Thermal variation of dielectric properties of two thermotropic liquid crystalline mixtures (code names: ZLI 1221 and ZLI 1291) containing identical moieties but possessing different mesogenic ranges have been investigated. Both mixtures contain the same constituents: phenyl cyclohexane, biphenyl cyclohexane, and cyclohexyl benzoate, but their distinct mesogenic ranges, due to different proportional constituents, make them interesting cases of study. In the present work, we have made a comparative study of the variation of dielectric permittivities (epsilon vertical bar and epsilon perpendicular to) as a function of temperature for both mixtures in an aligning magnetic field at different frequencies (1, 10, and 100kHz). From the present study and optical studies (performed earlier) [1], a comparison of the temperature variation of the angle of inclination of the molecular dipole moment with the director for both mixtures could be determined and compared. The variation of the dipole moment sol of the mixtures in solutions of varying concentrations (in %wt) at a particular temperature have been investigated and the molecular dipole moment iso of the isolated molecules have been determined. A method of estimating molecular weights using sol values (when the proportional composition is unknown) has also been developed.