Neutral Doublets at Atmospheric Pressure

Abstract

IN his papers on magneto-kathode rays, Prof. Righi assumes the presence of neutral doublets, formed of a positive and negative ion in more or less stable combination. Sir J. J. Thomson has independently put these in evidence very clearly in his experiments on positive rays. Working independently, we have made some observations which point to the existence of such doublets at atmospheric pressure. Ionised gas is drawn through two insulated metal tubes; along the axis of each a thick insulated wire electrode is fixed. These wires can be connected in turn to a Dolezalek electrometer, and the current between tube and electrode measured. The ionised gas is produced by splashing mercury, or by heating lime or aluminium phosphate on a strip of platinum foil. With a certain blast, in one case, the current reached its saturation value on the first electrode with a voltage of 320, being then 130 in arbitrary units. Raising the voltage to 656 did not increase this by one division; the extreme readings at the intermediate voltages were 128 and 130, so that the observations were quite regular. Nevertheless, with 656 volts on the first electrode a current can be detected at the second, this in some cases amounting to as much as 10 per cent. of the original.