No abstract

relative to the vapor pressures of the two compounds can adequately explain the various changes in nucleation rate, particle size, and composition which were measured. Therefore, it is proposed that the nucleation model presented describes the behavior of the reaction and that any further investigation of the reaction should include attention to both the effects of water vapor and the apparent parallel nucleation processes. SummaryThe results of this study show that the aerosol forming reaction between ammonia and sulfur dioxide is significant at reactant concentrations as low as 1000 ppm, and probably much lower, even when only a trace of water vapor is present. The aerosol sizes and production rates determined during this study indicate that the concentrations used greatly exceeded those required to initiate nucleation. Taking into account the catalytic effects of water vapor and the favorable influence of decreasing temperature on the nucleation process reported by other workers, it would appear that this reaction should not