The Surface Tension of Deuterium Oxide and of its Mixtures with Water

The surface tension, σ, of 97.8 percent deuterium oxide and of five more dilute mixtures with water has been compared with ordinary water by a modification of the capillary rise method. The results show that the relative surface tension is slightly less than that of pure water and is a linear function of the specific gravity. The data may be represented by the equation σ = 1 — 0.00501Δs, where Δs is the increase in specific gravity over ordinary water. By a slight extrapolation the surface tension of pure deuterium oxide at 25°C is estimated to be 0.999,46 of the surface tension of ordinary water at the same temperature.