Lighting-up Tubes with One Wire only (Marquis of Salisbury’s Observations).
One wire only connected with an electrode.
The vacuum-tubes employed were examined in the usual way, but one wire only was connected with an electrode. The other wire was attached to the end of a glass rod, and circuit was from time to time completed while the tube was before the spectroscope.
The large coil was used. In all cases, with the one wire, the glow was very faint as compared with that of the closed circuit.
Ether vapour.
(1) Ether Vapour.—With both wires, in company with the usual bright bands of the carbon spectrum, shading-off towards the violet, the H lines were very sharp and brilliant. With the one wire only, the carbon bands were left faintly shining, with both sides nebulous alike, and with no shading-off towards the violet. (We were not quite sure whether this was not the effect of the reduction of the light.) The H lines, though originally stronger than the carbon bands, quite disappeared from the spectrum.
Coal-gas.
(2) Coal-gas.—The same effects were produced; but we thought we could detect very faint traces of the H lines.
Nitrogen.
(3) Nitrogen.—The N lines, as well as those of H (also seen in the tube), were much fainter with one wire, but the H lines more so in proportion.