Transactions of the American Society of Civil Engineers, vol. LXX, Dec. 1910 | Page 6

Herbert M. Wilson

repeated five times under the same conditions before being established.
"NOTE.--At least 2 pounds of clay tamping will be used with
slow-burning explosives.
"Washington, D.C., January 9, 1909.
"In response to the above communication applications were received
from 12 manufacturers for the testing of 29 explosives. Of these
explosives, the 17 given in the following list have passed all the test
requirements set forth, and will be termed permissible explosives.
"Permissible explosives tested prior to May 15, 1909.
----------------------------+---------------------------------------- Brand. |
Manufacturer.
----------------------------+---------------------------------------- Ætna coal
powder A | Ætna Powder Co., Chicago, Ill. Ætna coal powder B | Do.
Carbonite No. 1 | E. I. Dupont de Nemours Powder Co., | Wilmington,
Del. Carbonite No. 2 | E. I. Du Pont de Nemours Powder Co., |
Wilmington, Del. Carbonite No. 3 | Do. Carbonite No. 1 L. F. | Do.
Carbonite No. 2 L. F. | Do. Coal special No. 1 | Keystone Powder Co.,

Emporium, Pa. Coal special No. 2 | Do. Coalite No. 1 | Potts Powder
Co., New York City. Coalite No. 2 D | Do. Collier dynamite No. 2 |
Sinnamahoning Powder Co., Emporium, Pa. Collier dynamite No. 4 |
Do. Collier dynamite No. 5 | Do. Masurite M. L. F. | Masurite
Explosive Co., Sharon, Pa. Meteor dynamite | E. I. Du Pont de
Nemours Powder Co., | Wilmington, Del. Monobel | Do.
----------------------------+----------------------------------------
"Subject to the conditions named below, a permissible explosive is
defined as an explosive which has passed gas and dust gallery tests Nos.
1, 2, and 3 as described above, and of which in test No. 4 1½ pounds
(680 grams) of the explosive has been fired into the mixture there
described without causing an ignition.
"Provided:
"1. That the explosive is in all respects similar to the sample submitted
by the manufacturer for test.
"2. That double-strength detonators are used of not less strength than 1
gram charge consisting by weight of 90 parts of mercury fulminate and
10 parts of potassium chlorate (or its equivalent), except for the
explosive 'Masurite M. L. F.' for which the detonator shall be of not
less strength than 1½ grams charge.
"3. That the explosive, if in a frozen condition, shall be thoroughly
thawed in a safe and suitable manner before use.
"4. That the amount used in practice does not exceed 1½ pounds (680
grams) properly tamped.
"The above partial list includes the permissible explosives that have
passed these tests prior to May 15, 1909. The announcement of the
passing of like tests by other explosives will be made public
immediately after the completion of the tests for such explosives.
"A description of the method followed in making these and the many
additional tests to which each explosive is subjected, together with the

full data obtained in each case, will be published by the Survey at an
early date.
"NOTES AND SUGGESTIONS.
"It may be wise to point out in this connection certain differences
between the permissible explosives as a class and the black powders
now so generally used in coal mining, as follows:
"(a) With equal quantities of each, the flame of the black powder is
more than three times as long and has a duration three thousand to
more than four thousand times that of one of the permissible explosives,
also the rate of explosion is slower.
"(b) The permissible explosives are one and one-fourth to one and
three-fourths times as strong and are said, if properly used, to do twice
the work of black powder in bringing down coal; hence only half the
quantity need be used.
"(c) With 1 pound of a permissible explosive or 2 pounds of black
powder, the quantity of noxious gases given off from a shot averages
approximately the same, the quantity from the black powder being less
than from some of the permissible explosives and slightly greater than
from others. The time elapsing after firing before the miner returns to
the working face or fires another shot should not be less for permissible
explosives than for black powder.
"The use of permissible explosives should be considered as
supplemental to and not as a substitute for other safety precautions in
mines where gas or inflammable coal dust is present under conditions
indicative of danger. As stated above, they should be used with strong
detonators; and the charge used in practice should not exceed 1½
pounds, and in many cases need not exceed 1 pound.
"Inasmuch as no explosive manufactured for use in mining is flameless,
and as no such explosive is entirely safe under all the variable mining
conditions, the use of the terms 'flameless' and 'safety' as applied to
explosives is likely to be misunderstood, may endanger human life, and

should be discouraged.
"JOSEPH A. HOLMES, "Expert in Charge Technologic Branch.
"Approved, May 18, 1909: "GEO.
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