The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1900-03-06
LIQUID AIR.
(Concluded.O
The Absolute Zero.


AS the work upon the Iiquefaction Of
gases proceeded, experimenters were
brought to more and more intimate
knowledge Of conditions which had
Deen matters of mathematical demon
SIrdtlon rather than of experience. The
measurement Of these conditions was
very difficult. The properties of sub
stances in this extreme cold were I'M
known, and great field of research
was at once opened.
As heat consists in the energy of r,o-
ton OF the molecules Of A bOdv- the
ldea at once presents itself that the
point might be reached, theoretically
al least, where the molecules. having
loSt their energy Of motion little by liz
tie as the temperature was reduced. |
mad eeen brought TO rest. Such a point
would mark the limit of cold and a
Dody at that temperature would pos
sess no heat at all. This point. for oh
VlOuS reasons, IS known as the ''ab51
lutte zero" Its value is determined bv
means Of the relation between expan-
! SION or gases and temperature. 10 lie
| between 2I3 degrees and PA degrees be-
low the zero of the centigrade scale.
Logically, all temperatures should be
reckoned from that point, as, indeed.
LOT many practical purposes, they. are.
Now. with all known gases Iiduefed.
D
this point. Just how near is as vet
somewhat a matter of inference. All
ordinary thermometers fail Even the
1 air thermometer is frozen solid and the
hydrogen thermometer is of little use.
Electrical methods are doubtful. be-
cause nobody knows Just how the cleo
trlcal properties Of substances vary at
such temperatures. Dewar, with
| liquid hydrogen, has obtained a tenn
! perature within about q degrees of the
absolute zerO-SOme $50 degrees cent?
grade, or more than 500 degrees Fab
| renheit colder than the temperature of
an ordinary summer day; and solid
( hydrogen is about 3 degrees centigrade
colder yet. 1t viii be interesting to re-
1 late, so far as they are yet known.
some of the properties Of substances at
these low temperatures.
Properties of Liquefed Gases.
The beautiful experiments which it is
! possible to perform before an audience
| with liquid air in quantity have become
we'll known All ordinary LIQUIDS are
| frozen. Alcohol becomes ice. mercury
a solid so hard that it will drive nails.
A jet of carbon dioxide gas falls as
/ snow; and to make the LIQUID air boil
violently it is only necessary TO set a
/ Kettle Of 1t upon a cake of ice. In spite
| OF this, liquid air is kept for hours in
| unsealed cans, in which evaporation is
/ comparatively slow. For the rarer
/ liquefied gases, in small quantities, De-
/ war has devised the vacuum flask. The
/ liquid oxygen or hydrogen, or whatever
! it may be, is in the inner vessel and
/ the space between that and the outer
| flask is exhausted, the two TASKS being
sealed together at the neck 1t is
/ found that the evaporation is only
about one-fifth as rapid as when this
| space is filled with air.
Under such conditions air may be
! seen as a clear, cOlorlesS LIQUID when
pure, or as a transparent solid when
very cold. The solid air at higher tenn
perature is characterized as nitrogen
jelly. from which strong magnet viii
draw the oxygen.
Oxygen as a liquid in considerable
quantity shows a pale blue color, as
does the solid oxygen. 1t is highly
magnetic and good insulator. Liquid
ozone is indigo blue and very expIo-
| sive. Nitrogen forms an Opaque solid
Hydrogen as a liquid is colorless and
| transparent, and as a solid is a trans
parent ice with a frothy surface, due
probably to very rapid evaporation. 1t
! is said to be distinctly nOn-metallic
/ Fluorine. very difficult TO liquefy, is a
| clear yellow liquid. very mobile It
does not attack glass at these low tenn
peratureS. Argon forms a cOlorless
liquid, and at very low temperatures
an Opaque solid. The liquids are gen.
orally colorless and transparent. except
fluorine and chlorine, which are both
yellow.
Effects of Very Low Temperatures.
Temperatures as low as these we are
considering have a very marked effect
upon the properties of familiar ma
terials and upon chemical action. Wires
of metal are made much more hard
and brittle and their tensile strength
is increased. Rubber, cork and such
substances are as hard as stones, and
organic substances Of all kinds are
frozen solid. Chemical action is very
much diminished or ceases altogether
and the action of light on Photographic
films is very weak
Upon living organisms the effects of
very low temperature are various
COld-blOOded animals show but slight
resistance, while warm-blooded animals
resist surprisingly well until the re-
sources Of the body are exhausted Few
insects can resist very low tempera-
lures, although snails were subjected
TO a temperature of -l20 degrees with
out apparent injury. Bacteria. unfor-
tunately, seem 10 be unaffected by the
IoTz-aSf fen7r,era fryreA fo witch th..1r b-,-a