Although a fundamental physical parameter, surface tension is difficult to measure. Common tensiometry inaccuracy comes from failure to control air-liquid-solid contact conditions, or account for liquid meniscus geometry and buoyancy corrections. This paper describes an in situ tensiometry technique, based on withdrawal of a thin-walled tube from the liquid interface, that enforces a known air-liquid-solid contact condition. This technique can be pursued at any level of experimental hygiene. Experimental results for filtered tap water, an alcohol-water solution, and a surfactant-water solution show that results repeatable to three significant digits are obtained with modest effort for a variety of geometrical parameters.
Experiments in Fluids
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