99_O_. WORTHINGTON’S EXPERIMENT. DISCHARGE OF ELECTRIFICATION BY FLAMES. _Brit. Asso. Rep._, ’90, p. 225.
99_P_. FLEMING’S EXPERIMENT. DISCHARGE BETWEEN ELECTRODES AT DIFFERENT TEMPERATURES IN AIR AND IN HIGH VACUA. § 99_M_, near end. _Proc. Ro. So._, LXVII., p. 118.
99_Q_. BRANLY’S EXPERIMENT. HALLWACH AND STOLSTOW’S EXPERIMENT. LOSS OF ELECTRIC CHARGE. _Lum. Elect._, LXI., pp. 143 to 144, ’91.—Branly obtained quantitative results. Hallwach found with the use of the arc light, a very small loss of positive electricity at high potentials; Stolstow, no such loss at potentials under 200 volts. Branly, with a 50 element battery and an arc light as the source of illumination, caused a discharge and thereby a constant deflection of 124 degrees of the galvanometer needle. The action of the light upon a positive disk caused a deflection of only three degrees by the same battery. With aluminum in the electrodes, the deflections were about 1400 and 24 respectively. Is it not sufficiently fully established that ultra-violet light will discharge not only negative but positive electricity? He experimented with substances heated to glowing or incandescence. Glass lamp chimneys at a dull, red heat, when covered with aluminum, oxide of bismuth, or lead oxides, withdraw positive charges. In the same way, for example, behaves a nickel tube in place of the lamp chimney.
99_R_. WANKA’S EXPERIMENT. A NEW DISCHARGE EXPERIMENT. _Abk. d. Deuts. Math. Ges. in Rrag._, ’92, pp. 57 to 63.—He confirms the principle that the ultra-violet rays are the most powerful. A glass plate, which, as well known, cuts off most of the ultra-violet rays, was properly interposed and then removed and the difference noted.
99_S_. BRANLY’S EXPERIMENT. DISCHARGE OF BOTH POSITIVE AND NEGATIVE ELECTRICITY BY ULTRA-VIOLET RAYS. _C. R._, CXIV., pp. 68 to 70, ’92.—He further proves that ultra-violet rays of light will dissipate a positive charge. The experiments in this connection seem to prove more and more that the discharging power is only a matter of sufficiently high refrangibility of the rays of light.
99_T_. BRANLY’S EXPERIMENT. LOSS OF ELECTRIC CHARGE IN DIFFUSE LIGHT AND IN THE DARK. _C. R._, CXVI., pp. 741 to 744. ’93.—A polished aluminum sheet was attached to the terminal of an electroscope properly surrounded by a metal screen. After a few days, the plate acted like any other metal plate polished or unpolished; it lost its charge very slowly, positive or negative alike, independently of the illumination. If it is then again polished, as for example, with emery paper and turpentine, it loses its charge rapidly in diffused light, which has passed through a pane of window glass, for example. Therefore, the ultra-violet rays are not alone effective, although most effective. The longer the time elapsing, after polishing, the slower the discharge takes place. Zinc behaved likewise, only more slowly. Other metals were tried. Bismuth acted differently from most metals. Whether charged positively or negatively, they exhibited rapid loss in the dark, in dry air under a metal bell, independently of the state of the polish.