(356a) Near-Critical Solutions and Supercritical Solubility - a Century of Experiments

The history is sketched of the discovery of the thermodynamic behavior of near-critical solutions, one of the foci of John O'Connell's work. The Leiden student Kuenen performed the first reliable measurements of fluid mixture behavior near critical points in the early 1890s. Initiated into Gibbs's phase theory by Van der Waals, the Amsterdam chemistry professor Bakhuis Roozeboom and his school systematically measured solubility of liquids and solids – Smits and Wuite, for instance, studied the solubility of sodium sulfate up to the water critical point in 1909. The work of the Dutch School was studied by the Moscow physical chemistry professor Krichevskii (1901-1993), whose large group of experimental collaborators, mostly women PhDs, landed several “firsts” through the 20th century, such as gas-gas equilibrium, and the asymmetric tricritical point. In the 1960s, to Krichevskii's initial disbelief, he and his collaborators found evidence of the path-dependence of the partial molar volume of the solvent, and the divergence of that of the solute, near the solvent critical point; one of them, Rozen, was able to explain this correctly in 1976. Many of the historic results were rediscovered when supercritical fluids became a global topic of interest in the 1980s.