Transactions of the American Society of Civil Engineers, vol. LXX, Dec. 1910 | Page 7

permissible explosives was issued, as follows:
"EXPLOSIVES CIRCULAR NO. 2. "DEPARTMENT OF THE INTERIOR. "United States Geological Survey. "October 1, 1909.
"LIST OF PERMISSIBLE EXPLOSIVES. "Tested prior to October 1, 1909.
"The following list of permissible explosives tested by the United States Geological Survey at Pittsburg, Pa., is hereby published for the benefit of operators, mine owners, mine inspectors, miners, and others interested.
"The conditions and test requirements described in Explosives Circular No. 1, issued under date of May 15, 1909, have been followed in all subsequent tests.
"Subject to the provisions named below, a permissible explosive is defined as an explosive which is in such condition that the chemical and physical tests do not show any unfavorable results; which has passed gas and dust gallery tests Nos. 1 and 3, as described in circular No. 1; and of which, in test No. 4, 1? pounds (680 grams) has been fired into the mixture there described without causing ignition.
"Permissible explosives tested prior to October 1, 1909.
"[Those reported in Explosives Circular No. 1 are marked *.]
------------------------------+------------------------------------- Brand. | Manufacturer. ------------------------------+------------------------------------- *?tna coal powder A | ?tna Powder Co., Chicago, Ill. ?tna coal powder AA | Do. *?tna coal powder B | Do. ?tna coal powder C | Do. Bituminite No. 1 | Jefferson Powder Co., Birmingham, | Ala. Black Diamond No. 3 | Illinois Powder Manufacturing Co., | St. Louis, Mo. Black Diamond No. 4 | Do. *Carbonite No. 1 | E. I. Du Pont de Nemours Powder Co., | Wilmington, Del. *Carbonite No. 2 | Do. *Carbonite No. 3 | Do. *Carbonite No. 1-L. F. | Do. *Carbonite No. 2-L. F. | Do. *Coalite No. 1 | Potts Powder Co., New York City. *Coalite No. 2-D. | Do. *Coal special No. 1 | Keystone Powder Co., Emporium, Pa. *Coal special No. 2 | Do. *Collier dynamite No. 2. | Sinnamahoning Powder Manufacturing | Co., Emporium, Pa. *Collier dynamite No. 4. | Do. *Collier dynamite No. 5. | Do. Giant A low-flame dynamite. | Giant Powder Co. (Con.), Giant, Cal. Giant B low-flame dynamite. | Do. Giant C low-flame dynamite. | Do. *Masurite M. L. F. | Masurite Explosives Co., Sharon, Pa. *Meteor dynamite. | E. I. Du Pont de Nemours Powder Co., | Wilmington, Del. Mine-ite A. | Burton Powder Co., Pittsburg, Pa. Mine-ite B. | Do. *Monobel. | E. I. Du Pont de Nemours Powder Co., | Wilmington, Del. Tunnelite No. 5. | G. R. McAbee Powder and Oil Co., | Pittsburg, Pa. Tunnelite No. 6. | Do. Tunnelite No. 7. | Do. Tunnelite No. 8. | Do. ------------------------------+-------------------------------------
"Provided:
"1. That the explosive is in all respects similar to sample submitted by the manufacturer for test.
"2. That No. 6 detonators, preferably No. 6 electric detonators (double strength), 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 1? grams charge.
"3. That the explosive, if frozen, shall be thoroughly thawed in a safe and suitable manner before use.
"4. That the amount used in practice does not exceed 1? pounds (680 grams), properly tamped.
"The above partial list includes all the permissible explosives that have passed these tests prior to October 1, 1909. The announcement of the passing of like tests by other explosives will be made public immediately after the completion of the tests.
"With a view to the wise use of these explosives it may be well in this connection to point out again 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; the rate of explosion also 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