The surface tensions against air of acetone-water solutions have been measured over the entire composition range from 20ยฐC. to generally within 1' to 10ยฐC. of the normal boiling points. The capillary-height method was employed and the results are thought to be accurate to better than =!=O.S%. Physical-property data for binary liquid systems up t o the boiling points of the solutions are scarce, and the present status of the kinetic theory of liquids is not sufficiently developed t o enable accurate predictions t o be made over the entire composition and temperature range. One of the aims of Research Project 1, Tray Efficiencies in Distillation Columns, sponsored by the American Institute of Chemical Engineers, has been t o determine the effect of the physical properties of the system on the distillation efficiency. The role of the boiling-point surface tension in relation t o distillation efficiency, for example, is not well defined. As this lack of understanding can be attributed in part to the scarcity of surface-tension data at the boiling temperatures, one of the purposes of this investigation was t o provide accurate surface-tension data up t o the boiling point for use in distillationefficiency correlations.
Morgan and Scarlett (8) have measured the surface tension of acetone-water solutions at 0", 25", and 45ยฐC. using the drop-weight method. Traube (15) reported surface-tension measurements for acetone-water solutions (up t o 2.0 mole %) at 15ยฐC. as measured by the capillaryheight method. All these data have been tabulated" and will be compared with