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Show SELECTING EXPLOSIVES. "As a result," says a Los . Angeles dispatch, "of Us Investigation into the causes ot mine disnsters with the hope of reducing tho number of fatalities fa-talities In the coal mines of the United States, the geologica.1 survey has just bMied a list of permissible explosives for the use of miners' and operators. Twelve manufacturers of explosives sent 29 different explosives to the station sta-tion to be tested. Six manufacturers were successful and six explosives rassed the requirements. The tests arc under tho general direction of Dr. Joseph A. Holmes, expert In charge of the technologic branch of tho geo-logical geo-logical survey. The explosives were given four tests under different conditions con-ditions under the large steel gallery. According fo Dr. Holmes, 'this gallery is 100 feet long and six feet in diameter diam-eter and Is filled with fire,danip air and coal dust or coal dust and air, of vvarlous mixtures, and the explosive is ' discharged into each mixture 10 times. If it fails to ignite the firedamp or coal dust in any instance, it Is considered con-sidered satisfactory and is termed a permissible explosive.' " |