Comment on: Rectilinear diameters and extended corresponding states theory

In a recent paper [R. R. Singh and K. S. Pitzer, J. Chem. Phys. 92, 3096 (1990)] it is shown that the slope of the coexistence curve diameter and the critical compressibility can be well described by linear functions of Pitzer’s acentric factor. Singh and Pitzer conclude that variations in these quantities are therefore due to changes in the two‐body intermolecular potential. We argue that they are primarily due to changes in the relative importance of three‐body interactions, as shown by Pestak et al. [Phys. Rev. B 36, 599 (1987)].