
which elements had up to that time been
looked upon as permanent gases