The temperature‐dependent solubility of hexanitrostilbene (HNS) [CAS# 20062‐22‐0] was determined in ten solvents and solvent blends using the Tyndall effect. Thermodynamic modeling of the data yielded Flory interaction parameters, the molar enthalpy of mixing, the molar entropy of mixing, and the molar Gibbs energy of mixing. All solutions exhibited endothermic enthalpies and positive entropies of mixing. The presence of water in some of the solvent blends made dissolution increasingly endothermic and disfavored solubility. The solubilities of HNS at 25 °C were used to determine the three‐component Hansen solubility parameters (HSP) (δD=18.6, δP=13.5, δH=6.1 MPa1/2) and the radius of the solubility sphere (R0=5.8 MPa1/2). The HSP determined for HNS using group‐additivity (δD=21.0, δP=13.3, and δH=8.6 MPa1/2) also correctly predicted the optimum solvents for this explosive.

This article outlines the construction of a large-capacity, digital ring tensiometer, using common laboratory equipment, and reports the validation of this instrument against National Institutes of Science and Technology (NIST) data. A Carver press is used as a hydraulically controlled platform that raises and lowers the temperature-controlled jacketed flask that contains the test solutions. The upper platen of the press supports a four-decimal-place scale with a Pt−Ir ring hanging from the underscale hook. The scale measures the pull on the ring as the solution interface is lowered by the press. The force measurements are transferred to a personal computer (PC) via RS-232 communications. Temperature is controlled via a water-recirculation bath. The experimental surface tension measurements for toluene and water at 13 different temperatures were, on average, 2.7% larger than the NIST data. The 25 °C surface tension measurements for water, 2-butanone, ethyl ethanoate, and toluene were, on average, 1.1% larger than those calculated using the Hansen solubility parameters.