Abstract: An apparatus for measuring the electrical charge condition of non-conductive particles in a liquid medium comprising a flow path having sensory means for developing a signal proportional to a desired ion activity and a reciprocating piston carrying a grounded electrode. The reciprocating piston induces liquid to flow past the sensory means and the electrode on the piston screens external galvanic interferences and lower electrode impedance. The electrical signals are monitored by an electronic component.

Abstract: The addition of a grounded electrode in a special location with respect to the location of the two sensing electrodes of an existing piston-inverted cylinder apparatus used in the measurement of the electric charge condition of non-conductive particles suspended in a mildly conductive electrolyte such as tap water converts the known apparatus into one whose accuracy, reliability and useful life are greatly increased. The grounded electrode is located nearer the open end of the cylinder than are the two sensing electrodes, and the grounded electrode should have a surface area which is several times that of the two sensing electrodes. All three electrodes must be made of the same metal.

Abstract: A method and portable apparatus for measuring particulate concentration in the atmosphere utilizing uniform laser pulses to traverse the atmosphere to be measured and a photo-electronic receiver which discriminates against stray light and detects the attenuation of the laser pulses. This attenuation is caused by particulates in the atmosphere which tend to scatter or absorb light. By using monochromatic laser pulses having wavelengths lying in transparent atmospheric windows, error is not introduced by the attenuation of the beam due to gases occurring naturally in the atmosphere including water vapor. Thus concentration of particulates such as smoke, fog, smog, dust and the like are measurable.