. The Becquerel rays and the properties of radium . al 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 gxeenluminosity 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 that asharp patch of green fluorescent light is visible on ELECTRIC DISCHARGE IN HIGH VACUA 3 the wall opposite to the negative electrode ; thispatch corresponds
. The Becquerel rays and the properties of radium . al 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 gxeenluminosity 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 that asharp patch of green fluorescent light is visible on ELECTRIC DISCHARGE 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 disc 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 Icind of influence is propagated out at rightangles to the cathode surface and travels through thetube till it reaches the wall. This influence goes by. Fin 3 —Eximrimcnt sliowiiig that tlio citliode rays arc always cinittcil at rigM anglestn siii-race of the caHiodn, and do not necc-isavily follow the line of the riiYS from the nat cathode, a, strike the wall ot the tube at b, causing phosphores-cence. They penetrate the glow of the main discharge, which curves away to the anode,c, in a lateral tube joined ou 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 patli 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
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
