New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1894-09-24
MORE INTENSE COLD THAN EVER.

PROFESSOR DEWAR LIQUEFIES HYDROGEN GAS
AND sUKPASsEs HIS FORMER ACHIEVEMENTS.
Professor James Dewar who surprised the scien-
unc world about two years ago by reducing oxy
gen and nitrogen dong believed to be permanent
gases to a liquid form by means of Intense cold
and who last winter succeeded In freezing air.
has within few weeks announced another re-
markabc performances Although he speaks OF 1t
with caution-and. of course nobody else is likely
to claim more foi II than he-he evidently believes
that he has converted hydrogen gas. the lightest
substance known, into IA liquid and produced a
temperature Of 2i0 degrees below zero. Centgrade
The theoretical basis OF all these experiments is
the fact that volatile substance. when evaporat-
ing Will produce on the surface Of the vessel con-
tanning il a temperature which is lower than that
of the surrounding air This effect may be height
cned If the fluid first be put under enormous pres
sure by mechanical means. and also by having the
evaporation occur in receiver from which as
much air az possible has been exhausted. Thus.
with liquid nitrous oxide, liberated under those
conditions between the outer and inner walls OF
double receptacle. Dewar got 80 c.. and re-
duced to that temperature more volatile fluid,
ethylene, contained in the Inner chamber. The
ethylene had also been put under pressure before
being set Free and gave 10 on evaporation.
Compressed oxygen brought to that temperature
by the ethylene. produced 2lO when liberated.
There for a time. Dewar thought he was effectu
ally baked 1t is not necessary. In order to change
a substance .from the gaseous to the liquid state,
TO reduce It's temperature to what is known as
its boiling point II it be subjected to great pres
sure II will quefy at n higher degree 1t must.
however be reduced below what is called It's 'crt-
cal point" Thus. liquid oxygen boils at -lS4 c.
But its critical point" Is lib C. Natterer sub
iected this gas to pressure OF thirty tons to the
SQUARE inch; but as ne used "A temperature above
lii his efforts failed. Dewar. on the other hand
NOT only employed enormous pressure. but cooled
his oxygen below its critical point. Hence he was
critical point of hydrogen Is -2l0. The utmost
skill Of the great oxperimenter would enable him
barely to reach that stage. but not 4 single
degree further His victory was finally achieved
nv making n ne, substance, "A mixture Of air and
hydrogen whose critical point was about 200
The old tactics thus became practicable. His
nroduct was sometimes sort Of paste or jelly.
and sometimes a white solid with clear liquid
volatile that he could not capture II. Both theo-
retical reasons and thermo-e electric apparatus en-
able him TO say that ii had temperature OF about
pto below zero G. He does not feel disposed posi-
lively to p.onounce the liquid to be hydrogen pure
md simple. but he Is unable to say what else 1t
u.s. and evidently believes It to be that gas In
form.
The difficulty which he has In collecting the
fluid owing to its volatility. is not his only embar-
rassment just at present. These experiments are
very costly, and IL Is intmated that he needs Pc
cuniary help in prosecuting them further. OF the
liquid air which he 10 able to produce two-thfds