Liquid metals. Part XII. The surface tension of liquid bismuth in pure and impure hydrogen, in other gases, and in vacuo

The Paper describes a modification of the drop-weight technique by means of which the surface tension at fresh surfaces is liquid metals and alloys of high density can be determined against various gases or vacuum. Values for the surface tension of pure liquid bismuth in hydrogen, nitrogen, argon, and carbon dioxide are in close agreement with values obtained in a vacuum, and show a constant temperature coefficient of –0·069 dyne/cm./degree over the range 300–500°; the tension is 378 dynes/cm. at the melting point (271°). Traces of oxygen and water vapour in a hydrogen atmosphere do not effect the surface tension above 400°. At lower temperatures the film produced is not reduced sufficiently rapidly by hydrogen, and values of surface tension up to 480 dynes/cm. have been observed at surfaces which show no visual evidence of contamination.