Spirit of the age. [volume] (Raleigh, N.C.) 1849-1865, 1855-09-26

Written for the spiris of the Age.
Familiar Chemical Letters.


REsPEcrFULLY DEDICATED TO MISS LAURA MURPHY.
ARTICLE VII
AT the conclusion of Article V, / at
tampted to explain the action which takes
place during the freezing of ice, and said
That ON o reduction of the temperature of
water below I00, we find that it, unlike 9th
or liquids expands, and that therefore, wa
ter az the temperature Of 400 was at its
maximum density. Besides, this water
when reduced in temperature SO as to form
ice, cxerts enormous mechanical force du- /
ring its expansion between 40 and 800, -
This was very satisfactorily proved by Ma
jor Williams, who took bomb shells and
filling them full Of water at temperature
Of 40', the fuse holes being then plugged
with iron rods, he placed them in a free.
zing mixture, and in short time the bombs
exploded or we're burst Some conception
of the force required for this, may be had
when we are informed that these bombs
were foot in diameter and the metal %
inches thick. At 2l2o far, we find that
water boils under the ordinary pressure of
the atmosphere, which is Is lbs upon ev-
cry square inch, but the boiling point of
water is much influenced by many circum-
stances; as for instance, the shape of the
vessel, the material Of which it is made,
and the pressure exerted by the atmosphere
on the water
Water will evaporate much faster in an
iron vessel than in an earthen.ware one
but Of all the circumstances that affect the
boiling point of water, that of the pressure
exerted upon it, is the one which inhuen-
ces it the most When the pressure is de-
creased, the boiling point is lower When
the pressure is increased, the boiling point
is necessarily higher We therefore say,
that the boiling point Of water varies accor-
ding to the pressure exerted Water has
been made to boil under the receiver of the
air pumps at almost the same temperature
at which it exists as such, viz: 800 From
these facts it follows that if we ascend il
the atmosphere, the boiling point will b
decreased; and if we descend into the eartl
las down mine for example) the boiling
point will be increased. This has beer
found to be true, and on this account'wa
ter has been employed to determine tn
height Of mountains A very beautiful
reduction Of temperature is performed thus
take glass containing hot water (not boil
iDg) and place 10 undor the recaiyer of thI
air pump, and by means Of the handle t.
that instrument exhaust the air; in shor
time, we will find that the water begin:
to boil, and the longer this operation il
carried on tho lower will be the tempera
ture, until at length with a good air puml
and compete exhaustion, the water will b.
found boilding at very little over 32o Du
ring the conversion of water into steam,
certain amount of heat is absorbed tn
escape or loss of which we cannot detect
Let us suppose that we have ascertaine
the temperature of the water in boile
and found il to be 1852. A short tim
after, we try it again and find that it is no,
200o. We try it again and we find thu
when boiling its temperature is 212o.-
We apply more heat, and in a short tin
more we again try its temperature, b,
what is this 7 why the temperature is ST
2120, the water is no hotter now than
was when we last examined it. Where tht
is all the heat going to? Is our fire st
burning2 Yes, and yet cannot raise Il
bempeIubuIo VI buS WdCcT duONc us DOllll
point. Where then you ask is the heat
going to; my answer is that it is passi
away with the steam in the state of late
heat. In the case of sea water, may
mark that it differs from fresh water as
CARDS its boiling and freezing points, becau
it is highly charged with different sail
matters, that is, it contains certain sa
dissolved in it, as is shown by the followi
table
Analysis Of sea water. English Mediterra