Dynamical properties of surface tension of some liquids are studied experimentally. After a liquid is sucked up into a long glass capillary, the lower end which is kept just to touch the liquid surface, the liquid column is let free to fall. As the process may be treated as quasi-stationary, the term of inertia in the equation of motion of liquid column can be neglected and we get the :following relation between the falling velocity (
v) and the length (
l) of the liquid column,
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where, γ is the radius of capillary, θ the inclination of capillary to a vertical line,
g the acceleration of gravity, ρ the density of liquid, η the coefficient of viscosity, σ the surface tension, and α the contact angle. From the linear relation between
v and 1/
l, η and σ cos α are determined. With the decreaseof flow velocity, the value of σ cos α decreases and the value of η tends to increase.
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