Abstract: A particle counter for determining the size and count of particulate substances suspended in an electrolytic solution includes a tube having an inlet hole for the passage of the solution therethrough, a pump connected to the tube for drawing the solution into the tube through the inlet hole, a pair of electrodes arranged on either side of the inlet hole in the flow path of the solution, and voltage monitoring apparatus for sensing fluctuations of voltage across the electrodes as particles pass through the inlet. A screen having precision size openings is disposed about the tube in the flow path of the solution prior to passage through the inlet hole for screening particles above a pre-determined size prior to reaching the inlet hole.