We have developed a flow diffusion nucleation chamber designed to quantitatively investigate the nucleation of vapors. The design and operational characteristics of the nucleation chamber are presented and discussed. Critical supersaturation data obtained with this nucleation chamber are compared to literature data obtained using a thermal diffusion cloud chamber. The flow nucleation chamber results accurately reproduce the diffusion cloud chamber data. Results of preliminary measurements of nucleation at ambient pressure in the presence of different background gases are presented. These data suggest that the nature of the background gas may influence nucleation at ambient pressure. These data, while still of a preliminary nature, are consistent with data already published obtained at elevated pressures using a specially designed high pressure cloud chamber also in our laboratory.