What is the equation for Gladstone and Dale's Law?

Answer 1

It is the same thing as the Lorenz-Lorentz Law and relates the index and the density of gases and liquids. At lower frequencies it is called Clausius-Mossotti relation

Answer 2

The equation for Gladstone and Dale's Law is:

( \frac{n^2-1}{n^2+2} = \frac{V_m}{V} ),

where n is the refractive index of the medium, V_m is the molar volume of the substance, and V is the specific volume of the substance.