On the Interpretation of Near-Critical Gas–Liquid Heat Capacities

This comment is in response to a comment by Sengers and Anisimov on the article “Gibbs density surface of fluid argon” that contradicts prevailing theory. It has not “been established experimentally that the thermodynamic properties of fluids satisfy scaling laws with universal critical exponents asymptotically close to a single critical point of the vapor–liquid phase transition.” Here we explain why an apparent divergence of Cv\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {C}_{\mathrm{v}}$$\end{document}, in historical experimental “evidence,” is based upon a misinterpretation of near-critical gas–liquid heat capacity measurements in the two-phase coexistence region. The conclusion that there is no “singular critical point” on Gibbs density surface still stands.