The Emmett index. [volume] (Emmett, Idaho) 1893-1925, 1894-04-14
BOILING POINTS.



rious study.
II is interesting 10 note that tho tenn
perature at which liquid boils * the
same as that at which It's vapor Is con-
donscd. precisely as the temperature at
which water freezes Is the Same as that
at which ice melts.
10 may seem supcrhuous TO observe
that there are more boiling points than
tho boiling point Of water. II IL were
not no, MI bodies would DO in the solid,
liquid or gaseous state together, and life
would be impossible. IL is partly by
giving every substance its own boiling
point, on rather its own set Of boiling
points-for the fixed temperature, even
for the same substance, is a fallacy-
that nature has rendered our physical
environment suitable 10 our needs.
What 10 generally understood by the
boiling point Of water Is temperature
Of PIG degrees on the Fahrenheit Their
mornotric scale. bnt Alpine climbers
know well that, on a high mountain.
water loils no q very much lower tenn
pcraturc--on tho summit OF Mont Blanc
at iSf degrees. Tho reason ~ that, at
these attitudes, the pressure Of the at
mo8phCro 10 very much reduced. since
the density Of the air decreases With the
distance above the earth surface, and
the wator expands at corr spondingly
lower temperature, passing more read
lily into the vnporous condition. In which
the Volume OF given mass of any sub
stance Is always far greater than that
OF tho Same mass when liquid. The
boiling point Of liquid Is, therefore,
seen 20 depend not only on temperature,
but also ON pressure, and the boiling
point of water mt 2I2 degrees CORE
spends 10 what Is called "a pressure Of
ono atmosphere, approximately 10
pounds 70 the square inch, or the pres
sure capable of supporting tho column
Of mercury in a mercurial barometer
at height Of 900 inches. This is
tho average pressure Of the atmosphere
at tho sen level, and II 1t is reduced the
boiling point IL lowered while II IL is
increased tho boiling point is raised.
A very curious result Ia arrived nt
II We place vessel Of water in tho re-
coivcr Of an nirpump and reduce the
pressure TO .006 Of an atmosphere, for
thon the water boils at 32 degrees that
Is, at ita freezing point under ordinary
pressure. Since IL Is now possible TO
produce an almost perfect vacuum,
water may DO boiled at still lower tenn
peraturcs.
All liquids do not boil'at the same
temperature. Thus. while water under
pressure Of one atmosphere boils ut
2i2 degrees, alcohol, which passes more
readily into the state of vapor. hoils
at i72.J degrees and ether at 03. y de-
grocs. which Is below the normal tenn
pcraturo Of the body.
Since increase Of pressure retards the
vaporixation OF liquid. il of course
facilitates tho liqucfaction Of a gas by
assisting the process OF contraction.
Consequently many gases are capable
of being liqueiicd by pressure alone,
though only when they are below what
Is called their critical temperature
different for every different gas. above
which cold as well as pressure becomes
necessary. Oxygen. hydrogen and nitfo-
gcn are the most remarkable examples
OF gases having low critical tcmpora-
lures, and u IA only recently that their
lqucfaction has been accomplished mt
all. They were long thought TO be
"pcrma emit gases, but it Is now
known that all gases are liquchablo
Tho boiling points of oxygen and nj
troyon arc respectively 355.S degrees
and $50 degrees Il. below tho froez-
ing point of watcr. and therefore
these arc th' highest temperatures at
which they can exist as liquids. To
produce these extremely low tompora-
lures II Is necessary 10 employ great
pressure along with freezing mixtures.
Tho most remarkable liquofaction which
has yet been accomplished is that of
air. II was supposed that, the oxygen
and nitrogen having different boiling
points, they would hqucfy separately.
This IS not the case; the mixture hque-
hCs as air and presents the appearance
OF water, but on being again ovaporatod
the nitrogen cvaporatcs FIRST and the OK
ygcn uftcrward This Is a puzzle in
physics which will doubtless he ox-
planned ere long Good Words.