Relative permittivity measurements are performed as a function of temperature and pressure using a direct capacitance method. An impedance gain-phase analyzer is used with a four arrangement configuration for absolute measurements of capacitance. The resolution of the instrument is 10^-4  pF. 

The cell used is a concentric cylinder with a capacitance under vacuum of approximately 5.3 pF. Relative permittivity is measured from the ratio between the capacitance of the cell with the sample and the same one under vacuum. Analysis of the data is performed using theories such as Kirkwood and Vedam. Correlations as a function of pressure and density are developed for industrial purpose.

The determination of molecular dipole moment provides valuable information about the structure of molecules and has been used to determine rigid structures and to study problems such as rotational isomerism and conformational equilibria.