  Yet another breeding ground for atomism came in the wake of the electromagnetic theory of light (1865) and the experimental production of electromagnetic radiation by an electric oscillator (1888). Helmholtz (1881) observed that optical dispersion could be readily explained if it were assumed that the transmission of light through a medium involved the oscillation of particles that were both massive and charged. The adsorption and emission of spectra characteristic of atoms also suggested that they were due to the oscillations of charged particles on the atomic or sub-atomic scale. These assumptions in conjunction with the kinetic theory of gases led to an explanation of the width of spectral lines as a Doppler shift due to the velocity of radiating molecule, making possible estimates of the velocities of molecules that were in agreement with those deduced from the diffusion rate of gases.