Clarksville weekly chronicle. (Clarksville, Tenn.) 1873-1890, 1883-06-23
FREEZING IN SUMMER.

ucCodieS S0rVIceaDio 10 man, 1t Il
t observed that the discovery of tn,
, principle precedes by long perioe
its application to useful purposes
| thus the properties of the magne
were known for centuries without
producing results better than phi
losophic toy before its principle was
applied in the construction of the
Mariners compass and the electric
telegraph.
The same impression will occur
to any one who has studied the ru-
dlments of physical science on visit.
ing the ice factory at the Poston's
Spring. 1t has long been known
that any substance which passes
rapidly from the solid to the liquid
state or from the liquid state to the
gaseous absorbs heat from surround
ing objects so as to depress their
temperature or, in palmer language,
to render them cold. Thus evapo-
ration (Which is the change from
the liquid to the gaseous State) al
ways produces cold in proportion
to its rapidity; the cooling of the
air which results from summers
shower is familiar example of this.
Before the shower the weather is
generally warm and no important
cooling takes place till the shower
Is over and evaporation from the
earth's surface commences when
in fact the water resumes the form
OF vapor. But this effect is more
strlklngly witnessed when the fluid
Is more 0OtttiLe than water, in other
words, when it evapOrates more
readily and rapidly. Thus children
who eat peppermint candy know
that if they draw their breath while
they have candy in their mouth,
intense cold is the result, because
the oil of peppermint is very vola-
tile: ether is still more volatile as
may be seen by pouring little in a
saucer which very rapidly becomes
dry and if instead of the saucer the
palm of the hand is used the cold is
very perceptible; if now the same
process takes place in a vacuum,
water in contact with the ether is
rapidly frozen, the evaporation of
the ether being then more rapid |
and the cold more intense.
This last instance brings us close
to the principle of the ice factory,
which is simply that a fluid which
evaporatcs or becomes gaseous very
is, while evaporating,
brought in contact with the vessels
containing the water to be frozen;
while eYaporating, it absorbs heat
very rapidly from the objects in con-
tact with it, producing in them in
tense cold. This fluid is anhydrous
ammonia in its liquid form: anhy-
irous ammonia means simply am
nonia without water. The ammo
MA of the drug stores, properly
'alled cQ,ta anlnsOniCe or water of
ammonia is preparation of this
1uid largely diluted with water;
even in this state the ammonia has
tendency to escape in the gaseous
orm il the bottle is left unstopped.
md this tendency is the greater in
proportion as the preparation is \
trOnger, the strongest solution +
aqua 0nanaOniCe W) having to be q
pened only when below freezing, fl
Z it would escape too rapidly for G
Sc; but the anhydrous or undiluted
has such a tendency to A
ecome gaseous that it is only under n
normOus pressure that it can be Il
lade to assume the liquid form; d
hen so reduced it has to be con- Il
ned in very strong iron retOrts or il
would burst the containing YES n
Els and at once become gaseous. ST
These retOrts are so constructed h.
XIV 4" pOlIAOA vi Nllc dnlulOflla can CT
let out by turning screw faucet; &C
lis rushes into the gaseous form to
18th lncOnceivable rapidity and in q
lat form passes into a system of ia
on pipes in which it absorbs heat ps
ON the surrounding objects so fast M
to cover the pipes and anything co
Sc in contact with them with a co
me frost; these pipes circulate i'm We
e water to be frozen which i'm con- as
quence parts with its heat so rap Lii
ly as to be quickly changed into tn
lid ice. on
But now comes part of the pro- lea
IS which furnishes an admirable fol
monstration that it is by the alb lee
'ptiOn of heat from the water that
e ammonia converts it into ice. for
ter freezing the water in the watts in
ammonia is, we may say, satu- loo
Ell with heat and is no longer pei
Fable of absorbing any from sur ito
lnding objects; it now goes car
'ough a process by which it passes to
TX into the liquid form, and in of
ng so gives off the heat which it KIN,
Orbed from the water; for this wit
pose it is received into another
OF pipes in which it is subjected Y
enormous pressure by means of
I'M power; this pressure converts
ack into the liquid form and, 7
lie undergoing it, the ammonia of {
es off the heat it absorbed from by
water so rapidly that the pipes ty,
tanning it are heated almost to cou
ness. From these pipes it is frie
ed back, now in the liquid form, kno
the retOrt from which it first of
rged and is secured there ready uses
'eeze more water as soon as the n
sure is removed so as to enable heir
'ain to emerge in the gaseous to h
l. crop
he ammonia nowhere escapes cool
the open air; it only emerges The
the retort in gaseous form benz
one set OF pipes in which its cron
ence freezes the water, and then have
IS into another set where, I'M stan,
DING compression, it is forced MAN
in, lnn