In a very short time the candle will
go out for want ot air, and It will be
fxiuhd that the two-glasses will stick
together very tightly, so that the up
per can lift the lower. Indeed, it will
require considerable ,force to sepa
rate the glasses thus joined. This is
due to the fact that some of the air
inside, heated by the candle, has risen
out of the glass, so that the pressure
outside Is greater thaa ^ftt.^within,
thus making the glasses adhere flrni
vy.
Experiment 2—A simple air pump
can be" made by using a large glass
jar or bottle. Close the mouth of this
with a tight rubber stopper. Through
this pass a piece of glass tubing, to
the upper end of which fasten a piece
-of rubber tubing about two inches
long/ making a continuous connection
to the inside of the jar from without.
Exhaust the air from your lungs, ap
ply your ntouth to the end of the rub
ber tube, and draw In with j'our
breath, taking the air from the Jar.
Pinch the tube closely with your fing
ers, to prevent the air from re-enter*
log the jar, and repeat this process
until you have exhausted the air from
the jar. If the air Is to be kept out
of the jar for any length of time tie
a stout piece of fine cord tightly
around the tube, or if possible fasten
a pinchcock to the tube, so that the
air may be released or retained at
will.
