Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1898-03-17

on Monuay afternoon and evening,
George +. Barker, professor of physics,
gavo two interesting lectures accom-
panied by experiments, on liquid air.
1t il only II few wooks since il was an
n0unced that Charles +. Triplcr Of
New York had discovered method OF
liquifying air by the gallon, and the
liquid air used by Prof Harker in his
experiments was produced by the
Triplor process.
In his lecture Monday evening Prof.
Barker gavo an explanation of tho
terms, critical temperature anil boiling
paint, and the fact that gaseous sun
stances are gaseous because for them
these temperatures arc below thnse of
ordinary experience. Gases will become
liquid and liquids solid, il tho tenn
perHture he sufficiently lowered. Nitro
gen, tho largast ingredient of air, re-
quiros a temperature of 3l5 degrees
below zero. Oxygen, this other chief
ingredient, takes 292 degrees below
zero. In Mr.. Triper'a process this
iucredibls low temperature il reached
by taking advantage OF the enormous
loss OF heat effected when compressed
air Is suddenly allowed to expand. By
an ingeninusly devised series Of coils,
80 that tho air from a compressor eX-
pands from each into the next through
fine opening. it happens TINT large
stroam OF common air enters the ma
chine, and small stream of liquid air
runs from it continuously whilo it is
working. Tho liquid air. as il runs
out, has clouded appearances, due to
the presence Of minute spicules of
aolid matter; but when filtered it be-
| comes quito clear ana pale blue In
color. This ia pure air Mt a tompera-
turs of 3l5 degrees below zero, and
each cubic foot Of mir becomes two
cubic inches of liquid. When freely
exposed ii boila necessarily from the
heat, which it abaurbB but il placed
in a suitable holder, surrounded by u
vacuum, it is quite still Some in
genious bulbs, made TO fulfil tho con
ditions, were shown by tho lecturer
| An inside bulb contained the liquid,
and an outer surrounding one was OK
hausted of air, thus defending the
inner one with vacuum through
which boat does not penetrate.
Prof. Barker showed series of bril-
liant experimental with the liquid air,
and while it was curious and interest
ing to sev the air we breathe poured
like water from ono vessel to another,
and watch it's gradual escape from the
tnraldom of cold which had captured
it. yet tbs most fascinating expert
ments were those which revealed tht
changes which seemed to take place in
the inner constitution Of common sub
stances when conditions arc changed.
Tin, ordinarily tenacious and flexible
became, when plunged into the liquid
air, M brittle as glass. Lead, similarly
| Ianan,a al n,
steel, while copper acquired additions
tenacity. a dramatic experiment wa
one in which ordinary eluaive liquiC
mercury was frozen so hard that ba
Of it was used to drive nail into
hoard. A lump of ice dropped into til,
liquid air caused violent seething ant
kissing, like that produced by plunginl
red hot iron In water, while luantit,
OF liquid alcohol became trunHparen
solid.
One of the most curious and yet in
structive experiments was that which
showed how the rays If the sun ma,
come across millions Of miles OF To
absolute zero OF space and still warn
, the earth. A conyerging beam of ligh
, from the electric arc was sent through
the LIQUID air, cold az II is, and at tn
fncus OF tho rays, burned hole 10
! sheet of paper. As tho liquid evRpo
t rates, the nitrogen GOES oil fastor thin
I tho oxygen, because Of tho lowor tom
: peraturo of its boiling point The re
J suit of this ia that the percentage O
t oxygen in the liquid left varies from
0 to 10 per cent. Under such circun
stances, any combuatihle material
Q when wet with the liquid, burns wit
terrific energy. Frozen alcohol, who
b saturated with il aud ienited. explode
o ike nitro glycerine. Cotton wool, whe
t stepped in it, goes oil like gun cotton
{ The liquid air used in these export
il ments was made in New York duriu
tho day and brought to Philadelphi
y by railroad train, in ordinary mil
. cans. Altogether, the discovery is on
Q of tho most interesting and surprisin
8 Of modern scientific research.