Determination of Particle Mass and Charge by One Electron Differentials
S. Arnold
J. Aerosol Science 10, 49-53(1979)

An instrument is described which is capable of measuring mass in picograms of a suspended particle to better than 0.5% and the exact number of electronic charges on the particles. The mass and charge are arrived by automatically rebalancing a particle on a Millikan chamber after the particle absorbs or emits a single electron.