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4. Vincentini’s Experiment. Condition of a Gas Around a Live Wire. Nuovo Cimento, Vol. XXXVI., No. 3. Nature, Lon., March 28, ’95, p. 514. The Elect., Lon., Feb. 8, ’95, p. 433. G. Vincentini and M. Cinelli found that the molecules of a gas at and near the surface of a platinum wire, rendered incandescent by a current, are electrified, and that with hydrogen their potential is about .025 volt above the mean potential of the wire. With air and carbonic acid gas the increment is about 1 volt. The apparatus, Fig. II., consists essentially of means for passing a current along a platinum wire, a bulb for preventing draughts, and an electrometer having a platinum disc electrode that could be adjusted to different positions. It was noticeable that the electrification did not reach a maximum instantaneously upon closing the current through the wire, but the time was less at points below the wire than above.

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5. Henry’s Experiment. Magnetizing Radiations from an Electric Spark. Proc. Inter. Elect. Cong., 1893, p. 119. Preece alluded to Prof. Henry’s original experiment illustrating the action of an electric discharge ssss1 at a distance. He placed a needle in the cellar. Disruptive discharges of a Leyden jar at 30 ft. distant, in an upper room, produced a magnetic effect upon the needle.