The paper gives results of measurements of metal partitioning between the fine condensation aerosol and the larger particles produced during rapid heating of polydisperse droplet streams of aqueous solutions containing nitrates of Cd, Pb, and Ni in a laboratory-scale furnace. Trimodal particle size distributions were observed. Partitioning of the larger particles between residual and intermediate modes is consistent with the dependence of particle porosity on condensed phase transformations during nitrate decomposition. In addition, ultrafine particles were produced. In the Ni tests, where vaporization is not a reasonable mechanism for inorganic aerosol formation over the range of temperatures studied (900-1500 K), 30-35% of the particles had aerodynamic diameters of<1 micrometer. Furthermore, a preponderance of cenospheres was observed in the large particle size fractions. It is conjectured that the NiO cenospheres form and burst to produce the submicron particles. In the Ca and Pb experiments, the amount of submicron particles produced was in qualitative agreement with the amount calculated for the time-dependent vaporization of the thermodynamically dominant monoxide species. However, two findings suggest that fragmentation contributed to submicron particle formation in these tests as well.