Determination of the dynamic surface tension of liquids from the instability of excited capillary jets and from the oscillation frequency of drops issued from such jets

Three methods were found to measure the dynamic surface tension of liquids. The first uses the growth rates of axisymmetric disturbances on excited capillary jets, the second the oscillation frequency of drops issued from such jets. When the dimensionless wavelength S of jet excitation was in the range 1 < S < S$^{\ast}$, where S$^{\ast}$ corresponds to the wavelength of maximum jet instability, the oscillation frequency of drops could be inferred from the symmetry of the stream of stroboscopically illuminated drops. In the course of these investigations a new phenomenon was found, namely that in the range S $\geq $ S$^{\ast}$ the drops do not oscillate freely but resonate the with jet excitation frequency. This explains the failure of previous investigators to determine the oscillation frequency of drops in this range. In this range of S, however, the oscillation frequency of drops equals the resonance band width, which gives the third method for the determination of dynamic surface tension. With the first two methods, the dynamic surface tension of water was determined with better than 1% accuracy in surfaces of less than 1 ms age.