Minerals and metals for war purposes : hearings before the Committee on Mines and Mining United States Senate, Sixty-fifth Congress, second session, on the bill H.R. 11259 to provide further for the national security and defense by encouraging the production, conserving the supply, and controlling the distribution of those ores, metals, and minerals which have formerly been largely imported, or of which there is or may by an inadequate supply. May 2, 1918