This work reports on the relationships that exist between the amplitudes of liquid-vapor average densities of several fluids and their molecular polarizabilities. The slope of the coexistence-curve diameter has been determined from an equation of state based on the crossover model. We found that the slope for each fluid near the critical point is directly correlated with its molecular polarizability. This correlation is the consequence of the three-body Axilrod-Teller interaction.
