Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1893-12-11
BOILING POINTS
These Are Snnuuacrable ana Fern q c..
r1ous Study.

0OtllN0 pONVA
Ihese Are Snnumcrable ana Fern . c..
rioas Study.
1t is interesting to note that the tenn
pcrataro at which liquid boils Is the
same as that at which its vapor is con-
densel, precisely as the temperature at
which water freezes is the same az that
at which ice melts.
It may seem superduous to observe
that there are more boiling points than
tho boiling point of water. If it were
not 90, all bodies would Ike in the solid,
liquid or gaseous state together, and life
would DO impossible. 1t is partly by
giving every substance its own boiling
point, or rather its own set of boiling
points-for the fixed temperature, even
for tho same Substance, is a fallacy-
that nature has rendered our physical
environment suitable to our needs.
What is generally understood by the
boiling point of water is temperature
Of 212 degrees on the Fahrenheit Their
mometric scale. Tut Alpine climbers
know well that, on a high mountain.
water boi.s ut a very much lower tenn
perature-on the summit of Mont Blanc
at 1874 degrees. The reason is that, at
these attitudes, the pressure Of the at
mOsphcre is very much reduced, since
the density of the air decreases with the
distance above the earth's surface, and
the water expands at a correspondingly
lower temperature. passing more read
lily into the vaporous condition. in which
Is e
stance is always far greater than that
Of the same mass when liquid. The
boiling point of liquid is, therefore,
seen to depend not only on temperature,
but also on pressure, and the boiling
point of water ct 212 degrees corre-
spends 20 what is called "a pressure OF
one atmosphere" approximately Is
pounds to the square inch, or the pres
sure capable Of supporting the column
at a height of 900 inches. This is
the average pressure of the atmosphere
at the sea level, and if it is reduced the
boiling point is lowered, while if tits
increased the boiling point is raised.
A very curious result is arrived at
ii we place a vessel of water in the re-
ceiver Of IA airpump and reduce the
pressure to zoe of an atmosphere, for
then the water boils ut 80 degrees-that
is, at its freezing point under ordinary
pressure. Since it is now possible to
produce an almost perfect vacuum,
water may be boiled ct still lower tenn
peraturcs.
All liquids 90 not boil ut the same
temperature. Thus, while water under
u pressure of one atmosphere boils at
212 degrees, alcohol, which passes more
readily into the state of vapor. boils
at 172.3 degrees and ether at 93.S de-
grees, which is below the normal tenn
peraturc of the Iody.
Since increase Of pressure retards the
vaporization of a liquid. it of course
facilitates the liquefaction of gas by
assisting the process of contraction.
Consequently many gases are capable
of being liQuefied by pressure alone,
though only when they are below what
is called their critical temperature
different for every different gas. above
which cold rs well as pressure becomes
necessary. Oxygen, hydrogen and nitro
Of gases having low critical tempera-
lures, and it is only recently that their
iquefcction has been accomplished at
all. They were long thought to he
permanent cases. but it is now
known that all gases are liquofablc.
The boiling points of oxygen and nj
trogen arc respectively 1888 degrees
and 356 degrees F. below the freez-
ing point Of water, and therefore
these are the highest temperatures at
which they can exist as liquids. To
produce these extremely low tempera-
lures it is necessary to employ great
pressure along with freezing mixtures.
Themost remarkable liQuefaction which
has yet been accomplished is that of
air. 1t was supposed that, the oxygen
and nitrogen having different boiling
points, they would liquefy separately.
This is not the case; the mixture lique-
fies as air and presents the appearance
of water. but on being again evaporated
the nitrogen evaporates first and the OK
ygen .fterward. This is q puzzle in
physics which will doubtless he ex-
planned ere lcng.-Good Words.