When a mixture of metallic aluminium powder and ferric oxide is subjected to ignition by a fuse or otherwise, the whole mass becomes incandescent, the aluminium combining with the oxygen of the iron oxide, and setting free the molten iron, which forms a layer below. The temperature realized in this process is estimated at about 3,500 degrees C., and being high enough to melt all known metals, the process is utilized, among other applications, for the repair of broken castings and joining up the ends of tramway rails without removal. For this latter purpose, a mould is placed round the rail ends in such wise as to receive a charge of the molten iron, the excess metal being afterwards cut away or otherwise removed as required.
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