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Liquid Wires and their Surface Films
Phys. Rev. 30, 697 – Published 1 November, 1927
DOI: https://doi.org/10.1103/PhysRev.30.697
Abstract
Function of oxide films in supporting molten wires of Pb, Sn, Zn and Bi.—A wire of low melting point metal may be made to glow when freely suspended and heated in air or oxygen. This has been shown to be due to the formation of an oxide film of sufficient tensile strength to permit the molten metal to be sustained even though its melting point is much lower than the glowing temperature. It has been shown that the assumption of Damianos, that the oxide film serves only as a network in preventing a surface change of the liquid and that the tensile strength of the molten metal holds it together is not tenable.
Ability of sulphide, bromide and chloride films to support molten wires.—Wires with clean surfaces when heated in nitrogen break at the melting point of the metal. Experiments with sulphide, bromide, and chloride films reveal three facts, (1) if there is not a firm coat at the melting point of the metal the wire breaks at that temperature, (2) if the melting point of the coat is between the melting point of the metal and the glowing temperature, then the wire breaks at the melting point of the coat, (3) if the melting point of the film is above the glowing point, the wire can be made to glow when freely suspended.
Temperature coefficients of resistance.—The suspension of molten metals by their oxide films affords a unique method of measuring the temperature coefficients of resistance of low melting point metals through the solid and liquid states.
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