The abundance of k B T ln γ ∞ values around zero (Figure ) is noteworthy and is potentially an artifact of the type of data which is available in ThermoML. Recall that a value of 0 here corresponds to an activity coefficient of 1 (see Section 1). Specifically, a large portion of the available data is for transfer of solute molecules to solvents of similar polarity -for example, transfer of a polar solute to a polar solvent, or (more commonly) transfer of a nonpolar solute to a nonpolar solvent. If the dataset contained more cases of transfer of a nonpolar solute to a polar solvent, or a polar solute to a nonpolar solvent, we would expect to see more values substantially different from 0. Thus, we believe that the IDAC data should be expanded to include more activity coefficients for compounds of very different polarity than the solvent, to capture more features of transfers between nonpolar (or weakly polar) environments to very polar environments.