PROFILE OF THE PLATEAU BORDER IN A VERTICAL FREE LIQUID-FILM

Profiles of the Plateau border at a vertical film in a 0.02 M cetyltrimethylammonium bromide solution are measured by optical interference, in the part of the border near the film, at two heights above the bulk liquid surface. The Laplace pressure in the border, calculated from these profiles, appears to be lower than the hydrostatic equilibrium pressure at a height close to the bulk liquid meniscus (6.2 mm); at a greater altitude (11.3 mm) the pressures are equal. An upward flow in the border close to the film is observed, while a downward flow takes place in the periphery of the border. Both effects can be explained by Marangoni flows. © 1990.