Some remarks on "Is there a fundamental difference between a liquid and a gas?"

The van der Waals equation is used to study the properties of a liquid-gas system in the region just above the critical point. The $P\text{−}T$ curve of maximum isothermal compressibility, which persists to 1.068 times the critical temperature, is found to be a natural extension of the liquid-vapor equilibrium curve. Since the van der Waals equation is analytic, the present results do not support the view, recently advanced by Douglass, that there might be a fundamental difference between a liquid and a gas.