The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1902-12-21
LIQUID AIR PALACES.
Why 1t Is Not Feasible to Use It for
Cold Storage or Power.

why 1t Is Not Feasible to Use It for
Cold Storage or Power.
London Globe.
A good deal Of nonsense has been written
about liquid air. principally in America. 1t
was to be the power of the future. BY its
means power to be obtained for moth
ing, and so on. In the lecture which he
gave before the Cold Storage Association
recently, DR.. Carl Linde, of Berlin, did good
service in clearing away a good many mis-
conceptions. 1t would not be economical to
employ 1t in cold storage work, he ex-
planned. because when you only require a
temperature of few degrees below the
freezing point of water. II is not economical
to produce a temperature $50 degrees
Fahrenheit below. Power has to be ex-
pended In producing cold and the power Is
roughly proportional to the degree of cold
produced. Liquid air in small quantities.
the lecturer observed, would be very useful,
say, for cooling dining or bathrooms. In
these cases the quantity of liquid air would
be so small that the high price at which il
was produced would not matter. Drawings
were shown of apparatus by which rooms
could be cooled in this way.
Liquid air is produced from ordinary at
mospneric air by continuous process OF
compression and cooling Every substances,
IL Is supposed, may exist in one of three
states, the solid. the liquid the gaseous,
according TO the surrounding conditions.
Each state presupposes the presence of
certain quantity of heat in the substance.
Thus, in the solid form, a smaller quantity
or heat is present, actually in the substance
itself, than in the liquid form: and again.
smaller quantity of heat is present in the
liquid form than in the gaseous. The addi-
uon or the subtraction of heat from any
substance, in sufficient quantities, will
cause the substance to change its state.
In addition, the three forms in which sub
stances may exist mean that the MOLE
cules, the very minute parts of the sub
stances, are very much closer together in
the solid form than in the liquid form, and
In the liquid form they are much closer to-
gether than in the gaseous form. So that
In order TO lIquefy a gas two things are
necessary, the closing up as il were of its
molecules and the extraction of a certain
quantity of heat from it. When air is
compressed, as in those cases where com
pressed air is used for mechanical pur-
poses, heat is generated in the air in the
act of compression.
1t represents a portion of the work done
upon the air, by the compressor. And this
heat has TO be extracted, as we'll as the
heat possessed by the air, in virtue of its
condition a gaseous mixture, before it
can be lquefed. And so in the process OF
making liquid air the air is continually
compressed, by successive stages, and con-
llnuOuSly cOOleO, very pretty QeNlCe De
ing made use of in the cooling. by which
the air which has been cooled 10 a certain
degree Is made TO cool air that has not
reached that point, so that the effect is Gu
mulative. When liquefaction Is finally
reached the air in its liquid form looks eX-
actly like water, and may be poured out,
just as water is-with certain precautions
The fact that the liquid air is at the ex-
tremely low temperature named makes it
dangerous to handle without precautions
similar to those which are taken in han
ding hot bodies. With very cold bodies
heat passes from the hand. say to.the OBJ
ject, at a very rapid rate, just as heat
passes from hot body to the hand at
rapid rate. 1t is the rate at which the heat
Is transferred, either to or from the human
body, which causes the pain and other
troubles. When poured out on table the
liquid air runs about in small globules, just
as mercury does and disappears in very
short time. 1t has returned to its gaseous
form.
When allowed to escape into the atmos-
phere its presence is shown by clouds or
mist. producing the impression that the
liquid air is converted into fog. This Is not
so, however. What really happens is the
aqueous yapor which Is always present in
the atmosphere, particularly that of rooms
in which a number OF people are assembled.
condenses and then freezes, or forms sort
of boar frost, and ii is that we see, not the
liquid air itself. Liquid air seizes every OPP
portunity of returning to the gaseous con-
dition. but IL can only do so by extracting
heat from surrounding bodies. When Ii is
alOWeO 10 escape INTO the atmosphere IL
extracts the heat from the air into which
Ii passes, the atmospheric air of the room,
i'm the immediate neighbOrhOod of the orr
flee from which ii is escaping. This lowers
the temperature of the air at that point,
and with lowered temperature il is no long
err able to maintain so much aqueous vapor
in suspension. The vapor is deposited as
water. and then freezes. The same action,
I'm a minor form, may be seen in any cold
storage engine house. where the cold pipe
Is covered with snow.
The method adopted for storing liquid air,
devised by Prof Dewar. is one Of the most
novel arrangements that has been seen in
the domain of physics for a long time The
air is stored in glass bottles each bottle
consisting of two distinct bottles, separated
by vacuum. maintained at as high a
figure as it is possible TO obtain. In addi-
ton the outside of the outer bottle is sill
Vered all over with mercury. The object
OF the arrangement is to prevent the access
of heat to the liquid air inside the inner
bottle The vacuum space offers a very
waves through or across il, and the mirror
formed by the mercury the outside of
the outer bottle reflects the heat waves
away from the bottle. The mouth of the
IL was stated by DR.. Linde that charge
OF liquid air would last for about fourteen
days During this time the charge is slow
ly disappearing by evaporation, by recon-
version to the gaseous form. from the pass
age of heat to the liquid. Closed bottles
cannot be used, as. IL being impossible To
exclude completely heat from the liquid
air the latter would be slowly changing
into the gaseous state. and in doing Gre
ating pressure within the bottle which no
vessel could withstand which would also
resist the passage OF heat through its walls.
The final pressure was given by Or Linde
as 1900 pounds per square inch when all
the liquid has returned to the gaseous form.