The Washington times., 1917-12-31
Wonders of Liquid Air
ONE OF THE CENTURY's MARvEIs.
"A Kettle of Liquid Air Set on
Chunk of Ice $50 Degrees
Hotter BOils Rapidly

OF about 30 atmosphereS (say 5SS
pounds to the square inch), the in
visible air turns into a visible
liquid as clear as water and nearly
as heavy. This liquid can be poured
like water from one vessel to an
other But unless Il IL Impsrvi-
oualy covered It continually wastes
away. heavy white Vapor Issuing
from IL and rolling in snowy clouds
over the floor.
This vaPor Is formed by eonden-
sAtion of the moisture In the air Of
the room, which Is coSied IN conss-
aueaee OF the rapid absorption OF
heat caused by the expansion of the
liquid air escaping from the open
vessel 1t turns back to gaseous air
again As fast as it can obtain
enough heat from its surroundinEs
to restore 1t to Its former volume.
In the liquid state It occupies
about l-75Oth OF the spacs that IL
occupied when in the form OF ordi-
nary air. In proportioh to its loss
OF volume it has gained potential
energy, and II confined will exert
pressure of about 10000 pounds to
the square inch. II heated above
the ordinary temperature of the air
It's expansive force may become
many tons per square inch.
Pure liquid air Is not explosive IL
unconnned, but when mixed with
oily cotton waste. or with cotton
wool filled with coal dust. It bee
comes a true explosive OF great
power. and has been used TO a
small extent in coal mines; but it
eVAporates too readily, and Is sub
jsct to too many other disadvan-
tages TO be of much practical use.
Thus, whsn-sfrorts have been
made to utilize its expansive force
In driving engines II has been found
that II freezes the moisture around
the apparatus and coats IL with
ice, and even plugs up with ice its
own points OF exit
A curious fact 10 that aIthourh the
two principal constituents of air.
oxygen and nitfGsGa have different
boiling Tv.n:5, yet they do not form
two separate liquids when tho AIR
Is hnuefied. but tome down slmvi-
taneuusly as Cae homozs le, "a
liquid" And by further cooling this
LGuid may be turned into a uhito
solid. In evaporatIng from the
ilquij back t. the gaseous statS
h"weT.T. the TiiIcEen boIIs on 1rstJ
ieaTtnS the remaining liquid rlcnsr
Ond uicnsr in oxygen. until q ooInt
is relsEed where the oxygen yoIa-
tilizes with equal rapidity. As the
liquid loses its nitrogen, it becomes
blue In color and its weight per
volume increases.
The maryels Of liquid air would
I'LL volume. II you dip your hand
i'te cup of liquid air and swiEtIy
remove it no harm will be done, the
mysterious liquid feeling like =
soft cushion" But IL you leave
yeuF hand there a few minutes It
will be cauterized as by an intense
fame. The reason for its protection
when merely dipped and instantly
Withdrawn IS that your hands heat
oondenses about it a layer of vapor
which, for e moment, prevents
actual contact with the liquid.
a kettle of liquid air ser on .
Chunk of ice. which is $50 degrees
hotter than the liquid. boiIs rapidly,
blowing white yapor from its spout
Enclosed in doubls-walled vesse;A
like thermos bottles. which have a
vacuum between their walls, LIQUID
air may be kept for weeks. but the
vessels must not be sealed, for then
they might be burst A little plug o.
cotton wool placed IN the neck OF
the bottle, in the manner Of . cork,
serves to prevent the escape OF the
liquid air, without causing q danger
Gus confinement OF its energy.