The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1875-07-22
Spontaneous Combustion.

Spontaneous Combustion.
Decay of inflammable substances, when
| exposed to the action Of atmospheric oxy-
| gen, is in fact very slow combustion,
WHICH by Liebig has been called ,Eremac-
ausis. : Thus, for example, a. piece of
wood Which, when burned, would produce
a rise of temperature 1000 deg. for say
one minute, will, when slowly decaying
during say 1000 days, evolve the same
1000 deg. Of heat but being diffused over
the length of time of 1000 days will only
evolve one deg. IN twenty-four hours, or
| 1-A0th Of degree per, minute, guam
Itityspf beat zuttdrl y inappreciable, as it is
constantly lost in the surrounding atmos-
phere. Every housekeeper knows that
decayed wood is next to worthless for fuel,
and the reason is simply that the heat o.
tanned when sound wood combines rapid
ly with oxygen was lost during the slow
combustion or decay.
| 1t is the same with coal when exposed
to the access of the air. Under shed it
loses, according to the experiments of
Varrcnstrass, Is per cent. of gas by oxida-
ton and 10 per cent. of-Ae, heat giving
pOwe9, while when exposed without the
| VI any oAClt, 81 VI lllC
| gaseous constituents are oxidiZed as to
cause the coal to lose one-thirtl of its orig
! inal weight and more than one-half of its
| heating power.
| OF course during such oxidation heat is
developed, but if the oxidation goes on
slowly the heat is carried off as soon as it
generates, and it is only, when this carry
ing off Of heat or cooling is prevented
that the temperature may rise. The rise
Of temperature increases the tendency to
oxidation; as nothing promotes more the
activity of the oxygen in combining with
combustible substances than heat, this in
creased oxidation again develops more
heat, and thus, the action and reaction con-
tinuing, at last the flame bursts out; and
this is what constitutes spontaneous COM
bustion.
| There are some substances very subject
to such a combustion, for instance, vegeta-
BILE and animal oils, especially drying oils.
Thus linseed oil 1.-THE drying of which is a
real oxidation) when poured upon heap
of sawdust or rags, placed SO the air has
access to the interior, will in a few hours
break out in flames; if the air is excluded
this will not take place-free access of air
or ventilation is necessary. When, how
ever, the sawdust or rags arc not placed in
single heap, but are diffrlsed over the
ground, so that the heat developed can
ditfusc itself by radiation, spontaneous
combustion will be prevented; notwith-
standing the continued oxidation promoted
by the free access of air, the mass will be
kept cool by the constant radiation OF heat
from the large surface exposed.
This is an important hint in regard to
the treatment of substances subject to
spontaneous combustion if it is impossi-
BILE to spread them out so as to expose a
large surface, and they have to be confined
to a small space, as is the case in loading
ships with such materials, ventilation
must be prevented, as it is not practical to
make it so active that the heat will be car
4 ried off more rapidly as it is developed by
creases in proportion to the force of ven
high temperature takes place at a lower
taneous combustion. ~ ~
The cases of spontaneous combustion of
bituminous coal are SO manifold and well
authenticated that it is really sign OF
utter ignorance of the facts taught by ex-
pcricnce to deny it. We have had it in
coal yards as we'll as on board of ships
and where it took place large mass OF
coal, say several thousand tons, was
placed, not on the ground, but on wood
en- floor, where air had access from below
and a steady upward aircuTrent took
place through the intersticcs of the coal
OF course the coal lost its gaseous don
stituents by oxidation, as proved BY the
observation of Varrenstrass, referred tC
4 above. This oxidation. by necessity, dc
IHelOped heat, and, as the heat could not es
cape from the interior of the large mass,
the Temperature was constantly raised
until, at last, combustion, lat tie Usual
|: high temperature, was established. !
Coal in. mines, before shafts have been
sunk, never H;gnites by spontaneous com
bustfOn; it is only when, by the sinking
ofsslafts, ventilation has been established
| that we hear of fires in coal mines; and
4 if we can lock up the coal in vessel as
! tightly as it is in mine before the shafts
have beer sunk the coal will be perfectly
i safe, and this none Of our antagonists dare
l.5 4 4 Il "a snicant fact that 10 fires have
occurred on board of coal vessels trans
8. porting coal across the Atlantic; Or s6ff any
voyage requiring no more time, but have
often taken place on board Of vessels go
ing to the East Indies, Ca1ifornia, and Ii
general distances requiring more haI
forty days. Of course where the action q
atmospheric oxygen on coal IN large, bull
can only raise the itemperattre OF the in
terror. ten degrees % Fair. + per day i
will in forty days, when starting at eight,
degrees, be only 490 degrees; bat evident
i " then the great danger commences, ant
I it is clear hoWsg GREAT an element time mus
be in this, physical operation, -Massa