The times., 1899-10-29

tue case OF lreS AR And II the liquid be I
Kept for time in an open vessel the nitro /
gen Will revert to gaseous condition
(Jhat is, viii evapOrate OF boil or more
rapidly than the oxygen. so that the per
centage Of oxygen continually increases /
Hence the liquefaCtion of air affords a rap
I'd and economical method Of obtaining OK
ygen for use in chemical and metallurgical
operations and for producing intense local
combustion with a corresponding accentua-
tion Of temperature.
Already Dr. BorChers in Germany has
applied this super -oXygenated mixture 10
the production OF calcium carbide for the
manufacture OF acetylene. / am using il
IN the cremation OF dead bodies and the
destruction Of garbage by a method which
allows of such operations being conducted
without evolving any offensive or deleteri-
Gus vapor.
4 Matter OF Chemical Composition
IF we disregard the question of chemi-
cal composition and regard liquid air in
a purely physical aspect, we are at once
struck by very singular fact OF great
Importance from the point Of view Of me-
chanical power. a liquid is a non-expln-
sive body; that is TO say, its molecules are
in such close proximity 10 each other that
their inter attraction suffices to keep them
from separating. until, indeed some heat
from the outside is introduced TO break
these internal bonds Now, we all know
that If air be compressed it requires 10 be
confined in some strong receptacle IN the
same way that steam is confined in the
boiler OF steam engine. We also know
that in the street cars now operated by
compressed air in New York and in the
auto trucks which will ere long do so much
TO relieve the cOngested condition Of city
thoroughtares, the motive power consists
OF very heavy and cumbrous steel reser-
voirs or TASKS containing air compressed
TO an initial pressure Of 1000 or $500
pounds per square inch. This means that
the air in question has been reduced to
about the one hundred and sixtieth part OF
its original bulk. Now, liquid air is re-
duced to one eight-hundredth part OF its
volume when free; or, in other words. il
has capacity Of expansion five times as
great as that possessed by the highest
grade of compressed air hitherto employed
in mechanical practice. Yet this enormous
potentiality Of power. equivalent to 10000
or $4,000 pounds per square inch, can be
kept in an ordinary tin can. It is in itself
harmless and inert and if used as source
OF power II requires no massive and
weighty reservoirs. Molecular attraction
has been substituted for steel walls.
The Compressed Article.
Here, then. we see the tremendous ad-
yantages which liquid air enjoys over com
pressed air. 1t gives US five times as much
power, volume for volume; and the appli-
l auces for storage and transport are ten
times less costly and cumbrous. But com
pressed air is a power that has of late
years come into continually extending use.
In the Howard Lectures delivered by Prof.
w. c. Unwin, F. A. S, in 1898, on the
! Development and Transmission OF Power
from central stations, said, among o-her
things Compressed air transmits on is
a perfectly general method Of distributing
power for all purposes. Whether in any
given case it is the most advantageous,
the least wasteful Of power, or the cheap
est in working cost, depends on various
circumstances NJ. Hanarte believes that
it is and will continue to be the most
economical method Of transmission to con
siderable distance. The loss in the air
mains is very small The motors worked
expansively are efficient. The mains can
be carried by any path, and diffeTenC s Of
elevation between the COMPRISING and
working points do not sensibly affect the
result. In hydraulic transmission, the wa
ter must be collected, stored and in some
cases filtered, and having actuated g mo-
tor, means must be found for removing it.
But air is everywhere available and can
be discharged anywhere without causing
trouble
Introducing Air Power.
at is no wonder then that engineers are
introducing air power to a greater and
greater extent from year to year. Even
the conservative British Government has
recently decided to employ air power in
its navy yards and is giving orders to
compressors and pneumatic tools Inas-
much, therefore, as liquid air is a vastly
superior form OF compressed air its field
of activity is Of cOrrespOndingly large eX-
tent. 1t Will not replace steam and elee-
tricity in their special spheres 1t viii
have its own work TO do.
While, however. it is true that liquid
air gives US the means of employing huge
air, it must not be supposed that the air
itself contains the power. This is where
the magazine scribes and popular lecturers
have blundered They have confused
mechanism with power But there is no
power inherent in the piston and cylinder
and driving wheels of a locomotive. They
merely transmit the force impaired TO
them by the steam. Even the steam itself
has no inherent power, II is merely
mechanism for collecting heat from the
boiler fire and delivering il for conversion
into mOlar motion in the cylinder. In like
manner there is no inherent power in
liquid air. Keep it at its own temperature
and it remains inert. But il is a body
that has a vast capacity for heat, and its
particles are packed together in a way
most advantageous for converting that
heat into mechanical power. 1t may be
regarded as a superior kind of water, and
when, by heating it regains a gaseous
form, the resulting air may be regarded as
a superior kind of steam. It does not fol-
low that weight for weight liquid air
can be made TO perform a greater total of
work than steam, but in many cases it
will be found more adaptable and general
ly efficient"
Dr. Emmens has been investigating the
subject of liquid air for years, and is well
qualified TO speak upon the matter. He is
identified with a metropolitan company for
the production of liquid air, as well as the
inventor of devices to be used in the new
industry. He has been conspicuous as
writer upon scientific subjects, and espe-
ciaIly upon liquid air.
HAVANA'S WATER MAIN.
An Interesting Engineering Feat
Performed by Americans.
(FrUm the New York JouruaI)