Abstract
It is shown that the formula for the drift velocity of electrons in gases presented by Braglia and Dallacasa, and also other more general formulas, can be derived from the Kubo-Greenwood relation without using Braglia and Dallacasa's assumptions about the angular distribution in the scattering and the form of the optical theorem. Several approximate drift-velocity formulas are tested numerically and compared with experimental data for the case of electrons in argon.