Coomber's relationship

Coomber's Relationship can be used to describe how the internal pressure and dielectric constant of a non-polar liquid are related.

As $$p_i=\left(\frac{\partial E}{\partial V}\right)_T\,$$, which defines the internal pressure of a liquid, it can be found that:

$$p_i=n\cdot{I}\cdot{b(T)}\frac{N^2\alpha^2}{V^{n+1}}\,$$

Where $$N\,$$ is equal to the number of molecules

$$I\,$$ is the ionization potential of the liquid

$$b(T)\,$$ is a temperature dependent relation based on numerical constants of the pair summation from inter-particle geometry

$$\alpha\,$$ is the polarizability

$$V\,$$ is the volume of the liquid

where for most non-polar liquids $$n=1\,$$