. The Becquerel rays and the properties of radium. val from the electrode itself (seefig. 1). Let the exhaustion now be carried further. It willbe found that the blue negative glow spreads outand that the dark space becomes broader. A greenluminosity begins to be visible on the wall of thetube opposite the negative electrode. At still higherexhaustions, such as can only be obtained by pro-longed use of the mercurial pump, it is found thata sharp patch of green fluorescent liglir is visible on ELECTKIC DISCHAEGE IN HIGH VACUA 3 the wall opposite to the negative electrode; thispatch corresponds
. The Becquerel rays and the properties of radium. val from the electrode itself (seefig. 1). Let the exhaustion now be carried further. It willbe found that the blue negative glow spreads outand that the dark space becomes broader. A greenluminosity begins to be visible on the wall of thetube opposite the negative electrode. At still higherexhaustions, such as can only be obtained by pro-longed use of the mercurial pump, it is found thata sharp patch of green fluorescent liglir is visible on ELECTKIC DISCHAEGE IN HIGH VACUA 3 the wall opposite to the negative electrode; thispatch corresponds in shape to the electrode itself, ifthe electrode is flat. Thus a round disk electrodewill produce a round patch only a little larger thanitself. A faint streak of blue luminosity appears inthe gas, stretching from the cathode to the phos-phorescent spot. It is evident from these phenomenathat some kind of influence is propagated out at rightangles to the cathode surface and travels through thetube till it reaches the wall. This influence goes by. Fio. 3.—Experiment showing that the cathode rays are always emitted at right anglesto the sui-face of the cathode, and do not necessarily follow the line of the rays from the flat cathode, a, strike the wall of the tube at 6, causing phosphores- ,cence. They penetrate the glow of the main discharge, which curves away to the anode,c, in a lateral tube joined on to the main one. the name of the cathode rays. The cathode raysalways proceed at right angles to the cathode,whether that is the direction in which the anode liesor not. The spark or glow discharge which, at theselow pressures, is quite inconspicuous, of course pro-ceeds from anode to cathode, and will turn a cornerwithout difficulty. This the cathode rays will not path is essentially rectilinear (fig. 3). A thick, solid obstacle placed in the path of thecathode rays casts a perfectly sharp and definiteshadow. The outline of the object is seen on the B 2
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradiati, bookyear1906
