Evening star. [volume] (Washington, D.C.) 1854-1972, 1911-02-12

II
the gentle occupation of bread making,
would be greatly surprised if informed that
the -four she used for this everyday domestic
purpose was, in some circumstances, one of
the most dangerous of explosives; compar-
able, indeed, in its destructive effects, to an
equal quantity of gunpowder.
To show that this does not overstate the
fact, one may quote Charles E. Munroe,
professor of chemistry in the George Wash
ington University, one of the foremost
authorities on explosives. He says that the
contents of a twenty-hve-pound sack of
flour, mixed with four thousand cubic feet of
air, will, if ignited, generate force enough to
throw a mass OF iron weighing one ton forty
five miles into the air.
1t will be noticed, however, that the flour
must be mixed with air. So long as it re-
mains in the sack, or barrel it is entirely
harmless; but let the housewife scatter it
broadcast in her kitchen, until the atmos-
phere of the room is heavily laden with it,
and the condition is one of danger. The
mere striking of a match is likely, IN such
circumstances, to cause an explosion that
will blow up the house. Gunpowder would
do no greater damage.
Within the last few years there have been
number of serious explosions of the kind,
involving the loss of many lives and the de-
struction of great deal of valuable property.
One of these, in Chicago, wiped out the
Another, on still larger scale, annihilated
group of huge -four mills at Minneapolis.
In the latter instance, walls of solid
masonry six feet thick at the base were RACED
to the ground, and sheets of corrugated iron
roofing six by two feet in size were thrown
distance of over two miles. Stout plate
glass windows quarter of a mile away were
torn out bodily, sash and ALL and an inn
mense volume of flame and smoke was dis
charged upward to height of eight hundred
feet.
How They Occur
EXPLOSIONS of this kind Zone of them
- destroyed a group of flour mills in Glas-
gov not many years ago. were tor long
time regarded as mysterious, and there was
much dispute as to the cause of them. But
the matter is now fully understood, the
whole secret of it being that flour is an ignit-
ible substance, and, if SO mixed with air as to
be supplied with plenty of oxygen for pur
poses of combustion will, when flame is
applied, burn with utmost rapidity. The
burning, of course, signifies its conversion
from a solid into a gas; and, if the trans
formation takes place within confined space,
the gas will burst its way out. The result,
in other words, is an explosion.
The same thing is true of any kind of in
fammable dust; such as sawdust, for exam
pie. As everybody has noticed, when wood
is burned in large sticks, the fire does not
start easily. When cut into kindlings, how
ever, it burns more rapidly. When the
kindlines are cut into shavings, they burn
still more rapidly. But, when wood is re-
duced to sawdust, and the latter is suspended
in air and set on fire, it burns with explosive
rapidity.
Hence the explosions that occur every
now and then in sawmills and woodpulp
mills. The two conditions requisite in all
such cases are that the substance shall be
combustible, and that it shall be mixed with
air. The ordinary dust in a room will not
explode, because, being mostly of a mineral
nature, it will not burn. 1t cannot ignite,
and SO cannot explode. What we call ex-
plosion is merely very rapid burning, which
generates large quantities of gases in con-
fined space.
There must be air to furnish the oxygen.
Load it with any kind of igntible dust,
and only flame is needed to produce an
explosion. Thus it was that the disaster
occurred recently at Granite City, Illinois,
where the great Corn Products Mills were
blown up, with loss of several lives. In
this instance it was maize dust, mixed with
air, that did the mischief
Every now and then q candv factory