Abstract: A condensation nucleus counter has a humidifier zone, through which the sle air is guided, and an approximately perpendicularly arranged condensation zone, as well as an optical detection system with a light source and detector. The humidifying zone has a duct made of a permeable material and a hollow space surrounding this duct, the hollow space being used for receiving the process fluid. The condensation zone has a duct which, in turn, has a hollow space used for receiving the coolant. The condensation zone is connected with the humidifying zone by a connection piece.

Abstract: An apparatus for analyzing the size distribution and quantity of small particles in an aerosol comprises at least one smooth filter bearing a reflecting coating and means for measuring the change in reflectance due to the deposition of intercepted particles. At least one additional filter contains linear pores extending substantially normal to the filter surface and has a negligible transmission outside the pores. Also realized are means for measuring the change in transmission due to the retention of particles in and around the pores.