Rock Island daily Argus. (Rock Island, Ill.) 1886-1893, 1892-08-29

The principle on which the manufacture
OF Ice IS based is exemplified in the relation
OF heat into the conversion of water into
gas steam. A certain amount of heat is
required for the conversion of any fuid
into gas. This heat becomes as we saw
latent-that is, is being employed for the
time in producing violent undulations of
the gas molecules.
whenever liquid is converted into
gas, heat must come from somewhere In
the making of steam it comes from the
nre; In the ordinary evaporation of the
water out of doors it comes from the sum-
When there is no special heating arrange
ment, but the conditions are favorable for
the gaseous change in the fluid, heat will
De taken up from surrounding substances
IT they have any.
III you dip your hand in water and then
wave 1T through the air the water will
evaporate-that is, be converted into gas
and you will appreciate by the cool sensa-
ton that heat has been distracted from
your hand. If you use instead of water
some fluid which more readily passes into
the gaseous state, such as alcohol or ether,
the sensation of GOODNESS will be more i'm
mediate and intense
Now this is the principle which is APP
piled in the manufacture of ice. Some
fluid which evaporates readily is forced to
do so under such conditions that the heat
which II must nave ana render latent In
Its vapor viii be extracted from limited
quantity of water, and this process being
made continuous, so much heat will finally
be distracted from the water that its mole
cules can no longer stay mobile, but fly to-
gether into crystals-the water freezes
The evaporating fluid used in practice
may be sulphuric ether or sulphurous acid
or ammonia. The last is perhaps nova
days most often used. These fluids are
kept in strong, close pipes and receivers,
and can under no conditions come into con-
tact with the water to be frozen.
Suppose we consider the ammonia freez-
ing machines very briefly only, for into the
details of the process it is not necessary for
us here to enter
But in order to understand this opera-
ton one more physical principle must be
stated, which is that the degree of pressure
to which substance Is exposed has a great
influence upon the temperature at which
1t passes from the fluid to the gaseous con-
dition. Water at the ordinary attitudes
boils-that is, is converted into vapor-at
100 dogs. centigrade (2l2degs. Fahrenheit).
But on a high mountain it will boil at a
lower temperature than this, because the
atmospheric pressure is less there.
On the other hand, if you put gas into
receiver, and expose it to a sufficiently
heavy pressure by powerful pump or in
some other way, it will in most cases be-
come n fluid forthwith. and the heat which
had been latent in it will be given out
Now this in general way is what is done
to the ammonia in getting it ready to
freeze the water Pure liquid ammonia
bolls-that Is, passes from the liquid into
the gaseous state-at n temperature about
240 degS. Fahrenheit lower than water
does. Hence ammonia is substance which
at ordinary temperature is n gas. That
which we buy at the drug stores as am
mOnla SlmDlV solution al the in,
water, and from this, every one knows,
it is readily given off. 1t is volatile, that
is, it tends under ordinary conditions to
get into the gaseous form.
Now in ice factories powerful engines
are used to force the ammonia gas by
pressure into the liquid state, and the heat
which is thus set free is carried off by cool
water pouring over the coils of stout iron
pipe in which it is confined This fluid
ammonia-kept fluid by the pressure to
which 1t is subjected, a pressure varying
from 125 to Us pounds to the square inch
is carried in pipes to coils in the freez-
ing tanks. These tanks are simply great
watts filed with brine and covered over
with a floor. Into this brine cans filled
with the water to be frozen are placed and
carefully covered. These cans are usually
between three and four feet deep, about
one foot thick and nearly two feet wide
Coils of pipe communicating with the
which is kept in motion by paddle wheels
moved by machinery.
The brine acts n carrier of the heat
from the water in its tight metallic cans
to the ammonia pipes. Brine is used be-
cause it does not as readily freeze as water
does and acts a good conductor or dis
tributor of the heat
Now, when all is ready, the find am
monia under its great pressure is allowed
to escape into the coils of pipe which
pass about in the brine, and in which the
pressure is so much less that the ammonia
as 1t PUSHES in becomes at once a gas But
to do this it must have heat 1t must have
it. From the walls of the pipes into which
it PUSHES it seizes it first. These take it
from the brine which bathes them until
its temperature goes down, down, and it
begins to draw through their iron walls
upon the heat stock of the water in the
cans. And so the mimic but relentless
warfare goes on. The ammonia vapor is
constantly pumped away from the cold
pipes in which it had expanded to be used
over again. while fresh liquid ammonia is
as constantly forced in from behind.
Some hours pass, and the heat stock in
the water is growing scantier and scantier
1t can stand it in this way but little longer;
it is down well nigh to zero centigrade
and the wild, Unsuitable vapor raging for
heat in the pipes not far off is still sucking
it away. The only thing which can be
done now to furnish more is for the water
to give up its latent heat, and that is to
sign its own death warrant as water for
if one may use such a turn of phrase,
without its latent heat water is ice.
The ice layers ON all sides slowly thicken,
and at last, in about sixty hours, all is
solid. The watchful attendant raises with
crane the great beautiful ice block, still
in its galvanized iron can, out of its cold