The Manchester journal. [volume] (Manchester, Vt.) 1861-current, 1870-02-08

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Let Tie gasslaau he PRO
Toess ia aHiItd oompsuy q psrs9ns
q 81 sgcs sad oecupztious Whni are
iAs bublsles whleh rise shroaFh baling
v.ier Sled 18th = Add nins o.. often
n then will aaarsr ~ ouce. They are
fasd wi.h ar Add The Sane large
Eslariiy ~ ihnsl upoa i that ibe T
white elsad vh,eb issue, from tie n3so
a The teal kettle ana she whistle q tbs
osanotire i steam.
Son both these IDEAS are vroag
The rising bubtles are faii q steam,
AID the white cioads i vktsry vApor
II vas 9nos steam, i Is true. bot i j.
now steam no longer II has already
retained ld~aier. wheacs Il came T
I, i ,he nat8re a water. when ga
posed 70 high degree q beat 20
change Suddenly from liquid state to
the form u a. Invisible gaseous fad,
which sc call steam As cold changes
water into ice, ~ bea, produces Ike
wonderful transformation, changing
waller in.o an Invisible Ra-. which Is, in
many respects. entirely unlike ms orr
go Water Is heavy steam is light.
Water i visible sieam is invisible,
just A. invisible A. air Water is non
elastic steam is ID The highes, degree
elastic Water is dense steam is rare.
4 small tbimblefal d water will make
large pailinl Of steam.
When An atom Of water lyiug at the
bottom Of kettle is exposed to 2i2
degrees Of beat, IT is inslantaneously
ctanged to steam, and occupies nearly
tao thousand times as large q space rs
il did before. As Satan Ia the Garden
~ Eden. erouching like toad at The
d sleeping Eve, spraBg instantly into
the stately proportions Of gigantic
man at tie touch Of Ithuriel's spear, so
the tiny particles Of water, under the
magical influence Of heat, suddenly
leap from their humble form INFO great
kissing bubbles Of steam. These, on
account Of their superior ligltness, be-
gin al once to struggle upwards out Of
their watery grave This great e1pan-
sion end rapid rising readily explain
the violent agitation Of boiling water.
II has been said above that this great
change takes place at the temperature
81 2l2 degrees But this degree Of
heat is not constant II varies with
the sver-yarying pressure OF the air up
on the surface u the water Travellers
who make their way TO lofty mountain
tops, where the pressure Of the air is
much less han at the level OF the sea,
End that water boils at a much lower
degree Of heat Cooks tell US that on
some days the a-kettle will boil much
quicker, aud that the water in the pot,
where meat is cooking will boil away
much faster than on other days 90
such days the barometer would show
that the pressure Of the air is compar-
altyely light II dish Of boiling wa
ter is removed from the FIRE and allow
ed to cool for short time, it will again
commence boiling violently, II placed
under the partially exhausted receiver
Of an air.pump. Or, if some water is
boiled over lamp in thin glass bot
tie, then removed from the FIRE aud
closely corked, il may again be set 10
boiling by pouring cold water upon the
bottle.
To understand the reason Of this, it
must be remembered that steam re-
mains steam only SO long as it's temper
AZURE Is kept up to 2l2 degrees The
momout it is cooled below that degree
il fenrns TO Mater again as quickly as
il was before changed to steam This
is called condensation. In the expert
ment with the glass bottle, the steam
which fills the flask above the boiling
water is at once condemned by the APP
plication Of cold water, aud the exier-
nal air being excluded by the cork,
there Is no pressure left upon the sur
face Of The water 10 prevent bnbblcs Of
steam rising through 1t at much low
er temperature than before