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THE COAL TRADE BULLETIN. 37
THE INFLAMMABLE GASES IN MINE AIR* \
r By Georfie A. Buriell and Frank M. Seihert f
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Much attention has been given in seveial Emo- faulty analytical work would not lead to wrong
pean countries to the study of the inflammable conclusions. That faulty methods may lead to
gases found in coal mines, but not nearly as many erroneous results is obvious. If a technical gas
analyses of gases from mines in the United States analysis apparatus is used in which the usual
have been published. Methane is generally re- experimental error of plus or minus 0.2 or o.3 c. c.
garded as the inflammable constituent of fire is not avoided, the resultant error becomes serious
damp, but it has been stated that hydrogen, ethy- as regards exact work.
lene, ancl members of the paraffin series higher To show the accuracy demanded in examining
than methane occur in some mines. It has been mine gases, the lollowing analytical results are
claimed, too, that carbon monoxide may be a given. A mine atmosphere of this composition
constituent under conditions other than those was recently examined at the bureau's laboratory:
well known to produce the gas, such as those at- Analysis of a mine atmosphere.
tending mine fires and explosions. Per cent.
That some of these gases may lie formed as a r;o 7.07
result of a fire or explosion in a mine is granted. o 1.2
for the reactions that occur during fires and ex- co .00
plosions are known to produce them, but tiie an- QJT 28.33
thors believe, as a result of their experiments, \ 63.51
that ethylene, hydrogen, carbon monoxide, or Th_ |0n0wing calculations show the procedure
ethane seldom occurs, even in very small quanti- a(lo])ted in determining the methane when the
ties, in the air of American coal mines thai aie siow-combustion method of burning the methane
operating under normal conditions. _as use(j.
Samples of mine air have been obtained from p p
many mines, in the main returns, splits, and en- V(llume „,* ,.,mpl. taken for analysis 100.00
tries, in places where the ail* was moving, and Volllme aftel. arjs0rption of CO, 92.93
also in places where the air was still, as at work- ^,Q f0und 7 07
ing faces, cavities in the roof, in the goave, ancl Vo,ume after absorption of O, 91.73
in sealed inclosures. In addition, samples have Q nourlri 120
been collected from parts of mines that were on volume of sample taken for combustion. .. . 45.86
fire ancl from mines shortly after explosions had Q ad(je(j ,01. combustion 54.14
occurred. Consequently, an excellent opportunity Tota, volume for combustion 100.00
has been afforded to study mine gases that have Volume after comllusti0n 71.78
accumulated under many different conditions, contraction due to combustion 28.22
Some results of this study are presented in Ihe Volume attei. absorption of CO 57.67
following paper whieli is published by the Bureau C Q produced by combustion 14.11
of Mines as a contribution to a better knowledge A duplicate anaiysis in which a smaller proporof
the causes of mine explosions. tion of the sample was taken for tne analysjs gave
If other combustible gases than methane are t]lp following results:
present under normal conditions of mine opeia- . .
1 Analysis ot a mine atmosphere.
tion. then the fact should be made known, because
ethane, hydrogen, ethylene, and carbon monoxide _ '
give to mine gas mixtures properties different "
from those of methane alone. Ethane, for in- ~ '
stance, has a lower explosive limit and ignition '
temperature than methane; hydrogen and ethy- ' "
lene also have lower ignition temperatures and
wider explosive ranges, and carbon monoxide is The calculations follow:
harmful in extremely small proportions.
Volume of sample taken 41.60
ACCUIIACY OF ANALYTICAL MET] s. Volume after absorption of CO, 38.70
In analytical yvork performed by the authors CO.. found 2.95
Iiarticnlar attention lias been paid to methods of Volume after absorption of O, 38.20
examination, and most samples have been exam- 0, found 50
ined in duplicate in order to make sure that Volume taken for combustion 38.20
•Technical Paper 39, 0. S. Bureau of Mines.
O added for combustion 68.55