Belmont chronicle. [volume] (St. Clairsville, Ohio) 1855-1973, 1888-10-04
AN INTERESTING STUDY.

A sENu-sCIENTIFIC ILLUSTRATION SHOW
ING WHY WATER PUTS OUT FIRE.
B. B. James in Tradesman.
have often been puzzled to answer
for myself why water extinguishes fire.
\ great many people say it is because
the water and its steam so envelop the
burning material as to exclude the oXy-
gen, and thus the fire must stop. This
seems to be an inefficient if not an en-
tirely erroneous reason Ny reason is
this: We know that nothing will burn
d. E., unite with oxygen with the evolu-
ton of heat and light unless and until
it has been raised to a given tempera-
ture. Thus: Sodium burns at ordinary
temperature about sixty degrees if dry
the gas of ordinary kerosene at about
10 degree or less, and so on. Why do
we tip a piece of stick with sulphur and
then with phosphorus to make matches?
Because, while wood must have quite a
high temperature, phosphorus will burn
at comparatively low temperature
low that the heat developed by slight
friction will ignite it. The phosphorus
makes heat enough to ignite the sui
phur, but not enough to start the wood.
But L will ask another question: Wood
ashes are white. Why is the remaining
end of the match and often most of it
black in color? Is it not because carbon
being black, and the wood being COM
posed of carbon and compound sub
stances, which are very inflammable, the
latter burn, but do not generate enough
heat to oxidize the former. This seems
to me the reason for the carbon remain
ing. Thus promising and showing that
carbon, which forms the bulk of wood
CaS well as of paper, cotton, etc. requires
to be very hot before it will unite with
the oxygen, we may consider the water
for a moment.
Perhaps the easiest way to make my
point clear is to take common illustra-
ton. Every one knows that if one puts
kettle of water on a heated stove he
must wait long time for it to become
boiling hot, or temperature of 212 de-
greeS F. Now, if he should put the
same amount of quicksilver on by the
side of the water, the latter would reach
2l2 degrees far sooner. Why is this? 1t ]
is because the water takes up large
amount of heat which is there in the
water, but which the thermometer does
not index. Now, if after reaching 212
degrees, he sets them off, the mercury
will reach the temperature of the sur
rounding air much more rapidly. Now, |
suppose we wish to boil all the water |
away, to evapOrate it-in that case re-
member that in passing from water to
steam the temperature is not raised even
degree, nor any fraction of one-cOuld |
he not make it all evaporate instantly by
raising the temperature little? Veal |
know he could not; that the fire has a
degree of heat several hundred degrees
higher, but the kettle must remain a
long time, while the water very gradual
ly goes off in steam. Why so? Because
the water, in becoming steam, must take
into itself large amount of heat not
shown by the thermometer, and as the
heat can be added only gradually, the
formation of steam is slow. Now, in the
large amount of heat which water can
take up, and the fact that ordinary in
must be raised to a high
in order to burn, we have
the cause of water putting out fire. Put
a burning match into very small drop
Of water and it is extinguished, because
Of the very large amount of heat taken
from the match in reducing the water
10 steam which renders the temperature ,
IF the match too far below 212 degrees,
or at least that far, if there is water
enough, and so the carbon and its COM
pounds forming the wood will no longer {
mite with the oxygen of the air. For s
he same reason hot iron thrust into t
he water is cooled, and water sprinkled
IN the floor cools the air, the heat of !
in the latter case coming
rom the air itself, thus cooling it. Now,
f we could find a fluid very plentiful, '
which requires more heat than water to G
make it boil, evidently we could put C
arge fires out much more rapidly. t