The morning news. [volume] (Savannah, Ga.) 1887-1900, 1898-03-20
CURIOUS EXPERIMENTS.
Professor Barker illustrates Some of
the Qualities of Liquid Air.

the Qualities of Liquid Air.
From the Philadelphia Ledger.
It was only little over month ago
that announcement was made that
Charles f. Tripler Of New York had
discovered a way of producing liquid air
by the gallon, and the announcement was
followed by IA private exhibition of its
properties at the University of Pennsyl-
vania, Prof. George L. Barker. the pro-
fessor of physics, giving an interesting
lecture that was reported In these col
umns at the time. Since this demonstra-
ton by Prof. Barker, efforts have been
made on all sides TO obtain liquid air and
repeat the experiments, but as Mr.. Tripler
Is engaged on certain dynamlcal problems
and requires the material for his own
work, he has generally declined to supply
IL. Prof. Barker, however, secured sup
ply that enabled him to lecture on the
subject Yesterday afternoon before the
chemical section al the university; and
last evening, under the auspices of the
new Alumnae Association of the Normal
School, the lecture and experiments were
repeated in the assembly room of that
school,
In introducing his lecture last evening,
terms, critical temperature and boiling
point, and the fact that gaseous substances
are gaseous because for them these tenn
peratures are below those OF ordinary eN-
perience. Gases will become LIQUID and
liquids solid If the temperature be sufIi-
GENTLY lowered Nitrogen, the largest In
gredent of air, requires a temperature of
Sl5 degrees below zero. Oxygen, the 9TH
er chief ingredient, takes 292 degrees below
zero. In Mr. Tripler's process this incre-
dtble low temperature is reached by taking
advantage of the enormous loss of heat
effected when compressed air is suddenly
allowed to expand. By an ingeniously
devised series of coils so that the air from
a compressor expands from each into the
next through a fine opening, IL happens
that large stream Of common air enters
the machine, and a small stream of liquid
air runs from it continuously while IL Is
working. The liquid air, as IL runs out
has a clouded appearance, due to the pres
ence of minute spicules of solid matter;
but when filtered It becomes quite clear
and pale blue in color This Is pure air
at temperature of 3l5 degrees Delow zero
and each cubic foot OF air becomes two
cubic inches of liquid When freely ex-
posed IL boils necessarily from the heat
which il absorbs; but il placed In a suita-
BILE holder, surrounded by a vacuum, 1t Is
| quite stil. Some ingenious bulbs, made to
| fulfil these conditions, were shown by the
lecturer. An inside bulb contained the
| liquid, and an outer surrounding one was
exhausted of air, thus defending the in
ner one with vacuum through which
heat does not penetrate.
Professor Barker showed a series of bril-
| liant experiments with the liquid air, and
| while it was curious and interesting 10
see the air we breathe poured like water
| from one vessel TO another, and watch It's
| gradual escape from the thraldom of cold
which had captured 1t, yet the most fas-
cinatng experiments were those which re-
vealed the changes which seemed to take
| place i'm the inner constitution of common
| substances when conditions are changed.
| Tin, ordinarily tenacious and flexible, be-
| came, when plunged into the liquid air,
| as brittle as glass Lead, similarly treat
| ed, became hard and elastic as steel, while
copper acquired additional tenacity A
| dramatic experiment was one in which
ordinary elusive liquid mercury was froz-
en- so hard that bar of 1t was used to
| drive a nail into a board. A lump of ice
dropped into the liquid air caused a vio-
lent seethng and Kissing, like that pro
duced by plunging a red hot iron In
water. while a quantity of liquid alcohol
became a transparent solid
| One of the most curious and yet in
structive experiments was that which
showed how the rays /of the sun may
come across millions OF miles of the alb
solute zero of space and eth warm the
earth. A converglng beam of light from
| the electric arc was sent through the
liquid air, cold as 1t is, and at the focus
of the rays, burned hole in a sheet OF
| paper.
AS the liquid eyaporates, the nitro
gen goes off faster than the oxygen, be.
cause of the lower temperature of its
boiling point
| The result of this Is that the percent
age of oxygen in the liquid left varies
from 20 to 70 per cent. Under such cir
| cumstances any combustible material,
when wet with the liquid, burns with ter
rife energy. Frozen alcohol, when satu-
rated with It and ignited, explodes like
! ntro-glycerlne. Cotton wool. when
stepped in 1t, goes Off like gun cotton.
The liquid air used in the afternoon and
evening lectures was manufactured IN
New York during the day, and was
brought over 20 Philadelphia In AN ordi-
|