The Bottineau pioneer. (Bottineau, N.D.) 1885-1895, 1894-02-17
The Properties Of Air.

Simplicity in the teaching Of science
is quite as great and rare q merit as
simplicity in literary composition. and
Prof. Dewar has the enviable faculty
OF making the most marvellous scienti.
nc discoveries so plain as to be appre-
clated by an essentially popular audi
ence. In his recent lectures before the
English Royal Institution he brought
gu many wonderful results of his in
veStigatiOnS, any one Of which may
work almost incredible industrial rev
olutions when turned to practical use.
For instance, in dealing with the ef-
fects OF low temperature, he covered
his experimental table with f1agOns Of
air that had been turned to liquid,
which was enyeloped in carbOnic acid
suOw, and proved that at absolute zero
all metals have the same conductivity
TO electricity, however much they diff
Ter at higher temperatures. A low tenn
peraturf was found to greatly increase
the strength of metals. Iron at $50 de-
grees centigrade had twice the cohe-
slve power it possesses at an ordinary
temperature. "A fully saturated magnet
lost much or Its power when reduced to
$50 degrees centigrade, and electricity
would not pass through a globe that
had been made intensely cold. What
did this mean? asked the Professor.
Obviously that something was now
frozen out which had before enabled
electricity to pass across the III
space. In discussing the properties Of
liquid oxygen and liquid air he dropped
a globule of alcohol into Il quantity OF
liquid oxygen. The alcohol froze in
stantly into a solid ball, and would not
ignite with a match when removed
from the oxygen; but it speedily thaw-
ed into a kind Of slush in tho warm air
OF the lecture room, and then burned
with It's ordinary blue or "snap-dragon"
flame. The temperature of liquid Oxy-
gen is so low that ycarbonic acid gas,
such as we exhale in breathing or pro-
duce by burning charcoal, Immediately
frOZe to snow on coming in contact
with 1t: A quantity of liquid oxygen in
q glass tube, rapidly eyaporated by ex-
haus'ing the tube, produced such an in
tense cold (no less than 2O5 degrees
centigrade below the freezing point
that the very air Of the lecture room,
heated as it was, was seen to liquify on
he outside Of the tube, and drop like
rain into a vessel placed below. One
OF The most beautiful experiments was
directed to show that air has color.
The Professor took 4 strong iron cylin-
der about 6 feet in length, and filled it
with oxygen compressed to a pressure
OF 100 atmospheres. Then a beam Of
electric light was sent through the tube
and on to a screen. Between the END
OF b tube and the screen 4 prism was
placed. This separated the light on the
screen into the spectrum. which, in
stead of being of the ordinary rainbow
tints. had three black lines across it
one in the blue, n in the yellow and
one in the grccn-which showed that
the oxygen land therefore air. was not
.colorless, but had selected certain tlnts.
Prof. Dewar also showed that the pro-
portions Of oxygen and nitrogen which
go to form air are almost uniform in
all climates, and stated that there was
not q hundredth per cent difference
between the constituents Of the air in
London and those Of the air at the
top Of the highest mountain in Peru.