An instrument is described that counts automatically according to size aerosol particles of certain specific chemical compositions. The technique employed depends on converting to current pulses the ions produced from airborne particles passing through the combustion zone of a flame. Because the amplitude of the current pulse resulting from an ionized particle passing through a flame is dependent on both the mass and the ionization potential of the particle, the FIPAPA can aid in submicron aerosol particle identification when used in combination with instruments employing other sensing zone types. By use of electronic pulse‐height circuits, these current pulses are subsequently counted in six ranges of magnitude. The minimum size particle detectable was found to be 0.15 &mgr; diam for KOH and 0.25 &mgr; diam for NaCl.