Abstract: J.Kloubek used the empirical equation 1/(δ_H2O-δ_t)=b/(At^1/2)+1/A to correlate his experimental data in a 1/(σ_H2O-σ_t)vs(1/t^1/2). It is possible to determine the static surface (interfacial) tension for solution, but the results were approximately in agreement with the literature.The article gives the theoretical derivation of the empirical equation and discusses the cause of deviation. A further investigation leads to use a extrapolating, the static surface tension is better than empirical equation.

Key words: Dynamic interfacial tension, Dynamic surface tension, Equilibrium interfacial tension, Equilibrium surface tension