,,radio-,,active ,,sub/ances4 ,,by ,,mdme4 ,,sklod[ska ,,curie4 ,!sis pres5t$ to ! ,facult des ,sci5ces de ,p>is4 ,repr9t$ f ! ,,*emical ,,news4 7,,second ,,edition74 ,,london3 ,,*emical ,,news ,,(fice1 #af1 ,,newca/le ,,/reet1 ,,f>r+don ,,/reet1 ,e4,c4 #aijd4 ,d4 ,,van ,,no/r& ,,company1 #bc ,,murray ,,& #bg ,,w>r5 ,,/reets1 ,,new ,,york4 ---------------------------------------- -------------------------------- ,a4 ,c4 ,,cossor1 #ed1 ,f>r+don ,road1 ,e4,c4 ,illu/ration ,,sp9?>iscopes1 ,,z ,,devis$ ,,by ,,sir ,,william ,,crookes4 ,%[+ ! ,sc9tillations ( ,radium4 ,,price #bas4 ea*4 ,illu/ration ,,pure ,,radium ,,bromide1 :5 available ,,pit*bl5de & ,,?orium ,,nitrate4 ,illu/ration ,,ozone ,,g5]ator1 ,complete1 ,) #a 94 sp>k coil1 #b #ags4 #f;d4 ,,crookes',s ,,high ,,vacuum ,,tubes1 %[+ ! fluoresc5ce ( v>i\s m9]als4 ,a good selection always 9 /ock1 includ+ sev]al specialities4 ,,spectrum ,,tubes1 ,,glass ,,bl[+1 8,x-,,ray0 ,,outfits & ,,tubes1 ,,high ,,frequ5cy ,,app>atus & ,,applicators1 & o!r ,sci5tific ,in/rum5ts4 ,exp]im5tal "w ( any k9d 9 ,glass or ,metal4 99 99 99 99 99 ,,radium ,,salts & ,o!r ,prep>ations & ,m9]als4 ,radium ,bromide1 ,radium-,b>ium ,bromide1 ,radium-,b>ium ,*loride1 9 ,tubes ( v>i\s quantities & /r5g?s4 ,phosphoresc5t ,z9c ,sulphide1 #a grm4 & #e grm4 ,tubes1 & p] oz4 ,phosphoresc5t ,z9c ,sulphide1 ,scre5s4 ,radium1 ,active ,scre5s = ,photographic effects4 ,uranium ,plat9o-cyanide ,scre5s1 f #g #e to #ae #aa4 ,pit*bl5de1 ,select$ ,radio-,active4 ,willemite1 ,autunite1 & o!r ,fluoresc5t ,m9]als4 ,salts ( ,uranium1 ,?orium1 ,calcium1 & o!r ,x-,ray ,mat]ials4 7,,subject ,,to ,,be+ ,,unsold47 ,*emicals = ,sci5tific ,inve/igation & ,laboratory ,"w4 ,,h>r+ton ,,bros41 #d1 ,oliv]'s ,y>d1 ,city ,road1 ,london1 ,e4,c4 ,,manufactur+ ,,*emi/s4 ---------------------------------------- -------------------------------- ,,radio-,,active ,,sub/ances ,,by ,,mdme4 ,,sklod[ska ,,curie ,!sis pres5t$ to ! ,facult des ,sci5ces de ,p>is4 ,repr9t$ f ! ,,*emical ,,news4 7,,second ,,edition74 ,,london3 ,,*emical ,,news ,,(fice1 #af1 ,,newca/le ,,/reet1 ,,f>r+don ,,/reet1 ,e4,c4 #aijd4 ,d4 ,,van ,,no/r& ,,company1 ,,new ,,york4 ,,london3 ,,pr9t$ ,,by ,,edw9 ,,john ,,davey1 #af1 ,,newca/le ,,/reet1 ,,f>r+don ,,/reet1 ,e4,c4 ---------------------------------------- -------------------------------- ,repr9t$ f ! ,,*emical ,,news1 #aijc1 ,vol4 #hh1 p4 #he et seq4 ,,radio-,,active ,,sub/ances4 ,,introduction4 ,! object ( ! pres5t "w is ! publication ( rese>*es :i* ,i h be5 c>ry+ on = m ?an f\r ye>s on radio-active bodies4 ,i began ^! rese>*es by a /udy ( ! phosphoresc5ce ( uranium1 discov]$ by ,m4 ,becqu]el4 ,! results to :i* ,i 0 l$ by ?is "w promis$ to af=d s int]e/+ a field t ,m4 ,curie put aside ! "w on :i* he 0 engag$1 & jo9$ me1 our object be+ ! extraction ( new radio-active sub/ances & ! fur!r /udy ( _! prop]ties4 ,s9ce ! comm5cem5t ( our rese>* we ?\ght x well to h& ov] specim5s ( ! sub/ances1 discov]$ & prep>$ by ourselves1 to c]ta9 physici/s1 9 ! fir/ place to ,m4 ,becqu]el1 to :om is due ! discov]y ( ! uranium rays4 ,9 ?is way we ourselves facilitat$ ! rese>* by o!rs besides ourselves on ! new radio-active bodies4 ,at ! t]m9ation ( our fir/ publications1 ,m4 ,giesel1 9 ,g]many1 also began to prep>e ^! sub/ances1 & pass$ on specim5s ( !m to sev]al ,g]man sci5ti/s4 ,f9ally1 ^! sub/ances 7 plac$ on sale 9 ,france & ,g]many1 & ! subject gr[+ 9 importance gave rise to a sci5tific movem5t1 su* t num]\s memoirs h appe>$1 & are con/antly appe>+ on radio-active bodies1 pr9cipally abroad4 ,! results ( ! v>i\s ,fr5* & =eign rese>*es are necess>ily confus$1 z is ! case ) all new subjects 9 c\rse ( inve/igation1 ! aspect ( ! "q becom+ modifi$ f day to day4 ,f ! *emical po9t ( view1 h[ev]1 "o po9t is def9itely e/abli%$3--i4e41 ! exi/5ce ( a new elem5t1 /rongly radio-active1 viz41 radium4 ,! prep>ation ( ! pure *loride ( radium & ! det]m9ation ( ! atomic weight ( radium =m ! *ief "p ( my own "w4 ,:il/ ?is "w adds to ! elem5ts actually kn[n ) c]ta9ty a new elem5t ) v curi\s prop]ties1 a new me?od ( *emical rese>* is at ! same "t e/abli%$ & ju/ifi$4 ,?is me?od1 bas$ on ! consid]ation ( radio-activity z an atomic prop]ty ( matt]1 is j t :i* enabl$ ,m4 ,curie & myself to discov] ! exi/5ce ( radium4 ,if1 f ! *emical po9t ( view1 ! "q t we und]took prim>ily may be look$ ^u z solv$1 ! /udy ( ! physical prop]ties ( ! radio-active bodies is 9 full evolution4 ,c]ta9 important po9ts h be5 e/abli%$1 b a l>ge numb] ( ! conclusions are /ill ( a provisional "*4 ,?is is n surpris+ :5 we consid] ! complexity ( ! ph5om5a due to radio-activity1 & ! diff]5ces exi/+ betwe5 ! v>i\s radio-active sub/ances4 ,! rese>*es ( physici/s on ^! sub/ances con/antly meet & ov]lap4 ,:il/ endeav\r+ to keep /rictly to ! limits ( ?is "w & to publi% my individual rese>* only1 ,i h be5 oblig$ at ! same "t to m5tion results ( o!r rese>*es1 ! k ( :i* is indisp5sable4 ,i desir$1 moreov]1 to make ?is "w an inclusive survey ( ! actual position ( ! "q4 ,i indicate at ! end ! p>ticul> que/ions ) :i* ,i am specially conc]n$1 & ^? :i* ,i inve/igat$ 9 conjunction ) ,m4 ,curie4 ,i c>ri$ on ! "w 9 ! laboratories ( ! ,s*ool ( ,physics & ,*emi/ry 9 ,p>is1 ) ! p]mission ( ,s*tz5b]g]1 late ,director ( ! ,s*ool1 & ,m4 ,lau?1 actual ,director4 ,i take ?is opportunity ( express+ my gratitude = ! k9d hospitality receiv$ 9 ?is s*ool4 ,hi/orical4 ,! discov]y ( ! ph5om5a ( radio-activity is connect$ ) rese>*es foll[$1 s9ce ! discov]y ( ! ,rntg5 rays1 ^u ! photographic effects ( phosphoresc5t & fluoresc5t sub/ances4 ,! fir/ tubes = produc+ ,rntg5 rays 7 )\t ! metallic antica?ode4 ,! s\rce ( ! ,rntg5 rays 0 ! glass surface imp+$ ^u by ! ca?ode rays2 ?is surface 0 at ! same "t actively fluoresc5t4 ,! "q !n 0 :e!r ! emission ( ,rntg5 rays necess>ily accompani$ ! production ( fluoresc5ce1 :atev] might be ! cause ( ! latt]4 ,?is idea 0 fir/ enunciat$ by ,m4 ,h5ri ,po9c>4 ,%ortly aft]w>ds1 ,m4 ,h5ry ann\nc$ t he _h obta9$ photographic impressions ?r\gh black pap] by means ( phosphoresc5t z9c sulphide4 ,m4 ,niew5gl[ski obta9$ ! same ph5om5on ) calcium sulphide expos$ to ! light4 ,f9ally1 ,m4 ,troo/ obta9$ /rong photographic impressions ) z9c sulphide artificially phosphoresc5t act+ across black pap] & ?ick c>dbo>d4 ,! exp]i5ces j cit$ h n be5 reproduc$1 9 spite ( num]\s attempts to ?is end4 ,x _c !re=e be consid]$ z prov$ t z9c sulphide & calcium sulphide are capable ( emitt+1 "u ! action ( light1 invisible rays :i* trav]se black pap] & act on photographic plates4 ,m4 ,becqu]el has made simil> exp]im5ts on ! salts ( uranium1 "s ( :i* are fluoresc5t4 ,he obta9$ photographic impressions ?r\gh black pap] ) ! d\ble sulphate ( uranium & potassium4 ,m4 ,becqu]el at fir/ believ$ t ?is salt1 :i* is fluoresc5t1 behav$ l ! sulphides ( z9c & calcium 9 ! exp]im5ts ( ,,mm4 ,h5ry1 ,niew5gl[ski1 & ,troo/4 ,b ! conclusion ( 8 exp]im5ts %[$ t ! ph5om5on obs]v$ 0 9 no way relat$ to ! fluoresc5ce4 ,x is n necess>y t ! salt %\ld be fluoresc5t2 fur!r1 uranium & all its comp\nds1 fluoresc5t or n1 act 9 ! same mann]1 & metallic uranium is ! mo/ active4 ,m4 ,becqu]el f9ally f\nd t by plac+ uranium comp\nds 9 complete d>kness1 !y cont9ue act+ on photographic plates ?r\gh black pap] = ye>s4 ,m4 ,becqu]el all[s t uranium & its comp\nds emit peculi> rays--uranium rays4 ,he prov$ t ^! rays c p5etrate ?9 metallic scre5s1 & t !y dis*>ge electrifi$ bodies4 ,he also made exp]im5ts f :i* he conclud$ t uranium rays und]go reflection1 refraction1 & pol>isation4 ,! "w ( o!r physici/s 7,el/] & ,geitel1 ,"l ,kelv91 ,s*midt1 ,ru!r=d1 ,beattie1 & ,smolu*[ski7 confirms & ext5ds ! results ( ! rese>*es ( ,m4 ,becqu]el1 ) ! exception ( ^? relat+ to ! reflection1 refraction1 & pol>isation ( uranium rays1 :i* 9 ?is respect behave l ,rntg5 rays1 z has be5 recognis$ fir/ by ,mr4 ,ru!r=d & !n by ,m4 ,becqu]el himself4 ,,*apt] ,i4 ,,radio-,,activity ,,( ,,uranium ,,& ,,?orium4 ,,radio-,,active ,,m9]als4 ,becqu]el ,rays4--,! uranium rays discov]$ by ,m4 ,becqu]el act ^u photographic plates scre5$ f ! light2 !y c p5etrate all solid1 liquid1 & gase\s sub/ances1 provid$ t ! ?ickness is suffici5tly r$uc$2 9 pass+ ?r\gh a gas1 !y cause x to become a feeble conductor ( electricity4 ,^! prop]ties ( ! uranium comp\nds are n due to any kn[n cause4 ,! radiation seems to be spontane\s2 x loses no?+ 9 int5sity1 ev5 on keep+ ! comp\nds 9 complete d>kness = sev]al ye>s2 h5ce !re is no "q ( ! phosphoresc5ce be+ specially produc$ by light4 ,! spontaneity & p]si/5ce ( ! uranium radiation appe> z a q unique physical ph5om5on4 ,m4 ,becqu]el kept a piece ( uranium = sev]al ye>s 9 ! d>k1 & he has affirm$ t at ! end ( ?is "t ! action ^u a photographic plate _h n s5sibly alt]$4 ,,mm4 ,el/] & ,geitel made a simil> exp]im5t1 & also f\nd ! action to rema9 con/ant4 ,i measur$ ! int5sity ( radiation ( uranium by ! effect ( ?is radiation on ! conductivity ( air4 ,! me?od ( measurem5t w be expla9$ lat]4 ,i also obta9$ figures :i* prove ! p]si/5ce ( radiation )9 ! limits ( accuracy ( ! exp]im5ts4 ,= ^! measurem5ts a metallic plate 0 us$ cov]$ ) a lay] ( p[d]$ uranium2 ?is plate 0 n o!rwise kept 9 ! d>k2 ?is precaution1 accord+ to ! exp]im5t]s already quot$1 be+ ( no importance4 ,! numb] ( measurem5ts tak5 ) ?is plate is v great1 & !y actually ext5d ov] a p]iod ( five ye>s4 ,"s rese>*es 7 conduct$ to discov] :e!r o!r sub/ances 7 capable ( act+ simil>ly to ! uranium comp\nds4 ,m4 ,s*midt 0 ! fir/ to publi% t ?orium & its comp\nds possess exactly ! same prop]ty4 ,a simil> rese>*1 made contemporane\sly1 gave me ! same result4 ,i publi%$ ?is n kn[+ at ! "t ( ,s*midt's publication4 ,we %all say t uranium1 ?orium1 & _! comp\nds emit ,becqu]el rays4 ,i h call$ radio-active ^? sub/ances :i* g5]ate emissions ( ?is nature4 ,?is "n has s9ce be5 adopt$ g5]ally4 ,9 _! photographic & electric effects1 ! ,becqu]el rays approximate to ! ,rntg5 rays4 ,!y also1 l ! latt]1 possess ! faculty ( p5etrat+ all matt]4 ,b _! capacity = p5etration is v diff]5t2 ! rays ( uranium & ( ?orium are arre/$ by "s millimetres ( solid matt]1 & _c trav]se 9 air a di/ance great] ?an a few c5timetres2 ?is at lea/ is ! case = ! great] "p ( ! radiation4 ,! rese>*es ( diff]5t physici/s1 & prim>ily ( ,mr4 ,ru!r=d1 h %[n t ! ,becqu]el rays und]go nei!r regul> reflection1 nor refraction1 nor pol>isation4 ,! feeble p5etrat+ p[] ( uranium & ?orium rays w\ld po9t to _! simil>ity to ! second>y rays produc$ by ! ,rntg5 rays1 & :i* h be5 inve/igat$ by ,m4 ,sagnac1 r ?an to ! ,rntg5 rays !mselves4 ,= ! re/1 ! ,becqu]el rays might be classifi$ z ca?ode rays propagat$ 9 ! air4 ,x is n[ kn[n t ^! diff]5t analogies are all legitimate4 ,measurem5t ( ! ,int5sity ( ,radiation4 ,illu/ration3 ,,fig4 #a4 ,! me?od employ$ consi/s 9 measur+ ! conductivity acquir$ by air "u ! action ( radio-active bodies2 ?is me?od possesses ! advantage ( be+ rapid & ( furni%+ figures :i* are comp>able4 ,! app>atus employ$ by me = ! purpose consi/s ess5tially ( a plate cond5s]1 ,a ,b 7,fig4 #a74 ,! active body1 f9ely p[]$1 is spread ov] ! plate ,b1 mak+ ! air betwe5 ! plates a conductor4 ,9 ord] to measure ! conductivity1 ! plate ,b is rais$ to a high pot5tial by connect+ x ) "o pole ( a batt]y ( small accumulators1 ,p1 ( :i* ! o!r pole is connect$ to e>?4 ,! plate ,a be+ ma9ta9$ at ! pot5tial ( ! e>? by ! connection ,c ,d1 an electric curr5t is set up betwe5 ! two plates4 ,! pot5tial ( plate ,a is record$ by an electromet]1 ,e4 ,if ! e>? connection be brok5 at ,c1 ! plate ,a becomes *>g$1 & ?is *>ge causes a deflection ( ! electromet]4 ,! velocity ( ! deflection is proportional to ! int5sity ( ! curr5t1 & s]ves to measure ! latt]4 ,b a pref]able me?od ( measurem5t is t ( comp5sat+ ! *>ge on plate ,a1 s z to cause no deflection ( ! electromet]4 ,! *>ges 9 "q are extremely weak2 !y may be comp5sat$ by means ( a qu>tz electric balance1 ,q1 "o %ea? ( :i* is connect$ to plate ,a & ! o!r to e>?4 ,! qu>tz lam9a is subject$ to a kn[n t5sion1 produc$ by plac+ weights 9 a plate1 2 ! t5sion is produc$ progressively1 & has ! effect ( g5]at+ progressively a kn[n quantity ( electricity dur+ ! "t obs]v$4 ,! op]ation c be s regulat$ t1 at ea* in/ant1 !re is comp5sation betwe5 ! quantity ( electricity t trav]ses ! cond5s] & t ( ! opposite k9d furni%$ by ! qu>tz4 ,9 ?is way1 ! quantity ( electricity pass+ ?r\gh ! cond5s] = a giv5 "t1 i4e41 ! int5sity ( ! curr5t1 c be measur$ 9 absolute units4 ,! measurem5t is indep5d5t ( ! s5sitiv5ess ( ! electromet]4 ,9 c>ry+ out a c]ta9 numb] ( measurem5ts ( ?is k9d1 x is se5 t radio-activity is a ph5om5on capable ( be+ measur$ ) a c]ta9 accuracy4 ,x v>ies little ) temp]ature2 x is sc>cely affect$ by v>iations 9 ! temp]ature ( ! surr\nd+s2 x is n influ5c$ by inc&esc5ce ( ! active sub/ance4 ,! int5sity ( ! curr5t :i* trav]ses ! cond5s] increases ) ! surface ( ! plates4 ,= a giv5 cond5s] & a giv5 sub/ance ! curr5t increases ) ! diff]5ce ( pot5tial betwe5 ! plates1 ) ! pressure ( ! gas :i* fills ! cond5s]1 & ) ! di/ance ( ! plates 7provid$ ?is di/ance be n too great 9 comp>ison ) ! diamet]74 ,9 e case1 = great diff]5ces ( pot5tial ! curr5t atta9s a limit+ value1 :i* is practically con/ant4 ,?is is ! curr5t ( saturation1 or limit+ curr5t4 ,simil>ly1 = a c]ta9 suffici5tly great di/ance betwe5 ! plates ! curr5t h>dly v>ies any long] ) ! di/ance4 ,x is ! curr5t obta9$ "u ^! conditions t 0 tak5 z ! measure ( radio-activity 9 my rese>*es1 ! cond5s] be+ plac$ 9 air at atmosph]ic pressure4 ,i app5d curves :i* repres5t ! int5sity ( ! curr5t z a function ( ! field e/abli%$ betwe5 ! plates = two diff]5t plate di/ances4 ,plate ,b 0 cov]$ ) a ?9 lay] ( p[d]$ metallic uranium2 plate ,a1 connect$ ) ! electromet]1 0 provid$ ) a gu>d-r+4 ,illu/ration3 ,,fig4 #b4 ,illu/ration3 ,,fig4 #c4 ,fig4 #b %[s t ! int5sity ( ! curr5t becomes con/ant = high pot5tial diff]5ces betwe5 ! plates4 ,fig4 #c repres5ts ! same curves on ano!r scale1 & compreh5ds only relative results = small diff]5ces ( pot5tial4 ,at ! orig91 ! curve is rectil9e>2 ! ratio ( ! int5sity ( ! curr5t to ! diff]5ce ( pot5tial is con/ant = weak =ces1 & repres5ts ! initial conduction betwe5 ! plates4 ,two important *>act]i/ic con/ants ( ! obs]v$ ph5om5on are !re=e to be recognis$3--7#a7 ,! initial conduction = small diff]5ces ( pot5tial2 7#b7 ! limit+ curr5t = great pot5tial diff]5ces4 ,! limit+ curr5t has be5 adopt$ z ! measure ( ! radio-activity4 ,besides ! diff]5ce ( pot5tial e/abli%$ betwe5 ! two plates1 !re exi/s betwe5 !m an electromotive =ce ( contact1 & ^! two s\rces ( curr5t comb9e _! effects2 = ?is reason1 ! absolute value ( ! int5sity ( ! curr5t *anges ) ! sign ( ! ext]nal diff]5ce ( pot5tial4 ,9 e case1 = consid]able pot5tial diff]5ces1 ! effect ( ! electromotive =ce ( contact is negligible1 & ! int5sity ( ! curr5t is !re=e ! same :atev] be ! direction ( ! field betwe5 ! plates4 ,! inve/igation ( ! conductivity ( air & o!r gases subject$ to ! action ( ,becqu]el rays has be5 und]tak5 by sev]al physici/s4 ,a v complete rese>* ^u ! subject has be5 publi%$ by ,mr4 ,ru!r=d4 ,! laws ( ! conductivity produc$ 9 gases by ! ,becqu]el rays are ! same z ^? f\nd = ! ,rntg5 rays4 ,! me*anics ( ! ph5om5on appe> to be ! same 9 bo? cases4 ,! !ory ( ionisation ( ! gases by ! action ( ! ,rntg5 or ,becqu]el rays agrees well ) ! obs]v$ facts4 ,?is !ory w n be put =w>d "h4 ,i w m]ely record ! results to :i* !y po9t3-- ,fir/ly1 ! numb] ( ions produc$ p] second 9 ! gas is consid]$ proportional to ! en]gy ( radiation absorb$ by ! gas4 ,secondly1 9 ord] to obta9 ! limit+ curr5t relatively to a giv5 radiation1 x is necess>y1 on ! "o h&1 to cause complete absorption ( ?is radiation by ! gas by employ+ a suffici5t mass ( x2 on ! o!r h&1 x is necess>y = ! production ( ! curr5t to use all ! ions g5]at$ by e/abli%+ an electric field ( su* /r5g? t ! numb] ( ! ions :i* recomb9e may be a negligible fraction ( ! total numb] ( ions produc$ 9 ! same "t1 mo/ ( :i* are c>ri$ by ! curr5t to ! electrodes4 ,! /r5g? ( ! electric field necess>y to give ?is result is proportional to ! am\nt ( ionisation4 ,accord+ to ! rec5t rese>*es ( ,mr4 ,t[ns5d1 ! ph5om5on is m complex :5 ! pressure ( ! gas is l[4 ,at fir/ ! curr5t appe>s to approa* to a con/ant limit+ value ) increas+ diff]5ce ( pot5tial2 b aft] a c]ta9 po9t has be5 rea*$1 ! curr5t beg9s aga9 to increase ) ! field1 & ) v great rapidity4 ,mr4 ,t[ns5d ascribes ?is increase to a new ionisation produc$ by ! ions !mselves :51 "u ! action ( ! electric field1 !y acquire a velocity su* t a molecule ( gas enc\nt]+ "o ( !m becomes brok5 d[n into its con/itu5t ions4 ,a /rong electric field & a l[ pressure are fav\rable to ! production ( ?is ionisation by ions already pres5t1 &1 z soon z ! action is set up1 ! int5sity ( ! curr5t increases uni=mly ) ! field betwe5 ! plates4 ,! limit+ curr5t c\ld1 !re=e1 only be obta9$ "u conditions ( ionisation ( :i* ! int5sity does n exce$ a c]ta9 value1 & 9 su* a mann] t saturation corresponds to fields 9 :i*1 f multiplicity ( ions1 ionisation c no long] take place4 ,?is condition has occurr$ 9 my exp]im5ts4 ,! ord] ( magnitude ( ! saturation curr5ts obta9$ ) uranium comp\nds is #aj-aa ampres = a cond5s] 9 :i* ! plates h a diamet] ( #h c4m41 & are at a di/ance ( #c c4m4 ,?orium comp\nds give rise to curr5ts ( ! same ord] ( magnitude1 & ! activity ( ! oxides ( uranium & ?orium is v simil>4 ,radio-activity ( ! ,comp\nds ( ,uranium & ,?orium4 ,! foll[+ are ! figures ,i obta9$ ) diff]5t uranium comp\nds4 ,i h repres5t$ ! int5sity ( ! curr5t 9 ampres by ! lett] i3-- i #ajaa4 ,metallic uranium 7conta9+ a little c>bon7 #bc ,black oxide ( uranium1 ,u#b,o#e #bf ,gre5 oxide ( uranium1 ,u#c,o#d #ah ,hydrat$ uranic acid #jf ,uranate ( sodium #ab ,uranate ( potassium #ab ,uranate ( ammonium #ac ,uranium sulphate #jg ,sulphate ( uranium & potassium #jg ,nitrate ( uranium #jg ,phosphate ( copp] & uranium #ji ,oxysulphide ( uranium #ab ,! ?ickness ( ! lay] ( ! uranium comp\nd us$ has little effect1 provid$ t ! lay] is uni=m4 ,! foll[+ illu/rate ?is po9t3-- ,?ickness ( lay]4 i #ajaa4 ,m4m4 ,uranium oxide #je #bg ,uranium oxide #cj #cj ,ammonium uranate #je #ac ,ammonium uranate #cj #ad ,x may be conclud$ f ?is t ! absorption ( uranium rays by ! sub/ance :i* g5]ates !m is v great1 s9ce ! rays proce$+ f deep lay]s produce no significant effect4 ,! figures ,i obta9$ ) ?orium comp\nds enable me to /ate3-- ,fir/ly1 t ! ?ickness ( ! lay] us$ has consid]able effect1 especially 9 ! case ( ! oxide4 ,secondly1 t ! action is only regul> if a suffici5tly ?9 lay] is us$ 7e4g41 #jbe m4m474 ,on ! contr>y1 :5 a ?ick lay] ( ! sub/ance is us$ 7#f m4m471 ! figures obta9$ v>y betwe5 two extreme limits1 especially 9 ! case ( ! oxide3-- ,?ickness ( lay]4 i #ajaa4 ,m4m4 ,?orium oxide #jbe #bb ,?orium oxide #je #be ,?orium oxide #be #dg ,?orium oxide #cj #ee 7mean7 ,?orium oxide #fj #ee 7mean7 ,?orium sulphate #jbe #jh 7mean7 ,!re is "h "s cause ( irregul>ities :i* d n exi/ 9 ! case ( ! uranium comp\nds4 ,! figures obta9$ = a lay] ( oxide #f m4m4 ?ick v>i$ betwe5 #cg & #gc4 ,! exp]im5ts t ,i made on ! absorption ( uranium & ?orium rays %[$ t ^? ( ?orium are m p5etrat+ ?an ^? ( uranium1 & t ! rays emitt$ by ! oxide ( ?orium 9 a ?ick lay] are m p5etrat+ ?an ^? emitt$ by a ?9 lay] ( ! same4 ,! foll[+ figures 7p4 #ac7 give ! fraction ( ! radiation transmitt$ by a %eet ( alum9ium #jja ?ick4 ,) ! uranium comp\nds1 ! absorption is ! same :atev] be ! comp\nd us$1 :i* leads to ! conclusion t ! rays emitt$ by ! diff]5t comp\nds are ( ! same nature4 ,radio-active sub/ance4 ,fraction ( radiation transmitt$ by ! %eet4 ,uranium #jah ,uranium oxide1 ,u#b,o#e #jbj ,uranate ( ammonium #jbj ,phosphate ( uranium & copp] #jba ,?orium oxide ( ?ickness #jbe m4m4 #jch ,?orium oxide ( ?ickness #je m4m4 #jdg ,?orium oxide ( ?ickness #cj m4m4 #jgj ,?orium oxide ( ?ickness #jfj m4m4 #jgj ,?orium sulphate #jbe m4m4 #jch ,! *>act]i/ics ( ! ?orium radiation h =m$ ! subject ( v complete publications4 ,mr4 ,ow5s has demon/rat$ t a uni=m curr5t is only obta9$ aft] "s "t has elaps$1 ) an enclos$ app>atus1 & t ! int5sity ( ! curr5t is greatly r$uc$ "u ! influ5ce ( a curr5t ( air 7:i* does n occur ) ! comp\nds ( uranium74 ,mr4 ,ru!r=d has made simil> exp]im5ts1 & has expla9$ !m by ! proposition t ?orium & its comp\nds produce1 besides ! ,becqu]el rays1 ano!r emanation1 compos$ ( extremely m9ute p>ticles1 :i* rema9 radio-active = "s "t aft] _! emission1 & are capable ( be+ swept along by a curr5t ( air4 ,! *>act]i/ics ( ! ?orium radiation1 :i* h ref]5ce to ! ?ickness ( ! lay] employ$ & to ! action ( air curr5ts1 h an intimate connection ) ! ph5om5on ( ! radio-activity induc$1 & ( its propagation f place to place4 ,?is ph5om5on 0 obs]v$ = ! fir/ "t ) radium1 & w be describ$ lat]4 ,! radio-activity ( ?orium & uranium comp\nds appe>s z an atomic prop]ty4 ,m4 ,becqu]el has already obs]v$ t all uranium comp\nds are active1 & _h conclud$ t _! activity 0 due to ! pres5ce ( ! elem5t uranium2 he also demon/rat$ t uranium 0 m active ?an its salts4 ,i h inve/igat$1 f ?is po9t ( view1 ! comp\nds ( ?orium & uranium1 & h tak5 a great _m measurem5ts ( _! activity "u diff]5t conditions4 ,! result ( all ^! det]m9ations %[s ! radio-activity ( ^! sub/ances to be decid$ly an atomic prop]ty4 ,x seems to dep5d ^u ! pres5ce ( atoms ( ! two elem5ts 9 "q1 & is n influ5c$ by any *ange ( physical /ate or *emical decomposition4 ,! *emical comb9ations & mixtures conta9+ uranium or ?orium are active 9 proportion to ! am\nt ( ! metal conta9$1 all inactive mat]ial act+ z in]t bodies & absorb+ ! radiation4 ,is ,atomic ,radio-activity a g5]al ,ph5om5on8 ,z ,i h said above1 ,i made exp]im5ts to discov] :e!r sub/ances o!r ?an comp\nds ( uranium & ?orium 7 radio-active4 ,i und]took ?is rese>* ) ! idea t x 0 sc>cely probable t radio-activity1 consid]$ z an atomic prop]ty1 %\ld belong to a c]ta9 k9d ( matt] to ! exclusion ( all o!r4 ,! det]m9ations ,i made p]mit me to say t1 = *emical elem5ts actually consid]$ z su*1 includ+ ! r>e/ & mo/ hypo!tical1 ! comp\nds ,i inve/igat$ 7 always at lea/ #ajj times less active 9 my app>atus ?an metallic uranium4 ,! foll[+ is a summ>y ( ! sub/ances exp]im5t$ ^u1 ei!r z ! elem5t or 9 comb9ation3-- #a4 ,all ! metals or non-metals easily procurable1 & "s1 m r>e1 pure products obta9$ f ! collection ( ,m4 ,et>d1 at ! ,ecole de ,physique et de ,*imie ,indu/rielles de la ,ville de ,p>is4 #b4 ,! foll[+ r>e bodies3--,gallium1 g]manium1 neodymium1 praseodymium1 niobium1 sc&ium1 gadol9ium1 erbium1 sam>ium1 & rubidium 7specim5s l5t by ,m4 ,dem>ay71 yttrium1 ytt]bium 7l5t by ,m4 ,urba974 #c4 ,a l>ge numb] ( rocks & m9]als4 ,)9 ! limits ( s5sitiv5ess ( any app>atus1 ,i f\nd no simple sub/ance1 o!r ?an uranium & ?orium1 possess+ atomic radio-activity4 ,x w be suitable to add a few words "h conc]n+ phosphorus4 ,:ite moi/ phosphorus1 plac$ betwe5 ! plates ( ! cond5s]1 causes ! air betwe5 ! plates to conduct4 ,h[ev]1 ,i d n consid] ?is body radio-active 9 ! same mann] z ?orium & uranium4 ,=1 "u ^! conditions1 phosphorus becomes oxidis$ & emits lum9\s rays1 :il/ uranium & ?orium comp\nds are radio-active )\t %[+ any *emical *ange :i* c be detect$ by any kn[n means4 ,fur!r1 phosphorus is n active 9 ! r$ v>iety1 nor 9 a /ate ( comb9ation4 ,9 a rec5t "w1 ,m4 ,blo* has demon/rat$ t phosphorus1 und]go+ oxidation 9 air1 gives rise to slightly motile ions1 :i* make ! air conduct1 & cause cond5sation ( aque\s vap\r4 ,uranium & ?orium are elem5ts :i* possess ! highe/ atomic weights 7#bdj & #bcb72 !y occur frequ5tly 9 ! same m9]als4 ,radio-active ,m9]als4 ,i h exam9$ _m m9]als 9 my app>atus2 c]ta9 ( !m gave evid5ce ( radio-activity1 e4g41 pit*bl5de1 ?orite1 orangite1 f]gusonite1 cleveite1 *alcolite1 autunite1 monazite1 c4 ,! foll[+ is a table giv+ 9 ampres ! int5sity1 i1 ( ! curr5t obta9$ ) metallic uranium & ) diff]5t m9]als3-- i #ajaa4 ,uranium #bc ,pit*bl5de f ,johanngeorg5/adt#hc ,pit*bl5de f ,joa*im/hal #gj ,pit*bl5de f ,pzibran #fe ,pit*bl5de f ,cornwallis #af ,cleveite #ad ,*alcolite #eb ,autunite #bg ,v>i\s ?orites #ja #jc #jg #ac #ad ,orangite #bj ,monazite #je ,x5otime #jjc s*ynite #jg ,f]gusonite 7two samples7 #jd #ja ,sam>skite #aa ,niobite 7two samples7 #ja #jc ,tantalite #jjb ,c>notite #fb ,! curr5t obta9$ ) orangite 7native oxide ( ?orium7 v>i$ greatly ) ! ?ickness ( ! lay]4 ,by increas+ ?is ?ickness f #jbe m4m4 to #f m4m4 ! curr5t increas$ f #ah to #bc4 ,all ! m9]als :i* %[$ radio-activity conta9$ uranium or ?orium3 _! activity is !re=e n surpris+1 b ! int5sity ( ! action 9 c]ta9 cases is unexpect$4 ,?us pit*bl5des 7ores ( uranium oxide7 are f\nd :i* are f\r times z active z metallic uranium4 ,*alcolite 7d\ble phosphate ( copp] & uranium7 is twice z active z uranium4 ,autunite 7phosphate ( uranium & calcium7 is z active z uranium4 ,^! facts d n accord ) previ\s conclusions1 accord+ to :i* no m9]al %\ld be s active z ?orium or uranium4 ,to ?r[ light on ?is po9t1 ,i prep>$ artificial *alcolite by ! process ( ,debray1 />t+ ) ! pure products4 ,! process consi/s 9 mix+ a solution ( uranium nitrate ) a solution ( copp] phosphate 9 phosphoric acid & w>m+ to #ej or #fj4 ,aft] "s "t1 cry/als ( *alcolite appe> 9 ! liquid4 ,*alcolite ?us obta9$ possesses a p]fectly normal activity1 giv5 by its composition2 x is two & a-half times less active ?an uranium4 ,x !re=e appe>$ probable t if pit*bl5de1 *alcolite1 & autunite possess s great a degree ( activity1 ^! sub/ances conta9 a small quantity ( a /rongly radio-active body1 diff]+ f uranium & ?orium & ! simple bodies actually kn[n4 ,i ?\ght t if ?is 7 inde$ ! case1 ,i might hope to extract ?is sub/ance f ! ore by ! ord9>y me?ods ( *emical analysis4 ,,*apt] ,,ii4 ,,me?od ,,( ,,rese>*4 ,! results ( ! inve/igation ( radio-active m9]als1 ann\nc$ 9 ! prec$+ *apt]1 l$ ,m4 ,curie & myself to endeav\r to extract a new radio-active body f pit*bl5de4 ,our me?od ( proc$ure c\ld only be bas$ on radio-activity1 z we "k ( no o!r prop]ty ( ! hypo!tical sub/ance4 ,! foll[+ is ! me?od pursu$ = a rese>* bas$ on radio-activity3--,! radio-activity ( a comp\nd is det]m9$1 & a *emical decomposition ( ?is comp\nd is effect$2 ! radio-activity ( all ! products obta9$ is det]m9$1 hav+ reg>d to ! proportion 9 :i* ! radio-active sub/ance is di/ribut$ among !m4 ,9 ?is way1 an indication is obta9$1 :i* may to a c]ta9 ext5t be comp>$ to t :i* spectrum analysis furni%es4 ,9 ord] to obta9 comp>able figures1 ! activity ( ! sub/ances mu/ be det]m9$ 9 ! solid =m well dri$4 ,polonium1 ,radium1 ,act9ium4 ,! analysis ( pit*bl5de ) ! help ( ! me?od j expla9$1 l$ u to ! discov]y 9 ?is m9]al ( two /rongly radio-active sub/ances1 *emically dissimil>3--,polonium1 discov]$ by ourselves1 & radium1 :i* we discov]$ 9 conjunction ) ,m4 ,bmont4 ,polonium f ! analytical po9t ( view1 is analog\s to bismu?1 & sep>ates out ) ! latt]4 ,by "o ( ! foll[+ me?ods ( fractionat+1 bismu? products are obta9$ increas+ly ri* 9 polonium3-- #a4 ,sublimation ( ! sulphides 9 vacuo2 ! active sulphide is mu* m volatile ?an bismu? sulphide4 #b4 ,precipitation ( solutions ( ! nitrate by wat]2 ! precipitate ( ! basic nitrate is mu* m active ?an ! salt :i* rema9s 9 solution4 #c4 ,precipitation by sulphurett$ hydrog5 ( a hydro*loric acid solution1 /rongly acid2 ! precipitat$ sulphides are consid]ably m active ?an ! salt :i* rema9s 9 solution4 ,radium is a sub/ance :i* accompanies ! b>ium obta9$ f pit*bl5de2 x resembles b>ium 9 its reactions1 & is sep>at$ f x by diff]5ce ( solubility ( ! *lorides 9 wat]1 9 dilute alcohol1 or 9 wat] acidifi$ ) hydro*loric acid4 ,we effect ! sep>ation ( ! *lorides ( b>ium & radium by subject+ ! mixture to fractional cry/allisation1 radium *loride be+ less soluble ?an t ( b>ium4 ,a ?ird /rongly radio-active body has be5 id5tifi$ 9 pit*bl5de by ,m4 ,debi]ne1 :o gave x ! "n ( act9ium4 ,act9ium accompanies c]ta9 memb]s ( ! iron gr\p conta9$ 9 pit*bl5de2 x appe>s 9 p>ticul> alli$ to ?orium1 f :i* x has n yet be5 f\nd possible to sep>ate x4 ,! extraction ( act9ium f pit*bl5de is a v difficult op]ation1 ! sep>ations be+ z a rule incomplete4 ,all ?ree ( ! new radio-active bodies occur 9 q inf9itesimal am\nt 9 pit*bl5de4 ,9 ord] to obta9 !m 9 a m conc5trat$ condition1 we 7 oblig$ to treat sev]al tons ( residue ( ! ore ( uranium4 ,! r\gh treatm5t 0 c>ri$ out 9 ! factory2 & ?is 0 foll[$ by processes ( purification & conc5tration4 ,we ?us succe$$ 9 extract+ f ?\s&s ( kilogrms4 ( crude mat]ial a few decigrammes ( products :i* 7 exce$+ly active z comp>$ ) ! ore f :i* !y 7 obta9$4 ,x is obvi\s t ?is process is long1 ardu\s1 & co/ly4 ,o!r new radio-active bodies h be5 notifi$ s9ce ! t]m9ation ( our "w4 ,m4 ,giesel1 on ! "o h&1 & ,,mm4 ,h(fmann & ,/rauss on ! o!r1 h ann\nc$ ! probable exi/5ce ( a radio-active body simil> to lead 9 its *emical prop]ties4 ,at pres5t only a few samples ( ?is sub/ance h be5 obta9$4 ,radium is1 s f>1 ! only memb] ( ! new radio-active sub/ances t has be5 isolat$ z ! pure salt4 ,spectrum ( ,radium4 ,x 0 ( ! fir/ importance to *eck1 by all possible means1 ! hypo!sis1 und]ly+ ?is "w1 ( new radio-active elem5ts4 ,9 ! case ( radium1 spectrum analysis 0 ! means ( confirm+ ?is hypo!sis4 ,m4 ,dem>ay und]took ! exam9ation ( ! new radio-active bodies by ! se>*+ me?ods :i* he employs 9 ! /udy ( photographic sp>k spectra4 ,! assi/ance ( s compet5t a sci5ti/ 0 ( ! greate/ value to u1 & we are deeply grateful to him = hav+ cons5t$ to take up ?is "w4 ,! results ( ! spectrum analysis br\ght conviction to u :5 we 7 /ill 9 d\bt z to ! int]pretation ( ! results ( our rese>*4 ,! fir/ specim5s ( fairly active b>ium *loride conta9+ radium1 exam9$ by ,m4 ,dem>ay1 exhibit$ toge!r ) ! b>ium l9es a new l9e ( consid]able int5sity & ( wave-l5g? #chadg 9 ! ultra-violet4 ,) ! m active products prep>$ subsequ5tly1 ,dem>ay saw ! l9e #chadg m di/9ctly2 at ! same "t o!r new l9es appe>$1 & ! int5sity ( ! new l9es 0 comp>able ) t ( ! b>ium l9es4 ,a fur!r conc5tration furni%$ a product = :i* ! new spectrum pr$om9at$1 & ! ?ree /ronge/ b>ium l9es1 alone visible1 m]ely indicat$ ! pres5ce ( ?is metal z an impurity4 ,?is product may be look$ ^u z ne>ly pure radium *loride4 ,f9ally1 by fur!r purification1 ,i obta9$ an exce$+ly pure *loride1 9 ! spectrum ( :i* ! two *ief b>ium l9es 7 sc>cely visible4 ,! foll[+ is a li/1 accord+ to ,dem>ay1 ( ! pr9cipal radium l9es = ! portion ( ! spectrum includ$ betwe5 #ejjj & #cejj 4 ,! int5sity ( ea* l9e is repres5t$ by a figure1 ! /ronge/ be+ m>k$ #af3-- 4 ,int5sity4 #dhbfc #aj #dgbfi #e #dfiih #c #dfiba #g #dfhcj #ad #dfdai #d #dfjjc #c #decce #i #ddcfa #h #dcdjf #ab #chadg #af #cfdif #ab ,all ! l9es are cle> & n>r[1 ! ?ree l9es #chadg1 #dfhcj1 #dcdjf are /rong1 & equal ! mo/ int5se ( ^? actually kn[n4 ,two well-m>k$ mi/y b&s are also visible 9 ! spectrum4 ,! fir/1 :i* is symmetrical1 ext5ds f #dfcaj to #dfbai1 ) a maximum at #dfbge4 ,! second1 :i* is /rong]1 fades t[>ds ! ultra-violet2 x beg9s1 %>ply def9$1 at #ddfcg1 & passes ?r\gh a maximum at #ddeeb2 ! region ( ! maximum ext5ds z f> z #ddecd1 !n a nebul\s b&1 gradually fad+1 ext5ds ab\t z f> z #dci4 ,9 ! lea/ refrangible "p1 n photograph$ 9 ! sp>k spectrum1 ! only significant l9e is #effe 7approx471 mu* m feeble1 h[ev]1 ?an #dhbfc4 ,! g5]al aspect ( ! spectrum is t ( ! metals ( ! alkal9e e>?s2 ^! metals are kn[n to h well-m>k$ l9e spectra ) c]ta9 nebul\s b&s4 ,accord+ to ,dem>ay1 ! position ( radium may be among ! bodies possess+ ! mo/ s5sitive spectrum reaction4 ,i also h conclud$ f ! "w ( conc5tration1 t 9 ! fir/ specim5 exam9$1 :i* %[$ cle>ly ! l9e #chadg1 ! proportion ( radium mu/ h be5 v small 7p]haps ab\t #jjb p] c5t74 ,nev]!less1 an activity fifty times z great z t ( metallic uranium is requir$ 9 ord] to di/+ui% cle>ly ! pr9cipal radium l9e 9 ! spectra photograph$4 ,) a s5sitive electromet] ! radio-activity ( a sub/ance only #a_/ajj ( t ( metallic uranium c be detect$4 ,x is cle> t1 9 ord] to detect ! pres5ce ( radium1 ! prop]ty ( radio-activity is sev]al ?\s& times m s5sitive ?an ! spectrum reaction4 ,bismu? conta9+ polonium & ?orium conta9+ act9ium1 bo? v active1 exam9$ by ,dem>ay1 h s f> ea* only yield$ bismu? & ?orium l9es4 ,9 a rec5t publication1 ,m4 ,giesel1 :o is occupi$ 9 prep>+ radium1 /ates t radium bromide gives a c>m9e flame col\ration4 ,! flame spectrum ( radium conta9s two beautiful r$ b&s1 "o l9e 9 ! blue-gre51 & two fa9t l9es 9 ! violet4 ,extraction ( ! ,new ,radio-active ,sub/ances4 ,! fir/ /age ( ! op]ation consi/s 9 extract+ b>ium ) radium f ! ores ( uranium1 also bismu? ) polonium & ! r>e e>?s conta9+ act9ium f ! same4 ,^! ?ree prim>y products hav+ be5 obta9$1 ! next /ep is 9 ea* case to endeav\r to isolate ! new radio-active body4 ,?is second "p ( ! treatm5t consi/s ( a process ( fractionation4 ,! difficulty ( f9d+ a v p]fect means ( sep>at+ closely alli$ elem5ts is well kn[n2 me?ods ( fractionation are !re=e q suitable4 ,besides ?is1 :5 a m]e trace ( "o elem5t is mix$ ) ano!r elem5t1 no me?od ( complete sep>ation c\ld be appli$ to ! mixture1 ev5 all[+ t su* a me?od 0 kn[n2 9 fact1 "o w\ld run ! risk ( los+ ! trace ( ! mat]ial to be sep>at$4 ,! p>ticul> object ( my "w has be5 ! isolation ( radium & polonium4 ,aft] work+ = sev]al ye>s1 ,i h s f> only succe$$ 9 obta9+ ! =m]4 ,pit*bl5de is an exp5sive ore1 & we h giv5 up ! treatm5t ( x 9 l>ge quantities4 ,9 ,europe ! extraction ( ?is ore is c>ri$ out 9 ! m9e ( ,joa*im/hal1 9 ,bohemia4 ,! cru%$ ore is roa/$ ) c>bonate ( soda1 & ! result+ mat]ial wa%$1 fir/ ) w>m wat] & !n ) dilute sulphuric acid4 ,! solution conta9s ! uranium1 :i* gives pit*bl5de its value4 ,! insoluble residue is reject$4 ,?is residue conta9s radio-active sub/ances2 its activity is f\r & a-half times t ( metallic uranium4 ,! ,au/rian ,gov]nm5t1 to :om ! m9e belongs1 pres5t$ u ) a ton ( ?is residue = our rese>*1 & au?oris$ ! m9e to give u sev]al tons m ( ! mat]ial4 ,x 0 n v easy to apply ! me?ods ( ! laboratory to ! prelim9>y treatm5t ( ! residue 9 ! factory4 ,m4 ,debi]ne inve/igat$ ?is "q1 & organis$ ! treatm5t 9 ! factory4 ,! mo/ important po9t ( 8 me?od is ! conv]sion ( ! sulphates into c>bonate by boil+ ! mat]ial ) a conc5trat$ solution ( sodium c>bonate4 ,?is me?od avoids ! necessity ( fus+ ) sodium c>bonate4 ,! residue *iefly conta9s ! sulphates ( lead & calcium1 silica1 alum9a1 & iron oxide4 ,9 addition ne>ly all ! metals are f\nd 9 great] or small] am\nt 7copp]1 bismu?1 z9c1 cobalt1 manganese1 nickel1 vanadium1 antimony1 ?allium1 r>e e>?s1 niobium1 tantalum1 ars5ic1 b>ium1 c474 ,radium is f\nd 9 ?is mixture z sulphate1 & is ! lea/ soluble sulphate 9 x4 ,9 ord] to dissolve x1 x is necess>y to remove ! sulphuric acid z f> z possible4 ,to d ?is1 ! residue is fir/ treat$ ) a boil+ conc5trat$ soda solution4 ,! sulphuric acid comb9$ ) ! lead1 alum9ium1 & calcium passes1 = ! mo/ "p1 into solution z sulphate ( sodium1 :i* is remov$ by repeat$ly wa%+ ) wat]4 ,! alkal9e solution removes at ! same "t lead1 silicon1 & alum9ium4 ,! insoluble portion is attack$ by ord9>y hydro*loric acid4 ,?is op]ation completely dis9tegrates ! mat]ial1 & dissolves mo/ ( x4 ,polonium & act9ium may be obta9$ f ?is solution2 ! =m] is precipitat$ by sulphurett$ hydrog51 ! latt] is f\nd 9 ! hydrates precipitat$ by ammonia 9 ! solution sep>at$ f ! sulphides & oxidis$4 ,radium rema9s 9 ! insoluble portion4 ,?is portion is wa%$ ) wat]1 & !n treat$ ) a boil+ conc5trat$ solution ( c>bonate ( soda4 ,?is op]ation completes ! trans=mation ( ! sulphates ( b>ium & radium into c>bonates4 ,! mat]ial is !n ?or\ghly wa%$ ) wat]1 & !n treat$ ) dilute hydro*loric acid1 q free f sulphuric acid4 ,! solution conta9s radium z well z polonium & act9ium4 ,x is filt]$ & precipitat$ ) sulphuric acid4 ,9 ?is way ! crude sulphates ( b>ium conta9+ radium & calcium1 ( lead1 & ( iron1 & ( a trace ( act9ium are obta9$4 ,! solution /ill conta9s a little act9ium & polonium1 :i* may be sep>at$ out z 9 ! case ( ! fir/ hydro*loric acid solution4 ,f "o ton ( residue #aj to #bj kilogrms4 ( crude sulphates are obta9$1 ! activity ( :i* is f ?irty to sixty times z great z t ( metallic uranium4 ,!y mu/ n[ be purifi$4 ,= ?is purpose !y are boil$ ) sodium c>bonate & trans=m$ into ! *lorides4 ,! solution is treat$ ) sulphurett$ hydrog51 :i* gives a small quantity ( active sulphides conta9+ polonium4 ,! solution is filt]$1 oxidis$ by means ( *lor9e1 & precipitat$ ) pure ammonia4 ,! precipitat$ hydrates & oxides are v active1 & ! activity is due to act9ium4 ,! filt]$ solution is precipitat$ ) sodium c>bonate4 ,! precipitat$ c>bonates ( ! alkal9e e>?s are wa%$ & conv]t$ into *lorides4 ,^! *lorides are evaporat$ to dryness1 & wa%$ ) pure conc5trat$ hydro*loric acid4 ,calcium *loride dissolves almo/ entirely1 :il/ ! *loride ( b>ium & radium rema9s insoluble4 ,?us1 f "o ton ( ! orig9al mat]ial ab\t #h kilogrms4 ( b>ium & radium *loride are obta9$1 ( :i* ! activity is ab\t sixty times t ( metallic uranium4 ,! *loride is n[ ready = fractionation4 ,polonium4 ,z ,i said above1 by pass+ sulphurett$ hydrog5 ?r\gh ! v>i\s hydro*loric acid solutions obta9$ dur+ ! c\rse ( ! process1 active sulphides are precipitat$1 ( :i* ! activity is due to polonium4 ,^! sulphides *iefly conta9 bismu?1 a little copp] & lead2 ! latt] metal occurs 9 relatively small am\nt1 because x has be5 to a great ext5t remov$ by ! soda solution1 & because its *loride is only slightly soluble4 ,antimony & ars5ic are f\nd among ! oxides only 9 ! m9ute/ quantity1 _! oxides hav+ be5 dissolv$ by ! soda4 ,9 ord] to obta9 ! v active sulphides1 ! foll[+ process 0 employ$3--,! solutions made /rongly acid ) hydro*loric acid 7 precipitat$ ) sulphurett$ hydrog52 ! sulphides ?us precipitat$ are v active1 & are employ$ = ! prep>ation ( polonium2 !re rema9 9 ! solution sub/ances n completely precipitat$ 9 pres5ce ( excess ( hydro*loric acid 7bismu?1 lead1 antimony74 ,to complete ! precipitation1 ! solution is dilut$ ) wat]1 & treat$ aga9 ) sulphurett$ hydrog51 :i* gives a second precipitate ( sulphides1 mu* less active ?an ! fir/1 & :i* h g5]ally be5 reject$4 ,= ! fur!r purification ( ! sulphides1 !y are wa%$ ) ammonium sulphide1 :i* removes ! la/ rema9+ traces ( antimony & ars5ic4 ,!y are !n wa%$ ) wat] & ammonium nitrate1 & treat$ ) dilute nitric acid4 ,complete solution nev] occurs2 !re is always an insoluble residue1 m or less consid]able1 :i* c be treat$ afre% if x is judg$ exp$i5t4 ,! solution is r$uc$ to a small volume & precipitat$ ei!r by ammonia or by excess ( wat]4 ,9 bo? cases ! lead & ! copp] rema9 9 solution2 9 ! second case1 a little bismu?1 sc>cely active at all1 rema9s also 9 solution4 ,! precipitate ( oxides or basic nitrates is subject$ to fractionation 9 ! foll[+ mann]3--,! precipitate is dissolv$ 9 nitric acid1 & wat] is add$ to ! solution until a suffici5t quantity ( precipitate is =m$2 x mu/ be borne 9 m9d t sometimes ! precipitate does n at once appe>4 ,! precipitate is sep>at$ f ! sup]natant liquid1 & re-dissolv$ 9 nitric acid1 aft] :i* bo? ! liquids ?us obta9$ are re-precipitat$ ) wat]1 & treat$ z be=e4 ,! diff]5t fractions are comb9$ accord+ to _! activity1 & conc5tration is c>ri$ out z f> z possible4 ,9 ?is way is obta9$ a v small quantity ( a sub/ance ( :i* ! activity is v high1 b :i*1 nev]!less1 has s f> only %[n bismu? l9es 9 ! spectroscope4 ,!re is1 un=tunately1 little *ance ( obta9+ ! isolation ( polonium by ?is means4 ,! me?od ( fractionation j describ$ pres5ts _m difficulties1 & ! case is simil> ) o!r wet processes ( fractionation4 ,:atev] be ! me?od employ$1 comp\nds are readily =m$ :i* are absolutely insoluble 9 dilute or conc5trat$ acids4 ,^! comp\nds c only be re-dissolv$ by r$uc+ !m to ! metallic /ate1 e4g41 by fusion ) potassium cyanide4 ,consid]+ ! numb] ( op]ations necess>y1 ?is circum/ance con/itutes an enorm\s difficulty 9 ! progress ( ! fractionation4 ,?is ob/acle is ! great] because polonium1 once extract$ f ! pit*bl5de1 dim9i%es 9 activity4 ,?is dim9ution ( activity is sl[1 = a specim5 ( bismu? nitrate conta9+ polonium only lo/ half its activity 9 elev5 mon?s4 ,no su* difficulty occurs ) radium4 ,! radio-activity rema9s ?r\gh\t an accurate gauge ( ! conc5tration2 ! conc5tration itself pres5ts no difficulty1 & ! progress ( ! "w f ! />t c be con/antly *eck$ by spectral analysis4 ,:5 ! ph5om5a ( induc$ radio-activity1 :i* w be discuss$ lat] on1 7 made kn[n1 x seem$ obvi\s t polonium1 :i* only %[s ! bismu? l9es & ^: activity dim9i%es ) "t1 0 n a new elem5t1 b bismu? made active by ! vic9ity ( radium 9 ! pit*bl5de4 ,i am n sure t ?is op9ion is correct4 ,9 ! c\rse ( my prolong$ "w on polonium1 ,i h not$ *emical effects1 :i* ,i h nev] obs]v$ ei!r ) ord9>y bismu? or ) bismu? made active by radium4 ,^! *emical effects are1 9 ! fir/ place1 ! extremely ready =mation ( insoluble comp\nds1 ( :i* ,i h spok5 above 7especially basic nitrates71 &1 9 ! second place1 ! col\r & appe>ance ( ! precipitates obta9$ by add+ wat] to ! nitric acid solution ( bismu? conta9+ polonium4 ,^! precipitates are sometimes :ite1 b m g5]ally ( a m or less vivid yell[1 v]g+ on r$4 ,! abs5ce ( l9es o!r ?an ^? ( bismu? does n necess>ily prove t ! sub/ance only conta9s bismu?1 because bodies exi/ ^: spectrum reaction is sc>cely visible4 ,x w\ld be necess>y to prep>e a small quantity ( bismu? conta9+ polonium 9 z conc5trat$ a condition z possible1 & to exam9e x *emically1 9 ! fir/ place det]m9+ ! atomic weight ( ! metal4 ,x has n yet be5 possible to c>ry out ?is rese>* on acc\nt ( ! difficulties ( a *emical nature already m5tion$4 ,if polonium 7 prov$ to be a new elem5t1 x w\ld be no less true t x _c exi/ indef9itely 9 a /rongly radio-active condition1 at lea/ :5 extract$ f ! ore4 ,!re are !re=e two aspects ( ! "q3--,fir/1 :e!r ! activity ( polonium is entirely induc$ by ! proximity ( sub/ances !mselves radio-active1 9 :i* case polonium w\ld possess ! faculty ( acquir+ atomic activity p]man5tly1 a faculty :i* does n appe> to belong to any sub/ance :atev]2 second1 :e!r ! activity ( polonium is an inh]5t prop]ty1 :i* is spontane\sly de/roy$ "u c]ta9 conditions1 & p]si/s "u c]ta9 o!r conditions1 su* z ^? :i* exi/ 9 ! ore4 ,! ph5om5on ( atomic activity induc$ by contact is /ill s little und]/ood1 t we lack ! gr\nd on :i* to =mulate any op9ion on ! matt]4 7,,note4--,a "w has rec5tly appe>$ on polonium by ,m4 ,m>ckwald4 ,he plunges a small rod ( pure bismu? into a hydro*loric acid solution ( ! bismu? extract$ f ! pit*bl5de residue4 ,aft] "s "t ! rod becomes coat$ ) a v active deposit1 & ! solution n[ conta9s only inactive bismu?4 ,m4 ,m>ckwald also obta9s a v active deposit by add+ t9 *loride to a hydro*loric acid solution ( radio-active bismu?4 ,f ?is he concludes t ! active elem5t is alli$ to tellurium1 & gives x ! "n ( radiotellurium4 ,?is active sub/ance ( ,m4 ,m>ckwald seems id5tical ) polonium1 f its behavi\r1 & f ! easily absorb$ rays x emits4 ,! *oice ( a new "n = ?is sub/ance is futile 9 ! pres5t /ate ( ! "q74 ,prep>ation ( ! ,pure ,*loride ( ,radium4 ,! me?od by :i* ,i extract$ pure radium *loride f b>ium *loride conta9+ radium consi/s 9 fir/ subject+ ! mixture ( ! *lorides to fractional cry/allisation 9 pure wat]1 !n 9 wat] to :i* hydro*loric acid has be5 add$4 ,! diff]5ce 9 solubility ( ! two *lorides is ?us made use (1 t ( radium be+ less soluble ?an t ( b>ium4 ,at ! beg9n+ ( ! fractionation1 pure di/ill$ wat] is us$4 ,! *loride is dissolv$1 & ! solution rais$ to boil+-po9t1 & all[$ to cry/allise by cool+ 9 a cov]$ capsule4 ,beautiful cry/als =m at ! bottom1 & ! sup]natant1 saturat$ solution is easily decant$4 ,if "p ( ?is solution be evaporat$ to dryness1 ! *loride obta9$ is f\nd to be ab\t five times less active ?an t :i* has cry/allis$ out4 ,! *loride is ?us divid$ into two portions1 ,a & ,b--portion ,a be+ m active ?an portion ,b4 ,! op]ation is n[ repeat$ ) ea* ( ! *lorides ,a & ,b1 & 9 ea* case two new portions are obta9$4 ,:5 ! cry/allisation is f9i%$1 ! less active fraction ( *loride ,a is add$ to ! m active fraction ( *loride ,b1 ^! two hav+ approximately ! same activity4 ,?us !re are n[ ?ree portions to und]go afre% ! same treatm5t4 ,! numb] ( portions is n all[$ to increase indef9itely4 ,! activity ( ! mo/ soluble portion dim9i%es z ! numb] increases4 ,:5 its activity becomes inconsid]able1 x is )drawn f ! fractionation4 ,:5 ! desir$ numb] ( fractions has be5 obta9$1 fractionation ( ! lea/ soluble portion is /opp$ 7! ri*e/ 9 radium71 & x is )drawn f ! rema9d]4 ,a fix$ numb] ( fractions is us$ 9 ! process4 ,aft] ea* s]ies ( op]ations1 ! saturat$ solution aris+ f "o fraction is add$ to ! cry/als aris+ f ! foll[+ fraction2 b if aft] "o ( ! s]ies ! mo/ soluble fraction has be5 )drawn1 !n1 aft] ! foll[+ s]ies1 a new fraction is made f ! mo/ soluble portion1 & ! cry/als ( ! mo/ active portion are )drawn4 ,by ! successive alt]ation ( ^! two processes1 an extremely regul> sy/em ( fractionation is obta9$1 9 :i* ! numb] ( fractions & ! activity ( ea* rema9s con/ant1 ea* be+ ab\t five times z active z ! subsequ5t "o1 & 9 :i*1 on ! "o h&1 an almo/ inactive product is remov$1 :il/1 on ! o!r1 is obta9$ a *loride ri* 9 radium4 ,! am\nt ( mat]ial conta9$ 9 ^! fractions gradually dim9i%es1 becom+ less z ! activity increases4 ,at fir/ six fractions 7 us$1 & ! activity ( ! *loride obta9$ at ! end 0 only #ja t ( uranium4 ,:5 mo/ ( ! inactive matt] has be5 remov$1 & ! fractions h become small1 "o fraction is remov$ f ! "o end1 & ano!r is add$ to ! o!r end consi/+ ( ! active *loride previ\sly remov$4 ,a *loride ri*] 9 radium ?an ! prec$+ is ?us obta9$4 ,?is sy/em is cont9u$ until ! cry/als obta9$ are pure radium *loride4 ,if ! fractionation has be5 ?or\ghly c>ri$ out1 sc>cely any trace ( ! int]m$iate products rema94 ,at an advanc$ /age ( ! fractionation1 :5 ! quantity ( mat]ial 9 ea* fraction is small1 ! sep>ation by cry/allisation is less efficaci\s1 ! cool+ be+ too rapid & ! volume ( ! solution to be decant$ too small4 ,x is !n advisable to add wat] conta9+ a kn[n quantity ( hydro*loric acid2 ?is quantity may be increas$ z ! fractionation proce$s4 ,! advantage ga9$ ?us consi/s 9 increas+ ! quantity ( ! solution1 ! solubility ( ! *lorides be+ less 9 wat] acidifi$ ) hydro*loric acid ?an 9 pure wat]4 ,by us+ wat] conta9+ mu* acid1 excell5t sep>ations are effect$1 & x is only necess>y to "w ) ?ree or f\r fractions4 ,! cry/als1 :i* =m 9 v acid solution1 are elongat$ ne$les1 ^? ( b>ium *loride hav+ exactly ! same appe>ance z ^? ( radium *loride4 ,bo? %[ d\ble refraction4 ,cry/als ( b>ium *loride conta9+ radium are col\rless1 b :5 ! proportion ( radium becomes great]1 !y h a yell[ col\ration aft] "s h\rs1 v]g+ on orange1 & sometimes a beautiful p9k4 ,?is col\r disappe>s 9 solution4 ,cry/als ( pure radium *loride are n col\r$1 s t ! col\ration appe>s to be due to ! mixture ( radium & b>ium4 ,! maximum col\ration is obta9$ = a c]ta9 degree ( radium pres5t1 & ?is fact s]ves to *eck ! progress ( ! fractionation4 ,i h sometimes notic$ ! =mation ( a deposit compos$ ( cry/als ( :i* "o "p rema9$ uncol\r$1 :il/ ! o!r 0 col\r$1 & x seems possible t ! col\rless cry/als might be sort$ out4 ,! fractional precipitation ( an aque\s solution ( b>ium *loride by alcohol also leads to ! isolation ( radium *loride1 :i* is ! fir/ to precipitate4 ,?is me?od1 :i* ,i fir/ employ$1 0 f9ally ab&on$ = ! "o j describ$1 :i* proce$s ) m regul>ity4 ,i h1 h[ev]1 occasionally made use ( precipitation by alcohol to purify radium *loride :i* conta9s traces ( b>ium *loride4 ,! latt] rema9s 9 ! slightly aque\s alcoholic solution1 & c ?us be remov$4 ,m4 ,giesel1 :o1 s9ce ! publication ( our fir/ rese>*es1 has be5 prep>+ radio-active bodies1 recomm5ds ! sep>ation ( b>ium & radium by fractional cry/allisation 9 wat] f a mixture ( ! bromides4 ,i c te/ify t ?is me?od is advantage\s1 especially 9 ! fir/ /ages ( ! fractionation4 ,det]m9ation ( ! ,atomic ,weight ( ,radium4 ,9 ! c\rse ( my "w ,i det]m9$ at int]vals ! atomic weight ( ! metal conta9$ 9 specim5s ( b>ium *loride conta9+ radium4 ,) ea* newly obta9$ product ,i c>ri$ ! conc5tration z f> z possible1 s z to h f #ja grm4 to #je grm4 ( mat]ial conta9+ mo/ ( ! activity ( ! mixture4 ,f ?is small quantity ,i precipitat$ ) alcohol or ) hydro*loric acid "s milligrams ( *loride = spectral analysis4 ,?anks to 8 excell5t me?od1 ,dem>ay only requir$ ?is small quantity ( mat]ial to obta9 ! photograph ( ! sp>k spectrum4 ,i made an atomic weight det]m9ation ) ! product rema9+4 ,i employ$ ! classic me?od ( weigh+ z silv] *loride ! *lor9e conta9$ 9 a kn[n weight ( ! anhydr\s *loride4 ,z control exp]im5t1 ,i det]m9$ ! atomic weight ( b>ium by ! same me?od1 "u ! same conditions1 & ) ! same quantity ( mat]ial1 fir/ #je grm4 & !n #ja grm4 ,! figures obta9$ 7 always betwe5 #acg & #ach4 ,i ?us saw t ! me?od gives satisfactory results1 ev5 ) a v small quantity ( mat]ial4 ,! fir/ two det]m9ations 7 made ) *lorides1 ( :i* "o 0 #bcj times & ! o!r #fjj times z active z uranium4 ,^! two exp]im5ts gave ! same figure z ! exp]im5t ) ! pure b>ium *loride4 ,!re 0 !re=e no hope ( f9d+ a diff]5ce except by us+ a mu* m active product4 ,! foll[+ exp]im5t 0 made ) a *loride1 ! activity ( :i* 0 ab\t #cejj times z great z t ( uranium2 & ?is exp]im5t enabl$ me1 = ! fir/ "t1 to obs]ve a small b di/9ct diff]5ce2 ,i f\nd1 z ! mean atomic weight ( ! metal conta9$ 9 ?is *loride1 ! numb] #adj1 :i* %[$ t ! atomic weight ( radium mu/ be high] ?an t ( b>ium4 ,by us+ m & m active products1 & obta9+ spectra ( radium ( increas+ int5sity1 ,i f\nd t ! figures obta9$ rose 9 proportion1 z is se5 9 ! foll[+ table 7p4 #bh74 ,! figures ( column ,a mu/ only be look$ ^u z a r\gh e/imate4 ,! calculation ( ! activity ( /rongly radio-active bodies is difficult1 = _m reasons :i* w be discuss$ lat]4 ,a4 ,m4 #cejj #adj ,spectrum ( radium fa9t4 #dgjj #ada #gejj #adeh ,spectrum ( radium /rong1 b t ( b>ium pr$om9at+4 ,ord] ( ,magnitude1 #agch ,! two spectra ( almo/ equal int5sity4 #ajf 444 #bbe ,only a trace ( b>ium pres5t4 ,a repres5ts ! activity ( ! *loride1 t ( uranium be+ unity2 ,m ! atomic weight f\nd4 ,at ! t]m9ation ( ! processes describ$ above1 ,i obta9$1 9 ,m>*1 #aijb1 #jab grm4 ( radium *loride1 ( :i* ,dem>ay made ! spectral analysis4 ,?is radium *loride1 9 ! op9ion ( ,dem>ay1 0 fairly pure2 its spectrum1 h[ev]1 %[$ ! ?ree pr9cipal b>ium l9es ) consid]able int5sity4 ,i made f\r successive e/imations ( ! *loride1 ! results ( :i* z foll[s3-- ,anhydr\s radium *loride4 ,silv] *loride4 ,m4 ,i4 #jaaej #jaacj #bbjg ,,ii4 #jaadj #jaaai #bbcj ,,iii4 #jaaace #jajhf #bbbh ,,iv4 #jajibe #jajfde #bbca ,i !n re-purifi$ ?is *loride1 & obta9$ a mu* pur] sub/ance1 9 ! spectrum ( :i* ! two /ronge/ b>ium l9es 7 v fa9t4 ,giv5 ! s5sitiv5ess ( ! spectrum reaction ( b>ium1 ,dem>ay e/imat$ t ! purifi$ *loride conta9$ only ! m]e/ traces ( b>ium1 incapable ( influ5c+ ! atomic weight to an appreciable ext5t4 ,i made ?ree det]m9ations ) ?is p]fectly pure radium *loride4 ,! results 7 z foll[s3-- ,anhydr\s radium *loride4 ,silv] *loride4 ,m4 ,i4 #jjiaib #jjhhij #bbec ,,ii4 #jjhicf #jjhfbg #bbeh ,,iii4 #jjhhci #jjhehi #bbdj ,! mean ( ^! numb]s is #bbe4 ,!y 7 calculat$ 9 ! same way z ! prec$+ ones by consid]+ radium z a bival5t elem5t1 ! *loride hav+ ! =mula ,ra,cl#b1 & tak+ = silv] & *lor9e ! values ,ag #ajgh1 ,cl #ced4 ,h5ce ! atomic weight ( radium is ,ra #bbe4 ,! weigh+s 7 made ) a ,curie ap]iodic balance1 p]fectly regulat$1 accurate to ! tw5tie? ( a milligrm4 ,?is direct read+ balance p]mits ( v rapid weigh+1 a condition :i* is ess5tial 9 ! case ( ! anhydr\s *lorides ( radium & b>ium1 :i* gradually absorb moi/ure1 9 spite ( ! pres5ce ( desiccat+ sub/ances 9 ! balance4 ,! bodies to be weigh$ 7 plac$ 9 a plat9um crucible2 ?is crucible _h be5 long 9 use1 & its weight did n v>y ! t5? "p ( a milligrm4 dur+ ! c\rse ( "o op]ation4 ,! hydrat$ *loride obta9$ by cry/allisation 0 plac$ 9 ! crucible & heat$ till conv]t$ into ! anhydr\s *loride4 ,:5 ! *loride has be5 kept = sev]al h\rs at #ajj its weight becomes con/ant1 & does n *ange ev5 if ! temp]ature is rais$ to #bjj4 ,! anhydr\s *loride ?us obta9$ con/itutes1 !re=e1 a p]fectly def9ite body4 ,! foll[+ is a s]ies ( det]m9ations on ?is po9t4 ,! *loride 7#ajj m4g47 is dri$ 9 ! ov5 at #ee1 & plac$ 9 a desiccator ov] anhydr\s phosphoric acid2 x !n gradually loses weight1 :i* proves t x /ill conta9s moi/ure2 9 ! c\rse ( twelve h\rs ! loss 0 #c m4g4 ,! *loride is replac$ 9 ! /ove1 & ! temp]ature rais$ to #ajj4 ,dur+ ?is process1 ! *loride lo/ #fc m4g4 9 weight4 ,aft] be+ left ?ree h\rs fifte5 m9utes 9 ! ov51 x lo/ #be m4g4 m4 ,! temp]ature 0 ma9ta9$ = =ty-five m9utes betwe5 #ajj & #abj1 :i* caus$ a loss ( weight ( #ja m4g4 ,!n aft] be+ kept = ?irty m9utes at #abe1 ! *loride %[$ no dim9ution 9 weight4 ,!n1 h[ev]1 aft] ?irty m9utes at #aej1 x lo/ #ja m4g4 ,f9ally1 aft] be+ heat$ = f\r h\rs at #bjj1 x lo/ #jae m4g4 ,dur+ ^! op]ations ! crucible v>i$ f #jje m4g4 ,aft] ea* det]m9ation ( ! atomic weight1 ! radium 0 conv]t$ into ! *loride 9 ! foll[+ mann]3--,to ! solution conta9+ ! weigh$ radium nitrate & excess ( silv] nitrate 0 add$ pure hydro*loric acid2 ! silv] *loride 0 filt]$ (f2 ! solution 0 evaporat$ to dryness sev]al times ) excess ( pure hydro*loric acid4 ,9 ?is way ! nitric acid is entirely remov$4 ,! precipitat$ silv] *loride 0 always radio-active & phosphoresc5t4 ,9 det]m9+ ! am\nt ( silv] conta9$ 9 x1 ,i satisfi$ myself t no pond]able am\nt ( radium _h be5 c>ri$ d[n ) x out ( ! solution4 ,! me?od ,i pursu$ 0 to r$uce ! silv] *loride precipitat$ 9 ! crucible by hydrog5 g5]at$ f dilute hydro*loric acid & z9c2 aft] wa%+1 ! crucible 0 weigh$ ) ! metallic silv] conta9$ 9 x4 ,i made ano!r exp]im5t :i* %[$ t ! weight ( radium *loride reg5]at$ 0 ! same z t be=e beg9n+ ! op]ation4 ,^! v]ifications are n s reliable z direct exp]im5ts2 b !y s]ve to indicate ! abs5ce ( any significant error4 ,f its *emical prop]ties1 radium is an elem5t ( ! gr\p ( alkal9e e>?s1 be+ ! memb] next above b>ium4 ,f its atomic weight also1 radium takes its place 9 ,m5deleeff's table aft] b>ium ) ! alkal9e e>? metals1 9 ! r[ :i* already conta9s uranium & ?orium4 ,*>act]i/ics ( ! ,radium ,salts4 ,! salts ( radium1 *loride1 nitrate1 c>bonate1 & sulphate1 resemble ^? ( b>ium1 :5 fre%ly prep>$1 b !y gradually become col\r$4 ,all ! radium salts are lum9\s 9 ! d>k4 ,9 _! *emical prop]ties1 ! salts ( radium are absolutely analog\s to ! correspond+ salts ( b>ium4 ,h[ev]1 radium *loride is less soluble ?an b>ium *loride2 ! solubility ( ! nitrates 9 wat] is approximately ! same4 ,! salts ( radium are ! s\rce ( a spontane\s & cont9u\s evolution ( heat4 ,fractionation ( ,ord9>y ,b>ium ,*loride4 ,we h endeav\r$ to det]m9e :e!r comm]cial b>ium *loride conta9s small quantities ( radium *loride1 :i* escape detection ) ! means ( e/imation at our comm&4 ,= ?is purpose we fractionat$ a great quantity ( comm]cial b>ium *loride1 9 ! hope ( ?us conc5trat+ ! trace ( radium *loride if su* 7 pres5t4 ,fifty kilos4 ( comm]cial b>ium *loride 7 dissolv$ 9 wat]2 ! solution 0 precipitat$ by hydro*loric acid free f sulphuric acid1 :i* yield$ #bj kilos4 ( ! precipitat$ *loride4 ,?is 0 dissolv$ 9 wat] & p>tially precipitat$ by hydro*loric acid1 :i* gave #he kilos4 ( precipitat$ *loride4 ,?is *loride 0 fractionat$ by ! me?od us$ = ! b>ium *loride conta9+ radium2 & at ! end ( ! process1 #aj grams ( *loride 7 obta9$1 correspond+ to ! lea/ soluble "p4 ,?is *loride %[$ no radio-activity2 x !re=e conta9$ no radium2 ?is sub/ance is1 consequ5tly1 abs5t f ! ores ( b>ium4 ,,*apt] ,,iii4 ,,radiation ,,( ,,! ,,new ,,radio-,,active ,,sub/ances4 ,me?ods ( ,inve/igation ( ! ,radiation4 ,9 ord] to inve/igate ! radiation emitt$ by radio-active bodies1 any "o ( ! prop]ties ( ?is radiation c be utilis$4 ,?us ! action ( ! rays on photographic plates may s]ve1 or _! prop]ty ( ionisation ( ! air1 :i* r5d]s x a conductor1 or _! capacity = caus+ fluoresc5ce ( c]ta9 bodies4 ,h5ce=?1 9 speak+ ( ^! diff]5t me?ods ( work+1 ,i %all use ! expressions radiographic me?od1 electrical me?od1 fluoroscopic me?od4 ,! fir/ two h be5 us$ f ! beg9n+ 9 ! /udy ( uranium rays2 ! fluoroscopic me?od c only be appli$ 9 ! case ( ! new bodies :i* are /rongly radio-active1 = ! feebly active bodies su* z uranium & ?orium produce no appreciable fluoresc5ce4 ,! electrical me?od is ! only "o :i* s]ves = exact det]m9ations ( int5sity2 ! o!r two are specially adapt$ = giv+ qualitative results1 & only furni% r\gh approximations4 ,! results obta9$ ) ! ?ree me?ods j consid]$ are n /rictly comp>able ! "o ) ! o!r4 ,! s5sitive plate1 ! gas :i* is ionis$1 ! fluoresc5t scre51 are 9 reality receiv]s1 :i* absorb ! en]gy ( ! radiation1 & trans=m x into ano!r k9d ( en]gy1 *emical en]gy1 ionic en]gy1 or lum9\s en]gy4 ,ea* receiv] absorbs a fraction ( ! radiation1 :i* dep5ds ess5tially ^u its nature4 ,lat] on1 we %all see t ! radiation is complex1 t ! fractions ( ! radiation absorb$ by ! diff]5t receiv]s may diff] among !mselves bo? quantitatively & qualitatively4 ,f9ally1 x is nei!r evid5t1 nor ev5 probable1 t ! en]gy absorb$ is entirely trans=m$ by ! receiv] into ! =m t we wi% = obs]vation2 "p ( ?is en]gy may be trans=m$ into heat1 into ! evolution ( second>y radiations :i* may or may n assi/ 9 ! production ( ! obs]v$ ph5om5on1 into *emical action :i* diff]s f t "u obs]vation1 c41 & "h also ! effective action ( ! receiv]1 ) ref]5ce to ! end we h 9 view1 dep5ds ess5tially ^u ! nature ( t receiv]4 ,let u comp>e two radio-active sub/ances1 "o conta9+ radium & ! o!r polonium1 & :i* %[ an equal degree ( activity 9 ! cond5s] ( ,fig4 #a4 ,if ea* is cov]$ ) a ?9 leaf ( alum9ium1 ! second appe>s consid]ably less active ?an ! fir/1 & ! same is ! case :5 !y are plac$ "u ! same fluoresc5t scre51 if ! latt] is ( suffici5t ?ickness1 or is plac$ at a c]ta9 di/ance f ! two radio-active bodies4 ,en]gy ( ,radiation4 ,:atev] be ! me?od ( rese>* employ$1 ! en]gy ( radiation ( ! new radio-active sub/ances is always f\nd to be consid]ably great] ?an t ( uranium & ?orium4 ,?us x is t1 at a %ort di/ance1 !y act in/antane\sly ^u a photographic plate1 :]eas an exposure ( tw5ty-f\r h\rs is necess>y :5 op]at+ ) uranium & ?orium4 ,a fluoresc5t scre5 is vividly illum9at$ by contact ) ! new radio-active bodies1 :il/ no trace ( lum9osity is visible ) uranium & ?orium4 ,f9ally1 ! ionis+ action ^u air is consid]ably /rong] 9 ! ratio ( #ajf approximately4 ,b x is1 /rictly speak+1 n possible to e/imate ! total int5sity ( ! radiation1 z 9 ! case ( uranium1 by ! electrical me?od describ$ at ! beg9n+ 7,fig4 #a74 ,) uranium1 = example1 ! radiation is almo/ completely absorb$ by ! lay] ( air betwe5 ! plates1 & ! limit+ curr5t is rea*$ at a t5sion ( #ajj volts4 ,b ! case is diff]5t = /rongly radio-active bodies4 ,"o portion ( ! radiation ( radium consi/s ( v p5etrat+ rays1 :i* p5etrate ! cond5s] & ! metallic plates1 & are n utilis$ 9 ionis+ ! air betwe5 ! plates4 ,fur!r1 ! limit+ curr5t _c always be obta9$ = ! t5sions suppli$2 = example1 ) v active polonium ! curr5t rema9s proportional to ! t5sion betwe5 #ajj & #ejj volts4 ,!re=e ! exp]im5tal conditions :i* give a simple int]pretation are n realis$1 &1 consequ5tly1 ! numb]s obta9$ _c be tak5 z repres5t+ ! measurem5t ( ! total radiation2 !y m]ely po9t to a r\gh approximation4 ,complex ,nature ( ! ,radiation4 ,! rese>*es ( v>i\s physici/s 7,,mm4 ,becqu]el1 ,mey] & von ,s*weidl]1 ,giesel1 ,vill>d1 ,ru!r=d1 ,m4 & ,mdme4 ,curie7 h prov$ ! complex nature ( ! radiation ( radio-active bodies4 ,x w be conv5i5t to specify ?ree k9ds ( rays1 :i* ,i %all d5ote1 accord+ to ! notation adopt$ by ,mr4 ,ru!r=d1 by ! lett]s 1 1 4 ,i4 ,! -rays are v slightly p5etrat+1 & appe> to con/itute ! pr9cipal "p ( ! radiation4 ,^! rays are *>act]is$ by ! laws by :i* !y are absorb$ by matt]4 ,! magnetic field acts v slightly ^u !m1 & !y 7 =m]ly ?\ght to be q unaffect$ by ! action ( ?is field4 ,h[ev]1 9 a /rong magnetic field1 ! -rays are slightly deflect$2 ! deflection is caus$ 9 ! same mann] z ) ca?ode rays1 b ! direction ( ! deflection is rev]s$2 x is ! same z = ! canal rays ( ! ,crookes tubes4 ,,ii4 ,! -rays are less absorbable z a :ole ?an ! prec$+ ones4 ,!y are deflect$ by a magnetic field 9 ! same mann] & direction z ca?ode rays4 ,,iii4 ,! -rays are p5etrat+ rays1 unaffect$ by ! magnetic field1 & comp>able to ,rntg5 rays4 ,illu/ration3 ,,fig4 #d4 ,consid] ! foll[+ imag9>y exp]im5t3--,"s radium1 ,r1 is plac$ at ! bottom ( a small deep cavity1 holl[$ 9 a block ( lead1 ,p 7,fig4 #d74 ,a %eaf ( rays1 rectil9e> & slightly exp&$1 /reams f ! receptacle4 ,let u suppose t a /rong uni=m magnetic field is e/abli%$ 9 ! neighb\rhood ( ! receptacle1 normal to ! plane ( ! figure & direct$ t[>ds ! back4 ,! ?ree gr\ps ( rays1 1 1 1 w n[ be sep>at$4 ,!n r fa9t -rays cont9ue 9 _! /raight pa? )\t a trace ( deviation4 ,! -rays are deflect$ 9 ! mann] ( ca?ode rays1 & describe circul> pa?s 9 ! plane ( ! figure4 ,if ! receptacle is plac$ on a photographic plate1 ,a ,c1 ! portion1 ,b ,c1 ( ! plate :i* receives ! -rays is act$ ^u4 ,la/ly1 ! -rays =m a v int5se %aft :i* is slightly deflect$1 & :i* is soon absorb$ by ! air4 ,^! rays describe 9 ! plane ( ! figure a pa? ( great curvature1 ! direction ( ! deflection be+ ! rev]se ( t ) ! -rays4 ,if ! receptacle is cov]$ ) a ?9 %eet ( alum9ium 7#ja m4m4 ?ick71 ! -rays are suppress$ almo/ entirely1 ! -rays are less5$1 & ! -rays d n appe> to be absorb$ to any great ext5t4 ,action ( ! ,magnetic ,field4 ,we h se5 t ! rays emitt$ by radio-active bodies h _m prop]ties common to ca?ode rays & to ,rntg5 rays4 ,ca?ode rays1 z well z ,rntg5 rays1 ionise ! air1 act on photographic plates1 cause fluoresc5ce1 und]go no regul> deflection4 ,b ! ca?ode rays diff] f ,rntg5 rays 9 be+ deflect$ f _! rectil9e> pa? by ! action ( ! magnetic field1 & 9 ! transportation ( *>ges ( negative electricity4 ,! fact t ! magnetic field acts ^u ! rays emitt$ by radio-active sub/ances 0 discov]$ almo/ simultane\sly by ,,mm4 ,giesel1 ,mey] & von ,s*weidl]1 & ,becqu]el4 ,^! physici/s obs]v$ t ! rays ( radio-active sub/ances are deflect$ by ! magnetic field 9 ! same mann] & direction z ! ca?ode rays2 _! obs]vations 7 9 relation to ! -rays4 ,m4 ,curie demon/rat$ t ! radiation ( radium comprises two gr\ps ( q di/9ct rays1 ( :i* "o is readily deflect$ by ! magnetic field 7-rays71 :il/ ! o!r seems to be unaffect$ by ! action ( ?is field 7- & -rays74 ,m4 ,becqu]el did n f9d t ! specim5s ( polonium prep>$ by u emitt$ rays ( ! ca?ode k9d4 ,on ! contr>y1 he fir/ notic$ ! effect ( ! magnetic field on a specim5 ( polonium prep>$ by himself4 ,none ( ! polonium prep>$ by u ev] gave rise to rays ( ! ca?ode ord]4 ,! polonium ( ,m4 ,giesel only gives rise to ^! rays :5 rec5tly prep>$1 & x is probable t ! emission is due to ! ph5om5on ( induc$ radio-activity ( :i* we %all speak lat]4 ,! foll[+ are exp]im5ts :i* prove t "o portion ( ! radiation ( radium1 & "o portion only1 consi/s ( easily deflect$ rays 7-rays74 ,^! exp]im5ts 7 done accord+ to ! electrical me?od4 ,! radio-active body ,a 7,fig4 #e7 s5ds =? radiations 9 ! direction ,a ,d betwe5 ! plates ,p & ,p4 ,! plate ,p is n[ at a pot5tial ( #ejj volts1 plate ,p is connect$ to an electromet] & to a qu>tz electric piezomet]4 ,! int5sity ( ! curr5t pass+ ?r\gh ! air "u ! influ5ce ( ! radiations is measur$4 ,! magnetic field c be e/abli%$ at w p]p5dicul> to ! plane ( ! figure ov] ! :ole region ,e ,e ,e ,e4 ,if ! rays are deflect$1 ev5 slightly1 !y no long] pass betwe5 ! plates1 & ! curr5t is suppress$4 ,! region ( ! passage ( ! rays is surr\nd$ ) masses ( lead1 ,b1 ,b1 ,b1 & by ! armatures ( ! electro-magnet2 :5 ! rays are deflect$1 !y are absorb$ by ! masses ( lead ,b & ,b4 ,illu/ration3 ,,fig4 #e4 ,! results obta9$ dep5d ess5tially on ! di/ance1 ,a ,d1 ( ! radiat+ sub/ance1 ,a1 f ! cond5s] at ,d4 ,if ! di/ance ,a ,d is great en\gh 7great] ?an #g c4m471 mo/ ( ! radium rays 7#ij to #ajj p] c5t7 arriv+ at ! cond5s] are deflect$ & suppress$ = a field ( #bejj units4 ,^! are ! -rays4 ,if ! di/ance ,a ,d is less ?an #fe m4m41 a small] "p ( ! rays are deflect$ by ! action ( ! field2 ?is portion is also entirely deflect$ by a field ( #bejj units1 & ! proportion ( ! rays suppress$ is n increas$ by increas+ ! field f #bejj to #gjjj units4 ,! proportion ( ! rays n suppress$ by ! field increases ) decrease ( ! di/ance1 ,a ,d1 betwe5 ! radiat+ body & ! cond5s]4 ,= small di/ances1 ! rays :i* c be easily deflect$ =m a v small fraction ( ! total radiation4 ,! p5etrat+ rays are !re=e1 = ! mo/ "p1 deviable rays ( ! ca?ode ord] 7-rays74 ,"u ! exp]im5tal conditions j describ$1 ! action ( ! magnetic field on ! -rays c\ld n be well obs]v$ = ! fields employ$4 ,! *ief radiation1 app>5tly und]go+ no deflection1 obs]v$ at a %ort di/ance f ! radiat+ s\rce1 consi/$ ( -rays2 ! undeflect$ radiation obs]v$ at a great] di/ance consi/$ ( -rays4 ,if an absorb+ lam9a 7alum9ium or black pap]7 is plac$ 9 ! pa? ( ! bundle ( rays1 ^? :i* pass ?r\gh are ne>ly all deflect$ by ! field 9 su* a way t1 ) ! aid ( ! scre5 & ! magnetic field1 almo/ all ! radiation is suppress$ 9 ! cond5s]1 ! rema9d] be+ due to ! -rays1 ! proportion ( :i* is small4 ,! -rays are absorb$ by ! scre54 ,an alum9ium plate ( #a_/ajj m4m4 ?ickness is suffici5t = ! suppression ( almo/ all ! rays n readily deflect$ :5 ! sub/ance is f> en\gh f ! cond5s]2 = small] di/ances 7#cd m4m4 & #ea m4m47 two pieces ( ?is alum9ium foil are necess>y to give ! same result4 ,simil> det]m9ations 7 made ) f\r sub/ances conta9+ radium 7*lorides or c>bonates7 ( v diff]5t activity2 analog\s results 7 obta9$4 ,x may be rem>k$ t1 9 all cases1 ! p5etrat+ rays deflect$ by ! magnet 7-rays7 =m only a small fraction ( ! total radiation2 !y influ5ce b slightly ! det]m9ations 9 :i* ! :ole radiation is made use ( to produce conductivity ( ! air4 ,! radiation emitt$ by polonium may be /udi$ by ! electrical me?od4 ,:5 ! di/ance1 ,a ,d1 ( ! polonium f ! cond5s] is v>i$1 no curr5t is obs]v$ at fir/ :ile ! di/ance is fairly great2 on ne>+ ! polonium1 ! radiation sudd5ly becomes manife/ ) great int5sity2 ! curr5t !n increases uni=mly :il/ approa*+ ! polonium1 b ! magnetic field produces no appreciable effect "u ^! conditions4 ,! radiation ( polonium is app>5tly limit$ 9 space1 & does n pass into ! air beyond a k9d ( %ea? surr\nd+ ! sub/ance to a ?ickness ( sev]al c5timetres4 ,! int]pretation ( ! exp]im5ts ,i h j describ$ mu/ be accompani$ by "s important g5]al res]vations4 ,9 speak+ ( ! proportion ( ! rays deflect$ by ! magnet1 ,i ref] only to t portion ( ! radiation capable ( caus+ a curr5t 9 ! cond5s]4 ,9 employ+ ! fluoresc5t action ( ! ,becqu]el rays1 or _! action on photographic plates1 ! proportion w\ld probably be diff]5t--a measure ( int5sity hav+1 z a rule1 no mean+ except = ! me?od ( measurem5t adopt$4 ,! rays ( polonium are -rays4 ,9 ! exp]im5ts j describ$1 ,i obs]v$ no action ( ! magnetic field ^u !m1 b ! exp]im5tal conditions 7 su* t a slight deflection w\ld pass unnotic$4 ,! exp]im5ts made by ! radiographic me?od confirm$ ! prec$+ results4 ,tak+ radium z ! s\rce ( radiation1 & receiv+ ! impression on a plate p>allel to ! primitive %aft & normal to ! field1 a v cle> pr9t is obta9$ ( two %afts sep>at$ by ! action ( ! field1 ! "o deflect$1 ! o!r n deflect$4 ,! -rays con/itute ! deflect$ beam2 ! -rays1 be+ v slightly deflect$1 are n to be di/+ui%$ f ! undeflect$ bundle ( ! -rays4 ,deflect$ -,rays4 ,! exp]im5ts ( ,m4 ,giesel & ,,mm4 ,mey] & von ,s*weidl] %[$ t ! radiation ( ! radio-active bodies is1 9 "p at lea/1 deflect$ by a magnetic field1 & t ?is deflection resembles t ( ! ca?ode rays4 ,m4 ,becqu]el inve/igat$ ! action ( ! field on ! rays by ! radiographic me?od4 ,! exp]im5tal arrangem5t 0 t ( ,fig4 #d4 ,! radium 0 plac$ 9 ! lead receptacle1 ,p1 & ?is receptacle 0 plac$ on ! s5sitive face ( a photographic plate1 ,a ,c1 cov]$ ) black pap]4 ,! :ole 0 plac$ betwe5 ! poles ( an electro-magnet1 ! magnetic field be+ normal to ! plane ( ! figure4 ,if ! field is direct$ to ! back ( ?is plane1 ! "p ,b ,c ( ! plate is act$ ^u by rays :i*1 aft] hav+ describ$ circul> pa?s1 return to ! plate & /rike x at a "r angle4 ,^! rays are -rays4 ,m4 ,becqu]el has demon/rat$ t ! impression consi/s ( a wide diffus$ b&1 a cont9u\s spectrum inde$1 %[+ t ! %eaf ( deviable rays emitt$ by ! s\rce is =m$ ( an inf9ite numb] ( radiations unequally deflect$4 ,if ! gelat9 ( ! plate be cov]$ ) diff]5t absorb5t scre5s 7pap]1 glass1 metals71 "o portion ( ! spectrum is suppress$1 & x is f\nd t ! rays mo/ deflect$ by ! magnetic field--o!rwise ^? :i* h ! smalle/ radius ( curvature--are ! mo/ completely absorb$4 ,) ea* scre51 ! impression on ! plate beg9s at a c]ta9 di/ance f ! s\rce ( radiation1 ?is di/ance be+ proportional to ! absorptive p[] ( ! scre54 ,*>ge ( ! ,deflect$ ,rays4 ,! ca?ode rays are1 z %[n by ,m4 ,p]r91 *>g$ ) negative electricity4 ,fur!r1 accord+ to ! exp]im5ts ( ,m4 ,p]r9 & ,m4 ,l5>d1 !y are capable ( c>ry+ _! *>ge ?r\gh ! metallic envelopes connect$ to e>? & ?r\gh isolat+ scre5s4 ,at e po9t :]e ! ca?ode rays are absorb$1 !re is a cont9u\s evolution ( negative electricity4 ,we h prov$ t ! same is ! case = ! deflect$ -rays ( radium4 ,! deviable -rays ( radium are *>g$ ) negative electricity4 7,,note4--,let ! radio-active sub/ance be plac$ on "o ( ! plates ( a cond5s]1 ?is plate be+ connect$ to e>?2 ! second plate is connect$ to an electromet]1 x receives & absorbs ! rays emitt$ by ! sub/ance4 ,if ! rays are *>g$1 a cont9u\s fl[ ( electricity into ! electromet] %\ld be obs]v$4 ,9 ?is exp]im5t1 c>ri$ out 9 air1 we 7 n able to detect a *>ge accompany+ ! rays1 b su* an exp]im5t is n delicate4 ,! air betwe5 ! plates be+ caus$ by ! rays to conduct1 ! electromet] is no long] isolat$1 & c only respond to *>ges if ^! be suffici5tly /rong4 ,9 ord] t ! -rays may n int]f]e ) ! exp]im5t1 !y may be suppress$ by cov]+ ! s\rce ( radiation ) a ?9 metallic scre54 ,we repeat$ ?is exp]im5t1 )\t m success1 by caus+ ! rays to pass ?r\gh ! int]ior ( a ,f>aday cyl9d] 9 connection ) ! electromet]74 ,accord+ to ! prec$+ exp]im5ts1 x 0 evid5t t ! *>ge ( ! rays ( ! radiat+ body employ$ 0 a weak "o4 ,9 ord] to fix a feeble evolution ( electricity ^u ! conductor :i* absorbs ! rays1 ?is conductor %\ld be completely insulat$2 ?is is effect$ by scre5+ x f ! air1 ei!r by plac+ x 9 a tube ) a v p]fect vacuum1 or by surr\nd+ x ) a good solid dielectric4 ,we employ$ ! latt] arrangem5t4 ,illu/ration3 ,,fig4 #f4 ,a conduct+ disc1 ,m ,m 7,fig4 #f71 is connect$ by ! wire1 t1 to ! electromet]2 ! disc & wire are completely envelop$ by ! insulat+ sub/ance i i i i2 ! :ole is aga9 surr\nd$ ) ! metallic cov]+1 ,e ,e ,e ,e1 :i* is 9 electric connection ) ! e>?4 ,! insulator1 p p1 & ! metallic envelope are v ?9 ^u "o ( ! faces ( ! disc4 ,?is face is expos$ to ! radiation ( ! b>ium & radium salt1 ,r1 plac$ outside 9 a lead receptacle4 ,! rays emitt$ by ! radium p5etrate ! metallic envelope & ! insulat+ lam9a1 p p1 & are absorb$ by ! metallic disc1 ,m ,m4 ,! latt] !n becomes ! s\rce ( a cont9u\s evolution ( negative electricity1 z det]m9$ by ! electromet]1 & is measur$ by means ( a qu>tz piezomet]4 ,! curr5t ?us creat$ is v weak4 ,) v active b>ium-radium *loride1 =m+ a lay] ( #be sq4 c4m4 9 area1 & ( #jb c4m4 9 ?ickness1 a curr5t ( magnitude #aj-aa ampres is obta9$1 ! rays utilis$ hav+ trav]s$1 be=e be+ absorb$ by ! disc ,m ,m1 a ?ickness ( alum9ium ( #jja m4m41 & a ?ickness ( ebonite ( #jc m4m4 ,we us$ successively lead1 copp]1 & z9c = ! disc ,m ,m1 ebonite & p>aff9 = ! insulator2 ! results obta9$ 7 ! same4 ,! curr5t dim9i%es ) increas+ di/ance f ! s\rce ( radiation1 ,r1 also :5 a less active product is us$4 ,we obta9$ ! same results aga9 :5 ! disc ,m ,m is replac$ by a ,f>aday cyl9d] fill$ ) air1 & cov]$ outside ) insulat+ mat]ial4 ,! op5+ ( ! cyl9d]1 clos$ by ! ?9 insulat+ plate1 p p1 0 opposite ! radiat+ s\rce4 ,illu/ration3 ,,fig4 #g4 ,f9ally1 we made ! inv]se exp]im5t1 :i* 0 to place ! lead receptacle ) ! radium 9 ! c5tre ( ! insulat+ mat]ial & 9 connection ) ! electromet] 7,fig4 #g71 ! :ole be+ surr\nd$ ) ! metallic cov]+ connect$ to e>?4 ,"u ^! conditions1 x is evid5t f ! electromet] t ! radium has a positive *>ge equal 9 magnitude to ! negative *>ge ( ! =m] exp]im5t4 ,! radium rays p5etrate ! ?9 dielectric plate1 p p1 & leave ! conductor inside c>ry+ ) !m negative electricity4 ,! -rays ( radium d n int]f]e 9 ^! exp]im5ts1 be+ almo/ completely absorb$ by a v ?9 lay] ( matt]4 ,! me?od j describ$ is n suitable = ! /udy ( ! *>ge ( ! rays ( polonium1 ^! rays v slightly p5etrat+4 ,we obs]v$ no indication ( any *>ge 9 ! case ( polonium1 :i* gives rise to -rays only2 b1 = ! reason j giv51 no conclusion c be drawn f ?is4 ,?us1 9 ! case ( ! deflect$ -rays ( radium1 z 9 ! case ( ca?ode rays1 ! rays c>ry a *>ge ( electricity4 ,b1 hi!rto1 ! exi/5ce ( electric *>ges uncomb9$ ) matt] has be5 unkn[n4 ,9 ! /udy ( ! emission ( ! -rays ( radium1 we are !re=e l$ to make use ( ! !ory :i* is 9 vogue = ! /udy ( ca?ode rays4 ,9 ?is balli/ic !ory1 =mulat$ by ,sir ,william ,crookes1 s9ce develop$ & complet$ by ,pr(4 ,j4 ,j4 ,?omson1 ! ca?ode rays consi/ ( extremely m9ute p>ticles1 :i* are hurl$ f ! ca?ode ) great velocity1 & :i* are *>g$ ) negative electricity4 ,we might simil>ly conceive t radium s5ds into space negatively electrifi$ p>ticles4 ,a specim5 ( radium1 enclos$ 9 a solid ?9 p]fectly insulat$ envelope1 %\ld become spontane\sly *>g$ to a v high pot5tial4 ,by ! balli/ic hypo!sis ! pot5tial w\ld increase until ! pot5tial diff]5ce ( ! surr\nd+ conductors became suffici5t to h9d] ! ejection ( ! electrifi$ p>ticles & to cause _! return to ! s\rce ( radiation4 ,we h p]=m$ an exp]im5t on ^! l9es4 ,a specim5 ( v active radium 0 enclos$ = "s "t 9 a glass vessel4 ,9 ord] to op5 ! vessel1 we made a trace on ! glass ) a glass cutt]4 ,:il/ s do+1 we cle>ly he>d ! report ( a sp>k1 & ^u exam9+ ! vessel ) a magnify+ glass1 we obs]v$ t ! glass _h be5 pi]c$ by a sp>k at ! spot :]e x _h be5 weak5$ by ! scrat*4 ,! ph5om5on produc$ is comp>able to ! rupture ( ! glass ( an ov]*>g$ ,leyd5 j>4 ,! same ph5om5on occurr$ ) ano!r glass4 ,fur!r1 at ! mom5t ( ! pass+ ( ! sp>k1 ,m4 ,curie1 :o 0 hold+ ! glass1 felt ! electric %ock ( dis*>ge 9 8 f+]s4 ,c]ta9 k9ds ( glass h good insulat+ prop]ties4 ,if ! radium is enclos$ 9 a seal$ glass vessel1 well insulat$1 x is to be expect$ t1 at a giv5 mom5t1 ! vessel w be spontane\sly p]=at$4 ,radium is ! fir/ example ( a body :i* is spontane\sly *>g$ ) electricity4 ,action ( ! ,electric ,field ^u ! ,deflect$ -,rays ( ,radium4 ,! -rays ( radium1 be+ analog\s to ! ca?ode rays1 %\ld be deflect$ by an electric field 9 a mann] simil> to ! latt]2 i4e41 z w\ld a p>ticle ( matt] negatively *>g$ & hurl$ into space ) a great velocity4 ,! exi/5ce ( su* a deflection has be5 demon/rat$ bo? by ,m4 ,dorn & ,m4 ,becqu]el4 ,let u consid] ! case ( a ray :i* trav]ses ! space situat$ betwe5 ! two plates ( a cond5s]4 ,suppose ! direction ( ! ray p>allel to ! plates3 :5 an electric field is e/abli%$ betwe5 ! latt]1 ! ray is subject$ to ! action ( ?is uni=m field along its :ole pa? 9 ! cond5s] l4 ,by reason ( ?is action ! ray is deflect$ t[>ds ! positive plate & describes ! arc ( a p>abola2 on leav+ ! field1 x cont9ues its pa? 9 a /raight l9e1 foll[+ ! tang5t to ! arc ( ! p>abola at ! po9t ( exit4 ,! ray c be receiv$ on a photographic plate p]p5dicul> to its orig9al direction4 ,obs]vations are tak5 ( ! impression produc$ on ! plate :5 ! field is z]o1 & :5 x has a kn[n value1 & f t is d$uc$ ! value ( ! deflection1 1 :i* is ! di/ance ( ! po9ts 9 :i* ! new direction ( ! ray & its orig9al direction meet a common plane p]p5dicul> to ! orig9al direction4 ,if h is ! di/ance ( ?is plane f ! cond5s]1 i4e41 at ! edge ( ! field1 we h1 by a simple calculation1-- e,fl 7l_/#b h7 ---------------------------------------- --2 mv#b m be+ ! mass ( ! mov+ p>ticles1 e its *>ge1 v its velocity1 & ,f ! /r5g? ( ! field4 ,! exp]im5ts ( ,m4 ,becqu]el enable him to assign a value approa*+ to 4 ,relation ( ! ,*>ge to ! ,mass = a ,p>ticle ,negatively ,*>g$ ,emitt$ by ,radium4 ,:5 a mat]ial p>ticle hav+ a mass m & a negative *>ge e1 is project$ ) a velocity v into a uni=m magnetic field p]p5dicul> to its initial velocity1 ?is p>ticle describes1 9 a plane normal to ! field & pass+ ?r\gh its initial velocity1 an arc ( a circle ( radius 1 s t--,h be+ ! /r5g? ( ! field--we h ! relation-- m ,h ------ v4 e ,if1 = ! same ray1 ! deflection1 1 & ! radius ( curvature1 1 be measur$ 9 a magnetic field1 values c\ld be f\nd f ^! two exp]im5ts = ! ratio e_/m & = ! velocity1 v4 ,! exp]im5ts ( ,m4 ,becqu]el ?rew ! fir/ light ^u ?is subject4 ,!y gave = ! ratio e_/m a value approximately equal to #ajg absolute electro-magnetic units1 & = v a magnitude ( #af #ajaj4 ,^! values are ( ! same ord] ( magnitude z ^? ( ! ca?ode rays4 ,accurate exp]im5ts h be5 made on ! same subject by ,m4 ,kaufmann4 ,?is physici/ subject$ a n>r[ beam ( radium rays to ! simultane\s action ( an electric field & a magnetic field1 ! two fields be+ uni=m & hav+ a simil> direction1 normal to ! orig9al direction ( ! beam4 ,! impression produc$ on a plate normal to ! primitive beam & plac$ beyond ! limits ( ! field ) ref]5ce to ! s\rce1 has ! =m ( a curve1 ea* po9t ( :i* corresponds to "o ( ! orig9al beam4 ,! mo/ p5etrat+ & lea/ deflect$ rays are at ! same "t ^? ) ! greate/ velocity4 ,x foll[s f ! exp]im5ts ( ,m4 ,kaufmann1 t = ! radium rays1 ( :i* ! velocity is consid]ably great] ?an t ( ! ca?ode rays1 ! ratio e_/m decreases1 :ile ! velocity increases4 ,accord+ to ! rese>*es ( ,j4 ,j4 ,?omson & ,t[ns5d1 we may assume t ! mov+ p>ticle1 :i* con/itutes ! ray1 possesses a *>ge1 e1 equal to t c>ri$ by an atom ( hydrog5 dur+ electrolysis1 ?is *>ge be+ ! same = all ! rays4 ,we are !re=e l$ to ! conclusion t ! mass ( ! p>ticle1 m1 increases ) increase ( velocity4 ,^! !oretical consid]ations lead to ! idea t ! in]tia ( ! p>ticle is due to its /ate ( *>ge dur+ motion1 ! velocity ( an electric *>ge 9 motion be+ incapable ( modification )\t exp5diture ( en]gy4 ,to /ate x o!rwise1 ! in]tia ( ! p>ticle is ( electro-magnetic orig91 & ! mass ( ! p>ticle is--9 "p at lea/--a virtual mass or an electro-magnetic mass4 ,m4 ,abraham goes fur!r1 & assumes t ! mass ( ! p>ticle is entirely an electro-magnetic mass4 ,if1 accord+ to ?is hypo!sis1 ! value ( ?is mass1 m1 be calculat$ = a kn[n velocity1 v1 we f9d t m approa*es inf9ity :5 v approa*es ! velocity ( light1 & t m approa*es a con/ant value :5 ! velocity1 v1 is mu* less ?an t ( light4 ,! exp]im5ts ( ,m4 ,kaufmann are 9 agreem5t ) ! results ( ?is !ory1 ! importance ( :i* is great because x =e%ad[s ! possibility ( e/abli%+ me*anical bases ^u ! dynamical ( little p>ticles ( matt] *>g$ 9 a /ate ( motion4 ,^! are ! figures obta9$ by ,m4 ,kaufmann = e_/m & v4 e_/m vc4m4_/sec4 ,electro-magnetic units4 #ahfe #ajg #jg #ajaj;,= ca?ode rays 7,simon74 #aca #ajg #bcf #ajaj;,= radium rays 7,kaufmann74 #aag #ajg #bdh #ajaj #jig #ajg #bei #ajaj #jgg #ajg #bgb #ajaj #jfc #ajg #bhc #ajaj ,m4 ,kaufmann concludes1 f comp>ison ( 8 exp]im5ts ) ! !ory1 t ! limit+ value ( ! ratio e_/m = radium rays ( relatively small velocity w\ld be ! same z ! value e_/m = ca?ode rays4 ,! mo/ complete exp]im5ts ( ,m4 ,kaufmann 7 made ) a m9ute quantity ( pure radium *loride1 ) :i* we provid$ him4 ,accord+ to ,m4 ,kaufmann's exp]im5ts1 c]ta9 -rays ( radium possess a velocity v ne> to t ( light4 ,^! rapid rays seem to possess great p5etrat+ capacity t[>ds matt]4 ,action ( ! ,magnetic ,field ^u ! -,rays4 ,9 a rec5t "w1 ,mr4 ,ru!r=d ann\nc$ t1 9 a p[]ful electric or magnetic field1 ! -rays ( radium are slightly deflect$1 9 ! mann] ( p>ticles positively electrifi$ & possess+ great velocity4 ,mr4 ,ru!r=d concludes f 8 exp]im5ts t ! velocity ( ! -rays is ( ! ord] ( magnitude #be #aji;c4m4_/sec4 & t ! ratio e_/m = ^! rays is ( ! ord] ( magnitude #f #ajc1 :i* is #ajd times z great z = ! deflect$ -rays4 ,we %all see lat] t ^! conclusions ( ,mr4 ,ru!r=d are 9 agreem5t ) ! prop]ties already kn[n ( ! -radiation1 & t !y acc\nt1 9 "p at lea/1 = ! law ( absorption ( ?is radiation4 ,! exp]im5ts ( ,mr4 ,ru!r=d h be5 confirm$ by ,m4 ,becqu]el4 ,m4 ,becqu]el has fur!r demon/rat$ t polonium rays behave 9 a magnetic field l ! -rays ( radium1 & t1 = ! same field1 !y seem to h ! same curvature z ! latt]4 ,x also appe>s f ,m4 ,becqu]el's exp]im5ts t ! -rays d n =m a magnetic spectrum1 b act r l a homog5e\s radiation1 all ! rays be+ equally deflect$4 ,action ( ! ,magnetic ,field on ! ,rays ( o!r ,radio-active ,sub/ances4 ,we h j se5 t radium gives (f -rays comp>able to ! tube rays1 -rays comp>able to ca?ode rays1 & -rays :i* are p5etrat+ & n deflect$4 ,polonium gives (f -rays only4 ,among/ ! o!r radio-active sub/ances1 act9ium seems to behave l radium1 b ! /udy ( its radiation has n yet advanc$ s f> z 9 ! case ( radium4 ,z reg>ds ! fa9tly radio-active bodies1 we "k to-day t uranium & ?orium give rise to -rays z well z -rays 7,becqu]el1 ,ru!r=d74 ,proportion ( -,rays 9 ! ,radiation ( ,radium4 ,z ,i h already m5tion$1 ! proportion ( -rays increases ) increase ( di/ance f ! s\rce ( radiation4 ,^! rays nev] occur alone1 & = great di/ances ! pres5ce ( -rays is always disc]nible4 ,! pres5ce ( v p5etrat+1 undeflect$ rays 9 ! radiation ( radium 0 fir/ obs]v$ by ,m4 ,vill>d4 ,^! rays con/itute only a small portion ( ! radiation measur$ by ! electrical me?od1 & _! pres5ce escap$ our notice 9 our fir/ exp]im5ts1 s t we believ$ falsely t ! radiation at great di/ances conta9$ only rays capable ( deflection4 ,! foll[+ are ! num]ical results obta9$ ) exp]im5ts made by ! electrical me?od ) an app>atus simil> to t ( ,fig4 #e4 ,! radium 0 only sep>at$ f ! cond5s] by ! surr\nd+ air4 ,i %all indicate by ! lett] d ! di/ance f ! s\rce ( radiation to ! cond5s]4 ,! numb]s ( ! second l9e repres5t ! curr5t subsi/+ :5 ! magnetic field is act+1 suppos+ ! curr5t obta9$ ) no field equal to #ajj = ea* di/ance4 ,^! numb]s may be consid]$ z giv+ ! p]c5tage ( ! total - & -rays1 ! deflection ( ! -rays hav+ be5 sc>cely obs]vable ) ! conditions employ$4 ,at great di/ances !re are no -rays1 & ! undeflect$ radiation is !re=e ( ! k9d only4 ,exp]im5ts made at %ort di/ances3-- d1 9 c5timetres #cd #ea #fj #fe ,p]c5tage ( undeflect$ rays #gd #ef #cc #aa ,exp]im5ts made at long di/ances ) a product consid]ably m active ?an t :i* 0 us$ = ! prec$+ s]ies3-- d1 9 c5timetres #ad #cj #ec #hj #ih ,p]c5tage ( undeflect$ rays #ab #ad #ag #ad #af d #abd #aeg ,p]c5tage ( undeflect$ rays #ad #aa ,x is ?us evid5t t aft] a c]ta9 di/ance ! proportion ( undeflect$ rays 9 ! radiation is approximately con/ant4 ,^! rays probably all belong to ! species4 ,! foll[+ is ano!r s]ies ( exp]im5ts 9 :i* ! radium 0 enclos$ 9 a v n>r[ glass tube1 plac$ bel[ ! cond5s] & p>allel to ! plates4 ,! rays emitt$ trav]s$ a c]ta9 ?ickness ( glass & air be=e ent]+ ! cond5s]3-- d1 9 c5timetres #be #cc #da #ei #ge #if #aac ,p]c5tage rays n deflect$ #cc #cc #ba #af #ad #aj #i d #aci #agb ,p]c5tage rays n deflect$ #i #aj ,z 9 ! prec$+ exp]im5ts1 ! numb] ( ! second l9e approximate to a con/ant value1 :5 ! di/ance d increases1 b ! limit is rea*$ = small] di/ances ?an 9 ! prec$+ s]ies1 because ! -rays h be5 m completely absorb$ by ! glass ?an ! - & -rays4 ,! foll[+ exp]im5t %[s t a ?9 %eet ( alum9ium 7#jja m4m4 ?ick7 absorbs pr9cipally -rays4 ,! product be+ plac$ #e c4m4 f ! cond5s]1 ! proportion ( rays o!r ?an 1 :5 ! magnetic field is act+1 is ab\t #ga p] c5t4 ,:5 ! same sub/ance is cov]$ ) ! %eet ( alum9ium1 ! di/ance rema9+ ! same1 ! radiation transmitt$ is f\nd to be almo/ totally deflect$ by ! magnetic field1 ! -rays hav+ be5 absorb$ by ! alum9ium4 ,! same result is obta9$ :5 pap] is us$ z ! absorb+ scre54 ,! greate/ "p ( ! radiation ( radium consi/s ( -rays1 :i* are probably emitt$ pr9cipally by ! sup]ficial lay] ( ! radiat+ matt]4 ,:5 ! ?ickness ( ! lay] ( radiat+ matt] is v>i$1 ! int5sity ( ! curr5t increases ) ?is ?ickness2 ! increase is n proportional to ! ?ickness = ! :ole ( ! radiation2 x is1 moreov]1 m consid]able = ! -rays ?an = ! -rays1 s t ! proportion ( -rays increases ) ! ?ickness ( ! active lay]4 ,! s\rce ( radiation be+ plac$ at a di/ance ( #e c4m4 f ! cond5s]1 x is f\nd t = a ?ickness equal to #jd m4m4 ( ! active lay]1 ! total radiation is giv5 by ! numb] #bh1 & ! proportion ( ! -rays is #bi p] c5t4 ,by mak+ ! lay] #b m4m4 ?ick1 i4e41 five times z ?ick1 a total radiation equal to #ajb1 & a proportion ( -rays equal to #de p] c5t are obta9$4 ,! total radiation :i* exi/s at ?is di/ance has !re=e be5 increas$ 9 ! ratio ( #cf1 & ! -radiation has become five times z /rong4 ,! prec$+ exp]im5ts 7 made by ! electrical me?od4 ,:5 ! radiographic me?od is us$1 c]ta9 results seem to be 9 contradiction ) :at prec$es4 ,9 ! exp]im5ts ( ,m4 ,vill>d1 a beam ( radium rays1 subject$ to ! action ( ! magnetic field1 0 receiv$ on to a pile ( photographic plates4 ,! undeflect$ & p5etrat+ -beam pass$ ?r\gh all ! plates1 leav+ its trace on ea*4 ,! deflect$ -beam produc$ an impression on ! fir/ plate only4 ,?is beam appe>$ !re=e to conta9 no rays ( great p5etration4 ,on ! contr>y1 9 our exp]im5ts a beam :i* is propagat$ 9 ! air conta9s at ! greate/ di/ances accessible to obs]vation ab\t #i_/aj ( -rays1 & ! same is ! case :5 ! s\rce ( radiation is enclos$ 9 a little seal$ glass vessel4 ,9 ,m4 ,vill>d's exp]im5ts1 ^! deflect$ & p5etrat+ -rays did n affect ! photographic plates beyond ! fir/1 because !y are to a great ext5t diffus$ 9 all directions by ! fir/ solid ob/acle enc\nt]$1 & no long] =m a beam4 ,9 our exp]im5ts ! rays giv5 (f by radium & transmitt$ ?r\gh ! glass ( ! vessel 7 also probably scatt]$ by ! glass1 b ! vessel be+ v small w\ld itself act z a s\rce ( -rays at its surface1 & we 7 able to foll[ ! c\rse ( ! latt] to a great di/ance f ! vessel4 ,! ca?ode rays ( ,crookes tubes c only trav]se v ?9 scre5s 7alum9ium scre5s ( #jja m4m4 ?ickness74 ,a beam ( rays /rik+ ! scre5 normally is scatt]$ 9 all directions2 b ! diffusion becomes less ) dim9i%+ ?ickness ( ! scre51 & = v ?9 scre5s ! em]g+ beam is practically ! prolongation ( ! incid5t beam4 ,! deflect$ -rays ( radium behave 9 a simil> mann]1 b ! transmitt$ beam exp]i5ces1 = ! same ?ickness ( scre51 a mu* slight] modification4 ,accord+ to ! exp]im5ts ( ,m4 ,becqu]el1 ! v readily deflect$ -rays ( radium 7^? ) a relatively small velocity7 are p[]fully scatt]$ by an alum9ium scre5 ( ?ickness #ja m4m42 b ! p5etrat+ & less deflect$ rays 7rays ( ! ca?ode k9d ( great velocity7 pass ?r\gh ?is scre5 )\t be+ s5sibly diffus$1 :atev] be ! incl9ation ( ! scre5 to ! direction ( ! beam4 ,! -rays ( great velocity p5etrate )\t diffusion a mu* great] ?ickness ( p>aff9 7sev]al c5timetres71 & 9 ?is ! curvature ( ! beam produc$ by ! magnetic field c be trac$4 ,! ?ick] ! scre51 & ! m absorb5t ! mat]ial ( :i* x is compos$1 ! great] is ! modification ( ! deflect$ primitive beam1 because1 ) increas+ ?ickness ( scre51 diffusion occurs progressively among fre% gr\ps ( rays ( increas+ p5etration4 ,! -rays ( radium exp]i5ce a diffusion 9 pass+ ?r\gh ! air1 :i* is v m>k$ = readily deflect$ rays1 b :i* is mu* slight] ?an t produc$ by equal ?icknesses ( solid sub/ances4 ,= ?is reason1 ! -rays trav]se long di/ances 9 ! air4 ,p5etrat+ ,p[] ( ! ,radiation ( ,radio-active ,bodies4 ,s9ce ! beg9n+ ( ! rese>*es on radio-active bodies1 inve/igations ( ! absorption produc$ by diff]5t scre5s ^u ! rays giv5 (f by ^! bodies h be5 c>ri$ on4 ,9 a previ\s pap] on ?is subject ,i gave figures 7quot$ at ! beg9n+ ( ?is "w7 repres5t+ ! p5etrat+ p[] ( uranium & ?orium rays4 ,mr4 ,ru!r=d has made a special /udy ( ! radiation ( uranium1 & prov$ x to be het]og5e\s4 ,mr4 ,ow5s has arriv$ at ! same results = ?orium rays4 ,:5 ! discov]y ( /rongly radio-active bodies imm$iately foll[$ ^u ?is1 ! p5etrat+ p[] ( _! rays 0 also /udi$ by v>i\s physici/s 7,becqu]el1 ,mey] & von ,s*weidl]1 ,curie1 ,ru!r=d74 ,! fir/ obs]vations br\ght to light ! complexity ( ! radiation1 :i* seems to be a g5]al ph5om5on1 & common to ! radio-active bodies4 ,9 !m we h s\rces :i* give rise to a v>iety ( radiations1 ea* ( :i* has a p[] ( p5etration prop] to itself4 ,radio-active bodies emit rays :i* are propagat$ bo? 9 ! air & 9 vacuo4 ,! propagation is rectil9e>2 ?is fact is prov$ by ! di/9ctness & %ape ( ! %ad[s =m$ by int]pos+ bodies opaque to ! radiation betwe5 ! s\rce & ! s5sitive plate or fluoresc5t scre5 :i* s]ves z receiv]1 ! s\rce be+ ( small magnitude 9 comp>ison ) its di/ance f ! receiv]4 ,v>i\s exp]im5ts demon/rat+ ! rectil9e> propagation ( uranium1 radium1 & polonium rays h be5 made by ,m4 ,becqu]el4 ,x is int]e/+ to "k ! di/ance t rays c travel 9 air4 ,we h f\nd t radium emits rays :i* c be detect$ 9 ! air at a di/ance ( sev]al metres f ! s\rce4 ,9 c]ta9 ( our electrical det]m9ations1 ! action ( ! s\rce ^u ! air ( ! cond5s] made itself felt at a di/ance ( betwe5 #b & #c metres4 ,we h also obta9$ fluoresc5t effects & radiographic impressions at simil> di/ances4 ,! exp]im5ts are n easily c>ri$ out1 except ) v int5se radio-active s\rces1 because1 indep5d5tly ( ! absorption by ! air1 ! action ^u a giv5 receiv] v>ies inv]sely z ! squ>e ( ! di/ance f a s\rce ( small dim5sions4 ,?is radiation1 :i* travels a long di/ance 9 ! case ( radium1 comprises rays ( ! ca?ode k9d & rays :i* are undeflect$2 h[ev]1 ! deflect$ rays pr$om9ate1 accord+ to ! results ( ! exp]im5ts already m5tion$4 ,! great] "p ( ! radiation 7-rays7 is1 on ! contr>y1 limit$ 9 air to a di/ance ( ab\t #g c4m4 f ! s\rce4 ,i made sev]al exp]im5ts ) radium enclos$ 9 a little glass vessel4 ,! rays em]g+ f ! vessel1 aft] trav]s+ a c]ta9 space ( air1 7 receiv$ 9 a cond5s]1 :i* s]v$ to measure _! ionis+ capacity by ! usual electrical me?od4 ,! di/ance1 d1 f ! s\rce to ! cond5s] 0 v>i$1 & ! curr5t ( saturation1 i1 obta9$ 9 ! cond5s] 0 measur$4 ,! foll[+ are ! results ( "o ( ! s]ies ( det]m9ations3-- d1 c4m4 i4 i d#b #aj-c4 #aj #abg #ac #bj #ch #ae #cj #agd #af #dj #aje #ag #ej #fi #ag #fj #dg #ag #gj #ch #ai #ajj #afe #ag ,aft] a c]ta9 di/ance1 ! int5sity ( radiation v>ies inv]sely z ! squ>e ( ! di/ance f ! cond5s]4 ,! radiation ( polonium is only propagat$ 9 air to a di/ance ( a few c5timetres 7#d to #f c4m47 f ! s\rce ( radiation4 ,9 ! case ( ! absorption ( radiations by solid scre5s1 we f9d ano!r fundam5tal diff]5ce betwe5 radium & polonium4 ,radium emits rays capable ( p5etrat+ great ?icknesses ( solid matt]1 e4g41 sev]al c5timetres ( lead or ( glass4 ,! rays :i* h pass$ ?r\gh a great ?ickness ( a solid body are extremely p5etrat+1 & x is practically impossible to absorb !m entirely by any mat]ial :atev]4 ,b ^! rays =m only a small fraction ( ! total radiation1 ! great] "p ( :i* is absorb$ by a slight ?ickness ( solid matt]4 ,polonium emits rays :i* are readily absorb$1 & :i* c only pass ?r\gh extremely ?9 scre5s4 ,! foll[+ are figures %[+ ! absorption produc$ by an alum9ium lam9a ( ?ickness #jja m4m4 ,?is lam9a 0 plac$ above & almo/ 9 contact ) ! sub/ance4 ,! direct radiation & t transmitt$ by ! alum9ium 7 measur$ by ! electrical me?od 7app>atus ( ,fig4 #a72 ! curr5t ( saturation 0 practically obta9$ 9 e case4 ,i h repres5t$ ! activity ( ! radiat+ body by a1 t ( uranium be+ unity4 a4 ,fraction ( radiation transmitt$4 ,*loride ( b>ium & radium #eg #jcb ,bromide ( b>ium & radium #dc #jcj ,*loride ( b>ium & radium #abjj #jcj ,sulphate ( b>ium & radium #ejjj #jbi ,sulphate ( b>ium & radium #aj1jjj #jcb ,metallic bismu? & polonium #jbb ,comp\nds ( uranium #jbj ,comp\nds ( ?orium 9 a ?9 lay] #jch ,we see t radium comp\nds ( diff]5t nature & activity give v simil> results1 z ,i h already po9t$ out 9 ! case ( uranium & ?orium comp\nds at ! beg9n+ ( ?is "w4 ,we see also t1 tak+ into acc\nt ! :ole ( ! radiation1 & ) a giv5 absorb5t scre51 ! diff]5t radio-active bodies c be arrang$ 9 ! foll[+ decreas+ ord] ( p5etrat+ p[]3--,?orium1 radium1 polonium1 uranium4 ,^! results are simil> to ^? :i* h be5 publi%$ by ,mr4 ,ru!r=d4 ,mr4 ,ru!r=d also f9ds t ! ord] is ! same :5 air is ! absorb5t sub/ance4 ,b x is probable t ?is ord] has no absolute value1 & w\ld n be ma9ta9$ indep5d5tly ( ! nature & ?ickness ( ! scre54 ,exp]im5t %[s1 inde$1 t ! law ( absorption is v diff]5t = polonium & radium1 & t1 = ! latt]1 ! absorption ( ! rays ( ea* ( ! ?ree gr\ps mu/ be consid]$ sep>ately4 ,polonium is p>ticul>ly well adapt$ to ! /udy ( -rays1 because ! specim5s :i* we possess emit no o!r k9d ( rays4 ,i made a prelim9>y s]ies ( exp]im5ts ) extremely active rec5tly prep>$ specim5s ( polonium4 ,i f\nd ! absorbability ( ! rays to increase ) increase ( ?ickness ( ! matt] trav]s$4 ,?is s+ul> law ( absorption is contr>y to t kn[n = o!r k9ds ( radiation4 ,i employ$ = ?is rese>* our app>atus = ! det]m9ation ( electrical conductivity arrang$ 9 ! foll[+ mann]3-- ,! two plates ( a cond5s]1 ,p ,p & ,p ,p 7,fig #h71 are horizontally dispos$ 9 a metallic box1 ,b ,b ,b ,b1 connect$ to e>?4 ,! active body1 ,a1 plac$ 9 a ?ick metallic box1 ,c ,c ,c ,c1 connect$ ) ! plate ,p ,p1 acts ^u ! air ( ! cond5s] across a metallic %eet1 ,t2 ! rays :i* pass ?r\gh ! %eet are alone utilis$ = produc+ ! curr5t1 ! electric field be+ limit$ by ! %eet4 ,! di/ance1 ,a ,t1 ( ! active body f ! %eet may be v>i$4 ,! field betwe5 ! plates is e/abli%$ by means ( a batt]y4 ,by plac+ 9 ,a ^u ! active body diff]5t scre5s1 & by adju/+ ! di/ance ,a ,t1 ! absorption ( rays :i* travel long or %ort di/ances 9 ! air may be det]m9$4 ,illu/ration3 ,,fig4 #h4 ,! foll[+ are ! results obta9$ ) polonium3-- ,= a c]ta9 value ( ! di/ance ,a ,t 7#d c4m4 & m71 no curr5t passes2 ! rays d n p5etrate ! cond5s]4 ,:5 ! di/ance ,a ,t is dim9i%$1 ! appe>ance ( ! rays 9 ! cond5s] is manife/$ some:at sudd5ly1 a weak curr5t *ang+ to "o ( consid]able /r5g? = a slight dim9ution ( di/ance2 ! curr5t !n increases regul>ly z ! active body cont9ues to approa* ! %eet ,t4 ,:5 ! active body is cov]$ ) a %eet ( alum9ium #a_/ajj m4m4 ?ick1 ! absorption produc$ by ! lam9a becomes great]1 ! great] ! di/ance ,a ,t4 ,if a second simil> lam9a ( alum9ium be plac$ ^u ! fir/1 ea* absorbs a fraction ( ! radiation x receives1 & ?is fraction is great] = ! second lam9a ?an = ! fir/4 ,9 ! foll[+ table ,i h repres5t$ 9 ! fir/ l9e ! di/ances 9 c5timetres betwe5 ! polonium & ! %eet ,t2 9 ! second l9e ! p]c5tage ( ! rays transmitt$ by a %eet ( alum9ium2 9 ! ?ird l9e ! p]c5tage ( ! rays transmitt$ by two %eets ( ! same alum9ium3-- ,di/ance ,a ,t #ce #be #ai #ade #je ,p]c5tage ( rays transmitt$ by "o lam9a #j #j #e #aj #be ,p]c5tage ( rays transmitt$ by two lam9 #j #j #j #j #jg ,9 ^! exp]im5ts ! di/ance ( ! plates1 ,p & ,p1 0 #c c4m4 ,we see t ! int]position ( ! alum9ium scre5 dim9i%es ! int5sity ( ! radiation to a great] degree at fur!r di/ances ?an at ne>] di/ances4 ,?is effect is /ill m m>k$ ?an ! prec$+ figures seem to indicate4 ,= a di/ance ( #je c4m4 #be p] c5t repres5ts ! mean p5etration = all ! rays :i* pass beyond ?is di/ance4 ,if1 = example1 only ^? rays betwe5 #je c4m4 & #a c4m4 be compreh5d$1 ! p5etration w\ld be great]4 ,& if ! plate ,p be plac$ at a di/ance ( #je c4m4 f ,p ! fraction ( ! radiation transmitt$ by ! alum9ium lam9a 7= ,a ,t #je c4m47 is #dg p] c5t1 & ?r\gh two lam9 x is #e p] c5t ( ! orig9al radiation4 ,i h rec5tly p]=m$ a second s]ies ( exp]im5ts ) ^! same specim5s ( polonium1 ! activity ( :i* 0 consid]ably dim9i%$1 ! int]val ( "t betwe5 ! two s]ies ( exp]im5ts be+ ?ree ye>s4 ,9 ! =m] exp]im5ts1 polonium nitrite 0 us$2 9 ! latt]1 ! polonium 0 9 ! /ate ( metallic p>ticles obta9$ by fus+ ! nitrite ) potassium cyanide4 ,i f\nd t ! radiation ( polonium _h pres]v$ its ess5tial *>act]i/ics1 & ,i discov]$ new results4 ,! foll[+1 = diff]5t values ( ! di/ance ,a ,t1 are ! fractions ( ! radiation transmitt$ by a scre5 compos$ ( f\r sup]pos$ v ?9 leaves ( beat5 alum9ium4 ,di/ance ,a ,t1 9 c5timetres #j #ae #bf ,p]c5tage ( rays transmitt$ by ! scre5 #gf #ff #ci ,i also f\nd t ! fraction ( ! radiation absorb$ by a giv5 scre5 increases ) ! ?ickness ( ! mat]ial already trav]s$ by ! radiation1 b ?is only occurs aft] ! di/ance ,a ,t has rea*$ a c]ta9 value4 ,:5 ?is di/ance is z]o 7! polonium be+ 9 contact ) ! %eet1 ei!r outside or inside ! cond5s]71 x is obs]v$ t ) sev]al simil> sup]pos$ scre5s1 ea* absorbs ! same fraction ( ! radiation x receives2 o!rwise express$1 ! int5sity ( ! radiation dim9i%es !re=e accord+ to an expon5tial law z a function ( ! ?ickness ( ! mat]ial trav]s$1 z 9 ! case ( homog5e\s radiation transmitt$ by ! lam9a )\t *ang+ its nature4 ,! foll[+ num]ical results are giv5 ) ref]5ce to ^! exp]im5ts3-- ,= a di/ance ,a ,t equal to #ae c4m4 a ?9 alum9ium scre5 transmits ! fraction #jea ( ! radiation x receives :5 act+ alone1 & ! fraction #jcd ( ! radiation x receives :5 x is prec$$ by ano!r simil> scre54 ,on ! contr>y1 = a di/ance ,a ,t equal to z]o1 ! same scre5 transmits 9 bo? ! cases consid]$ ! same fraction ( ! radiation x receives1 & ?is fraction is equal to #jga2 x is !re=e great] ?an 9 ! prec$+ case4 ,! foll[+ numb]s indicate = a di/ance ,a ,t equal to #j & = a succession ( ?9 sup]pos$ scre5s1 ! ratio ( ! radiation transmitt$ to ! radiation receiv$ = ea* scre53-- ,s]ies ( n9e v ?9 copp] ,s]ies ( sev5 v ?9 alum9ium leaves4 leaves4 #jgb #j4fi #jgh #j4id #jge #j4ie #jgg #j4ia #jgj #j4ib #jgg #j4ic #jfi #j4id #jgi #jfh ,tak+ into acc\nt ! difficulties ( ! manipulation ( v ?9 scre5s & ( ! sup]position ( scre5s 9 contact1 ! numb]s ( ea* column may be look$ ^u z con/ant2 ! fir/ numb] only ( ! alum9ium column indicates a great] absorption ?an t indicat$ by ! foll[+ numb]s4 ,! -rays ( radium behave simil>ly to ! rays ( polonium4 ,^! rays may be inve/igat$ almo/ isolat$ by deflect+ to "o side ! -rays ) ! magnetic field2 ! -rays seem ( slight importance 9 comp>ison ) ! -rays4 ,! op]ation c only be c>ri$ on at "s di/ance f ! s\rce ( radiation4 ,! foll[+ are ! results ( an exp]im5t ( ?is k9d4 ,! fraction ( ! radiation transmitt$ by a lam9a ( alum9ium #jja m4m4 ?ick is measur$2 ?is scre5 0 plac$ always 9 ! same position1 above & at a little di/ance f ! s\rce ( radiation4 ,) ! app>atus ( ,fig4 #e1 ! curr5t produc$ 9 ! cond5s] = diff]5t values ( ! di/ance ,a ,d is obs]v$1 bo? ) & )\t ! scre53-- ,di/ance ,a ,d #fj #ea #cd ,p]c5tage ( rays transmitt$ by ! alum9ium #c #g #bd ,! rays :i* travel fur!/ 9 ! air are ^? mo/ absorb$ by ! alum9ium4 ,!re is !re=e a great simil>ity betwe5 ! absorbable -rays ( radium & ! rays ( polonium4 ,! deflect$ -rays & ! undeflect$ p5etrat+ -rays are1 on ! contr>y1 ( a diff]5t nature4 ,! exp]im5ts1 notably ( ,,mm4 ,mey] & von ,s*weidl]1 cle>ly %[ t1 consid]+ ! radiation ( radium z a :ole1 ! p5etrat+ p[] ( ?is radiation increases ) ! ?ickness ( ! mat]ial trav]s$1 z is ! case ( ,rntg5 rays4 ,9 ^! exp]im5ts ! -rays produce sc>cely any effect1 be+ = ! mo/ "p suppress$ by v ?9 absorb5t scre5s4 ,^? :i* p5etrate are1 on ! "o h&1 -rays m or less scatt]$2 on ! o!r h&1 -rays1 :i* appe> simil> to ,rntg5 rays4 ,! foll[+ are ! results ( "s ( my exp]im5ts on ! subject3-- ,! radium is enclos$ 9 a glass vessel4 ,! rays1 :i* em]ge f ! vessel1 trav]se #cj c4m4 ( air1 & are receiv$ ^u a s]ies ( glass plates1 ea* ( ?ickness #ac m4m42 ! fir/ plate transmits #di p] c5t ( ! radiation x receives1 ! second transmits #hd p] c5t ( ! radiation x receives1 ! ?ird transmits #he p] c5t ( ! radiation x receives4 ,9 ano!r s]ies ( exp]im5ts ! radium 0 enclos$ 9 a glass vessel plac$ #aj c4m4 f ! cond5s] :i* receiv$ ! rays4 ,a s]ies ( simil> scre5s ( lead ea* #jaae m4m4 ?ick 7 plac$ on ! vessel4 ,! ratio ( ! radiation transmitt$ to ! radiation receiv$ is giv5 = ea* ( ! successive scre5s by ! foll[+ numb]s3-- #jdj #jfj #jgb #jgi #jhi #jib #jid #jid #jig ,= a s]ies ( f\r scre5s ( lead1 ea* ( :i* 0 #ae m4m4 ?ick1 ! ratio ( ! radiation transmitt$ to ! radiation receiv$ 0 giv5 = ! successive scre5s by ! foll[+ numb]s3-- #jji #jgh #jhd #jhb ,! results ( ^! exp]im5ts %[ t :5 ! ?ickness ( ! lead trav]s$ increases f #ja m4m4 to #f m4m41 ! p5etrat+ p[] ( ! radiation increases4 ,i f\nd t1 "u ! exp]im5tal conditions m5tion$1 a scre5 ( lead #ah c4m4 ?ick transmits #b p] c5t ( ! radiation x receives2 a scre5 ( lead #ec c4m4 ?ick transmits #jd p] c5t ( ! radiation x receives4 ,i also f\nd t ! radiation transmitt$ by a ?ickness ( lead ( #ae m4m4 consi/s l>gely ( rays capable ( deflection 7ca?ode ord]74 ,! latt] are !re=e capable ( trav]s+ n only great di/ances 9 ! air1 b also consid]able ?icknesses ( v absorb5t solids1 su* z lead4 ,9 inve/igat+ ) ! app>atus ( ,fig4 #b ! absorption ex]cis$ by an alum9ium scre5 #jja m4m4 ?ick ^u ! total radiation ( radium1 ! scre5 be+ always plac$ at ! same di/ance f ! radiat+ body1 & ! cond5s] be+ plac$ at a v>iable di/ance1 ,a ,d1 ! results obta9$ are ! sum ( ^? due to ! ?ree gr\ps ( ! radiation4 ,at a long di/ance ! p5etrat+ rays pr$om9ate1 & ! absorption is slight2 at a %ort di/ance ! -rays pr$om9ate1 & ! absorption becomes less ) ne>] approa* to ! sub/ance2 = an int]m$iate di/ance ! absorption passes ?r\gh a maximum & ! p5etration ?r\gh a m9imum4 ,di/ance ,a ,d #ga #fe #fj #ea #cd ,p]c5tage ( rays transmitt$ by alum9ium #ia #hb #eh #da #dh ,c]ta9 exp]im5ts made 9 connection ) absorption always demon/rate a c]ta9 simil>ity betwe5 ! -rays & ! -rays4 ,?us x 0 t ,m4 ,becqu]el discov]$ t ! absorb5t action ( a solid scre5 ^u ! -rays increases ) ! di/ance ( ! scre5 f ! s\rce1 su* t if ! rays are subject$ to a magnetic field1 z 9 ,fig4 #d1 a scre5 plac$ 9 contact ) ! s\rce ( radiation all[s a l>g] portion ( ! magnetic spectrum to be 9 evid5ce ?an does ! same scre5 plac$ ^u ! photographic plate4 ,?is v>iation ( ! absorb5t effect ( ! scre5 ) ! di/ance ( ! scre5 f ! s\rce is simil> to t :i* occurs ) ! -rays2 ?is has be5 v]ifi$ by ,,mm4 ,mey] & von ,s*weidl]1 :o op]at$ by means ( ! fluoroscopic me?od2 ,m4 ,curie & ,i obs]v$ ! same fact :5 work+ by ! electrical me?od4 ,h[ev]1 :5 ! radium is enclos$ 9 a glass tube & plac$ at a di/ance f ! cond5s]1 :i* is itself enclos$ 9 a ?9 alum9ium box1 x becomes a matt] ( indiff]5ce :e!r ! scre5 be plac$ aga9/ ! s\rce or aga9/ ! cond5s]2 ! curr5t obta9$ is ! same 9 bo? cases4 ,! inve/igation ( ! -rays l$ me to ! reflection t ^! rays behave l projectiles hav+ a c]ta9 initial velocity1 & :i* lose _! =ce on enc\nt]+ ob/acles4 ,^! rays1 moreov]1 travel by rectil9e> propagation1 z has be5 %[n by ,m4 ,becqu]el 9 ! foll[+ exp]im5t3--,polonium emitt+ rays 0 plac$ 9 a v n>r[ /raight cavity holl[$ 9 a %eet ( c>dbo>d4 ,?us a l9e> s\rce ( radiation 0 produc$4 ,a copp] wire1 #ae m4m4 9 diamet]1 0 plac$ p>allel & opposite to ! s\rce at a di/ance ( #di m4m4 ,beyond 0 plac$ a p>allel photographic plate at a di/ance ( #hfe m4m4 ,aft] an exposure ( t5 m9utes1 ! geometric %ad[ ( ! wire 0 p]fectly reproduc$1 ) a n>r[ p5umbra correspond+ to ! size ( ! s\rce4 ,! same exp]im5t succe$$ equally well :5 a d\ble leaf ( beat5 alum9ium 0 plac$ aga9/ ! wire1 ?r\gh :i* ! rays mu/ pass4 ,!re are !re=e rays capable ( giv+ p]fect geometric %ad[s4 ,! exp]im5t ) ! alum9ium %[s t ^! rays are n scatt]$ 9 trav]s+ ! scre51 & t ?is scre5 does n give rise to any noticeable ext5t to second>y rays simil> to ! second>y rays ( ! ,rntg5 rays4 ,! exp]im5ts ( ,mr4 ,ru!r=d %[ t ! projectiles :i* con/itute ! -rays are deflect$ by a magnetic field1 z if !y 7 positively *>g$4 ,! deflection 9 a magnetic field becomes less z ! product mv_/e becomes great]2 m be+ ! mass ( ! p>ticle1 v its velocity1 & e its *>ge4 ,! ca?ode rays ( radium are b slightly deflect$1 because _! velocity is enorm\s2 !y are1 on ! o!r h&1 v p5etrat+1 because ea* p>ticle has a v small mass toge!r ) a great velocity4 ,b p>ticles :i*1 ) an equal *>ge & a less velocity1 h a great] mass1 w\ld be also only slightly influ5c$ by ! action ( ! field1 & w\ld give rise to v absorbable rays4 ,f ! results ( ,mr4 ,ru!r=d's exp]im5ts1 ?is seems to take place 9 ! case ( ! -rays4 ,! p5etrat+ -rays appe> to be ( q ano!r nature & simil> to ,rntg5 rays4 ,we h n[ se5 h[ complex a ph5om5on is ! radiation ( radio-active bodies4 ,! difficulties ( inve/igation are increas$ by ! "q z to :e!r ! radiation und]goes a m]ely selective absorption on ! "p ( ! mat]ial1 or :e!r a m or less radical trans=mation4 ,little is s f> kn[n ) reg>d to ?is "q4 ,if ! radiation ( radium be reg>d$ z conta9+ rays bo? ( ! ca?ode & ,rntg5 species1 x might be expect$ to und]go trans=mations 9 trav]s+ scre5s4 ,x is kn[n3--,fir/ly1 t ca?ode rays em]g+ f a ,crookes tube ?r\gh an alum9ium w9d[ are greatly scatt]$ by ! alum9ium2 &1 fur!r1 t ! passage ?r\gh ! scre5 entails a dim9ution ( ! velocity ( ! rays4 ,9 ?is way1 ca?ode rays ) a velocity equal to #ad #ajaj c4m4 lose #aj p] c5t ( _! velocity 9 pass+ ?r\gh #jja m4m4 ( alum9ium4 ,secondly1 ca?ode rays on /rik+ an ob/acle give rise to ! production ( ,rntg5 rays4 ,?irdly1 ,rntg5 rays1 on /rik+ a solid ob/acle1 give rise to ! production ( second>y rays1 :i* p>tly consi/ ( ca?ode rays4 ,! exi/5ce1 by analogy1 ( all ^! prec$+ ph5om5a may !re=e be pr$ict$ = ! rays ( radio-active sub/ances4 ,9 inve/igat+ ! transmission ( polonium rays ?r\gh a scre5 ( alum9ium1 ,m4 ,becqu]el obs]v$ nei!r ! production ( second>y rays nor any trans=mation into ca?ode rays4 ,i endeav\r$ to demon/rate a trans=mation ( ! rays ( polonium by us+ ! me?od ( int]*angeable scre5s4 ,two sup]pos$ scre5s1 ,e#a & ,e#b1 be+ trav]s$ by ! rays1 ! ord] 9 :i* !y are trav]s$ %\ld be immat]ial if ! passage ?r\gh ! scre5s does n trans=m ! rays2 if1 on ! contr>y1 ea* scre5 trans=ms ! rays dur+ transmission1 ! ord] ( ! scre5s is ( mom5t4 ,if1 = example1 ! rays are trans=m$ into m absorbable rays 9 pass+ ?r\gh lead1 & no su* effect is produc$ by alum9ium1 !n ! sy/em lead-alum9ium w be m opaque ?an ! sy/em alum9ium-lead2 ?is takes place ) ,rntg5 rays4 ,my exp]im5ts %[ t ?is ph5om5on is produc$ ) ! rays ( polonium4 ,! app>atus employ$ 0 t ( ,fig4 #h4 ,! polonium 0 plac$ 9 ! box1 ,c ,c ,c ,c1 & ! absorb+ scre5s1 ( necessity v ?91 7 plac$ ^u ! metallic %eet ,t4 ,scre5s employ$4 ,?ickness4 ,curr5t obs]v$4 ,m4m4 ,alum9ium #jja #agi ,brass #jjje ,brass #jjje #fg ,alum9ium #jja ,alum9ium #jja #aej ,t9 #jjje ,t9 #jjje #abe ,alum9ium #jja ,t9 #jjje #aci ,brass #jjje ,brass #jjje #dd ,t9 #jjje ,! results obta9$ prove t ! radiation is modifi$ 9 pass+ ?r\gh a solid scre54 ,?is conclusion accords ) ! exp]im5ts 9 :i*1 ( two simil> sup]pos$ metallic scre5s1 ! fir/ is less absorb5t ?an ! second4 ,f ?is x is probable t ! trans=m+ action ( a scre5 increases ) ! di/ance ( ! scre5 f ! s\rce4 ,?is fact has n be5 v]ifi$1 & ! nature ( ! trans=mation has n be5 /udi$ 9 detail4 ,i repeat$ ! same exp]im5ts ) a v active salt ( radium2 ! result 0 negative4 ,i only obs]v$ insignificant v>iations 9 ! int5sity ( ! radiation transmitt$ ) int]*ange ( ! ord] ( ! scre5s4 ,! foll[+ sy/ems ( scre5s 7 exp]im5t$ )3-- ,alum9ium1 ?ickness #jee m4m4 ,alum9ium1 ?ickness #jee m4m4 ,alum9ium1 ?ickness #jee m4m4 ,alum9ium1 ?ickness #ajg m4m4 ,alum9ium1 ?ickness #jee m4m4 ,alum9ium1 ?ickness #ajg m4m4 ,alum9ium1 ?ickness #jae m4m4 ,alum9ium1 ?ickness #jae m4m4 ,alum9ium1 ?ickness #jae m4m4 ,plat9um1 ?ickness #jja m4m4 ,lead1 ?ickness #ja m4m4 ,t91 ?ickness #jjje m4m4 ,copp]1 ?ickness #jje m4m4 ,brass1 ?ickness #jjje m4m4 ,brass1 ?ickness #jjje m4m4 ,plat9um1 ?ickness #jja m4m4 ,z9c1 ?ickness #jje m4m4 ,lead1 ?ickness #ja m4m4 ,! sy/em lead-alum9ium 0 slightly m opaque ?an ! sy/em alum9ium-lead1 b ! diff]5ce 0 n great4 ,?us1 ,i 0 unable to discov] an appreciable trans=mation ( ! rays ( radium4 ,h[ev]1 9 v>i\s radiographic exp]im5ts1 ,m4 ,becqu]el obs]v$ v int5se effects due to scatt]$ or second>y rays1 emitt$ by solid scre5s :i* receiv$ radium rays4 ,lead seem$ to be ! mo/ active sub/ance 9 ?is respect4 ,ionis+ ,action ( ,radium ,rays on ,insulat+ ,liquids4 ,m4 ,curie has po9t$ out t radium rays & ,rntg5 rays act ^u liquid dielectrics z ^u air1 imp>t+ to !m a c]ta9 electrical conductivity4 ,! exp]im5t 0 c>ri$ out 9 ! foll[+ mann] 7,fig4 #i73-- ,! exp]im5tal liquid is plac$ 9 a metal vessel1 ,c ,d ,e ,f1 into :i* a ?9 copp] tube1 ,a ,b1 is plung$2 ^! two pieces ( metal s]ve z electrodes4 ,! out] vessel is ma9ta9$ at a kn[n pot5tial1 by means ( a batt]y ( small accumulators1 "o pole ( :i* is connect$ to e>?4 ,! tube1 ,a ,b1 is connect$ to ! electromet]4 ,:5 a curr5t trav]ses ! liquid ! electromet] is kept at z]o by means ( a qu>tz electrical piezomet]1 :i* gives ! /r5g? ( ! curr5t4 ,! copp] tube1 ,m ,n ,m ,n1 connect$ to e>?1 s]ves z a gu>d tube1 prev5t+ ! passage ( ! curr5t ?r\gh ! air4 ,a bulb conta9+ ! radium-b>ium salt may be plac$ at ! bottom ( ! tube1 ,a ,b2 ! rays act on ! liquid aft] hav+ p5etrat$ ! glass ( ! bulb & ! sides ( ! metal tube4 ,! radium may also be all[$ to act by plac+ ! bulb b5ea? ! side1 ,d ,e4 ,9 work+ ) ,rntg5 rays ! c\rse ( ! rays is ?r\gh side ,d ,e4 ,! increase ( conductivity by ! action ( ! radium rays or ! ,rntg5 rays seems to be produc$ 9 ! case ( all liquid dielectrics2 b 9 ord] to det]m9e ?is increase1 ! conductivity ( ! liquid itself mu/ be s slight z n to mask ! effect ( ! rays4 ,m4 ,curie obta9$ results ( ! same ord] ( magnitude ) bo? radium rays & ,rntg5 rays4 ,:5 inve/igat+ ) ! same app>atus ! conductivity ( air or ( ano!r gas "u ! action ( ! ,becqu]el rays1 ! int5sity ( ! curr5t obta9$ is f\nd to be proportional to ! diff]5ce ( pot5tial betwe5 ! electrodes1 z long z ! latt] does n exce$ a few volts2 b at high] t5sions1 ! int5sity ( ! curr5t increases less & less rapidly1 & ! saturation curr5t is practically atta9$ = a t5sion ( #ajj volts4 ,liquids exam9$ ) ! same app>atus & ! same radio-active body behave diff]5tly2 ! int5sity ( ! curr5t is proportional to ! t5sion :5 ! latt] v>ies betwe5 #j & #dej volts1 & :5 ! di/ance betwe5 ! electrodes does n exce$ #f m4m4 ,illu/ration3 ,,fig4 #i4 ,! figures ( ! foll[+ table multipli$ by #aj-aa give ! conductivity 9 megohms p] c4c43-- ,c>bon bisulphide #bj ,petroleum e!r #ae ,amyl5e #ad ,b5z9e #d ,liquid air #ac ,vasel9e oil #af ,we may1 h[ev]1 assume t liquids & gases behave simil>ly1 b t1 9 ! case ( liquids1 ! curr5t rema9s proportional to ! t5sion up to a mu* high] limit ?an 9 ! case ( gases4 ,x !re=e seem$ probable t ! limit ( proportionality c\ld be l[]$ by us+ a mu* m feeble radiation1 & ?is idea 0 v]ifi$ by exp]im5t4 ,! radio-active body employ$ 0 #aej times less active ?an t :i* _h s]v$ = ! previ\s exp]im5ts4 ,= t5sions ( #ej1 #ajj1 #bjj1 #djj volts1 ! int5sities ( ! curr5t 7 repres5t$ respectively by ! numb]s #aji1 #ahe1 #bee1 #cce4 ,! proportionality 0 no long] ma9ta9$1 b ! curr5t %[$ great v>iation :5 ! diff]5ce ( pot5tial 0 d\bl$4 ,"s ( ! liquids exam9$ are ne>ly p]fect insulators :5 ma9ta9$ at a con/ant temp]ature & :5 scre5$ f ! action ( ! rays4 ,su* are liquid air1 petroleum e!r1 vasel9e oil1 & amyl5e4 ,x is !re=e v easy to /udy ! effect ( ! rays4 ,vasel9e oil is mu* less s5sitive to ! action ( ! rays ?an is petroleum e!r4 ,?is fact may h "s relation to ! diff]5ce 9 volatility :i* exi/s betwe5 ^! two hydroc>bons4 ,liquid air1 :i* has boil$ = "s "t 9 ! exp]im5tal vessel1 is m s5sitive to ! action ( ! rays ?an t newly p\r$ 92 ! conductivity produc$ by ! rays is "o-f\r? z great aga9 9 ! =m] case4 ,m4 ,curie has inve/igat$ ! action ( ! rays ^u amyl5e & ^u petroleum e!r at temp]atures ( #aj & -#ag4 ,! conductivity due to ! radiation dim9i%es by "o-t5? ( its value only1 9 pass+ f #aj to -#ag4 ,9 ! exp]im5ts 9 :i* ! temp]ature ( ! liquid is v>i$1 ! temp]ature ( ! radium may be ei!r t ( ! surr\nd+ atmosph]e or t ( ! liquid2 ! same result is obta9$ 9 bo? cases4 ,?is leads to ! conclusion t ! radiation ( radium does n v>y ) ! temp]ature1 & rema9s unalt]$ ev5 at ! temp]ature ( liquid air4 ,?is fact has be5 v]ifi$ directly by measurem5ts4 ,v>i\s ,effects & ,applications ( ! ,ionis+ ,action ( ! ,rays ,emitt$ by ,radio-active ,sub/ances4 ,! rays ( ! new radio-active sub/ances h a /rongly ionis+ action ^u air4 ,by ! action ( radium ! cond5sation ( sup]saturat$ wat] vap\r c be easily induc$1 j z happ5s by ! action ( ca?ode rays & ,rntg5 rays4 ,"u ! influ5ce ( ! rays emitt$ by ! new radio-active sub/ances1 ! di/ance ( dis*>ge betwe5 two metallic conductors = a giv5 diff]5ce ( pot5tial is increas$2 to put x o!rwise1 ! passage ( ! sp>k is facilitat$ by ^! rays4 ,9 caus+ conductivity1 by ! action ( radio-active bodies1 9 ! air 9 ! neighb\rhood ( two metallic conductors1 "o ( :i* is connect$ to e>? & ! o!r to a well-insulat$ electromet]1 ! electromet] is se5 to be p]man5tly deflect$1 :i* gives a measure ( ! electromotive =ce ( ! batt]y =m$ by ! air & ! two metals 7electromotive =ce ( contact ( ! two metals1 :5 !y are sep>at$ by air74 ,?is me?od ( measurem5t 0 employ$ by ,"l ,kelv9 & 8 /ud5ts1 ! radiat+ body be+ uranium2 a simil> me?od _h be5 previ\sly employ$ by ,m4 ,p]r91 :o 0 us+ ! ionis+ action ( ,rntg5 rays4 ,radio-active bodies may be employ$ 9 ! /udy ( atmosph]ic electricity4 ,! active sub/ance is enclos$ 9 a little box ( ?9 alum9ium fix$ at ! extremity ( a metal wire connect$ ) ! electromet]4 ,! air is made to conduct 9 ! neighb\rhood ( ! end ( ! wire1 & ! latt] adopts ! pot5tial ( ! surr\nd+ air4 ,radium ?us replaces1 ) advantage1 ! flames or ! app>atus ( runn+ wat] ( ,"l ,kelv91 till n[ 9 g5]al use = ! inve/igation ( atmosph]ic electricity4 ,fluoresc5t & ,lum9\s ,effects4 ,! rays emitt$ by ! new radio-active bodies cause fluoresc5ce ( c]ta9 sub/ances4 ,m4 ,curie & myself fir/ discov]$ ?is ph5om5on :5 caus+ polonium to act ^u a lay] ( b>ium plat9ocyanide ?r\gh alum9ium foil4 ,! same exp]im5t succe$s yet m easily ) b>ium conta9+ radium4 ,:5 ! sub/ance is /rongly radio-active ! fluoresc5ce produc$ is v beautiful4 ,a l>ge numb] ( bodies are capable ( becom+ phosphoresc5t or fluoresc5t by ! action ( ! ,becqu]el rays4 ,m4 ,becqu]el /udi$ ! effect ^u ! uranium salts1 ! diamond1 c4 ,m4 ,b>y has demon/rat$ t ! salts ( ! metals ( ! alkalis & alkal9e e>?s1 :i* are all fluoresc5t "u ! action ( lum9\s rays & ,rntg5 rays1 are also fluoresc5t "u ! action ( ! rays ( radium4 ,pap]1 cotton1 glass1 c41 are all caus$ to fluoresce 9 ! neighb\rhood ( radium4 ,among ! diff]5t k9ds ( glass1 ,?ur+ian glass is specially lum9\s4 ,metals d n seem to become lum9\s4 ,b>ium plat9ocyanide is mo/ conv5i5tly us$ :5 ! radiation ( ! radio-active bodies is to be inve/igat$ by ! fluoroscopic me?od4 ,! effect ( ! radium rays may be foll[$ at di/ances great] ?an #b m4 ,phosphoresc5t z9c sulphide is made extremely lum9\s1 b ?is body has ! inconv5i5t prop]ty ( pres]v+ its lum9osity = "s "t aft] ! action ( ! rays has ceas$4 ,! fluoresc5ce produc$ by radium may be obs]v$ :5 ! fluoresc5t scre5 is sep>at$ f ! radium by absorb5t scre5s4 ,we 7 able to obs]ve ! illum9ation ( a scre5 ( b>ium plat9ocyanide across ! human body4 ,h[ev]1 ! action is incomp>ably great] :5 ! scre5 is plac$ imm$iately 9 contact ) ! radium1 be+ sep>at$ f x by no solid scre5 at all4 ,all ! gr\ps ( rays appe> capable ( produc+ fluoresc5ce4 ,9 ord] to obs]ve ! action ( polonium1 ! sub/ance mu/ be plac$ close to ! fluoresc5t scre51 )\t ! int]v5tion ( a solid scre51 unless ! latt] be extremely ?94 ,! lum9osity ( fluoresc5t sub/ances expos$ to ! action ( radio-active bodies dim9i%es ) "t4 ,at ! same "t ! fluoresc5t sub/ance und]goes a trans=mation4 ,! foll[+ are examples3-- ,radium rays trans=m b>ium plat9ocyanide into a br[n1 less lum9\s v>iety 7an action simil> to t produc$ by ,rntg5 rays1 & describ$ by ,m4 ,vill>d74 ,uranium sulphate & potassium sulphate are simil>ly alt]$4 ,! *ang$ b>ium plat9ocyanide is p>tially reg5]at$ by ! action ( light4 ,if ! radium be plac$ b5ea? a lay] ( b>ium plat9ocyanide spread on pap]1 ! plat9ocyanide becomes lum9\s2 if ! sy/em be kept 9 ! d>k1 ! plat9ocyanide becomes *ang$1 & its lum9osity dim9i%es consid]ably4 ,b if ! :ole be expos$ to light1 ! plat9ocyanide is p>tially reg5]at$1 & if ! :ole is replac$ 9 d>kness ! lum9osity reappe>s ) vig\r4 ,by means ( a fluoresc5t body & a radio-active body1 we h !re=e obta9$ a sy/em :i* acts z a phosphoresc5t body capable ( long duration ( phosphoresc5ce4 ,glass made fluoresc5t by ! action ( radium becomes col\r$ br[n or violet4 ,at ! same "t its fluoresc5ce dim9i%es4 ,if ! glass ?us *ang$ be w>m$1 x is decoloris$1 & :5 ?is occurs ! glass becomes lum9\s4 ,! glass has n[ rega9$ its fluoresc5t prop]ty 9 ! same degree z be=e ! trans=mation4 ,z9c sulphide1 :i* has be5 expos$ = a suffici5t l5g? ( "t to ! action ( radium1 gradually becomes us$ up1 & loses its phosphoresc5t prop]ty1 :e!r "u ! action ( radium or t ( light4 ,! diamond becomes phosphoresc5t "u ! action ( radium1 & may ?us be di/+ui%$ f pa/e imitations1 :i* h only a v fa9t lum9osity4 ,all ! b>ium-radium comp\nds are spontane\sly lum9\s4 ,! dry anhydr\s halog5 salts emit a p>ticul>ly int5se light4 ,?is illum9ation _c be se5 9 broad daylight1 b x is easily visible 9 ! twilight or by gas-light4 ,! light emitt$ may be /rong en\gh to read by 9 ! d>k4 ,! light emitt$ emanates f ! entire body ( ! product1 :il/ 9 ! case ( a common phosphoresc5t body1 ! light emanates specially f ! portion ( ! surface illum9at$4 ,radium products lose mu* ( _! lum9osity 9 damp air1 b !y rega9 x on dry+ 7,giesel74 ,!re is app>5tly cons]vation ( lum9osity4 ,aft] _m ye>s no s5sible modification is produc$ 9 ! lum9osity ( feebly active products1 kept 9 ! d>k 9 seal$ tubes4 ,9 ! case ( v active & v lum9\s radium-b>ium *loride1 ! light *anges col\r aft] sev]al mon?s2 x becomes m violet & loses 9 int5sity2 at ! same "t ! product und]goes trans=mations2 on re-dissolv+ ! salt 9 wat] & dry+ x afre%1 ! orig9al lum9osity is re/or$4 ,solutions ( b>ium-radium salts1 :i* conta9 a l>ge proportion ( radium1 are equally lum9\s2 ?is fact may be obs]v$ by plac+ ! solution 9 a plat9um capsule1 :i* n be+ itself lum9\s p]mits ( ! fa9t lum9osity ( ! solution be+ se54 ,:5 a solution ( a b>ium-radium salt conta9s cry/als deposit$ 9 x1 ^! cry/als are lum9\s at ! bottom ( ! solution1 & mu* m s ?an ! solution itself1 s t !y alone appe> lum9\s4 ,m4 ,giesel has made a prep>ation ( b>ium-radium plat9ocyanide4 ,:5 ?is salt is newly cry/allis$1 x has ! appe>ance ( ord9>y b>ium plat9ocyanide & is v lum9\s4 ,b gradually ! salt becomes spontane\sly col\r$1 tak+ a br[n t9t1 ! cry/als at ! same "t becom+ di*roic4 ,9 ?is /ate ! salt is mu* less lum9\s1 al?\gh its radio-activity is increas$4 ,! radium plat9ocyanide1 prep>$ by ,m4 ,giesel1 *anges /ill m rapidly4 ,radium comp\nds are ! fir/ example ( self-lum9\s bodies4 ,evolution ( ,heat by ! ,salts ( ,radium4 ,,mm4 ,curie & ,laborde h rec5tly discov]$ t ! salts ( radium are ! s\rce ( a spontane\s & cont9u\s evolution ( heat4 ,?is evolution has ! effect ( keep+ ! salts ( radium at a temp]ature high] ?an t ( _! surr\nd+s2 an excess ( temp]ature ( #ae has be5 obs]v$4 ,?is excess ( temp]ature is dep5d5t ^u ! !rmal insulation ( ! body4 ,,mm4 ,curie & ,laborde h det]m9$ ! am\nt ( heat produc$ 9 ! case ( radium4 ,!y f\nd t ! output is ( ! ord] ( magnitude ( #ajj calories p] grm4 ( radium p] h\r4 ,"o grm4-atom 7#bbe grm47 ( radium give rise 9 "o h\r to #bb1ejj cal41 a quantity ( heat comp>able to t produc$ by ! combu/ion ( #a grm4-atom 7#a grm47 ( hydrog54 ,s great an evolution ( heat c be expla9$ by no ord9>y *emical reaction1 m p>ticul>ly z ! condition ( ! radium rema9s unaffect$ = ye>s4 ,! evolution ( heat might be attribut$ to a sl[ trans=mation ( ! radium atom4 ,if ?is 7 ! case1 we %\ld be l$ to conclude t ! quantities ( en]gy g5]at$ dur+ ! =mation & trans=mation ( ! atoms are consid]able1 & t !y exce$ all t is s f> kn[n4 ,*emical ,effects produc$ by ! ,new ,radio-active ,bodies4 ,col\rations4--,! radiations ( /rongly radio-active bodies are capable ( caus+ c]ta9 *emical reactions4 ,! rays emitt$ by radium products ex]cise col\r+ actions ^u glass & porcela94 ,! col\ration ( glass1 g5]ally br[n or violet1 is v deep2 x is produc$ 9 ! body ( ! glass1 & rema9s aft] removal ( ! radium4 ,all glasses become col\r$ aft] a long] or a %ort] int]val ( "t1 & ! pres5ce ( lead is n ess5tial4 ,?is fact may be comp>$ to t rec5tly obs]v$ ( ! col\ration ( ! glass ( vacuum tubes1 aft] hav+ be5 long 9 use = ! production ( ,rntg5 rays4 ,m4 ,giesel has demon/rat$ t ! cry/allis$ halog5 salts ( ! alkali metals become col\r$ "u ! influ5ce ( radium1 z "u ! action ( ca?ode rays4 ,m4 ,giesel po9ts out t simil> col\rations are obta9$ :5 ! salts ( ! alkalis are expos$ to sodium vap\r4 ,i inve/igat$ ! col\ration ( a collection ( glasses ( kn[n composition1 k9dly l5t me = ! occasion by ,m4 ,le ,*ateli]4 ,i obs]v$ no great v>iety 9 ! col\ration4 ,x is g5]ally br[n1 violet1 yell[1 or grey4 ,x appe>s to be associat$ ) ! pres5ce ( ! alkali metals4 ,) ! pure cry/allis$ alkali salts m v>i$ & m vivid col\rs are obta9$2 ! salt1 orig9ally :ite1 becomes blue1 gre51 yell[1 br[n1 c4 ,m4 ,becqu]el has discov]$ t yell[ phosphorus is trans=m$ into ! r$ v>iety by ! action ( radium4 ,pap] is *ang$ & col\r$ by ! action ( radium4 ,x becomes brittle1 scor*$1 &1 f9ally1 resembles a col&] p]=at$ ) holes4 ,"u "s circum/ances !re is a production ( ozone 9 ! neighb\rhood ( v active comp\nds4 ,rays em]g+ f a seal$ j> conta9+ radium d n produce ozone 9 ! air !y pass ?r\gh4 ,on ! contr>y1 a /rong od\r ( ozone is detect$ :5 ! j> is op5$4 ,9 a g5]al way1 ozone is produc$ 9 ! air :5 ! latt] is 9 direct contact ) ! radium4 ,communication by a *annel1 ev5 if extremely n>r[1 suffices2 x appe>s z if ! production ( ozone is associat$ ) ! propagation ( induc$ radio-activity1 ( :i* we %all speak lat]4 ,radium comp\nds appe> to *ange ) lapse ( "t1 d\btless "u ! action ( _! own radiation4 ,x 0 se5 above t cry/als ( b>ium-radium *loride1 :i* are col\rless :5 =m$1 become gradually col\r$ fir/ yell[ or orange1 !n p9k2 ?is col\ration disappe>s 9 solution4 ,b>ium-radium *loride g5]ates oxyg5 comp\nds ( *lor9e2 ! bromide ^? ( brom9e4 ,^! sl[ *anges g5]ally manife/ !mselves "s "t aft] ! prep>ation ( ! solid product1 :i* at ! same "t *anges 9 =m & col\r1 becom+ yell[ or violet4 ,! light emitt$ also becomes m violet4 ,a solution ( a radium salt evolves hydrog5 7,giesel74 ,pure radium salts seem to und]go ! same *anges z ^? conta9+ b>ium4 ,h[ev]1 cry/als ( ! *loride1 deposit$ 9 acid solution1 d n become s5sibly col\r$ aft] "s "t has elaps$1 :]eas cry/als ( b>ium-radium *loride1 ri* 9 radium1 become deeply col\r$4 ,production ( ,!rmo-lum9osity4--,c]ta9 bodies1 su* z fluorite1 become lum9\s :5 heat$2 !y are !rmo-lum9esc5t4 ,_! lum9osity disappe>s aft] "s "t1 b ! capacity ( becom+ lum9\s afre% ?r\gh heat is re/or$ to !m by ! action ( a sp>k1 & also by ! action ( radium4 ,radium c ?us re/ore to ^! bodies _! !rmo-lum9esc5t prop]ty4 ,fluorite :5 heat$ und]goes a *ange1 :i* is accompani$ by ! emission ( light4 ,if ! fluorite is aft]w>ds subject$ to ! action ( radium1 an inv]se *ange occurs1 :i* is also accompani$ by an emission ( light4 ,an absolutely simil> ph5om5on occurs :5 glass is expos$ to radium rays4 ,"h also a *ange is produc$ 9 ! glass :ile lum9\s f ! effect ( ! radium rays2 ?is *ange %[s itself 9 ! col\ration :i* appe>s & gradually increases4 ,if ! glass is aft]w>ds heat$1 ! inv]se *ange takes place1 ! col\r disappe>s1 & ?is ph5om5on is accompani$ by production ( light4 ,x appe>s v probable t we h "h a *ange ( a *emical nature1 & ! production ( light is associat$ ) ?is *ange4 ,?is ph5om5on may be g5]al4 ,x might be t ! production ( fluoresc5ce by ! action ( radium & ! lum9osity ( radium comp\nds is ( necessity associat$ ) "s *emical or physical *ange 9 ! sub/ance emitt+ ! light4 ,radiographs4--,! radiographic action ( ! new radio-active bodies is v m>k$4 ,h[ev]1 ! me?od ( op]at+ %\ld be v diff]5t ) polonium & radium4 ,polonium acts only at v %ort di/ances1 & its action is consid]ably weak5$ by solid scre5s2 x is practically annihilat$ by means ( a scre5 ( slight ?ickness 7#a m4m4 ( glass74 ,radium acts at consid]ably great] di/ances4 ,! radiographic action ( radium rays may be obs]v$ at m ?an #b m4 di/ance 9 air1 ev5 :5 ! active product is enclos$ 9 a glass vessel4 ,! rays act+ "u ^! conditions belong to ! - & -gr\ps4 ,ow+ to ! diff]5ces 9 transp>5cy ( diff]5t mat]ials to ! rays1 radiographs ( diff]5t objects may be obta9$1 z 9 ! case ( ,rntg5 rays4 ,metals are1 z a rule1 opaque1 ) ! exception ( alum9ium1 :i* is v transp>5t4 ,!re is no notewor?y diff]5ce ( transp>5cy betwe5 fle% & bone4 ,! op]ation may be c>ri$ on at a great di/ance & ) a s\rce ( v small dim5sions2 & v delicate radiographs are ?us produc$4 ,! beauty ( ! radiograph is enhanc$ by deflect+ to "o side ! -rays1 by means ( a magnetic field1 & utilis+ only ! -rays4 ,! -rays1 9 trav]s+ ! object to be radiograph$1 und]go a c]ta9 am\nt ( diffusion1 & ?us cause a slight fog4 ,9 suppress+ !m1 a long] "t ( exposure is necess>y1 b bett] results are obta9$4 ,! radiograph ( an object1 su* z a purse1 requires "o day ) a radiat+ s\rce compos$ ( sev]al c5tigrams ( a radium salt1 enclos$ 9 a glass vessel1 & plac$ at a di/ance ( #a m4 f ! s5sitive plate1 9 front ( :i* ! object is plac$4 ,if ! s\rce is at a di/ance ( #bj c4m4 f ! plate1 ! same result is obta9$ 9 "o h\r4 ,9 ! imm$iate vic9ity ( ! s\rce ( radiation1 a s5sitive plate is in/antane\sly act$ ^u4 ,physiological ,effects4 ,radium rays ex]t an action ^u ! epid]mis4 ,?is has be5 obs]v$ by ,m4 ,walkh(f & confirm$ by ,m4 ,giesel1 s9ce also by ,,mm4 ,becqu]el & ,curie4 ,if a celluloid or ?9 indi>ubb] capsule conta9+ a v active salt ( radium be plac$ ^u ! sk91 & be left ?us = "s "t1 a r$ness is produc$ ^u ! sk91 ei!r imm$iately or at ! end ( "s "t1 :i* is long] 9 proportion z ! action is weak]2 ?is r$ spot appe>s 9 ! place :i* has be5 expos$ to ! action2 ! local *ange 9 ! sk9 appe>s & acts l a burn4 ,9 c]ta9 cases a bli/] is =m$4 ,if ! exposure 0 ( long duration1 an ulc]ation is produc$ :i* is long 9 heal+4 ,9 "o exp]im5t1 ,m4 ,curie caus$ a relatively weak radio-active product to act ^u 8 arm = t5 h\rs4 ,! r$ness appe>$ imm$iately1 & lat] a w\nd 0 caus$ :i* took f\r mon?s to heal4 ,! epid]mis 0 locally de/roy$1 & =m$ aga9 sl[ly & ) difficulty1 leav+ a v m>k$ sc>4 ,a radium burn ) half-an-h\r's exposure appe>$ aft] fifte5 days1 =m$ a bli/] & heal$ 9 fifte5 days4 ,ano!r burn1 caus$ by an exposure ( only eight m9utes1 occasion$ a r$ spot :i* appe>$ two mon?s aft]1 its effect be+ q insignificant4 ,! action ( radium ^u ! sk9 c take place across metal scre5s1 b ) weak5$ effect4 ,! action ( radium ^u ! sk9 has be5 inve/igat$ by ,dr4 ,daulos1 at ! ,hospital ( ,/4 ,l\is1 z a process ( treat+ c]ta9 affections ( ! sk91 simil> to ! treatm5t ) ! ,rntg5 rays or ! ultra-violet rays4 ,9 ?is respect radium gives enc\rag+ results2 ! epid]mis p>tially de/roy$ by ! action ( ! radium is r5ew$ 9 a heal?y condition4 ,! action ( radium is m p5etrat+ ?an t ( light1 & its use is easi] ?an t ( light or ( ,rntg5 rays4 ,! /udy ( ! conditions ( application is ( necessity r l5g?y1 because ! effect ( ! application does n at once appe>4 ,m4 ,giesel has obs]v$ ! action ( radium ^u plant leaves4 ,! leaves ?us treat$ turn yell[ & )] away4 ,m4 ,giesel has also discov]$ ! action ( radium rays ^u ! eye4 ,if a radio-active sub/ance be plac$ 9 ! d>k 9 ! vic9ity ( ! clos$ eye or ( ! temple1 a s5sation ( light fills ! eye4 ,?is ph5om5on has be5 /udi$ by ,,mm4 ,him/$t & ,nagel4 ,^! physici/s h demon/rat$ t ! c5tre ( ! eye is r5d]$ fluoresc5t by ! action ( radium1 & ?is expla9s ! s5sation ( light exp]i5c$4 ,bl9d p ^: ret9a is intact are s5sitive to ! action ( radium1 :il/ ^? ^: ret9a is diseas$ d n exp]i5ce any s5sation ( lum9osity4 ,radium rays ei!r arre/ or h9d] ! developm5t ( colonies ( microbes1 b ?is action is n v int5se4 ,m4 ,danysz has rec5tly demon/rat$ ! ready action ( radium ^u ! m>r[ & bra94 ,aft] "o h\r's exposure p>alysis ( ! animals exp]im5t$ ^u occurr$1 & ! latt] usually di$ 9 a few days4 ,influ5ce ( ,temp]ature ^u ,radiation4 ,!re is s f> b little in=mation reg>d+ ! mann] ( v>iation ( ! radiation ( radio-active bodies ) temp]ature4 ,we "k1 h[ev]1 t radiation subsi/s at l[ temp]atures4 ,m4 ,curie plac$ a glass tube conta9+ b>ium-radium *loride 9 liquid air4 ,! lum9osity ( ! radio-active body p]si/$ "u ^! conditions4 ,at ! mom5t1 inde$1 ( remov+ ! tube f ! cold ba?1 x appe>s m lum9\s ?an at ! ord9>y temp]ature4 ,at ! temp]ature ( liquid air radium cont9ues to cause fluoresc5ce 9 ! sulphates ( uranium & potassium4 ,m4 ,curie has v]ifi$1 by electrical det]m9ations1 t ! radiation1 measur$ at a c]ta9 di/ance f ! s\rce1 possesses ! same int5sity :e!r ! radium be at ! temp]ature ( ! atmosph]e or ( liquid air4 ,9 ^! exp]im5ts ! radium 0 plac$ at ! bottom ( a tube clos$ at "o end4 ,! rays em]g$ f ! tube at ! op5 end1 trav]s$ a c]ta9 space 9 ! air1 & 7 receiv$ into a cond5s]4 ,! action ( ! rays ^u ! air ( ! cond5s] 0 det]m9$ bo? on leav+ ! tube 9 ! air & on surr\nd+ x to a c]ta9 height ) liquid air4 ,! same result 0 obta9$ 9 bo? cases4 ,! radio-activity ( radium p]si/s at high temp]atures4 ,b>ium-radium *loride aft] be+ fus$ 7t[>ds #hjj7 is radio-active & lum9\s4 ,h[ev]1 prolong$ heat+ at a high temp]ature has ! effect ( tempor>ily l[]+ ! radio-activity ( ! body4 ,?is decrease is v consid]able2 x may con/itute #ge p] c5t ( ! total radiation4 ,! decrease is less 9 proportion = ! absorbable rays ?an = ! p5etrat+ rays1 :i* are to "s ext5t suppress$ by heat+4 ,9 "t ! radiation ( ! product rega9s ! int5sity & composition t x possess$ be=e heat+2 ?is occurs aft] ! lapse ( ab\t two mon?s f ! occasion ( heat+4 ,,*apt] ,,iv4 ,,communication ,,( ,,radio-,,activity ,,to ,,sub/ances ,,initially ,,inactive4 ,dur+ ! c\rse ( our rese>*es on radio-active sub/ances ,m4 ,curie & ,i h obs]v$ t e sub/ance :i* rema9s = "s "t 9 ! vic9ity ( a radium salt becomes itself radio-active4 ,9 our fir/ publication on ?is subject1 we conf9$ ourselves to prov+ t ! radio-activity ?us acquir$ by sub/ances initially inactive is n due to ! transf]5ce ( radio-active p>ticles to ! surface ( ^! sub/ances4 ,?is is prov$ beyond dispute by all ! exp]im5ts :i* w be "h describ$1 & by ! laws accord+ to :i* ! radio-activity excit$ 9 naturally inactive bodies disappe>s :5 ! latt] are remov$ f ! influ5ce ( radium4 ,we h giv5 ! "n ( induc$ radio-activity to ! new ph5om5on ?us discov]$4 ,9 ! same publication1 we indicat$ ! ess5tial *>act]i/ics ( induc$ radio-activity4 ,we excit$ scre5s ( diff]5t sub/ances by plac+ !m 9 ! neighb\rhood ( solid radium salts1 & we inve/igat$ ! radio-activity ( ^! scre5s by ! electrical me?od4 ,we obs]v$ ! foll[+ facts3-- #a4 ,! activity ( a scre5 expos$ to ! action ( radium increases ) ! "t ( exposure1 approa*+ to a def9ite limit accord+ to an asymptotic law4 #b4 ,! activity ( a scre5 :i* has be5 excit$ by ! action ( radium1 & :i* is aft]w>ds )drawn f its action1 disappe>s 9 a few days4 ,?is induc$ activity approa*es z]o z a function ( ! "t1 foll[+ an asymptotic law4 #c4 ,o!r ?+s be+ equal1 ! radio-activity induc$ by ! same radium product ^u diff]5t scre5s is indep5d5t ( ! nature ( ! scre54 ,glass1 pap]1 metals1 all acquire ! same degree ( activity4 #d4 ,! radio-activity induc$ 9 "o scre5 by diff]+ radium products has a limit+ value :i* rises ) ! increas$ activity ( ! product4 ,%ortly aft]w>ds1 ,mr4 ,ru!r=d publi%$ a rese>*1 :i* %[$ t comp\nds ( ?orium are capable ( produc+ ! ph5om5on ( induc$ radio-activity4 ,mr4 ,ru!r=d discov]$ = ?is ph5om5on ! same laws z ^? j enunciat$1 besides ?is additional important fact1 t bodies *>g$ ) negative electricity become m active ?an o!rs4 ,mr4 ,ru!r=d also obs]v$ t air pass$ ov] ?orium oxide pres]ves a notable conductivity = ab\t t5 m9utes4 ,air 9 ?is condition communicates induc$ radio-activity to inactive sub/ances1 especially to ^? negatively *>g$4 ,mr4 ,ru!r=d expla9s 8 exp]i5ces by ! supposition t comp\nds ( ?orium1 p>ticul>ly ! oxide1 give rise to a radio-active emanation capable ( be+ c>ri$ by air curr5ts & *>g$ ) positive electricity4 ,?is emanation w\ld be ! orig9 ( induc$ radio-activity4 ,m4 ,dorn has repeat$1 ) salts ( b>ium conta9+ radium1 ! exp]im5ts ( ,mr4 ,ru!r=d ) ?orium oxide4 ,m4 ,debi]ne has %[n t act9ium causes1 to a m>k$ degree1 induc$ activity ( bodies plac$ 9 its vic9ity4 ,z 9 ! case ( ?orium1 !re is a consid]able c>riage ( activity by air curr5ts4 ,induc$ radio-activity has v>i\s aspects1 & irregul> results are obta9$ :5 ! activity ( a sub/ance 9 ! neighb\rhood ( radium is excit$ 9 free air4 ,,mm4 ,curie & ,debi]ne h obs]v$1 h[ev]1 t ! ph5om5on is q regul> :5 op]at+ 9 a clos$ vessel2 !y !re=e inve/igat$ induc$ activity 9 a clos$ space4 ,activity ,induc$ 9 an ,enclos$ ,space4 ,! active mat]ial is plac$ 9 a little glass j>1 a1 op5 at ,o 7,fig4 #aa71 9 ! c5tre ( a clos$ space4 ,sev]al plates1 ,a1 ,b1 ,c1 ,d1 ,e1 plac$ 9 ! enclosure become radio-active aft] "o day's exposure4 ,! activity is ! same :atev] be ! nature ( ! plate1 = equal dim5sions 7lead1 copp]1 alum9ium1 glass1 ebonite1 wax1 c>dbo>d1 p>aff974 ,! activity ( "o face ( "o ( ! plates is great] 9 proportion to ! am\nt ( free space ab\t ?is face4 ,if ! prec$+ exp]im5t be repeat$ ) ! j>1 a1 completely clos$1 no activity is induc$4 ,! radiation ( radium does n directly affect ! production ( induc$ radio-activity4 ,= ?is reason1 9 ! prec$+ exp]im5t ! plate ,d1 scre5$ f ! radiation by a lead plate ( ?ickness1 ,p ,p1 is made z active z ,b & ,e4 ,radio-activity is transmitt$ by ! air by degrees f ! radiat+ body to ! body to be excit$4 ,x c ev5 be transmitt$ to a di/ance by v n>r[ capill>y tubes4 ,induc$ radio-activity is bo? m int5se & m regul> if ! solid radium salt be replac$ by an aque\s solution ( ! same4 ,liquids are capable ( acquir+ induc$ radio-activity4 ,= example1 pure wat] may be r5d]$ active by plac+ x ) a solution ( a radium salt )9 an enclosure4 ,illu/ration3 ,,fig4 #aa ,c]ta9 sub/ances become lum9\s :5 plac$ 9 an active enclosure 7phosphoresc5t & fluoresc5t bodies1 glass1 pap]1 cotton1 wat]1 salt solutions74 ,phosphoresc5t z9c sulphide is p>ticul>ly brilliant "u ! circum/ances4 ,! radio-activity ( ^! lum9\s bodies is1 h[ev]1 ! same z t ( a piece ( a metal or o!r body :i* is excit$ "u ! same conditions )\t becom+ lum9\s4 ,:atev] be ! sub/ance made active 9 a clos$ vessel1 ?is sub/ance acquires an activity :i* increases ) l5g? ( "t until x atta9s a limit+ value1 always ! same1 = ! same mat]ial & ! same exp]im5tal arrangem5t4 ,! limit ( induc$ radio-activity is indep5d5t ( ! nature & pressure ( ! gas inside ! active enclosure 7air1 hydrog51 c>bonic acid74 ,! limit ( induc$ radio-activity = ! same enclosure dep5ds only on ! quantity ( radium pres5t 9 ! /ate ( solution1 & is app>5tly proportional to x4 ,"p play$ by ,gases 9 ! ,ph5om5a ( ,induc$ ,radio-activity4 ,emanation4--,! gases pres5t 9 an enclosure conta9+ a solid salt or a solution ( a salt ( radium are radio-active4 ,?is radio-activity p]si/s :5 ! gas is drawn (f ) a tube & collect$ 9 a te/-tube4 ,! sides ( ! te/-tube become !mselves radio-active1 & ! glass ( ! te/-tube is lum9\s 9 ! d>k4 ,! activity & lum9osity ( ! te/-tube f9ally completely disappe>1 b v gradually1 & a mon? aft]w>ds radio-activity may /ill be detect$4 ,s9ce ! beg9n+ ( our rese>*es1 ,m4 ,curie & ,i h1 by heat+ pit*bl5de1 extract$ a /rongly radio-active gas1 b1 z 9 ! prec$+ exp]im5t1 ! activity ( ?is gas f9ally completely vani%$4 ,we c\ld disc]n no new ray 9 ! spectrum ( ?is gas2 ?is 0 !re=e n a case ( a new radio-active gas1 & we und]/ood lat] t x 0 ! ph5om5on ( induc$ radio-activity4 ,?us1 = ?orium1 radium1 & act9ium induc$ radio-activity is progressively propagat$ ?r\gh ! gases1 f ! radiat+ body to ! walls ( ! enclosure conta9+ x1 & ! excit+ pr9ciple is c>ri$ away ) ! gas itself1 :5 ! latt] is extract$ f ! enclosure4 ,:5 ! radio-activity ( radium comp\nds is measur$ by ! electrical me?od by means ( ! app>atus ( ,fig4 #a1 ! air betwe5 ! plates is itself radio-active2 h[ev]1 on pass+ a curr5t ( air betwe5 ! plates1 !re is no obs]vable l[]+ ( ! int5sity ( ! curr5t1 :i* proves t ! radio-activity di/ribut$ 9 ! space betwe5 ! plates is ( little acc\nt 9 comp>ison ) t ( ! radium itself 9 ! solid /ate4 ,x is q o!rwise ) ?orium4 ,! irregul>ities :i* ,i obs]v$ 9 det]m9+ ! radio-activity ( ! ?orium comp\nds arose f ! fact t at ?is po9t ,i 0 work+ ) a cond5s] op5 to ! air2 ! lea/ air curr5t caus$ a consid]able *ange 9 ! int5sity ( ! curr5t1 because ! radio-activity disp]s$ 9 ! space 9 ! vic9ity ( ! ?orium is consid]able z comp>$ ) ! radio-activity ( ! sub/ance4 ,?is effect is /ill m m>k$ 9 ! case ( act9ium4 ,a v active comp\nd ( act9ium appe>s mu* less active :5 a curr5t ( air is pass$ ov] ! sub/ance4 ,! radio-active en]gy is !re=e conta9$ 9 ! gas 9 a special =m4 ,mr4 ,ru!r=d sugge/s t radio-active bodies g5]ate an emanation or gase\s mat]ial :i* c>ries ! radio-activity4 ,9 ! op9ion ( ,m4 ,curie & myself1 ! g5]ation ( a gas by radium is a supposition :i* is n s f> ju/ifi$4 ,we consid] ! emanation z radio-active en]gy /or$ up 9 ! gas 9 a =m hi!rto unkn[n4 ,dissipation 9 ,free ,air ( ! ,induc$ ,activity ( ,solid ,bodies4 ,a solid body1 :i* has be5 excit$ by radium 9 an enclos$ space = a suffici5t l5g? ( "t1 & :i* has !n be5 remov$ f ! enclosure1 p>ts ) its activity 9 free air accord+ to an expon5tial law1 :i* is ! same = all bodies repres5t$ by ! foll[+ =mula3-- ,i ,i#j7;ae-t_/#a - 7a - #a7;e-t_/#b74 ,i#j be+ ! initial int5sity ( ! radiation at ! mom5t ( )draw+ ! plate f ! enclosure2 ,i1 ! int5sity aft] "t1 t2 a is a num]ical coeffici5t1 a #dbj2 #a & #b are "t con/ants1 #a #bdbj secs41 #b #ahfj secs4 ,aft] two or ?ree h\rs ?is law becomes practically a simple expon5tial1 & ! effect ( ! second expon5tial ^u ! value ( ,i is negligible4 ,! law ( dissipation is !re=e su* t ! int5sity ( radiation becomes dim9i%$ to "o-half its value 9 tw5ty-eight m9utes4 ,?is f9al law may be consid]$ z *>act]i/ic = ! dissipation 9 an unconf9$ air space ( ! activity induc$ 9 solid bodies by radium4 ,solid bodies excit$ by act9ium lose _! activity 9 ! op5 air1 accord+ to an expon5tial law simil> to ! prec$+1 ! dissipation be+1 h[ev]1 r sl[]4 ,solid bodies1 made active by ?orium1 lose _! activity mu* m sl[ly2 ! int5sity ( ! radiation is r$uc$ to "o-half 9 elev5 h\rs4 ,dissipation ( ,activity 9 a ,conf9$ ,space4 ,velocity ( ,de/ruction ( ! ,emanation4 ,an enclosure1 made active by radium & !n remov$ f its influ5ce1 loses its activity by a law :i* is mu* less rapid ?an t ( dissipation 9 ! op5 air4 ,! exp]im5t may be c>ri$ out ) a glass tube1 r5d]$ active int]nally by plac+ x = "s "t 9 contact ) a solution ( a salt ( radium4 ,! tube is !n seal$ 9 ! flame1 & ! int5sity ( radiation emitt$ by ! walls ( ! tube is measur$ :ile ! dissipation takes place4 ,! law ( dissipation is an expon5tial law4 ,x is giv5 v accurately by ! =mula4 ,i ,i#j;et_/4 ,i#j initial int5sity ( radiation4 ,i int5sity ( radiation at "t1 t4 a "t con/ant1 #digj #aje secs4 ,! int5sity ( ! radiation is r$uc$ to "o-half 9 f\r days4 ,?is law ( dissipation is absolutely inv>iable :atev] be ! exp]im5tal conditions 7dim5sions ( enclosure1 nature ( ! walls1 nature ( ! gas )9 ! enclosure1 duration ( action1 c474 ,! law ( dissipation rema9s ! same = any temp]ature betwe5 -#ahj & #dej4 ,! law is !re=e altoge!r *>act]i/ic4 ,9 ^! exp]im5ts x is ! radio-active en]gy accumulat$ 9 ! gas t ma9ta9s ! activity ( ! walls4 ,if ! gas be )drawn & a vacuum caus$ 9 ! enclosure1 we h f\nd t dissipation ( activity at once occurs 9 ! rapid me?od2 ! int5sity ( radiation be+ r$uc$ to "o-half 9 tw5ty-eight m9utes4 ,! same result is obta9$ :5 ord9>y air is sub/itut$ = ! active air 9 ! enclosure4 ,! law ( dissipation ) r$uction ( int5sity ( radiation to "o-half 9 f\r days1 is !re=e *>act]i/ic ( ! disappe>ance ( radio-active en]gy accumulat$ 9 ! gas4 ,by mak+ use ( ! expression adopt$ by ,mr4 ,ru!r=d1 ! emanation f radium may be said to disappe> spontane\sly z a function ( ! "t1 ) r$uction to "o-half 9 f\r days4 ,! emanation f ?orium is ( ano!r k9d1 & disappe>s mu* m rapidly4 ,! int5sity ( radiation dim9i%es to "o-half 9 ab\t "o m9ute t5 seconds4 ,! emanation f act9ium disappe>s /ill m rapidly2 r$uction to "o-half takes place 9 a few seconds4 ,v>iation ( ,activity ( ,liquids r5d]$ ,active & ( ,radium ,solutions4 ,any liquid :atev] becomes radio-active :5 plac$ 9 an active conf9$ space4 ,on be+ remov$ & left freely expos$ to ! air1 ! liquid rapidly loses its activity1 imp>t+ x to ! gas & solid bodies surr\nd+ x4 ,if a liquid ?us made active be plac$ 9 a clos$ flask1 x loses its activity mu* m sl[ly2 ! latt] be+ r$uc$ 9 int5sity to "o-half 9 f\r days1 j z w\ld a gas "u simil> circum/ances4 ,?is fact may be expla9$ by assum+ t ! radio-active en]gy is /or$ 9 liquids 9 exactly ! same =m z 9 gases 79 ! =m ( an emanation74 ,a solution ( a radium salt behaves 9 a some:at simil> mann]4 ,at fir/1 x is a rem>kable fact t ! solution ( a radium salt plac$ = "s "t 9 a conf9$ space is no m active ?an pure wat] plac$ 9 a vessel 9 ! same enclosure1 :5 ! equilibrium ( activity is e/abli%$4 ,if ! radium solution be remov$ f ! enclosure & left /&+ 9 ! air 9 a wide-neck$ vessel1 ! activity spreads itself into space1 & ! solution becomes ne>ly inactive1 ?\gh /ill conta9+ radium4 ,if ?is solution be n[ enclos$ 9 a /opp]$ flask1 x gradually rega9s1 9 ab\t a =tnight1 a maximum ( activity1 :i* may be consid]able4 ,on ! o!r h&1 a liquid made active1 b n conta9+ radium1 does n rega9 its activity 9 a clos$ flask aft] hav+ be5 expos$ to ! atmosph]e4 ,!ory ( ,radio-activity4 ,! foll[+ is1 accord+ to ,,mm4 ,curie & ,debi]ne1 a v g5]al !ory :i* all[s ( ! co-ord9ation ( ! results ( ! inve/igation ( induc$ radio-activity1 :i* results ,i h j /at$1 & :i* con/itute facts ap>t f any hypo!sis4 ,x may be said t ea* atom ( radium acts z a con/ant & cont9u\s s\rce ( en]gy1 )\t actually def9+ ! orig9 ( ?is en]gy4 ,! radio-active en]gy :i* accumulates 9 ! radium t5ds to become dissipat$ 9 two diff]5t ways3--7#a7 ,by radiation 7rays bo? *>g$ & un*>g$ ) electricity72 7#b7 by conduction1 i4e41 by gradual transmission to surr\nd+ bodies 9 a m$ium ( gases & liquids 7production ( an emanation & trans=mation into induc$ radio-activity74 ,! loss ( radio-active en]gy1 bo? by radiation & by conduction1 increases ) ! am\nt ( en]gy accumulat$ 9 ! radio-active body4 ,! sy/em is necess>ily 9 equilibrium :5 ! d\ble loss ( :i* ,i h j made m5tion comp5sates ! con/ant ga9 due to ! action ( radium4 ,?is mann] ( reg>d+ ! subject is simil> to t 9 use = calorific ph5om5a4 ,if 9 ! int]ior ( any body !re is1 ow+ to any cause1 a cont9u\s & con/ant evolution ( heat1 ! heat accumulates 9 ! body & ! temp]ature rises until ! loss ( heat by radiation & conduction is 9 equilibrium ) ! con/ant ga9 ( heat4 ,9 g5]al1 except "u c]ta9 special circum/ances1 ! activity is n propagat$ ?r\gh solid bodies4 ,:5 a solution is kept 9 a seal$ tube1 ! loss by radiation alone takes place1 & ! radiat+ activity ( ! solution is ( a high] degree4 ,if1 on ! contr>y1 ! solution /&s 9 an op5 vessel1 ! loss ( activity by conduction becomes consid]able1 & :5 ! /ate ( equilibrium is atta9$1 ! radiat+ activity ( ! solution is v feeble4 ,! radiat+ activity ( a solid radium salt left expos$ to ! air does n s5sibly dim9i%1 because ! propagation ( activity by conduction n tak+ place ?r\gh solid bodies1 x is a v ?9 sup]ficial lay] only t produces induc$ radio-activity4 ,! solution1 h[ev]1 ( ! same salt produces mu* m int5se ph5om5a ( induc$ radio-activity4 ,) a solid salt ! radio-active en]gy accumulates 9 ! salt1 & is dissipat$ *iefly by radiation4 ,on ! o!r h&1 :5 ! salt has be5 = sev]al days 9 aque\s solution1 ! radio-active en]gy is divid$ betwe5 ! salt & ! wat]1 & if sep>at$ by di/illation ! wat] c>ries ) x a l>ge portion ( ! activity1 & ! solid salt is mu* less active 7t5 or fifte5 times7 ?an be=e solution4 ,aft]w>ds ! solid salt gradually rega9s its orig9al activity4 ,! prec$+ !ory may be yet fur!r def9$ by suppos+ ! radio-activity ( radium itself to be produc$ ?r\gh ! m$ium ( ! radio-active en]gy emitt$ 9 ! =m ( an emanation4 ,ea* atom ( radium may be consid]$ z a con/ant & cont9u\s s\rce ( emanation4 ,at ! same mom5t t ?is =m ( en]gy is produc$1 x und]goes a progressive trans=mation into radio-active en]gy ( ! ,becqu]el radiation4 ,! velocity ( ?is trans=mation is proportional to ! quantity ( ! emanation accumulat$4 ,:5 a radium solution is plac$ )9 an enclosure1 ! emanation is able to exp& into ! enclosure & to spread out ov] ! walls4 ,"h x is1 !re=e1 t x is trans=m$ into a radiation1 ! solution giv+ (f b few ,becqu]el rays2 ! radiation is1 9 "s sort1 ext]nalis$4 ,on ! o!r h&1 ) solid radium1 ! emanation n be+ able to escape readily1 accumulates1 & is trans=m$ into ! ,becqu]el radiation on ! spot2 ?is radiation !re=e acquires a high] value4 ,if ?is !ory ( radio-activity 7 g5]al1 we %\ld h to say t all radio-active bodies give rise to an emanation4 ,n[ ?is emission has be5 confirm$ 9 ! case ( radium1 ?orium1 & act9ium2 ) ! latt] 9 p>ticul> ! emission is enorm\s1 ev5 9 ! solid /ate4 ,uranium & polonium d n seem to emit any emanation1 ?\gh !y g5]ate ,becqu]el rays4 ,^! bodies produce no induc$ radio-activity 9 an enclos$ space1 z d ! radio-active bodies m5tion$ be=e4 ,?is fact is n 9 absolute contradiction to ! prec$+ !ory4 ,if uranium & polonium 7 to emit emanations :i* become de/roy$ ) v great rapidity1 x w\ld be v difficult to obs]ve ! c>riage ( su* emanations by ! air & ! effects ( induc$ radio-activity produc$ by !m ^u neighb\r+ bodies4 ,su* a hypo!sis is n improbable1 s9ce ! times requir$ = c]ta9 quantities ( ! emanations ( radium & ?orium to dim9i% to "o-half are 9 ! proportion ( #ejjj to #a4 ,we %all see1 moreov]1 t1 "u c]ta9 conditions1 uranium c excite induc$ activity4 ,ano!r ,=m ( ,induc$ ,radio-activity4 ,accord+ to ! law ( dissipation 9 ! op5 air ( ! activity induc$ by radium 9 solid bodies1 ! activity aft] "o day is almo/ imp]ceptible4 ,c]ta9 bodies1 h[ev]1 =m exceptions2 su* are celluloid1 p>aff91 ca\t*\c1 c4 ,:5 ^! bodies h be5 act$ ^u to a suffici5t degree1 !y lose _! activity m sl[ly ?an ! law c acc\nt =1 & x is (t5 fifte5 or tw5ty days be=e ! activity becomes imp]ceptible4 ,^! bodies appe> to h ! prop]ty ( becom+ *>g$ ) radio-active en]gy 9 ! =m ( an emanation2 !y aft]w>ds lose x gradually1 caus+ induc$ radio-activity 9 ! vic9ity4 ,induc$ ,radio-activity ) ,sl[ ,dissipation4 ,!re is yet ano!r =m ( induc$ radio-activity1 :i* appe>s to be produc$ 9 all bodies :i* h be5 kept = mon?s 9 an active enclosure4 ,:5 ^! bodies are remov$ f ! enclosure _! activity at fir/ dim9i%es to a v l[ value accord+ to ! ord9>y law 7dim9ution to "o-half 9 half-an-h\r72 b :5 ! activity has fall5 to ab\t #a_/bj1jjj ( ! initial value1 x dim9i%es no fur!r1 or at lea/ x is dissipat$ v sl[ly1 sometimes ev5 increas+ 9 am\nt4 ,we h %eets ( copp]1 alum9ium1 & glass :i* /ill reta9 a residual activity aft] six mon?s4 ,^! ph5om5a ( induc$ radio-activity appe> to be ( a diff]5t k9d f ! ord9>y ones1 & %[ a mu* sl[] process ( evolution4 ,a consid]able "t is also necess>y bo? = ! production & dissipation ( ?is =m ( induc$ radio-activity4 ,radio-activity ,induc$ ^u ,sub/ances 9 ,solution ) ,radium4 ,:5 a radio-active ore conta9+ radium is treat$1 ) ! object ( extract+ ! radium1 *emical sep>ations are effect$1 aft] :i* ! radio-activity is conf9$ entirely to "o ( ! products4 ,9 ?is way active products1 :i* may be sev]al hundr$ times z active z uranium1 are sep>at$ f totally inactive products1 su* z copp]1 antimony1 ars5ic1 c4 ,c]ta9 o!r bodies 7iron1 lead7 7 nev] sep>at$ 9 an entirely inactive /ate4 ,z ^! active bodies are conc5trat$1 ! case is no long] ! same2 ea* *emical sep>ation no long] furni%es absolutely inactive products2 all ! result+ products ( a sep>ation are active 9 v>y+ degrees4 ,aft] ! discov]y ( induc$ radio-activity1 ,m4 ,giesel 0 ! fir/ to attempt to excite activity 9 ord9>y inactive bismu? by keep+ x 9 solution ) v active radium4 ,he ?us obta9$ radio-active bismu?1 & f ?is he conclud$ t ! polonium extract$ f pit*bl5de 0 probably bismu? made active by ! vic9ity ( ! radium conta9$ 9 ! pit*bl5de4 ,i h also prep>$ active bismu? by keep+ bismu? 9 solution ) a v active radium salt4 ,! difficulties ( ?is exp]im5t consi/ 9 ! extreme precautions :i* mu/ be tak5 to remove all traces ( radium f ! solution4 ,if we realise :at an inf9itesimal quantity ( radium suffices to produce v consid]able radio-activity 9 #a grm4 ( mat]ial1 x is difficult to believe 9 ! possibility ( suffici5tly wa%+ & purify+ ! active product4 ,ea* purification causes a dim9ution ( activity ( ! product1 :e!r ?is be due to removal ( traces ( radium or t ! induc$ radio-activity is1 "u ^! circum/ances1 n pro( aga9/ *emical reactions4 ,! results ,i obta9$ appe>1 h[ev]1 to e/abli% ) c]ta9ty ! fact t ! activity is produc$ & p]si/s aft] ! radium is remov$4 ,on fractionat+ ! nitrate ( my active bismu? by precipitation ) wat] f ! nitric acid solution1 ,i f\nd t aft] c>eful purify+ x fractionat$ l polonium1 ! mo/ active portion be+ precipitat$ fir/4 ,if ! purification is n complete ! opposite occurs1 %[+ t traces ( radium /ill rema94 ,i ?us obta9$ active bismu? :i* f ! mann] ( fractionation %[$ great purity & :i* 0 #bjjj times z active z uranium4 ,?is bismu? dim9i%es 9 activity ) lapse ( "t4 ,b ano!r portion ( ! same product1 prep>$ ) ! same precautions1 & fractionat+ 9 ! same mann]1 pres]ves its activity )\t dim9ution = actually a p]iod ( ab\t ?ree ye>s4 ,?is activity is #aej times z great z t ( uranium4 ,i h also prep>$ active lead & silv] by leav+ !m 9 solution ) radium4 ,g5]ally induc$ radio-activity obta9$ 9 ?is way sc>cely less5s ) lapse ( "t1 b x does n z a rule )/& _m successive *emical *anges ( ! active body4 ,m4 ,debi]ne made active b>ium by plac+ x 9 solution ) act9ium4 ,?is b>ium rema9s active aft] sev]al *emical reactions1 its activity be+ !re=e a some:at /able atomic prop]ty4 ,active b>ium *loride fractionates l b>ium-radium *loride1 ! m active portions be+ ! lea/ soluble 9 wat] & dilute hydro*loric acid4 ,! dry *loride is spontane\sly lum9\s3 its ,becqu]el radiation is simil> to t ( b>ium-radium *loride4 ,m4 ,debi]ne has prep>$ an active b>ium *loride #ajjj times z active z uranium4 ,?is b>ium1 h[ev]1 _h n acquir$ all ! *>act]i/ics ( radium1 = x %[$ none ( ! /ronge/ radium l9es 9 ! spectroscope4 ,fur!r1 its activity dim9i%$ on /&+1 & aft] ?ree weeks x _h become "o-?ird ( its orig9al value4 ,!re is a wide field = rese>* ^u ! radio-activity induc$ 9 sub/ances 9 solution ) active bodies4 ,x appe>s t1 accord+ to ! conditions ( exp]im5t1 m or less /able =ms ( induc$ atomic radio-activity may be obta9$4 ,! radio-activity induc$ "u ^! circum/ances is p]haps id5tical ) t =m1 :i* dissipates sl[ly1 obta9$ by prolong$ exposure at a di/ance 9 an active enclosure4 ,we h reason to enquire to :at degree induc$ radio-activity affects ! *emical nature ( ! atom1 & if x is able to modify ! *emical prop]ties ( ! latt]1 ei!r tempor>ily or p]man5tly4 ,! *emical inve/igation ( bodies excit$ at a di/ance is r5d]$ difficult by ! fact t ! induc$ activity is limit$ to a v ?9 sup]ficial lay]1 & t1 consequ5tly1 only a v small proportion ( ! mat]ial has be5 affect$4 ,induc$ radio-activity also results f leav+ c]ta9 sub/ances 9 solution ) uranium4 ,! exp]im5t succe$$ 9 ! case ( b>ium4 ,if1 z 0 done by ,m4 ,debi]ne1 sulphuric acid be add$ to a solution conta9+ uranium & b>ium1 ! precipitate ( b>ium sulphate acquires radio-activity1 &1 at ! same "t1 ! uranium salt loses "p ( its activity4 ,m4 ,becqu]el f\nd1 aft] repeat+ ?is exp]im5t sev]al times1 t almo/ inactive uranium 0 obta9$4 ,?is might lead to ! op9ion t a radio-active body diff]+ f uranium _h be5 sep>at$ f ! latt]1 its pres5ce produc+ radio-activity 9 uranium4 ,?is1 h[ev]1 is n ! case1 = aft] "s mon?s ! uranium rega9s its orig9al activity2 ! precipitat$ b>ium sulphate1 on ! contr>y1 loses :at x acquir$4 ,a simil> ph5om5on is obs]v$ ) ?orium4 ,mr4 ,ru!r=d precipitat$ a solution ( a salt ( ?orium ) ammonia2 he sep>at$ (f ! solution & evaporat$ x to dryness4 ,he ?us obta9$ a small v active residue1 & ! precipitat$ ?orium 0 obs]v$ to be less active ?an be=e4 ,?is active residue1 to :i* ,mr4 ,ru!r=d gives ! "n ( ?orium ,x1 loses its activity aft] a "t1 :il/ ! ?orium rega9s its orig9al activity4 ,x appe>s1 !n1 t conc]n+ induc$ radio-activity all bodies d n behave 9 a simil> mann]1 & t c]ta9 ( !m are mu* m readily excit$ ?an o!rs4 ,dissem9ation ( ,radio-active ,p>ticles & ,induc$ ,radio-activity ( ! ,laboratory4 ,9 mak+ inve/igations ( /rongly radio-active bodies1 p>ticul> precautions mu/ be obs]v$ = obta9+ delicate det]m9ations4 ,! diff]5t objects us$ 9 ! *emical laboratory & ^? us$ = physical exp]im5ts soon acquire radio-activity1 & act ^u photographic plates ?r\gh black pap]4 ,du/ p>ticles1 ! air ( ! room1 clo?+1 all become radio-active4 ,! air ( ! room becomes a conductor4 ,9 our laboratory ! evil has become acute1 & we no long] h any app>atus prop]ly insulat$4 ,special precautions mu/ !re=e be tak5 to avoid z mu* z possible ! dissem9ation ( active du/ p>ticles1 & to avoid also ! ph5om5a ( induc$ activity4 ,! objects employ$ 9 *emi/ry %\ld nev] be br\ght into ! room :]e physical rese>* is c>ri$ on1 & z f> z possible %\ld be avoid$ any unnecess>y keep+ ( active sub/ances 9 ?is room4 ,be=e beg9n+ our rese>*es we 7 9 ! habit1 9 ! case ( electrical exp]im5ts1 ( mak+ a connection betwe5 ! diff]5t p>ts ( ! app>atus by insulat$ metallic wires1 protect$ by metal cyl9d]s connect$ to e>?1 :i* scre5$ ! wires f all outside electrical =ces4 ,9 ! inve/igation ( radio-active bodies ?is arrangem5t is q defective2 ! air be+ a conductor !re is incomplete insulation betwe5 ! ?read & ! cyl9d]1 & ! inevitable electromotive =ce ( contact betwe5 ! ?read & ! cyl9d] t5ds to produce a curr5t ?r\gh ! air1 & to cause a deflection ( ! electromet]4 ,we n[ scre5 all ! wires f ! air by plac+ !m inside cyl9d]s fill$ ) p>aff9 or o!r insulat+ mat]ial4 ,x w\ld also be advantage\s 9 ^! inve/igations to make use ( c>efully enclos$ electromet]s4 ,activity ,induc$ ,outside ! ,influ5ce ( ,radio-active ,sub/ances4 ,attempts 7 made to produce induc$ radio-activity outside ! action ( radio-active bodies4 ,m4 ,vill>d subject$ to ! action ( ! ca?ode rays a piece ( bismu? plac$ z antica?ode 9 a ,crookes tube2 ! bismu? 0 ?us r5d]$ active to a v slight degree1 = x requir$ an exposure ( eight days to obta9 a photographic impression4 ,mr4 ,mac,lennan has expos$ diff]5t salts to ! action ( ca?ode rays1 aft]w>ds w>m+ !m slightly4 ,! salts !n acquir$ ! prop]ty ( neutralis+ bodies positively *>g$4 ,/udies ( ?is k9d are ( great int]e/4 ,if1 by us+ kn[n physical ag5ts1 x 7 possible to create a consid]able radio-activity 9 bodies orig9ally inactive1 we might hope !nce to discov] ! cause ( ! spontane\s radio-activity ( c]ta9 sub/ances4 ,v>iations ( ,activity ( ,radio-active ,bodies4 ,effects ( ,solution4 ,! activity ( polonium1 z ,i h said above1 dim9i%es ) "t4 ,?is dim9ution is sl[1 & does n take place at ! same rate ) diff]5t specim5s4 ,a sample ( bismu?-polonium nitrate lo/ half its activity 9 elev5 mon?s1 & #ie p] c5t 9 ?irty-?ree mon?s4 ,o!r specim5s h evid5c$ simil> dim9ution4 ,a specim5 ( metallic bismu? conta9+ polonium 0 prep>$ f ! nitrite1 its activity aft] prep>ation be+ #ajj1jjj times t ( uranium4 ,! metal is n[ only a body ( m$ium radio-activity 7#bjjj times t ( uranium74 ,its radio-activity is det]m9$ at int]vals4 ,9 six mon?s x has lo/ #fg p] c5t ( its activity4 ,! loss ( activity does n seem to be facilitat$ by *emical action4 ,9 rapid *emical *anges no consid]able loss ( activity has 9 g5]al tak5 place4 ,9 contra/ to t :i* occurs ) polonium1 radium salts possess a p]man5t radio-activity :i* evid5ces no appreciable dim9ution aft] _m ye>s4 ,a fre%ly prep>$ radium salt 9 ! solid /ate does n at fir/ possess an activity ( con/ant /r5g?4 ,its activity increases f ! "t ( prep>ation until x atta9s a practically con/ant limit+ value aft] ab\t "o mon?4 ,! opposite is ! case = a solution4 ,:5 fre%ly prep>$ ! solution is v active1 b :5 left expos$ to ! air x rapidly loses activity1 & f9ally rea*es a limit+ activity :i* may be consid]ably less ?an ! orig9al4 ,^! v>iations ( activity 7 fir/ obs]v$ by ,m4 ,giesel4 ,!y are easily acc\nt$ = by ! emanation !ory4 ,! dim9ution ( ! activity ( ! solution corresponds to ! loss ( ! emanation :i* escapes into space2 ?is dim9ution is mu* less :5 ! solution is conta9$ 9 a seal$ tube4 ,a solution :i* has lo/ its activity 9 air recov]s a great] activity 9 a seal$ tube4 ,! "t ( increase ( ! activity ( ! salt :i*1 aft] solution1 has be5 rec5tly obta9$ 9 ! solid /ate1 is t dur+ :i* ! emanation is be+ newly /or$ 9 ! solid radium4 ,! foll[+ are "s exp]im5ts on ?is subject3-- ,a solution ( b>ium-radium *loride left expos$ to ! air = two days becomes #cjj times less active4 ,a solution is enclos$ 9 a /opp]$ vessel2 ! vessel is op5$1 ! solution p\r$ into a di%1 & ! activity det]m9$3-- ,activity imm$iately det]m9$ #fg ,activity aft] two h\rs #bj ,activity aft] two days #jbe ,a solution ( b>ium-radium *loride1 :i* has be5 kept op5 to ! air1 is enclos$ 9 a seal$ glass tube1 & ! radiation ( ?is tube det]m9$4 ,! foll[+ results 7 obs]v$3-- ,activity det]m9$ imm$iately #bg ,activity det]m9$ aft] #b days #fa ,activity det]m9$ aft] #c days #gj ,activity det]m9$ aft] #d days #ha ,activity det]m9$ aft] #g days #ajj ,activity det]m9$ aft] #aa days #ajj ,! initial activity ( a solid salt aft] prep>ation is feeble 9 proportion z ! "t ( solution 0 long4 ,a great] proportion ( activity is !n transmitt$ to ! solv5t4 ,! foll[+ figures give ! initial activity ) a *loride ^: limit+ activity is #hjj1 & :i* 0 kept = a giv5 "t 9 solution2 ! salt 0 aft]w>ds dri$1 & its activity imm$iately det]m9$3-- ,limit+ activity #hjj ,initial activity aft] solution & imm$iate evaporation #ddj ,initial activity aft] ! salt has rema9$ dissolv$ #e days #abj ,initial activity aft] ! salt has rema9$ dissolv$ #ah days #acj ,initial activity aft] ! salt has rema9$ dissolv$ #cb days #aad ,dur+ ?is exp]im5t ! dissolv$ salt 0 plac$ 9 a vessel m]ely cov]$ ) a wat*-glass4 ,i made ) ! same salt two solutions :i* ,i kept 9 seal$ tubes = ?irte5 mon?s2 "o ( ^! solutions 0 eight times ! /r5g? ( ! o!r3-- ,initial activity ( ! salt 9 conc5trat$ solution aft] evaporation #bjj ,initial activity ( ! salt 9 dilute solution aft] evaporation #ajj ,! loss ( activity ( ! salt is !re=e great] :5 ! am\nt ( solv5t is great]1 ! radio-active en]gy transmitt$ to ! liquid hav+ a great] volume ( liquid to saturate & a great] space to fill4 ,! two specim5s ( ! same salt1 :i* ?us _h a diff]5t initial activity1 fur!r increas$ 9 activity at v diff]5t rates at fir/2 at ! end ( "o day !y _h ! same activity1 & ! increase ( activity n[ cont9u$ 9 ! same mann] = bo? till ! limit 0 rea*$4 ,:5 ! solution is dilute ! loss ( activity by ! salt is v rapid1 z is %[n by ! foll[+ exp]im5ts3--,?ree equal portions ( ! same radium salt are dissolv$ 9 equal quantities ( wat]4 ,! fir/ solution 7a7 is all[$ to /& 9 contact ) ! air = "o h\r1 & is !n evaporat$4 ,! second solution 7b7 has a curr5t ( air pass$ ?r\gh x = "o h\r1 & is !n evaporat$4 ,! ?ird solution 7c7 is left expos$ to ! air = ?irte5 days1 & !n evaporat$ to dryness4 ,! initial activity ( ea* ( ! ?ree salts is3-- ,= portion a #adeb ,= portion b #adaf ,= portion c #ajbf ,! limit+ activity ( ! same salt is ab\t #dgj4 ,we ?us see t ! greate/ "p ( ! effect 0 produc$ at ! end ( "o h\r4 ,fur!r1 ! air curr5t bubbl+ ?r\gh solution b = "o h\r produc$ little effect4 ,! proportion ( salt 9 solution 0 ab\t #je p] c5t4 ,radio-active en]gy 9 ! =m ( an emanation is propagat$ ) difficulty f solid radium 9 air2 x exp]i5ces ! same resi/ance to propagation f solid radium 9 a liquid4 ,:5 radium sulphate is %ak5 ) wat] = a :ole day1 its activity aft] ! op]ation is practically ! same z t ( a portion ( ! same sulphate left expos$ to air4 ,on plac+ ! radium salt 9 a vacuum1 all ! emanation capable ( displacem5t is )drawn4 ,h[ev]1 ! radio-activity ( a radium *loride kept 9 vacuo = six days 0 n s5sibly affect$ by ! op]ation4 ,?is exp]im5t %[s t ! radio-activity ( ! salt is pr9cipally due to ! radio-active en]gy g5]at$ )9 ! p>ticles1 & :i* is unaffect$ by ! vacuum4 ,! loss ( activity t radium und]goes :5 9 solution is relatively great] = ! p5etrat+ rays ?an = ! absorbable rays4 ,! foll[+ are examples ( ?is3-- ,a radium *loride :i* _h rea*$ its limit ( activity1 #dgj1 0 dissolv$ & left 9 solution = "o h\r2 x 0 !n evaporat$1 & its initial radio-activity det]m9$ by ! electrical me?od4 ,! total initial radiation 0 f\nd to be equal to ! fraction #jc ( ! total limit+ radiation4 ,if ! det]m9ation ( ! int5sity ( radiation be made by cov]+ ! active body ) an alum9ium scre5 #jja m4m4 ?ick1 ! initial radiation :i* trav]ses ?is scre5 is f\nd to be only ! fraction #jag ( ! limit+ radiation trav]s+ ! same scre54 ,:5 ! salt has be5 ?irte5 days 9 solution1 ! total initial radiation is f\nd to be ! fraction #jbb ( ! total limit+ radiation1 & is #jac ( ! limit+ radiation aft] trav]s+ #jja m4m4 ( alum9ium4 ,9 ! two cases ! ratio ( ! initial radiation aft] solution to ! limit+ radiation is #ag times z great = ! total radiation z = ! radiation :i* has trav]s$ #jja m4m4 ( alum9ium4 ,x mu/ fur!r be m5tion$ t on evaporat+ ! product aft] solution1 x is impossible to avoid a c]ta9 p]iod ( "t dur+ :i* ! product is 9 an int]m$iate condition1 nei!r entirely solid nor entirely liquid4 ,nei!r c "o avoid w>m+ ! product to remove ! wat] quickly4 ,= ^! two reasons x is sc>cely possible to det]m9e ! true initial activity ( ! product pass+ f solution to ! solid /ate4 ,9 ! exp]im5ts j quot$1 equal quantities ( ! active bodies 7 dissolv$ 9 ! same quantity ( wat]1 & ! solutions 7 !n evaporat$ to dryness "u conditions z id5tical z possible1 & )\t heat+ above #abj or #acj4 ,i inve/igat$ ! law accord+ to :i* ! activity ( a solid radium salt increases1 f ! mom5t 9 :i* ! salt is obta9$ dry aft] solution to ! mom5t 9 :i* x rea*es its limit ( activity4 ,9 ! tables :i* foll[1 ! int5sity ( radiation1 ,i1 is repres5t$ z a function ( ! "t1 ! limit+ int5sity be+ suppos$ equal to #ajj1 & ! "t be+ reckon$ f ! mom5t at :i* ! product 0 dri$4 ,table ,i4 7,fig4 #ab1 ,curve ,i47 ref]s to ! total radiation4 ,table ,,ii4 7,fig4 #ab1 ,curve ,,ii47 ref]s only to ! p5etrat+ rays 7rays :i* h trav]s$ #c c4m4 ( air & #jja m4m4 ( alum9ium74 ,,table ,i4 ,,table ,,ii4 ,"t4 ,i4 ,"t4 ,i4 ,days4 ,days4 #j #ba #j #ac #a #be #a #ai #c #dd #c #dc #e #fj #f #fj #aj #gh #ae #gj #ai #ic #bc #hf #cc #ajj #df #id #fg #ajj ,illu/ration3 ,,fig4 #ab4 ,i made sev]al o!r s]ies ( det]m9ations ( ! same k9d1 b !y d n absolutely agree ) "o ano!r1 al?\gh ! g5]al "* ( ! curves obta9$ rema9s ! same4 ,x is difficult to obta9 v regul> results4 ,x may1 h[ev]1 be rem>k$ t ! acquisition ( activity requires m ?an "o mon? = its production1 & t ! mo/ p5etrat+ rays are ! mo/ deeply affect$ by solution4 ,! initial int5sity ( ! radiation :i* is able to trav]se #c c4m4 ( air & #jja m4m4 ( alum9ium is only #a p] c5t ( ! limit+ int5sity1 :il/ ! initial int5sity ( ! total radiation is #ba p] c5t ( ! total limit+ radiation4 ,a radium salt :i* has be5 dissolv$ & rec5tly evaporat$ to dryness possesses ! same p[] ( caus+ induc$ activity 7&1 consequ5tly1 ( all[+ ! escape ( an emanation71 z a specim5 ( ! same salt :i*1 aft] hav+ be5 prep>$ 9 ! solid /ate1 has rema9$ 9 ?is condition long en\gh to h atta9$ its limit+ radio-activity4 ,! radiant activity ( ^! two products is1 h[ev]1 q diff]5t2 ! =m] is1 = example1 five times less active ?an ! latt]4 ,v>iations ( ! ,activity ( ,radium ,salts on ,heat+4 ,:5 a radium comp\nd is heat$1 x gives (f an emanation & loses activity4 ,! m int5se & ! m prolong$ ! heat+1 ! great] is ! loss ( activity4 ,?us1 on heat+ a radium salt = "o h\r to #acj1 x loses #aj p] c5t ( its total radiation2 on ! o!r h&1 heat+ = t5 m9utes to #djj produces no app>5t effect4 ,heat+ to r$ness = sev]al h\rs de/roys #gg p] c5t ( ! total radiation4 ,! loss ( activity on heat+ is m consid]able = ! p5etrat+ ?an = ! absorbable rays4 ,?us1 heat+ = sev]al h\rs de/roys ab\t #gg p] c5t ( ! total radiation1 b ! same am\nt ( heat+ de/roys ne>ly ! :ole 7#ii p] c5t7 ( ! radiation t trav]ses #c c4m4 ( air & #jja m4m4 ( alum9ium4 ,if b>ium-radium *loride be kept fus$ = sev]al h\rs 7t[>ds #hjj7 #ih p] c5t ( ! radiation capable ( trav]s+ #jc m4m4 ( alum9ium is de/roy$4 ,! p5etrat+ rays may be consid]$ z no long] 9 exi/5ce aft] int5se & prolong$ heat+4 ,:5 a radium salt has lo/ "p ( its activity by heat+1 ! dim9ution is n la/+2 ! activity ( ! salt is spontane\sly reg5]at$ at ! ord9>y temp]ature1 & approa*es a c]ta9 limit+ value4 ,i h obs]v$ ! curi\s fact t ?is limit is high] ?an ! limit+ activity ( ! salt be=e be+ heat$--?is1 at lea/1 is ! case ) ! *loride4 ,i give examples ( ?is3--,a specim5 ( b>ium-radium *loride :i*1 aft] hav+ be5 prep>$ 9 ! solid /ate1 has long s9ce atta9$ its limit+ activity1 possesses a total radiation repres5t$ by ! numb] #dgj1 & a radiation capable ( trav]s+ #jja m4m4 ( alum9ium1 repres5t$ by ! numb] #aeg4 ,?is1 specim5 is heat$ to r$ness = sev]al h\rs4 ,two mon?s aft] ! heat+ x atta9s its limit ( activity ) a total radiation equal to #fij1 & a radiation ?r\gh #jja m4m4 ( alum9ium1 equal to #bbg4 ,! total radiation & ! radiation transmitt$ by alum9ium are !re=e increas$ respectively 9 ! ratios #fij_/dgj & #bbg_/aef4 ,^! two ratios are practically equal to "o ano!r1 & are equival5t to #ade4 ,a specim5 ( radium-b>ium *loride :i*1 aft] hav+ be5 prep>$ 9 ! solid /ate1 has atta9$ a limit+ activity ( #fb1 is ma9ta9$ 9 a /ate ( fusion = "s h\rs2 ! fus$ product is !n p[d]$4 ,! product rega9s a new limit+ activity equal to #adj1 :i* is twice z great z t to :i* x 0 able to atta9 :5 prep>$ 9 ! solid /ate )\t hav+ be5 s5sibly heat$ dur+ evaporation4 ,i h inve/igat$ ! law ( increase ( activity ( radium comp\nds aft] heat+4 ,! foll[+ are ! results ( two s]ies ( det]m9ations3--,! figures ( ,table ,i4 & ,,ii4 repres5t ! int5sity ( ! radiation 7,i7 z a function ( "t1 ! limit+ int5sity be+ suppos$ equal to #ajj1 & ! "t be+ reckon$ f ! close ( ! heat+4 ,table ,i4 7,fig4 #ac1 ,curve ,i47 ref]s to ! total radiation ( a specim5 ( b>ium-radium *loride4 ,table ,,ii4 7,fig4 #ac1 ,curve ,,ii47 relates to ! p5etrat+ radiation ( a specim5 ( b>ium-radium sulphate1 ! int5sity ( ! radiation :i* trav]s$ #c c4m4 ( air & #jja m4m4 ( alum9ium hav+ be5 det]m9$4 ,! two products 7 subject$ to a bright r$ heat = sev5 h\rs4 ,,table ,i4 ,,table ,,ii4 ,"t4 ,i4 ,"t4 ,i4 ,days4 ,days4 #j #afb #j #jh #jf #bed #jg #ac #a #bgd #a #ah #b #ch #ai #bfd #c #dfc #f #dfb #d #ed #aj #eee #f #fge #ad #fd #aj #hd #ah #gah #bd #ie #bg #ha #eg #ajj #cf #ia #ej #iee #eg #ii #hd #ajj ,i made sev]al o!r s]ies ( det]m9ations1 b ! results did n agree well4 ,! effect ( heat+ does n p]si/ :5 ! heat$ radium comp\nd is dissolv$4 ,( two specim5s ( ! same radium comp\nd ( activity #ahjj1 "o 0 /rongly heat$ & its activity !reby r$uc$ to #fgj4 ,! two portions be+ n[ dissolv$ & left 9 solution = tw5ty h\rs1 _! initial activities 9 ! solid /ate 7 #dfj = ! n heat$ portion & #dbj = ! heat$ "o2 ! diff]5ce betwe5 ! two portions 0 !re=e n consid]able4 ,b if ! two products d n rema9 = a suffici5t l5g? ( "t 9 solution--if1 = example1 !y are evaporat$ to dryness1 imm$iately aft] solution--! n heat$ product is mu* m active ?an ! heat$ "o2 a c]ta9 "t is necess>y 9 ! dissolv$ /ate = ! effects ( heat+ to disappe>4 ,a product ( activity #cbjj 0 heat$1 & its activity !reby r$uc$ to #ajcj4 ,?is product & a simil> portion :i* _h n be5 heat$ 7 simultane\sly dissolv$1 & ! two !n imm$iately evaporat$ to dryness4 ,! initial activity 0 #adej = ! n heat$ portion1 & #gfj = ! heat$ "o4 ,illu/ration3 ,,fig4 #ac4 ,9 ! case ( solid radium salts ! capacity = excit+ induc$ radio-activity is l>gely affect$ by heat+4 ,dur+ heat+ radium comp\nds give (f a l>g] am\nt ( emanation ?an at ! ord9>y temp]ature2 b on be+ cool$ to ! ord9>y temp]ature1 n only is _! radio-activity mu* less ?an be=e heat+1 b _! capacity = induc+ activity is mu* dim9i%$4 ,dur+ ! "t t foll[s ! heat+1 ! radio-activity ( ! product increases1 & may ev5 exce$ ! orig9al value4 ,! induction capacity is also p>tially re-e/abli%$2 h[ev]1 aft] prolong$ heat+ to r$ness1 ?is capacity is almo/ entirely de/roy$ )\t spontane\s re-appe>ance aft]w>ds4 ,! induction capacity may be re/or$ to ! radium salt by dissolv+ x 9 wat]1 & dry+ x 9 ! ov5 at a temp]ature ( #abj4 ,?is seems to h ! effect ( leav+ ! salt 9 a peculi> physical condition1 9 :i* ! emanation is giv5 (f ) mu* less facility ?an is ! case ) ! same solid product n heat$ to a high temp]ature1 & x foll[s naturally t ! salt atta9s a high] limit ( activity ?an t :i* x possess$ be=e heat+4 ,to trans=m ! salts into ! physical condition prop] to x be=e heat+1 x suffices to dissolve x & to evaporate x to dryness )\t heat+ x above #aej4 ,! foll[+ are num]ical examples ( ! above3-- ,i repres5t by a ! limit ( induc$ activity produc$ 9 a clos$ vessel ^u a plate ( copp] by a specim5 ( b>ium-radium c>bonate ( activity #afjj4 ,suppose a #ajj = ! n heat$ product4 ,we f9d-- #a day aft] heat+ a #cc #d days aft] heat+ a #ga #aj days aft] heat+ a #ae #bj days aft] heat+ a #ae #cg days aft] heat+ a #ae ,! radio-activity ( ! product _h dim9i%$ #ij p] c5t by heat+1 b "o mon? aft]w>ds ! orig9al value 0 rega9$4 ,! foll[+ is an exp]im5t ( ! same k9d made ) a b>ium-radium *loride ( activity #cjjj4 ,! induction capacity is det]m9$ 9 ! same mann] z be=e4 ,= ! product n heat$ a #ajj4 ,induction capacity ( ! product aft] be+ heat$ to r$ness = ?ree h\rs3-- #b days aft] heat+ #bc #e days aft] heat+ #gj #aa days aft] heat+ #hb #ah days aft] heat+ #hb ,induction capacity ( ! unheat$ sub/ance :i* has be5 dissolv$ & !n dri$ at #aej #ib ,induction capacity ( ! heat$ sub/ance :i* has be5 dissolv$ & !n dri$ at #aej #aje ,!ory ( ,int]pretation ( ! ,causes ( ,v>iations ( ,activity ( ,radium ,salts aft] ,solution & aft] ,heat+4 ,! facts previ\sly indicat$ may be 9 "p expla9$ by ! !ory accord+ to :i* ! en]gy ( radium is produc$ 9 ! =m ( an emanation1 :i* is !n trans=m$ into ! en]gy ( radiation4 ,:5 a radium salt is dissolv$1 ! emanation produc$ by x spreads beyond ! solution1 & causes radio-activity outside ! s\rce f :i* x proce$s2 :5 ! solution is evaporat$1 ! solid salt obta9$ is b slightly active1 because x conta9s only a small am\nt ( emanation4 ,gradually ! emanation is accumulat$ 9 ! salt1 ! activity ( :i* rises to a limit+ value1 :i* is rea*$ :5 ! production ( ! emanation by ! radium comp5sates ! loss by ext]nal emission & by local trans=mation into ,becqu]el rays4 ,:5 a radium salt is heat$1 ! ext]nal emission ( ! emanation is greatly increas$1 & ! ph5om5a ( induc$ radio-activity are m int5se ?an :5 ! salt is at ! ord9>y temp]ature4 ,b :5 ! salt returns to ! ord9>y temp]ature x is exhau/$1 z is ! case aft] be+ dissolv$1 & conta9s b a small am\nt ( emanation1 its activity hav+ become greatly r$uc$4 ,gradually ! emanation accumulates afre% 9 ! solid salt1 & ! radiation increases4 ,x may be said t radium gives rise to a con/ant g5]ation ( any emanation--"p ( :i* escapes to ! ext]ior1 ! rema9d] be+ trans=m$ 9 ! radium itself into ,becqu]el rays4 ,:5 radium is rais$ to a r$ heat1 x loses ! great] "p ( its capacity to cause ! induction ( activity2 o!rwise /at$1 ! evolution ( ! emanation is less5$4 ,consequ5tly1 ! proportion ( ! emanation utilis$ 9 ! radium itself %\ld be great]1 & ! sub/ance atta9s a high] limit ( radio-activity4 ,we w endeav\r to e/abli% !oretically ! law ( rise ( activity ( a solid radium salt :i* has be5 dissolv$ or has be5 heat$4 ,we w assume t ! int5sity ( radiation ( radium is1 at ea* in/ant1 proportional to ! quantity ( emanation1 q1 pres5t 9 ! radium4 ,we "k t ! emanation is spontane\sly de/roy$ accord+ to a law su* t1 at ea* in/ant-- q q#j;e-t_/ 4 4 4 4 4 4 4 4 4 #a1 q#j be+ ! am\nt ( ! emanation at ! mom5t ( />t+ ! obs]vation1 & ! "t con/ant1 equal to #dig #aje secs4 ,n[ let be ! evolution ( ! emanation by radium1 a quantity :i* ,i w assume con/ant4 ,let u consid] :at w\ld occur if no emanation 7 escap+ to ! ext]ior4 ,! emanation g5]at$ w\ld !n be completely utilis$ by ! radium = ! production ( ! radiation4 ,we h f ,=mula #a-- dq_/dt -7q#j_/7;e-t_/ -q_/2 & consequ5tly1 9 ! /ate ( equilibrium1 ! radium w\ld conta9 a c]ta9 quantity ( emanation1 ,q1 su* t-- ,q_/ 4 4 4 4 4 #b1 & ! radiation ( ! radium w\ld !n be proportional to ,q4 ,let u suppose ! radium plac$ 9 ! circum/ances "u :i* x gives (f ! emanation to ! ext]ior2 ?is is obta9$ by dissolv+ ! radium comp\nd or by heat+ x4 ,! equilibrium w be di/urb$1 & ! activity ( ! radium dim9i%$4 ,b z soon z ! cause ( ! loss ( emanation has be5 aboli%$ 7! body be+ re/or$ to ! solid /ate or ! heat+ hav+ ceas$71 ! emanation is accumulat$ afre% 9 ! radium & we h a p]iod dur+ :i* ! evolution1 1 surpasses ! velocity ( de/ruction1 q_/4 ,we !n h-- dq_/dt - q_/ 7,q - q7_/1 f :i*-- 7d_/dt77,q - q7 -7,q - q7_/1 ,q - q 7,q - q#j7;e-t_/ #c1 q#j be+ ! am\nt ( emanation pres5t 9 ! radium at "t t #j4 ,accord+ to ,=mula #c1 ! excess ( ! quantity ( emanation1 ,q1 conta9$ by ! radium 9 a /ate ( equilibrium above ! quantity1 q1 conta9$ at a giv5 mom5t1 decreases z a function ( ! "t accord+ to an expon5tial law1 :i* is also ! law ( ! spontane\s disappe>ance ( ! emanation4 ,! radiation ( radium be+ proportional to ! am\nt ( emanation1 ! excess ( ! int5sity ( ! limit+ radiation above ! actual int5sity %\ld decrease z a function ( ! "t by ! same law2 ! excess %\ld ?us dim9i% to "o-half 9 ab\t f\r days4 ,! prec$+ !ory is incomplete1 s9ce ! loss ( emanation to ! ext]ior has be5 neglect$4 ,x is also difficult to det]m9e ! mann] 9 :i* ?is acts z a function ( ! "t4 ,9 comp>+ ! results ( exp]im5t ) ^? ( ?is incomplete !ory1 !re is f\nd to be no satisfactory agreem5t2 ! conviction is1 h[ev]1 reta9$ t ! !ory 9 "q is p>tially true4 ,! law by :i* ! excess ( limit+ activity above ! actual activity dim9i%es to "o-half 9 f\r days repres5ts approximately ! c\rse ( ! r5ewal ( activity aft] heat+ = t5 days4 ,9 ! case ( ! r5ewal ( activity aft] solution1 ! same law appe>s to hold approximately = a c]ta9 p]iod ( "t1 :i* beg9s two or ?ree days aft] evaporation to dryness & cont9ues = t5 or fifte5 days4 ,! ph5om5a are o!rwise complex2 ! !ory sket*$ out does n expla9 ! reason ( ! suppression ( ! p5etrat+ rays 9 great] proportion ?an ! absorbable rays4 ,,nature ,,& ,,cause ,,( ,,! ,,ph5om5a ,,( ,,radio-,,activity4 ,f ! beg9n+ ( rese>* ^u ! radio-active bodies1 & :5 ! prop]ties ( ^! bodies 7 yet h>dly kn[n1 ! spontaneity ( _! radiation pres5t$ itself z a problem hav+ ! greate/ int]e/ = physici/s4 ,to-day we h advanc$ consid]ably 9 ! und]/&+ ( radio-active bodies1 & are able to isolate "o ( v great p[]1 viz41 radium4 ,) ! object ( mak+ use ( ! rem>kable prop]ties ( radium1 a pr(\nd inve/igation ( ! rays emitt$ by radio-active bodies is indisp5sable2 ! v>i\s gr\ps ( rays "u inve/igation pres5t po9ts ( simil>ity ) ! gr\ps ( rays exi/+ 9 ,crookes tubes3 ca?ode rays1 ,rntg5 rays1 canal rays4 ,! same gr\ps ( rays are f\nd 9 ! second>y radiation produc$ by ,rntg5 rays1 & 9 ! radiation ( bodies :i* h acquir$ radio-activity by induction4 ,b if ! nature ( ! radiation is actually bett] kn[n1 ! cause ( ?is spontane\s radiation rema9s a my/]y1 & ! ph5om5a always pres5ts itself to u z a pr(\nd & wond]ful enigma4 ,! spontane\sly radio-active bodies1 & 9 ! fir/ place radium1 are s\rces ( en]gy4 ,! evolution ( en]gy1 to :i* !y give rise1 is manife/$ by ,becqu]el radiation1 by *emical & lum9\s effects1 & by ! cont9u\s g5]ation ( heat4 ,! "q (t5 arises z to :e!r en]gy is creat$ )9 ! radio-active bodies !mselves1 or :e!r x is borr[$ by !m f ext]nal s\rces4 ,no "o ( ! num]\s hypo!ses aris+ f ^! two po9ts ( view has yet receiv$ exp]im5tal confirmation4 ,! radio-active en]gy may be assum$ to h be5 initially accumulat$ & !n gradually dissipat$1 z happ5s 9 ! case ( long cont9u$ phosphoresc5ce4 ,we imag9e ! evolution ( radio-active en]gy to correspond to a trans=mation ( ! nature ( ! atom ( ! active body2 ! fact ( ! cont9u\s g5]ation ( heat by radium speaks 9 fav\r ( ?is hypo!sis4 ,! trans=mation may be assum$ to be accompani$ by a loss ( weight & by an emission ( mat]ial p>ticles con/itut+ ! radiation4 ,! s\rce ( en]gy may yet be s\ght 9 ! en]gy ( gravitation4 ,f9ally1 we may imag9e t space is con/antly trav]s$ by radiations yet unkn[n1 :i* are arre/$ 9 _! c\rse by radio-active bodies & trans=m$ into radio-active en]gy4 ,_m reasons are adduc$ = & aga9/ ^! diff]5t views1 & mo/ (t5 attempts at exp]im5tal v]ifications ( ! conclusions drawn f ^! hypo!ses h giv5 negative results4 ,! radio-active en]gy ( uranium & radium app>5tly nei!r becomes exhau/$ nor v>ies appreciably ) lapse ( "t4 ,dem>ay exam9$ spectroscopically a specim5 ( pure radium *loride aft] a five mon?s' int]val1 & obs]v$ no *ange 9 ! spectrum4 ,! pr9cipal b>ium l9e1 :i* 0 visible 9 ! spectrum indicat+ ! pres5ce ( a trace ( b>ium1 _h n increas$ 9 int5sity dur+ ! int]val1 %[+ !re=e t !re 0 no trans=mation ( radium into b>ium to an appreciable ext5t4 ,! v>iations ( weight ann\nc$ by ,m4 ,heydweill] 9 radium comp\nds _c yet be look$ ^u z e/abli%$ facts4 ,el/] & ,geitel f\nd t ! radio-activity ( uranium is n affect$ at ! bottom ( a m9e-%aft #hej m4 deep2 a lay] ( e>? ( ?is ?ickness w\ld !re=e n affect ! hypo!tical prim>y radiation :i* w\ld be excit$ by ! radio-activity ( uranium4 ,we h det]m9$ ! radio-activity ( uranium at midday & at midnight1 ?9k+ t if ! hypo!tical prim>y radiation _h its orig9 9 ! sun x w\ld be p>tly absorb$ 9 trav]s+ ! e>?4 ,! exp]im5t %[$ no diff]5ce 9 ! two det]m9ations4 ,conclusions4 ,i w def9e1 9 conclusion1 ! "p ,i h p]sonally tak5 9 ! rese>*es ^u radio-active bodies4 ,i h inve/igat$ ! radio-activity ( uranium comp\nds4 ,i h exam9$ o!r bodies = ! exi/5ce ( radio-activity1 & f\nd ! prop]ty to be possess$ by ?orium comp\nds4 ,i h made cle> ! atomic "* ( ! radio-activity ( ! comp\nds ( uranium & ?orium4 ,i h conduct$ a rese>* ^u radio-active sub/ances o!r ?an uranium & ?orium4 ,to ?is end ,i inve/igat$ a l>ge numb] ( sub/ances by an accurate electrometric me?od1 & ,i discov]$ t c]ta9 m9]als possess activity :i* is n to be acc\nt$ = by _! cont5t ( uranium & ?orium4 ,f ?is ,i conclud$ t ^! m9]als mu/ conta9 a radio-active body diff]5t f uranium & ?orium1 & m /rongly radio-active ?an ! latt] metals4 ,9 conjunction ) ,m4 ,curie1 & subsequ5tly ) ,,mm4 ,curie & ,bmont1 ,i 0 able to extract f pit*bl5de two /rongly radio-active bodies--polonium & radium4 ,i h be5 cont9u\sly engag$ ^u ! *emical exam9ation & prep>ation ( ^! sub/ances4 ,i effect$ ! fractionations necess>y to ! conc5tration ( radium1 & ,i succe$$ 9 isolat+ pure radium *loride4 ,concurr5tly ) ?is "w1 ,i made sev]al atomic weight det]m9ations ) a v small quantity ( mat]ial1 & 0 f9ally able to det]m9e ! atomic weight ( radium ) a v fair degree ( accuracy4 ,! "w has prov$ t radium is a new *emical elem5t4 ,?us ! new me?od ( inve/igat+ new *emical elem5ts1 e/abli%$ by ,m4 ,curie & myself1 bas$ ^u radio-activity1 is fully ju/ifi$4 ,i h inve/igat$ ! law ( absorption ( polonium rays1 & ( ! absorbable rays ( radium1 & h demon/rat$ t ?is law ( absorption is peculi> & diff]5t f ! kn[n laws ( o!r radiations4 ,i h inve/igat$ ! v>iation ( activity ( radium salts1 ! effect ( solution & ( heat+1 & ! r5ewal ( activity ) "t1 aft] solution or aft] heat+4 ,9 conjunction ) ,m4 ,curie1 ,i h exam9$ diff]5t effects produc$ by ! new radio-active sub/ances 7electric1 photographic1 fluoresc5t1 lum9\s col\rations1 c474 ,9 conjunction ) ,m4 ,curie1 ,i h e/abli%$ ! fact t radium gives rise to rays *>g$ ) negative electricity4 ,our rese>*es ^u ! new radio-active bodies h giv5 rise to a sci5tific movem5t1 & h be5 ! />t+-po9t ( num]\s rese>*es 9 connection ) new radio-active sub/ances1 & ) ! inve/igation ( ! radiation ( ! kn[n radio-active bodies4 ---------------------------------------- -------------------------------- ,,radium ,,& ,,o!r ,,radio-,,active ,,elem5ts4 ,a ,popul> acc\nt ( ,radium & o!r ,radio-active ,elem5ts treat$ exp]im5tally4 ,includ+ a numb] ( ,radium ,photographs & o!r ,illu/rations4 ,by ,,leon>d ,a4 ,,levy & ,,h]b]t ,g4 ,,willis4 ,,price #bs4 #f;d4 net2 po/ free #bs4 #i;d4 ,,cont5ts4 ,,introduction4--,*ap4 ,i4 ,! ,discov]y ( ,radium2 its ,extraction4--,*ap4 ,,ii4 ,! ,radium ,emanation4--,*ap4 ,,iii4 ,physical ,effects 7,electrical & ,magnetic74--,*ap4 ,,iv4 ,physical ,effects 7cont9u$74--,*ap4 ,v4 ,*emical ,effects4--,*ap4 ,,vi4 ,actions on ,animal ,life & ,liv+ ,tissues4--,*ap4 ,,vii4 ,o!r ,radio-active ,elem5ts4--,app5dix4--,exp]im5tal ,app>atus4 ,,p]cival ,,m>%all ,,co41 #bf-bi1 ,,popp9',s ,,c\rt1 ,,fleet ,,/reet1 ,,london1 ,e4,c4 99 99 99 99 99 ,,radium ,,sp9?>iscopes4 ,,z ,,design$ ,,by ,,sir ,,william ,,crookes1 ,f4,r4,s41 ,= ,demon/rat+ ! ,radio-activity ( ,radium4 ,,kunzite4 ,,! ,,new ,,m9]al4 ,respond+ 9 a high degree to ! ,emanations f ,radium4 ,,z9c ,,sulphide ,,scre5s4 ,,calcium ,,sulphide--,phosphoresc5t4 ,,z9c ,,sulphide--,phosphoresc5t4 ,,pit*bl5de--,specim5s4 ,write = p>ticul>s to ,,john ,j4 ,,griff9 ,,sons1 ,ltd41 #bj1 #bb1 #bd1 #bf1 ,,s>d9ia ,,/reet1 ,,london1 ,w4,c4 ---------------------------------------- -------------------------------- ,,radium ,,applicators ,its employm5t 9 ,!rapeutics & = sci5tific rese>*4 7,mac,leod7 ,surface1 ea* #gs4 #f;d4 ,?roat1 #a #as4 ,,b>ium ,,plat9ocyanide ,,scre5s1 p] sq4 in*1 #i;d4 ,,calcium ,,sulphide1 lum9\s1 p] lb41 #h_/- ,,kunzite1 p] ,gm41 #a_/- ,,polonium1 ,,on ,,bismu? ,,copp] ,,discs1 ea* #be_/- ,,pit*bl5de1 specim5s1 ea*1 p] oz41 #b_/f4 ,,uranium ,,nitrate1 oz41 #a_/-4 ,,?orium ,,hydroxide1 oz41 #d_/-2 lb41 #dh_/-4 ,,?orium ,,hydroxide ,,pads1 ea* #aj_/f4 ,,willemite1 ,natural ,specim5s1 #b_/- ea*4 ,,willemite1 ,artificial ,specim5s1 #a_/- ea*4 ,,z9c ,,sulphide1 ,active1 ,gm4 #a_/f4 ,,z9c ,,sulphide ,,scre5s1 #aj #aj c5timetres1 ea* #g_/f4 ,illu/ration ,special ,quotations = ,quantity4 ,,*emicals ,,& ,,app>atus = ,sci5tific ,rese>*4 7,write = ,price ,li/47 ,,sp9?>iscopes %[+ ! ,sc9tillations ( ,radium1 #ba_/- ,illu/ration ,w4 ,,m>t9dale1 ,manufactur+ ,*emi/1 #aj ,,new ,,cav5di% ,,/reet1 ,w4 ,telegraphic ,address3 8,m>t9dale1 ,*emi/1 ,london40 ,telephone3 #agig ,padd+ton4 99 99 99 99 99 ,,radium ,,on ,,sale ,,& ,,let ,,on ,,hire4--,write = ,t]ms4 ,! foll[+ c be _h by return ( po/4 ,pit*bl5de1 direct f ,joa*im/hal1 v radio-active1 f #a_/- to #cj_/- p] piece4 ,itacolomite1 or flexible s&/one1 #aj_/- to #be_/- p] piece 7v r>e74 ,kunzite1 #a_/- p] gramme4 ,select$1 cle>1 #b_/- ,sp>teite 7see ,,nature1 #ca #c_/jd1 fol4 #ebc71 #b_/- & upw>ds4 ,*lorophane1 #b_/- & upw>ds4 ,b>ium ,plat9o ,cyanide 9 l>ge ,cry/als 9 c\rse ( manufacture4 7,,ord]s ,,book$74 ,z9c ,sulphide4 ,phosphoresc+ a beautiful ,gre51 #b_/f p] tube4 ,z9c ,sulphide4 ,phosphoresc+ a beautiful ,yell[1 #b_/f p] tube4 ,calcium ,sulphide ,phosphoresc+ a beautiful ,violet1 #a_/- p] tube4 ,radio-active ,residue f :i* ,radium is made2 v sc>ce1 #b_/- tube4 ,polonium ,sulphide1 9 tubes ( "o gramme1 #ba_/- ,polonium on ,bismu? ,rod or ,disc1 #be_/- ,polonium on ,copp] ,rod or ,disc1 #be_/- ,radio-active ,scre5s 7,willemite71 #f;d4 p] sq4 in*4 ,plat4 ,b>4 ,cyan ,scre541 #i;d4 sq4 in* ,radio-active ,scre5s 7,z9c ,sulph471 #aj #aj cm4 #g_/f4 99 99 99 99 99 ,pr(essional ,m51 ,univ]sities1 ,s*ools1 c41 all[$ special t]ms4 99 99 99 99 99 ,our newly inv5t$ ,?orium ,inhal]s may be _h on hire4 99 99 99 99 99 ,,armbre*t1 ,,nelson ,,co41 #ga #gc1 ,duke ,/reet1 ,grosv5or ,squ>e1 ,london1 ,w4 ,telephone3 ,,g]r>d #didb4 99 99 99 99 99 ,n4,b4--,we h to-day receiv$ a consignm5t ( ! ,new ,zeal& ,vegetable ,cat]pill>2 x is f #b to #c in*es long1 ) a /em %[+ fructification gr[+ out ( its head4 ,sci5tific "n ( ! insect is ,hepialus viresc5s2 ! "n ( ! fungus is ,spha]ia ,rob]tsiana4 ,specim5s may be _h f #aj_/f to #ba_/-1 accord+ to quality & size4 ,,t]ms ,,ca% ,,) ,,ord]4 ,goods may be return$ if n approv$ (1 :5 money w be refund$4 ---------------------------------------- -------------------------------- ,,transcrib]',s ,,notes #a4 ,sil5tly correct$ typographical errors & v>iations 9 spell+4 #b4 ,ana*roni/ic1 non-/&>d1 & unc]ta9 spell+s reta9$ z pr9t$4 #c4 ,enclos$ italics font 9 und]scores4 #d4 ,enclos$ bold font 9 equals4 #e4 ,sup]scripts are d5ot$ by a c>et be=e a s+le sup]script "* or a s]ies ( sup]script$ *>act]s enclos$ 9 curly braces1 e4g4 ,mr4 or ,mi/]4 #f4 ,subscripts are d5ot$ by an und]score be=e a s]ies ( subscript$ *>act]s enclos$ 9 curly braces1 e4g4 ,h#b,o4