HIGH FREQUENCY AND HIOII POTENTIAL CURRENTS. 351

connected to tlie opposite coatings of a battery of condensers,or generally in such way, that the high frequency or suddendischarges are made to traverse them. I connect first anordinary 50-volt incandescent lamp to the bars by means ofthe clamps c c. The discharges being passed through the lamp,the filament is rendered incandescent, though the currentthrough it is very small, and would not be nearly sufficient toproduce a visible effect under the conditions of ordinary use ofthe lamp. Instead of this I now attach to the bars anotherlamp exactly like the first, but with tlie seal broken off, the bulbbeing therefore filled with air at ordinary pressure. When thedischarges are directed through the filament, as before, it doesnot become incandescent. But the result might still be attri-buted to one of the many possible reactions. I therefore connectboth the lamps in multiple arc as illustrated in Fig. 186a. Passing

Fig. 186b.

Fig. 186c.

Fig. 186a.

the discharges through both the lamps, again the filament in theexhausted lamp l glows very brightly while that in the non-ex-hausted lamp l t remains dark, as previously. But it should notbe thought that the latter lamp is taking only a small fraction ofthe energy supplied to both the lamps; on the contrary, it mayconsume a considerable portion of the energy and it may becomeeven hotter than the one which burns brightly. In this experi-ment the potential difference at the terminals of the lamps variesin sign theoretically three to four million times a second. Theends of the filaments are correspondingly electrified, and the gasin the bulbs is violently agitated and a large portion of the sup-plied energy is thus converted into heat. In the non-exhaustedbulb, there being a few million times more gas molecules than inthe exhausted one, the bombardment, which is most violent atthe ends of the filament, in the neck of the bulb, consumes a