Joseph John Thomson

“ The experiments which I will now describe, which I made in 1906, show that the discrepancies between the theory and the experiments are due to the pressure of the gas In the discharge tube in Wien's experiments having been so high that the particles forming the positive rays collided with the molecules of the gas whilst they were passing through the electric and magnetic fields. The effect of these collisions is to ionize the gas so the gas through which the positive rays have to pass is full of charged particles, some charged with positive others with negative electricity. ”

“ It is remarkable that the slope of these bands, and therefore, by page 12, the velocity of the particles, varies little if at all with the potential difference between the anode and cathode of the discharge tube. This potential difference may be increased three or four times without producing any appreciable effect upon the slope of the bands of phosphorescence. When air is in the tube, the appearances of the bands is much the same as when the tube contains hydrogen, though the phosphorescence is not so bright. ”