. The Becquerel rays and the properties of radium . in allrespects like air which is exposed to radium; butit is able to keep itself constantly ionised by theradio-active material which it contains; whereas theionisation of ordinary air only continues as long asthe radium acts upon it. If the radium is with-drawn, the conducting power disappears in the courseof one or two minutes, owing to recombination of theions already present, and the failure of the supply ofnew ones. If the electro-motive force is acting all no THE BECQUEREL RAYS the time, the ions are used up immediately, and thephenomen
. The Becquerel rays and the properties of radium . in allrespects like air which is exposed to radium; butit is able to keep itself constantly ionised by theradio-active material which it contains; whereas theionisation of ordinary air only continues as long asthe radium acts upon it. If the radium is with-drawn, the conducting power disappears in the courseof one or two minutes, owing to recombination of theions already present, and the failure of the supply ofnew ones. If the electro-motive force is acting all no THE BECQUEREL RAYS the time, the ions are used up immediately, and thephenomena cease the moment the radium is with-drawn. The emanation behaves like other gases in one veryimportant property. It can be condensed to the liquid or solid formby cooling. Diifer-ent gases differvery greatly in thisrespect. Steam orwater vapour, forinstance, can bealmost completelycondensed out of aspace which con-tains it by meansof ice, though toremove absolutelyall perceptibletraces of it wouldrequire a lowertemperature condense the. emanation com- t\—Arrangement for condensation of the eniana- •^if^jl-,,. ^f io ■nanao tion by liquid air. a is a solution of radium bromide, P---^^^--yj 1^ 1 neCOS-which yields the emanation. Air is bubbled through it, , -i n and carries the emanation through to the U-tube, It, ini- Sary tO maKO USe 01mersed in liquid air, where it is condensed. The liquid air is contained in a double-walled vessel, c, witli a vacuum tllC mUCll ffrCaterbetween the walls. This serves to prevent the access of ^ heat. While ft is surrounded by liquid air, no emanation prvlrl wlllpTl \VP fUn can escape through v llioil YV C ^aix Plwer. When the liquid air is removed, the accumulated |^/-vt-v->yv-. .! K-ir fVio emanation evaporates, and tlie issuing air is strongly t^OllllllcinU. Dj tileradio-active. p i • • i use 01 liquid condensation can be shown in the followingway. Air bubbled through the solution of radiumbromide
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1906
