Show LIQUID OXYGEN explosives the bureau of 0 mines department of 0 the interior has recently issued technical paper no development of liquid oxygen explosives during the war by geo S rice chief mining engineer the paper describes the results of experiments conducted by the bureau at its explosives testing station near pittsburgh pennsylvania and gives an account of 0 the methods of use as developed in germany observe tion on its use by the germans for destroying french iron and steel plants and an abstract of a german military paper on instructions for using liquid air explosive during the war the growing scarcity of glycerin and ammonia greatly increased the cost of dynamite this caused the bureau of mines to investigate the possibilities of liquid oxygen explosives which do not require nitrates results of the preliminary testing begun in april 1917 were decidedly favorable mr rice while in europe in 1919 as a member of a committee to observe progress in postwar post war industries paid special attention to liquid oxygen explosive the germans were found to have used the explosive known as extensively in nongaseous non gaseous coal mines in excavating subways and tunnels in quarrying and in iron mines as well as for destroying french steel plants results of tests since 1897 the explosive was first tested at a coal mine in germany in 1897 following lindes invention of his liquefying apparatus in 1895 trials made in driving the simplon tunnel are said to have been favorable in 1900 claude of france patented the re principle linde in 1902 designed his rectification apparatus both types of apparatus are extensively employed in liquefying gases in 1904 dewar of great britain invented the dewar flash a container for liquefied gases further development of liquid oxygen for blasting purposes was small until the war began As already stated its use was widely extended in germany during the war the allied countries being able to import nitrates from chile did not take up its use but it the war had continued the united states would probably have been compelled to do so the method will now have to depend on its merits and on commercial conditions blasting strength greater than dynamite the experiments of the bureau of mines have shown that a liquid oxygen explosive can be prepared which has a blasting strength greater than 40 per cent straight nitroglycerin dynamite this was shown by tests in the standard testing apparatus of the burdua as well as in blasting the procedure adopted was to place a no 6 detonator in the inner cartridge a cheese cloth sack containing carbonaceous material the cartridge is soaked in liquid oxygen ten to afif fifteen teen minutes in an improved container devised by the bureau the cartridge frozen stiff is slipped into a pasteboard container placed in the hole a wad of cotton placed on it a brass tube inserted and clay tamped camped around the tube the hole left by the tube provides an outlet for evaporating oxygen until the shot is fired advantages and disadvantages the advantages as compared with dynamite and black blasting powder are lower cost per ton of material blasted elimination of dangers in transportation from premature ignition misfires or anex plodded sticks in ore or coal in handling and thawing or in storage magazines the disadvantages are the liquid oxygen because of its rapid evaporation must be used quickly after charging thus limiting the number of shots A liquefying plant must be maintained near the mine the explosive can not be used in gaseous coal mines its introduction into mines is difficult because miners are not accustomed to it the method offers great possibilities tor for lessening blasting costs in nongaseous non gaseous coal mines and in metal and mineral mines using a chamber method where only a few shots are fired at one time the chief cost is that of the oxygen but there is hope of a decided reduction in cost through promised improvement in the liquefying machines |