We also included a set of 191 molecules with more than nine heavy atoms to provide further evaluation of the models. These molecules were selected in a previous study, where we identified molecules with between 10 and 14 heavy atoms from the Pedley Compilation 28 that have accurate measurements of formation enthalpy. These molecules capture molecular motifs that are impossible to form with fewer than 10 heavy atoms, such as polycyclic aromatic compounds. We denote these molecules our "Pedley test set." They were not selected randomly but drawn from a set of molecules for which solvation energies have been measured experimentally (unlike the QM9 training set, which were generated procedurally) and, further, were chosen to exhibit qualities desirable for validation (e.g., possessing molecular motifs not included in the QM9-Solvation dataset).