Shape factors for dry aerosol particles generated from 1% solutions by weight of sodium chloride, uranine, or combinations of these two compounds were measured. A factor was obtained for each aerosol, relating particle projected area diameter to aerodynamic diameter, mass, and resistance to viscous flow. The density of dry uranine aerosol particles was calculated to be 1.51 ± 0.12 gm/cm3, or essentially the same as the material's bulk density.