The farmer and mechanic. [volume] (Raleigh, N.C.) 18??-19??, 1911-09-12

that the bureau of mines VS. created.
The Big Pittsburgh Cylinder.
Inc bureau of mines is q branch
OF the Interior Department. 1t oc-
cup1es a new building back of the
patent office here at Washington, but
It's chlef experiment stations are
scattered throughout the mining re-
g1ons. The most important of these
Is at pittsburgh, where there are all
sorts or arrangements for testing
explosives and studying the rescue
work, both above and below ground.
one OF the most interesting pieces Of
apparatus there is a great steel cyl
lnder, 100 feet long and SO thick that
a man without STOPPING can stand
In the top of the cylinder, at six feet
apart, are manholes with lids which
fly open at each explosion to let the
upright within it. This is to repre-
Sent a mine tunnel.
1t one end of the cylinder is q
ann embedded in concrete. which
closes the mouth of the cylinder, and
at the other end is a paper dia-
phragm which holds in the gas, fire
damp or dust which may be forced
into it. When the cylinder is filled
with ratuTal gas, it has practically
the same conditions as though it
were full Of fire damp. The naturai
gas explodes the same way. and bv
ShS>1
of the various mediums can be seen.
Coal Dust Explosions.
One of the most interesting results
Of these tests has been to show that
coal dust alone is even more deadly
than fire damp or dust mixed with
fire damp. In the past both miners
and mine operators have believed
that the dust would not ignite unless
from a fire damp explosion and tnat
n vet ~ a i f-o~ f~~~1 o~,,l
not explode. To test this a lot Of
dust was put in the steel tube, which
was then free from gas. The can
non vas loaded with black powder
ta1nped with clay and discharged.
The result vas a terrible explosion.
which threw open the manhOles and
sent great volumes Of smoke and
Indeed, the danger from this
source is SO great that Director
Holmes has issued a %ircul in
structing the miners to keep the
mines clear Of dust n suggesting
hat they sprinkle the dust with
water or cover it with rock, clay or
sand. DR.. Holmes says that dry coal
dust floating in the air will explode
whether there is any inflammable
gas present or not, and that the finer
the dus the greater the explosion.
Some Of the dust in the. Pittsburg
cylinder was so fine that it passed
through a sieve with a mesh of 200
openings to an inch. This exploded
when there was only a small proper
ton of it in the air.
GDl.F IL k. 1905. 1905. 1890.
The bureau of mines advises that
the coal dust should be frequently
washed from the timber and the
mines be kept wet. They say that a
cry mine is a dangerous mine and
thot Tho firor fho duet tho miro uafor
required. Under no conditions should
coal dust be used for tamping the
holes filled with other explosives.
The Danger From Dust.
DIR. Holmes tells me that many eX-
plosions Of coal dust have occurred
in and about coal bins n that
similar explosions have happened in
some explosions of that kind last year
at st. Louis and there was one in a
cement plant in Colorado. In the
latter case nine men were so badly
burned by the flaming dust that they
died.
1t must not be thought that coal
Gust is the My kind of dust that
will explode without inflammable gas.
The dusts Of flour, starch and ugar,
all of which contain carbon. will do
the same thing. This is we'll known
in the flour milling centers, many
of the hills having been blown TO
pieces by such explosions. One such
instance occurred at Minneapolis IN
1878. and another at Granite City. ILL.,.
in 1910. Other mineral substances
than coal a dusts that will ex-
plode. This is 50 Of grahamite and
%gilsonite, both of which contain car
bon. Last December a violent explo-
sion which vas due to dust, occurred
in one Of the asphalt mines Of Okla
hOma.
kECUI.ED OR