The Birmingham age-herald., 1923-08-12
EXPERTSCOMMEND
 LIQUID GAS FOR CHEAPER BLASTING
Oxygen Said To Be Cheaper { For Certain Class Of
 Explosives

WASHINGTON, August 11.-(By Associated Press.)-The use of liquid oxygen as an excellent and cheap ex- plosive in salt, metal and other non- gaseous mines and in quarry and other outside blasting, Is recom- mended by the United States bureau of mines after a series of tests. Pre- Hminary experiments in this novel explosive, conducted at the bureaus experimental station at Pittsburg, indicate that 1t may be used to ad- vantage where dusts and gases are not present. but is especially useful elsewhere in lessening the cost of blasting.
 While liquid oxygen has not been used in this country so far for this purpose, 1t is already widely used in Mexican mines; has been employed in large quantities in the Upper Silesian mines of Germany since the war, and has been adapted to tunnel work, iron mining, subway and excavation work in cities in that country. It was used not only in Germany but an the French iron mines of Lorraine after the German seizure, and applied by them also to the destruction of of the Briey iron district believe the explosive has come to stay, and the bureau Is conducting negotiations with Alaskan companies for its adop- ton there.
 Prepared mt Low Cost.
 An advantage is that it can be pre- pared on the job at low cost after the erection of compressing plants, which will make 1t of especial value an Alaska. As liquid oxygen can be made at the place of consumption, @ ton of other explosives can be done away with. Low production cost, lessening the cost per unit of mate rial blasted, is another advantage.
 Ill the use of liquid oxygen explo- sives there Is practically no danger of premature ignition, it was found. The danger of misfires, too, is elimi- mated by wait of 80 or 40 minutes after the fuse Is lighted, when prac- tically all of the oxygen will have evaporated. Another advantage is the elimination of the danger of un- exploded sticks in shoveling and sub sequent handling of coal or ore going out of the mine. Other sources of danger avoided are the handling and thawing processes such as are neces sary with frozen dynamite, and the hazard from lightning or fire when stored.
 Certain Disadvantages.
 But there are certain disadvan- tages in the use of this explosive, the bureau says. Because of its rapid evaporation. liquid oxygen must be used quickly and within a definite time after the hole is charged, thus limiting the number of holes that can be fired simultaneously. although in Germany as many as 2S have been fired at once. Its use virtually re- quires the installation of liquidat- ing plant at considerable first cost, and this plant must be kept running regularly to obtain low cost explo- sive, as the main cost Is in the power used.
 That the power of liquid oxygen as an explosive Is favorably compar- able with other explosives is shown In the fact that 5,300,0 pounds of liquid oxygen are equal to S.000,000 pounds of dynamite.
 One of the interesting features of the high Edevelopmen mt of this ex- plosive in Germany has been the de- signing of small portable liquid oxy- gen-making plants to produce three liters an hour. Such plants have been constructed to move about on trucks, making the material much more available for small operators.