On the rate at which particles take up random velocities from encounters according to the inverse square law

Abstract
This paper deals theoretically with the changes in the velocities of particles which move through a cloud of particles interacting according to the inverse square law. The formulæ obtained—for low densities—lead to “effective mean free paths” shorter than might have been expected. It seems not impossible that the rapid rate at which beams of electrons moving through highly ionised gases have been observed by Langmuir to take up Maxwellian velocity distributions may be explained in this way.