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February, 1905 COAL AND TIMBER 19
produced at such a temperature as would
be generated by the burning of inflammable
matter, such as the gases given off by coal
when it is heated. It is evident that in such
occurences it is not the fixed carbon but
the volatile matter of the dust that is the
cause of the rapid ignition that makes coal
dust in air explosive.
When coal dust that contains much volatile
matter is heated above 212 degrees F.,
it gives off inflammable gas and when the
temperature is still further increased, the
gas is disengaged with increasing rapidity;
consequently, every particle of dust in the
air, as well as on the roof and sides, projects
or spurts into the surrounding air little
jets of gas that will mix with the air
and make a violent explosive mixture. According
to the data given by Mr. Jackson's
paper when' a violent dust explosion occurs,
the temperature is raised to about
6000 degrees F.; this I am inclined to doubt.
However, the temperature was raised to
such great heat in the Harwick mine that
we found the sides of the ribs blistered
and spoiled by the heat. This intense heat
doubtless would have fired the mine in
a number of places had there been any uncombed
oxygen left in the air to support
Speaking of watering the mines, we have
a mine on record now where the system is
carried on very thoroughly; that is, a system
of pipes all over the mines—in the
rooms and plugs at intervals, and a man
to keep all roads, roof and sides sprinkled.
In that way we keep the dust down. Now
for instance, take the Harwick mine where
the explosion was mostly due to the coal
dust; you can go into the mine since they
have these pipes in there and you will find
that it is practically a damp mine, and
where there are fans that can't run to a
very high water gauge, I think that their
system is the best one to employ.
By Mr. Roby.
In regard to the Harwick mine, in our
recommendations for safeguarding the
mine, we recommended that the coal dust
be carefully cleaned, and that the
pipes ol the mine be arranged that the
water couid reach the working faces before
shots are fired. We also recommend that
the least flaming and safest known explosives
be used. As it has been shown by
Mr. Jackson's paper that it is possible to
get an explosion even though there is no
fire damp present, it certainly is very necessary
that extra precautions be taken along
the line where flaming explosives are used;
that is, in the way of keeping the dust
practically all cleaned out and well watered
before they fire the shots.
combustion. You may have some slight
idea as to the rapidity of this force and
the great pressure produced as a result of
the combination of dust along with an unknown
quantity of fire damp, when we remember
that it caught a mule up from the
bottom of the shaft, and hurled it some 75
By Mr. Joseph Williams.
I have been giving this matter serious
attention for some time and I have learned
that where the heat of the mine is the
greatest and the dryest, coal dust becomes
or 100 feet above the top of the shaft. Including
the most dangerous. In shallow mines
the depth of the shaft, the mule
was thrown to a height of some 300 feet.
There are several very dry mines in my
district, and I notice after the miners have
been working for a few hours, their lamps
become very dusty from this finedust that
is floatingin the air which silts through
the shield on to the gauze and renders the
lamps unsafe in the presence of fire damp;
so that by the careless use of lamps they
are rendered unsafe in a few hours after
they are taken in the mine. There is no
where I have found considerable dust, I
have not found anything to occur from
the dust, but in shallow mines where it has
been dry, excessive explosions have been
effected until the atmosphere beyond the
current of air has become hot and lives
lost ever}' time. I have been in a mine
where a room was turned off from the current
of air and the room gone in about 20
feet at a pitch of about 45 degrees where
considerable blasting was being done by
men not used to working in bituminous
doubt these lamps arc the safest thing we mines, but who were anthracite miners
have, and a God-send to those who have to using the drills which they had used
work in mines that generate fire damp, yet in the anthracite mines and also
where the mine is so very dry the dust adds
very materially to the possibility of the
safest lamp itself starting an initial explosion,if
gas was to suddenly back down
on the lamp. It is a problem that is pretty
hard to deal with efficiently and safely in
using an excessive powder. They put the
condition of the atmosphere in that place
of work so that you could feel the heat in
there, and upon firing a blast, the flame
would extend 18 feet out of the rooms and
go in a direction at right angles outside
a mine. Fire damp alone can be very of the room for a distance of 200 feet. The
readily disposed of by circulating large volumes
of air through the mine, but coal
dust is not near so easy to get rid of as
entrance was driven over 100 feet inside
of this room and, I presume, it also extended
in there. One man, who had gone
fire damp, and where you have coal dust inside and another man on the outside both
you have a dangerous element, and it adds lost their lives when the explosion occurred.
very materially to the dangers that exist
in the mine and that might lead up to an
explosion.
By Mr. Cunningham.
I have come to the conclusion that
where the mine is very dry and where the
atmosphere is very warm, coal dust is a
very dangerous element.
By the Chairman.
What Mr. Williams has said confirmed
something that had come under my observation
some time ago, and this was in a
very wet mine. There was no dust in
the mine, but there was a distance of about
100 feet, where about 70 head of stock
passed through every morning and night,
and it is only a few feet from an engine,
which is operated by steam and not very
far from the pump room, and close to the
shaft where all the return air from the
lettirn mine comes, and that point is so
dusty that if it is not cleaned out ever}'
day or two the dust will accumulate to a
depth of six or more inches in one week,
and there is no dust in any other place in
that mine. There is a great deal of truth
in Mr. William's statement, but it is a fact
that dust is there, always will be there, and
must be taken care of every few days.
By William Duncan.
Coal being an organic matter, we know
that it is undergoing decomposition from
the exposure to air, from the fact that
when coal is shipped any great distance
it loses some of its value from being exposed
to the air. I care not whether it
is in a coal fieldor wherever coal may be,
the carbon hydrogen is escaping from that
coal, and the more finelythe coal is pulverized,
the more rapidly will the carbon
hydrogen escape. I took a bag of air out
of a coal bin and applied it to the test and
I cannot say that there was any fine particles
of dust in the air. but I applied it
on the instrument and found that the air
which I took out of the coal bin contained
one per cent, of carbonate of hydrogen and
for that reason, I believe, that carbonate
of hydrogen is always present wherever
there is coal or coal dust, as it is always
escaping from the coal, and the higher the
temperature, the more rapidly decomposition
takes place.
By Mr. Phillips.
T would like to ask Mr. Duncan whether.
he thinks that new fresh coal is more
dangerous than coal that has been exposed
to the air for some time.
By Mr. Duncan.
I would say yes; the fresher the coal, the
more powerful the gas and the more rapidly
will it escape from the coal.
By H. H. Stoek.
I think it is now generally admitted as a
fact that you can have a dust explosion
without the presence of gas, though for
many years a combination of the two was
thought necessary.
In Colorado there is a plant where there
was an outside plane down which coal was
lowered from the mine to the tipple. One
day a trip of cars broke loose and came
down the plane and over the tipple stirring
up a great deal of dust. There was a stove
in the tipple and an explosion occurred inside
the tipple, the flames shooting out
some distance in front, giving a conclusive
proof to my mind that you can have an ex-