An improved maximum-bubble-pressure system using the sugden twin- capillary method for measuring the surface tension and density of molten metals is described. Improvements include (1) internally ground capillary tips, (2) electronic pressure transducers, (3) micrometer adjustment of immersion depth for density measurements, (3) micrometer adjustment of immersion depth for density measurements, (4) valving arrangements to allow operation at other than atmospheric pressure, (5) temperature range to 1,100 deg. C, and (6) recorder readout of pressures. Data for surface tension of mercury from 20 deg. to 300 deg. C are given.