The presence of a dispersion of the dielectric constant of pure organic solvents in ultra-low frequency band has been already examined for several organic solvents such as benzene and dioxane. Recently, we have introduced theoretically a dispersion formula of organic solvent mixture and discussed experimentally on its adaptability to very low frequency band. In these investigations, we have noticed a phenomenon that the observed dielectric constant varies with changing applied voltage. This phenomenon can not be observed in ordinal band of high frequency but observed only in very low frequency band below 1 Hz.
In the present paper, the author has examined experimentally in detailes for the above mentioned dispersion in ultra-low frequency band on the stand-point of voltage dependence. The results obtained in these experiments showed that the observed dispersion clearly related to the applied voltage, and the exterpolation of the curve, dispersion v. s. applied voltage, to zero voltage showed a constant value for the material examined.