,radio-,activity ,,cambridge ,,physical ,,s]ies4 ,,g5]al ,,editors3--,f4 ,h4 ,,neville1 ,m4,a41 ,f4,r4,s4 ,,& ,w4 ,c4 ,d4 ,,:e?am1 ,m4,a41 ,f4,r4,s4 ,,radio-,,activity ,,cambridge ,,univ]sity ,,press ,,w>eh\se ,c4 ,f4 ,,clay1 ,,manag]4 ,london3 ,,fett] ,,lane1 ,e4,c4 ,glasg[3 #ej1 ,,well+ton ,,/reet4 ,,also ,london3 ,h4 ,k4 ,,lewis1 #acf1 ,,g[] ,,/reet1 ,w4,c4 ,leipzig3 ,f4 ,a4 ,,brockhaus4 ,new ,york3 ,,! ,,macmillan ,,company4 ,bombay & ,calcutta3 ,,macmillan ,,& ,,co41 ,,ltd4 ,all ,rights res]v$4 ,,radio-,,activity ,,by ,e4 ,,ru!r=d1 ,d4,sc41 ,f4,r4,s41 ,f4,r4,s4,c4 ,,macdonald ,,pr(essor ,,( ,,physics1 ,mc,g,i,l,l ,,univ]sity1 ,,montreal ,,second ,,edition ,,cambridge ,,at ,,! ,,univ]sity ,,press #aije ,fir/ ,edition #aijd ,second ,edition #aije ,j4 ,j4 ,,?omson ,a ,,tribute ,,( ,,my ,,respect ,,& ,,admiration ,,preface ,,to ,,! ,,fir/ ,,edition4 ,9 ?is "w1 ,i h endeav\r$ to give a complete & connect$ acc\nt1 f a physical /&po9t1 ( ! prop]ties possess$ by ! naturally radio-active bodies4 ,al?\gh ! subject is comp>atively a new "o1 our k ( ! prop]ties ( ! radio-active sub/ances has advanc$ ) great rapidity1 & !re is n[ a v l>ge am\nt ( in=mation on ! subject scatt]$ ?r\gh\t ! v>i\s sci5tific j\rnals4 ,! ph5om5a exhibit$ by ! radio-active bodies are extremely complicat$1 & "s =m ( !ory is ess5tial 9 ord] to connect 9 an intelligible mann] ! mass ( exp]im5tal facts t h n[ be5 accumulat$4 ,i h f\nd ! !ory t ! atoms ( ! radio-active bodies are und]go+ spontane\s dis9tegration extremely s]viceable1 n only 9 correlat+ ! kn[n ph5om5a1 b also 9 sugge/+ new l9es ( rese>*4 ,! int]pretation ( ! results has1 to a l>ge ext5t1 be5 bas$ on ! dis9tegration !ory1 & ! logical d$uctions to be drawn f ! application ( ! !ory to radio-active ph5om5a h also be5 consid]$4 ,! rapid advance ( our k ( radio-activity has be5 dep5d5t on ! in=mation already ga9$ by rese>* into ! electric prop]ties ( gases4 ,! action possess$ by ! radiations f radio-active bodies ( produc+ *>g$ c>ri]s or ions 9 ! gas1 has =m$ ! basis ( an accurate quantitative me?od ( exam9ation ( ! prop]ties ( ! radiations & ( radio-active processes1 & also all[s u to det]m9e ) consid]able c]ta9ty ! ord] ( magnitude ( ! diff]5t quantities involv$4 ,= ^! reasons1 x has be5 ?\ght advisable to give a brief acc\nt ( ! electric prop]ties ( gases1 to ! ext5t t is necess>y = ! int]pretation ( ! results ( measurem5ts 9 radio-activity by ! electric me?od4 ,! *apt] on ! ionization !ory ( gases 0 writt5 be=e ! publication ( ,j4 ,j4 ,?omson's rec5t book on 8,conduction ( ,electricity ?r\gh ,gases10 9 :i* ! :ole subject is treat$ 9 a complete & connect$ mann]4 ,a %ort *apt] has be5 add$1 9 :i* an acc\nt is giv5 ( ! me?ods ( measurem5t :i*1 9 ! exp]i5ce ( ! writ] & o!rs1 are mo/ suitable = accurate "w 9 radio-activity4 ,x is hop$ t su* an acc\nt may be ( "s s]vice to ^? :o may wi% to obta9 a practical acqua9tance ) ! me?ods employ$ 9 radio-active measurem5ts4 ,my ?anks are due to ,mr ,w4 ,c4 ,dampi] ,:e?am1 ,f4,r4,s41 "o ( ! editors ( ! ,cambridge ,physical ,s]ies1 = _m valuable sugge/ions1 & = ! great c>e & tr\ble he has tak5 9 revis+ ! pro( %eets4 ,i am also mu* indebt$ to my wife & ,miss ,h4 ,brooks = _! k9d assi/ance 9 correct+ ! pro(s1 & to ,mr ,r4 ,k4 ,mc,clung = revis+ ! index4 ,e4 ,r4 ,,macdonald ,,physics ,,build+1 ,,montreal1 ,febru>y1 #aijd4 ,,preface ,,to ,,! ,,second ,,edition4 ,i feel t "s apology is due to my read]s = br++ out at su* an e>ly date a new edition :i* includes s mu* new mat]ial1 & 9 :i* ! re>rangem5t is s ext5sive z to con/itute almo/ a new "w4 ,?\gh only a ye> has pass$ s9ce ! book fir/ made its appe>ance1 ! rese>*es t h be5 c>ri$ out 9 t "t h be5 too num]\s & ( too important a "* to p]mit ! publi%+ ( a m]e repr9t1 unless ! au?or 7 to rel9qui% 8 purpose ( pres5t+ ! subject z x /&s at ! pres5t mom5t4 ,! ?ree new *apt]s :i* h be5 add$ possibly con/itute ! mo/ important *ange 9 ! "w4 ,^! *apt]s include a detail$ acc\nt ( ! !ory ( successive *anges & ( its application to ! analysis ( ! s]ies ( trans=mations :i* occur 9 radium1 ?orium1 & act9ium4 ,! dis9tegration !ory1 :i* 0 put =w>d 9 ! fir/ edition z an explanation ( radio-active ph5om5a1 has 9 ^! lat] rese>*es prov$ to be a mo/ p[]ful & valuable me?od ( analys+ ! connection betwe5 ! s]ies ( sub/ances :i* arise f ! trans=mation ( ! radio-elem5ts4 ,x has disclos$ ! orig9 ( radium1 ( polonium & radio-tellurium1 & ( radio-lead1 & n[ b9ds toge!r 9 "o coh]5t :ole ! l>ge mass ( app>5tly het]og5e\s exp]im5tal facts 9 radio-activity :i* h be5 accumulat+ s9ce #ahif4 ,! !ory has receiv$ a rem>kable measure ( v]ification 9 ! pa/ ye>1 &1 9 _m cases1 has (f]$ a quantitative z well z a qualitative explanation ( ! connection betwe5 ! v>i\s prop]ties exhibit$ by ! radio-active bodies4 ,9 ! light ( ?is evid5ce1 radio-activity may claim to h assum$ ! position ( an indep5d5t subject1 ?\gh "o ) close aff9ities to physics on ! "o h& & to *emi/ry on ! o!r4 ,! pres5t edition includes a l>ge am\nt ( new mat]ial relat+ to ! nature & prop]ties ( ! radiations & ! emanations4 ,9 ! limits ( ?is book1 x w\ld h be5 f\nd impossible1 ev5 _h x be5 ?\ght desirable1 to include m ?an a brief sket* ( ! physiological effects ( ! rays4 ,! lit]ature on ?is subject is already l>ge1 & is increas+ rapidly4 ,= reasons ( space1 ,i h n be5 able to ref] m ?an briefly to ! mass ( pap]s t h appe>$ deal+ ) ! exam9ation ( v>i\s spr+ & well wat]s1 s$im5ts1 & soils1 = ! pres5ce ( radio-active matt]4 ,9 ord] to make ! book m self-conta9$1 a %ort acc\nt has be5 giv5 9 ,*apt] ,,ii ( ! magnetic field produc$ by an ion 9 motion1 ( ! action ( an ext]nal magnetic & electric field ^u x1 & ( ! det]m9ation ( ! velocity & mass ( ! p>ticles con/itut+ ! ca?ode /ream4 ,two app5dices h be5 add$1 "o giv+ an acc\nt ( "s "w ^u ! rays :i* 0 complet$ too late = inclusion 9 ! subject matt] ( ! book1 & ! o!r conta9+ a brief summ>y ( :at is kn[n 9 reg>d to ! *emical con/itution ( ! v>i\s radio-active m9]als1 ! localities 9 :i* !y are f\nd1 & _! probable geologic age4 ,= ! prep>ation ( ! latt]1 ,i am indebt$ to my fri5d ,dr ,boltwood ( ,new ,hav51 :o1 9 ! c\rse ( 8 rese>*es1 has _h occasion to analyse mo/ ( ^! m9]als 9 ord] to det]m9e _! cont5t ( uranium & radium4 ,i hope t ?is acc\nt ( radio-active m9]als w prove ( value to ^? :o are endeav\r+ to elucidate ! connection betwe5 ! v>i\s radio-active sub/ances & ! inactive products :i* arise f _! trans=mation4 ,= ! conv5i5ce ( ^? :o h read ! fir/ edition1 a li/ ( ! sections & *apt]s :i* conta9 ! mo/ important additions & alt]ations is add$ bel[ ! table ( cont5ts4 ,! writ+ ( a complete acc\nt ( a subject l radio-activity1 9 :i* s mu* new "w is con/antly appe>+1 has be5 a matt] ( no little difficulty4 ,among o!r ?+s x has involv$ a cont9u\s revision ( ! "w :ile ! volume 0 pass+ ?r\gh ! press4 ,i wi% to express my ?anks to my colleague ,pr(essor ,h>kness = ! c>e & tr\ble he has tak5 9 revis+ ! pro(s & = _m useful sugge/ions2 also to ,mr ,r4 ,k4 ,mc,clung = 8 assi/ance 9 correct+ "s ( ! pro(s & 9 prep>+ ! index4 ,e4 ,r4 ,,mcgill ,,univ]sity1 ,,montreal1 #i ,may1 #aije4 ,transcrib]'s ,note3 ,! pla9 text v]sion ( ?is ebook includes complex ma!matical =mulas 9 ,te,x notation4 ,^! =mulas are enclos$ betwe5 d\ble doll> signs4 ,! ,,html v]sion includes ! same =mulas r5d]$ 9 _! orig9al =m4 ,,errata4 ,transcrib]'s ,note3 ,^! corrections h be5 appli$ to ! text 9 ! book4 page #dh1 l9e #bd section #bah %\ld read section #bhd #gg1 la/ l9e #bfc #bgj #abc1 #e? l9e f bottom #bed #bfa #abd1 #aj? #bdf #bec #aea1 l9e #c #bbh #bbi #aef1 #ac? l9e f bottom #bfa #bfh #bjj1 l9e #i #bdf #bec #baf1 l9e #c #bfj #bfg #ahd1 at ! top ( #e? column ( table ! lett] %\ld be ins]t$4 ,,table ,,( ,,cont5ts4 ,i4 ,radio-active ,sub/ances #a ,,ii4 ,ionization ,!ory ( ,gases #ca ,,iii4 ,me?ods ( ,measurem5t #hb ,,iv4 ,nature ( ! ,radiations #ajh ,v4 ,prop]ties ( ! ,radiations #bja ,,vi4 ,cont9u\s ,production ( ,radio-active ,matt] #bah ,,vii4 ,radio-active ,emanations #bch ,,viii4 ,excit$ ,radio-activity #bie ,,ix4 ,!ory ( ,successive ,*anges #cbe ,x4 ,trans=mation ,products ( ,uranium1 ,?orium & ,act9ium #cdf ,,xi4 ,trans=mation ,products ( ,radium #cga ,,xii4 ,rate ( ,emission ( ,en]gy #dah ,,xiii4 ,radio-active ,processes #dcg ,,xiv4 ,radio-activity ( ! ,atmosph]e & ( ,ord9>y ,mat]ials #eja ,app5dix ,a4 ,prop]ties ( ! ,rays #edc ,app5dix ,b4 ,radio-active ,m9]als #eed ,index #eei ,plate 7,fig4 #df;,a3 ,spectrum ( ,radium ,bromide7 to face p4 #bjf 99 99 99 99 99 ,= ! conv5i5ce ( ! read]1 ! sections & *apt]s :i* conta9 mo/ly new matt]1 or h be5 ei!r p>tly or :olly rewritt51 are app5d$ bel[4 ,*ap4 ,i4 ,sections #ah1 #bj-bc4 ,,ii4 #dh-eb4 ,,iii4 #fi4 ,,iv4 #hc-he1 #ib1 #ic1 #ajc1 #ajd1 #ajf-ajh1 #aaa1 #aab4 ,v4 #aae1 #aag1 #aai1 #abb4 ,,vii4 #aga-agc4 ,,viii4 #ahb-ahd1 #aij4 ,,ix-,,xiv4 ,mo/ly rewritt54 ,,abbreviations ,,( ,,ref]5ces ,,to ,,"s ,,( ,,! ,,j\rnals4 ,b]4 d4 deuts*4 ,*em4 ,ges4 ,b]i*te d] deuts*5 *emis*5 ,gesells*aft4 ,b]l94 ,c4 ,r4 ,comptes ,r5dus des ,sances de l',acadmie des ,sci5ces4 ,p>is4 ,*em4 ,news4 ,*emical ,news4 ,london4 ,drude's ,annal4 ,annal5 d] ,physik4 ,leipzig4 ,phil4 ,mag4 ,philosophical ,magaz9e & ,j\rnal ( ,sci5ce4 ,london4 ,phil4 ,trans4 ,philosophical ,transactions ( ! ,royal ,society ( ,london4 ,phys4 ,rev4 ,physical ,review4 ,new ,york4 ,phys4 ,zeit4 ,physikalis*e ,zeits*rift4 ,proc4 ,camb4 ,phil4 ,soc4 ,proce$+s ( ! ,cambridge ,philosophical ,society4 ,cambridge4 ,proc4 ,roy4 ,soc4 ,proce$+s ( ! ,royal ,society ( ,london4 ,?ses-,p>is4 ,?ses prs5tes la ,facult des ,sci5ces de l',univ]sit de ,p>is4 ,wi$4 ,annal4 ,annal5 d] ,physik4 ,leipzig4 ,,*apt] ,i4 ,,radio-,,active ,,sub/ances4 #a4 ,introduction4 ,! close ( ! old & ! beg9n+ ( ! new c5tury h be5 m>k$ by a v rapid increase ( our k ( t mo/ important b comp>atively little kn[n subject--! connection betwe5 electricity & matt]4 ,no /udy has be5 m fruitful 9 surprises to ! inve/igator1 bo? f ! rem>kable nature ( ! ph5om5a exhibit$ & f ! laws controll+ !m4 ,! m ! subject is exam9$1 ! m complex mu/ we suppose ! con/itution ( matt] 9 ord] to expla9 ! rem>kable effects obs]v$4 ,:ile ! exp]im5tal results h l$ to ! view t ! con/itution ( ! atom itself is v complex1 at ! same "t !y h confirm$ ! old !ory ( ! discont9u\s or atomic /ructure ( matt]4 ,! /udy ( ! radio-active sub/ances & ( ! dis*>ge ( electricity ?r\gh gases has suppli$ v /rong exp]im5tal evid5ce 9 support ( ! fundam5tal ideas ( ! exi/+ atomic !ory4 ,x has also indicat$ t ! atom itself is n ! smalle/ unit ( matt]1 b is a complicat$ /ructure made up ( a numb] ( small] bodies4 ,a great impetus to ! /udy ( ?is subject 0 initially giv5 by ! exp]im5ts ( ,l5>d on ! ca?ode rays1 & by ,rntg5's discov]y ( ! ,x rays4 ,an exam9ation ( ! conductivity imp>t$ to a gas by ! ,x rays l$ to a cle> view ( ! me*anism ( ! transport ( electricity ?r\gh gases by means ( *>g$ ions4 ,?is ionization !ory ( gases has be5 %[n to af=d a satisfactory explanation n only ( ! passage ( electricity ?r\gh flames & vap\rs1 b also ( ! complicat$ ph5om5a obs]v$ :5 a dis*>ge ( electricity passes ?r\gh a vacuum tube4 ,at ! same "t1 a fur!r /udy ( ! ca?ode rays %[$ t !y consi/$ ( a /ream ( mat]ial p>ticles1 project$ ) great velocity1 & possess+ an app>5t mass small comp>$ ) t ( ! hydrog5 atom4 ,! connection betwe5 ! ca?ode & ,rntg5 rays & ! nature ( ! latt] 7 also elucidat$4 ,mu* ( ?is admirable exp]im5tal "w on ! nature ( ! electric dis*>ge has be5 done by ,pr(essor ,j4 ,j4 ,?omson & 8 /ud5ts 9 ! ,cav5di% ,laboratory1 ,cambridge4 ,an exam9ation ( natural sub/ances1 9 ord] to see if !y gave out d>k radiations simil> to ,x rays1 l$ to ! discov]y ( ! radio-active bodies :i* possess ! prop]ty ( spontane\sly emitt+ radiations1 invisible to ! eye1 b readily detect$ by _! action on photographic plates & _! p[] ( dis*>g+ electrifi$ bodies4 ,a detail$ /udy ( ! radio-active bodies has reveal$ _m new & surpris+ ph5om5a :i* h ?r[n mu* light1 n only on ! nature ( ! radiations !mselves1 b also on ! processes occurr+ 9 ^? sub/ances4 ,not)/&+ ! complex nature ( ! ph5om5a1 ! k ( ! subject has advanc$ ) great rapidity1 & a l>ge am\nt ( exp]im5tal data has n[ be5 accumulat$4 ,9 ord] to expla9 ! ph5om5a ( radio-activity1 ,ru!r=d & ,soddy h advanc$ a !ory :i* reg>ds ! atoms ( ! radio-active elem5ts z suff]+ spontane\s dis9tegration1 & giv+ rise to a s]ies ( radio-active sub/ances :i* diff] 9 *emical prop]ties f ! p>5t elem5ts4 ,! radiations accompany ! break+-up ( ! atoms1 & af=d a comp>ative measure ( ! rate at :i* ! dis9tegration takes place4 ,?is !ory is f\nd to acc\nt 9 a satisfactory way = all ! kn[n facts ( radio-activity1 & welds a mass ( disconnect$ facts into "o homog5e\s :ole4 ,on ?is view1 ! cont9u\s emission ( en]gy f ! active bodies is d]iv$ f ! int]nal en]gy inh]5t 9 ! atom1 & does n 9 any way contradict ! law ( ! cons]vation ( en]gy4 ,at ! same "t1 h[ev]1 x indicates t an enorm\s /ore ( lat5t en]gy is resid5t 9 ! radio-atoms !mselves4 ,?is /ore ( en]gy has n be5 obs]v$ previ\sly1 on acc\nt ( ! impossibility ( break+ up into simpl] =ms ! atoms ( ! elem5ts by ! action ( ! *emical or physical =ces at our comm&4 ,on ?is !ory we are witness+ 9 ! radio-active bodies a v]itable trans=mation ( matt]4 ,?is process ( dis9tegration 0 inve/igat$1 n by direct *emical me?ods1 b by means ( ! prop]ty possess$ by ! radio-active bodies ( giv+ out specific types ( radiation4 ,except 9 ! case ( a v active elem5t l radium1 ! process ( dis9tegration takes place s sl[ly1 t hundr$s if n ?\s&s ( ye>s w\ld be requir$ be=e ! am\nt trans=m$ w\ld come )9 ! range ( detection ( ! balance or ! spectroscope4 ,9 radium1 h[ev]1 ! process ( dis9tegration takes place at su* a rate t x %\ld be possible )9 a limit$ space ( "t to obta9 def9ite *emical evid5ce on ?is "q4 ,! rec5t discov]y t helium c be obta9$ f radium adds /rong confirmation to ! !ory2 = helium 0 indicat$ z a probable dis9tegration product ( ! radio-active elem5ts be=e ?is exp]im5tal evid5ce 0 =?com+4 ,sev]al products ( ! trans=mation ( ! radio-active bodies h already be5 exam9$1 & ! fur!r /udy ( ^! sub/ances promises to op5 up new & important fields ( *emical enquiry4 ,9 ?is book ! exp]im5tal facts ( radio-activity & ! connection betwe5 !m are int]pret$ on ! dis9tegration !ory4 ,_m ( ! ph5om5a obs]v$ c be inve/igat$ 9 a quantitative mann]1 & prom95ce has be5 giv5 to "w ( ?is "*1 = ! agreem5t ( any !ory ) ! facts1 :i* x attempts to expla91 mu/ ultimately dep5d ^u ! results ( accurate measurem5t4 ,! value ( any work+ !ory dep5ds ^u ! numb] ( exp]im5tal facts x s]ves to correlate1 & ^u its p[] ( sugge/+ new l9es ( "w4 ,9 ^! respects ! dis9tegration !ory1 :e!r or n x may ultimately be prov$ to be correct1 has already be5 ju/ifi$ by its results4 #b4 ,radio-active ,sub/ances4 ,! t]m 8radio-active0 is n[ g5]ally appli$ to a class ( sub/ances1 su* z uranium1 ?orium1 radium1 & _! comp\nds1 :i* possess ! prop]ty ( spontane\sly emitt+ radiations capable ( pass+ ?r\gh plates ( metal & o!r sub/ances opaque to ord9>y light4 ,! *>act]i/ic prop]ty ( ^! radiations1 besides _! p5etrat+ p[]1 is _! action on a photographic plate & _! p[] ( dis*>g+ electrifi$ bodies4 ,9 addition1 a /rongly radio-active body l radium is able to cause m>k$ phosphoresc5ce & fluoresc5ce on "s sub/ances plac$ ne> x4 ,9 ! above respects ! radiations possess prop]ties analog\s to ,rntg5 rays1 b x w be %[n t1 = ! major "p ( ! radiations emitt$1 ! resemblance is only sup]ficial4 ,! mo/ rem>kable prop]ty ( ! radio-active bodies is _! p[] ( radiat+ en]gy spontane\sly & cont9u\sly at a con/ant rate1 )\t1 z f> z is kn[n1 ! action ^u !m ( any ext]nal excit+ cause4 ,! ph5om5a at fir/ sight appe> to be 9 direct contradiction to ! law ( cons]vation ( en]gy1 s9ce no obvi\s *ange ) "t occurs 9 ! radiat+ mat]ial4 ,! ph5om5a appe> /ill m rem>kable :5 x is consid]$ t ! radio-active bodies mu/ h be5 /eadily radiat+ en]gy s9ce ! "t ( _! =mation 9 ! e>?'s cru/4 ,imm$iately aft] ,rntg5's discov]y ( ! production ( ,x rays1 sev]al physici/s 7 l$ to exam9e if any natural bodies possess$ ! prop]ty ( giv+ out radiations :i* c\ld p5etrate metals & o!r sub/ances opaque to light4 ,z ! production ( ,x rays seem$ to be connect$ 9 "s way ) ca?ode rays1 :i* cause /rong fluoresc5t & phosphoresc5t effects on v>i\s bodies1 ! sub/ances fir/ exam9$ 7 ^? t 7 phosphoresc5t :5 expos$ to light4 ,! fir/ obs]vation 9 ?is direction 0 made by ,niew5gl[ski#a1 :o f\nd t sulphide ( calcium expos$ to ! sun's rays gave out "s rays :i* 7 able to pass ?r\gh black pap]4 ,a little lat] a simil> result 0 record$ by ,h4 ,becqu]el#b = a special calcium sulphide prep>ation1 & by ,troo/#c = a specim5 ( hexagonal bl5d4 ,^! results 7 confirm$ & ext5d$ 9 a lat] pap] by ,arnold#d4 ,no satisfactory explanations ( ^! some:at d\btful results h yet be5 giv51 except on ! view t ! black pap] 0 transp>5t to "s ( ! light waves4 ,at ! same "t ,le ,bon#e %[$ t1 by ! action ( sunlight on c]ta9 bodies1 a radiation 0 giv5 out1 invisible to ! eye1 b active ) reg>d to a photographic plate4 ,^! results h be5 ! subject ( mu* discussion2 b !re seems to be little d\bt t ! effects are due to %ort ultra-violet light waves1 capable ( pass+ ?r\gh c]ta9 sub/ances opaque to ord9>y light4 ,^! effects1 :ile int]e/+ 9 !mselves1 are q di/9ct 9 "* f ^? %[n by ! radio-active bodies :i* w n[ be consid]$4 #c4 ,uranium4 ,! fir/ important discov]y 9 ! subject ( radio-activity 0 made 9 ,febru>y1 #ahif1 by ,m4 ,h5ri ,becqu]el#f1 :o f\nd t a uranium salt1 ! d\ble sulphate ( uranium & potassium1 emitt$ "s rays :i* gave an impression on a photographic plate envelop$ 9 black pap]4 ,^! rays 7 also able to pass ?r\gh ?9 plates ( metals & o!r sub/ances opaque to light4 ,! impressions on ! plate c\ld n h be5 due to vap\rs giv5 (f by ! sub/ances1 s9ce ! same effect 0 produc$ :e!r ! salt 0 plac$ directly on ! black pap] or on a ?9 plate ( glass ly+ ^u x4 ,becqu]el f\nd lat] t all ! comp\nds ( uranium z well z ! metal itself possess$ ! same prop]ty1 &1 al?\gh ! am\nt ( action v>i$ slightly = ! diff]5t comp\nds1 ! effects 9 all cases 7 comp>able4 ,x 0 at fir/ natural to suppose t ! emission ( ^! rays 0 9 "s way connect$ ) ! p[] ( phosphoresc5ce1 b lat] obs]vations %[$ t !re 0 no connection :atev] betwe5 !m4 ,! uranic salts are phosphoresc5t1 :ile ! uran\s salts are n4 ,! uranic salts1 :5 expos$ to ultra-violet light 9 ! phosphoroscope1 give a phosphoresc5t light la/+ ab\t #ja seconds4 ,:5 ! salts are dissolv$ 9 wat]1 ! duration is /ill less4 ,! am\nt ( action on ! photographic plate does n dep5d on ! p>ticul> comp\nd ( uranium employ$1 b only on ! am\nt ( uranium pres5t 9 ! comp\nd4 ,! non-phosphoresc5t are equally active ) ! phosphoresc5t comp\nds4 ,! am\nt ( radiation giv5 out is unalt]$ if ! active body be kept cont9u\sly 9 d>kness4 ,! rays are giv5 out by solutions1 & by cry/als :i* h be5 deposit$ f solutions 9 ! d>k & nev] expos$ to light4 ,?is %[s t ! radiation _c be due 9 any way to ! gradual emission ( en]gy /or$ up 9 ! cry/al 9 consequ5ce ( exposure to a s\rce ( light4 #d4 ,! p[] ( giv+ out p5etrat+ rays ?us seems to be a specific prop]ty ( ! elem5t uranium1 s9ce x is exhibit$ by ! metal z well z by all its comp\nds4 ,^! radiations f uranium are p]si/5t1 &1 z f> z obs]vations h yet gone1 are un*ang$1 ei!r 9 int5sity or "*1 ) lapse ( "t4 ,obs]vations to te/ ! con/ancy ( ! radiations = long p]iods ( "t h be5 made by ,becqu]el4 ,samples ( uranic & uran\s salts h be5 kept 9 a d\ble box ( ?ick lead1 & ! :ole has be5 pres]v$ f exposure to light4 ,by a simple arrangem5t1 a photographic plate c be introduc$ 9 a def9ite position above ! uranium salts1 :i* are cov]$ ) a lay] ( black pap]4 ,! plate is expos$ at int]vals = #dh h\rs1 & ! impression on ! plate comp>$4 ,no p]ceptible weak5+ ( ! radiation has be5 obs]v$ ov] a p]iod ( f\r ye>s4 ,mme ,curie#g has made det]m9ations ( ! activity ( uranium ov] a space ( five ye>s by an electric me?od describ$ lat]1 b f\nd no appreciable v>iation dur+ t p]iod4 ,s9ce ! uranium is ?us cont9u\sly radiat+ en]gy f itself1 )\t any kn[n s\rce ( excitation1 ! "q arises :e!r any kn[n ag5t is able to affect ! rate ( its emission4 ,no alt]ation 0 obs]v$ :5 ! body 0 expos$ to ultra-violet light or to ultra-r$ light or to ,x rays4 ,becqu]el /ates t ! d\ble sulphate ( uranium & potassium %[$ a slight increase ( action :5 expos$ to ! arc light & to sp>ks1 b he consid]s t ! feeble effect obs]v$ 0 ano!r action sup]impos$ on ! con/ant radiation f uranium4 ,! int5sity ( ! uranium radiation is n affect$ by a v>iation ( temp]ature betwe5 #bjj ,c4 & ! temp]ature ( liquid air4 ,?is "q is discuss$ 9 m detail lat]4 #e4 ,9 addition to ^! actions on a photographic plate1 ,becqu]el %[$ t uranium rays1 l ,rntg5 rays1 possess ! important prop]ty ( dis*>g+ bo? positively & negatively electrifi$ bodies4 ,^! results 7 confirm$ & ext5d$ by ,"l ,kelv91 ,smolan & ,beattie#h4 ,! writ] made a detail$ comp>ison#i ( ! nature ( ! dis*>ge produc$ by uranium ) t produc$ by ,rntg5 rays1 & %[$ t ! dis*>g+ prop]ty ( uranium is due to ! production ( *>g$ ions by ! radiation ?r\gh\t ! volume ( ! gas4 ,! prop]ty has be5 made ! basis ( a qualitative & quantitative exam9ation ( ! radiations f all radio-active bodies1 & is discuss$ 9 detail 9 *apt] ,,ii4 ,! radiations f uranium are ?us analog\s1 z reg>ds _! photographic & electrical actions1 to ,rntg5 rays1 b1 comp>$ ) ! rays f an ord9>y ,x ray tube1 ^! actions are extremely feeble4 ,:ile ) ,rntg5 rays a /rong impression is produc$ on a photographic plate 9 a few m9utes or ev5 seconds1 sev]al days' exposure to ! uranium rays is requir$ to produce a well-m>k$ action1 ev5 ?\gh ! uranium comp\nd1 envelop$ 9 black pap]1 is plac$ close to ! plate4 ,! dis*>g+ action1 :ile v easily measurable by suitable me?ods1 is also small comp>$ ) t produc$ by ,x rays f an ord9>y tube4 #f4 ,! rays f uranium %[ no evid5ce ( direct reflection1 refraction1 or pol>ization#aj4 ,:ile !re is no direct reflection ( ! rays1 !re is app>5tly a diffuse reflection produc$ :]e ! rays /rike a solid ob/acle4 ,?is is due 9 reality to a second>y radiation set up :5 ! prim>y rays imp+e ^u matt]4 ,! pres5ce ( ?is second>y radiation at fir/ gave rise to ! errone\s view t ! rays c\ld be reflect$ & refract$ l ord9>y light4 ,! abs5ce ( reflection1 refraction1 or pol>ization 9 ! p5etrat+ rays f uranium necess>ily foll[s 9 ! light ( our pres5t k ( ! rays4 ,x is n[ kn[n t ! uranium rays1 ma9ly responsible = ! photographic action1 are deviable by a magnetic field1 & are simil> 9 all respects to ca?ode rays1 i4e4 ! rays are compos$ ( small p>ticles project$ at great velocities4 ,! abs5ce ( ! ord9>y prop]ties ( transv]se light waves is ?us to be expect$4 #g4 ,! rays f uranium are complex 9 "*1 &1 9 addition to ! p5etrat+ deviable rays1 !re is also giv5 (f a radiation v readily absorb$ by pass+ ?r\gh ?9 lay]s ( metal foil1 or by trav]s+ a few c5timetres ( air4 ,! photographic action due to ^! rays is v feeble 9 comp>ison ) t ( ! p5etrat+ rays1 al?\gh ! dis*>ge ( electrifi$ bodies is ma9ly caus$ by !m4 ,besides ^! two types ( rays1 "s rays are emitt$ :i* are ( an extremely p5etrat+ "* & are non-deviable by a magnetic field4 ,^! rays are difficult to detect photographically1 b c readily be exam9$ by ! electric me?od4 #h4 ,! "q naturally arose :e!r ! prop]ty ( spontane\sly giv+ out p5etrat+ radiations 0 conf9$ to uranium & its comp\nds1 or :e!r x 0 exhibit$ to any appreciable ext5t by o!r sub/ances4 ,by ! electrical me?od1 ) an electromet] ( ord9>y s5sitiv5ess1 any body :i* possesses an activity ( ! ord] ( ( t ( uranium c be detect$4 ,) an electroscope ( special con/ruction1 su* z has be5 design$ by ,c4 ,t4 ,r4 ,wilson = 8 exp]im5ts on ! natural ionization ( air1 a sub/ance ( activity & probably ( t ( uranium c be detect$4 ,if an active body l uranium be mix$ ) an inactive body1 ! result+ activity 9 ! mixture is g5]ally consid]ably less ?an t due to ! active sub/ance alone4 ,?is is due to ! absorption ( ! radiation by ! inactive matt] pres5t4 ,! am\nt ( decrease l>gely dep5ds on ! ?ickness ( ! lay] f :i* ! activity is det]m9$4 ,mme ,curie made a detail$ exam9ation by ! electrical me?od ( ! great majority ( kn[n sub/ances1 includ+ ! v r>e elem5ts1 to see if !y possess$ any activity4 ,9 cases :]e x 0 possible1 sev]al comp\nds ( ! elem5ts 7 exam9$4 ,) ! exception ( ?orium & phosphorus1 none ( ! o!r sub/ances possess$ an activity ev5 ( ! ord] ( ( uranium4 ,! ionization ( ! gas by phosphorus does n1 h[ev]1 seem to be due to a p5etrat+ radiation l t f\nd 9 ! case ( uranium1 b r to a *emical action tak+ place at its surface4 ,! comp\nds ( phosphorus d n %[ any activity1 & 9 ?is respect diff] f uranium & ! o!r active bodies4 ,le ,bon#aa has also obs]v$ t qu99e sulphate1 if heat$ & !n all[$ to cool1 possesses = a %ort "t ! prop]ty ( dis*>g+ bo? positively & negatively electrifi$ bodies4 ,x is necess>y1 h[ev]1 to draw a %>p l9e ( di/9ction betwe5 ph5om5a ( ?is k9d & ^? exhibit$ by ! naturally radio-active bodies4 ,:ile bo?1 "u special conditions1 possess ! prop]ty ( ioniz+ ! gas1 ! laws controll+ ! ph5om5a are q di/9ct 9 ! two cases4 ,= example1 only "o comp\nd ( qu99e %[s ! prop]ty1 & t comp\nd only :5 x has be5 subject$ to a prelim9>y heat+4 ,! action ( phosphorus dep5ds on ! nature ( ! gas1 & v>ies ) temp]ature4 ,on ! o!r h&1 ! activity ( ! naturally radio-active bodies is spontane\s & p]man5t4 ,x is exhibit$ by all comp\nds1 & is n1 z f> z is yet kn[n1 alt]$ by *ange 9 ! *emical or physical conditions4 #i4 ,! dis*>g+ & photographic action alone _c be tak5 z a crit]ion z to :e!r a sub/ance is radio-active or n4 ,x is necess>y 9 addition to exam9e ! radiations1 & to te/ :e!r ! actions take place ?r\gh appreciable ?icknesses ( all k9ds ( matt] opaque to ord9>y light4 ,= example1 a body giv+ out %ort waves ( ultra-violet light c be made to behave 9 _m respects l a radio-active body4 ,z ,l5>d#ab has %[n1 %ort waves ( ultra-violet light w ionize ! gas 9 _! pa?1 & w be absorb$ rapidly 9 ! gas4 ,!y w produce /rong photographic action1 & may pass ?r\gh "s sub/ances opaque to ord9>y light4 ,! simil>ity to a radio-active body is ?us fairly complete z reg>ds ^! prop]ties4 ,on ! o!r h&1 ! emission ( ^! light waves1 unlike t ( ! radiations f an active body1 w dep5d l>gely on ! molecul> /ate ( ! comp\nd1 or on temp]ature & o!r physical conditions4 ,b ! great po9t ( di/9ction lies 9 ! nature ( ! radiations f ! bodies 9 "q4 ,9 "o case ! radiations behave z transv]se waves1 obey+ ! usual laws ( light waves1 :ile 9 ! case ( a naturally active body1 !y consi/ = ! mo/ "p ( a cont9u\s flight ( mat]ial p>ticles project$ f ! sub/ance ) great velocity4 ,be=e any sub/ance c be call$ 8radio-active0 9 ! s5se 9 :i* ! t]m is us$ to describe ! prop]ties ( ! natural radio-active elem5ts1 x is ?us necess>y to make a close exam9ation ( its radiation2 = x is unadvisable to ext5d ! use ( ! t]m 8radio-active0 to sub/ances :i* d n possess ! *>act]i/ic radiat+ prop]ties ( ! radio-active elem5ts :i* we h describ$1 & ! active products :i* c be obta9$ f !m4 ,"s ( ! pseudo-active bodies w h[ev] be consid]$ lat] 9 *apt] ,,ix4 #aj4 ,?orium4 ,9 ! c\rse ( an exam9ation ( a l>ge numb] ( sub/ances1 ,s*midt#ac f\nd t ?orium1 its comp\nds1 & ! m9]als conta9+ ?orium1 possess$ prop]ties simil> to ^? ( uranium4 ,! same discov]y 0 made indep5d5tly by ,mme ,curie#ad4 ,! rays f ?orium comp\nds1 l ^? f uranium1 possess ! prop]ties ( dis*>g+ electrifi$ bodies & act+ on a photographic plate4 ,"u ! same conditions ! dis*>g+ action ( ! rays is ab\t equal 9 am\nt to t ( uranium1 b ! photographic effect is di/9ctly weak]4 ,! radiations f ?orium are m complicat$ ?an ^? f uranium4 ,x 0 e>ly obs]v$ by sev]al exp]im5t]s t ! radiation f ?orium comp\nds1 especially ! oxide1 :5 te/$ by ! electrifi$ me?od1 0 v v>iable & unc]ta94 ,a detail$ inve/igation ( ! radiations f ?orium "u v>i\s conditions 0 made by ,ow5s#ae4 ,he %[$ t ?orium oxide1 especially 9 ?ick lay]s1 0 able to produce conductivity 9 ! gas :5 cov]$ ) a l>ge ?ickness ( pap]1 & t ! am\nt ( ?is conductivity c\ld be greatly v>i$ by bl[+ a curr5t ( air ov] ! gas4 ,9 ! c\rse ( an exam9ation#af ( ?is action ( ! air curr5t1 ! writ] %[$ t ?orium comp\nds gave out a mat]ial emanation made up ( v small p>ticles !mselves radio-active4 ,! emanation behaves l a radio-active gas2 x diffuses rapidly ?r\gh por\s sub/ances l pap]1 & is c>ri$ away by a curr5t ( air4 ,! evid5ce ( ! exi/5ce ( ! emanation & its prop]ties1 is consid]$ 9 detail lat] 9 *apt] ,,viii4 ,9 addition to giv+ out an emanation1 ?orium behaves l uranium 9 emitt+ ?ree types ( radiation1 ea* ( :i* is simil> 9 prop]ties to ! correspond+ radiation f uranium4 #aa4 ,radio-active m9]als4 ,mme ,curie has exam9$ ! radio-activity ( a l>ge numb] ( m9]als conta9+ uranium & ?orium4 ,! electrical me?od 0 us$1 & ! curr5t measur$ betwe5 two p>allel plates #h cms4 9 diamet] & #c cms4 ap>t1 :5 "o plate 0 cov]$ ) a uni=m lay] ( ! active matt]4 ,! foll[+ numb]s give ! ord] ( ! saturation curr5t obta9$ 9 amp]es4 ,pit*bl5de f ,johanngeorg5/adt #hc #aj ,joa*im/hal #gj ,pzibran #fe ,cornwall #af ,cleveite #ad ,*alcolite #eb ,autunite #bg ,?orite f #jc to #ad ,orangite #bj ,monazite #je ,x5ot9e #jjc ,aes*ynite #jg ,f]gusonite #jd ,sam>skite #aa ,niobite #jc ,c>notite #fb ,"s activity is to be expect$ 9 ^! m9]als1 s9ce !y all conta9 ei!r ?orium or uranium or a mixture ( bo?4 ,an exam9ation ( ! action ( ! uranium comp\nds ) ! same app>atus & "u ! same conditions l$ to ! foll[+ results3 ,uranium 7conta9+ a little c>bon7 #bc #aj amp]es ,black oxide ( uranium #bf ,gre5 #ah ,acid uranic hydrate #jf ,uranate ( sodium #ab ,uranate ( potassium #ab ,uranate ( ammonia #ac ,uran\s sulphate #jg ,sulphate ( uranium & potassium #jg ,acetate #jg ,phosphate ( copp] & uranium #ji ,oxysulphide ( uranium #ab ,! int]e/+ po9t 9 connection ) ^! results is t "s specim5s ( pit*bl5de h f\r times ! activity ( ! metal uranium2 *alcolite1 ! cry/alliz$ phosphate ( copp] & uranium1 is twice z active z uranium2 & autunite1 a phosphate ( calcium & uranium1 is z active z uranium4 ,f ! previ\s consid]ations1 none ( ! sub/ances %\ld h %[n z mu* activity z uranium or ?orium4 ,9 ord] to be sure t ! l>ge activity 0 n due to ! p>ticul> *emical comb9ation1 ,mme ,curie prep>$ *alcolite artificially1 />t+ ) pure products4 ,?is artificial *alcolite _h ! activity to be expect$ f its composition1 viz4 ab\t #jd ( ! activity ( ! uranium4 ,! natural m9]al *alcolite is ?us five times z active z ! artificial m9]al4 ,x ?us seem$ probable t ! l>ge activity ( "s ( ^! m9]als1 comp>$ ) uranium & ?orium1 0 due to ! pres5ce ( small quantities ( "s v active sub/ance1 :i* 0 diff]5t f ! kn[n bodies ?orium & uranium4 ,?is supposition 0 completely v]ifi$ by ! "w ( ,m4 & ,mme ,curie1 :o 7 able to sep>ate f pit*bl5de by purely *emical me?ods two active bodies1 "o ( :i* 9 ! pure /ate is ov] a million times m active ?an ! metal uranium4 ,?is important discov]y 0 due entirely to ! prop]ty ( radio-activity possess$ by ! new bodies4 ,! only guide 9 _! sep>ation 0 ! activity ( ! products obta9$4 ,9 ?is respect ! discov]y ( ^! bodies is q analog\s to ! discov]y ( r>e elem5ts by ! me?ods ( spectrum analysis4 ,! me?od employ$ 9 ! sep>ation consi/$ 9 exam9+ ! relative activity ( ! products aft] *emical treatm5t4 ,9 ?is way x 0 se5 :e!r ! radio-activity 0 conf9$ to "o or ano!r ( ! products1 or divid$ betwe5 bo?1 & 9 :at ratio su* division occurr$4 ,! activity ( ! specim5s ?us s]v$ z a basis ( r\gh qualitative & quantitative analysis1 analog\s 9 "s respects to ! indication ( ! spectroscope4 ,to obta9 comp>ative data x 0 necess>y to te/ all ! products 9 ! dry /ate4 ,! *ief difficulty lay 9 ! fact t pit*bl5de is a v complex m9]al1 & conta9s 9 v>y+ quantities ne>ly all ! kn[n metals4 #ab4 ,radium4 ,! analysis ( pit*bl5de by *emical me?ods1 us+ ! proc$ure sket*$ above1 l$ to ! discov]y ( two v active bodies1 polonium & radium4 ,! "n polonium 0 giv5 to ! fir/ sub/ance discov]$ by ,mme ,curie 9 hon\r ( ! c\ntry ( h] bir?4 ,! "n radium 0 a v happy inspiration ( ! discov]]s1 = ?is sub/ance 9 ! pure /ate possesses ! prop]ty ( radio-activity to an a/oni%+ degree4 ,radium is extract$ f pit*bl5de by ! process us$ to sep>ate b>ium1 to :i* radium is v closely alli$ 9 *emical prop]ties#ag4 ,aft] ! removal ( o!r sub/ances1 ! radium rema9s beh9d mix$ ) b>ium4 ,x c1 h[ev]1 be p>tially sep>at$ f ! latt] by ! diff]5ce 9 solubility ( ! *lorides 9 wat]1 alcohol1 or hydro*loric acid4 ,! *loride ( radium is less soluble ?an t ( b>ium1 & c be sep>at$ f x by ! me?od ( fractional cry/allization4 ,aft] a l>ge numb] ( precipitations1 ! radium c be fre$ almo/ completely f ! b>ium4 ,bo? polonium & radium exi/ 9 inf9itesimal quantities 9 pit*bl5de4 ,9 ord] to obta9 a few decigrammes ( v active radium1 x is necess>y to use sev]al tons ( pit*bl5de1 or ! residues obta9$ f ! treatm5t ( uranium m9]als4 ,x is ?us obvi\s t ! exp5se & lab\r involv$ 9 prep>ation ( a m9ute quantity ( radium are v great4 ,m4 & ,mme ,curie 7 indebt$ = _! fir/ work+ mat]ial to ! ,au/rian gov]nm5t1 :o g5]\sly pres5t$ !m ) a ton ( ! treat$ residue ( uranium mat]ials f ! ,/ate manufactory ( ,joa*im/hal 9 ,bohemia4 ,) ! assi/ance ( ! ,academy ( ,sci5ce & o!r societies 9 ,france1 funds 7 giv5 to c>ry out ! labori\s "w ( sep>ation4 ,lat] ! ,curies 7 pres5t$ ) a ton ( residues f ! treatm5t ( pit*bl5de by ! ,socit ,c5trale de ,produits ,*imiques ( ,p>is4 ,! g5]\s assi/ance af=d$ 9 ?is important "w is a welcome sign ( ! active int]e/ tak5 9 ^! c\ntries 9 ! fur!r+ ( purely sci5tific rese>*4 ,! r\gh conc5tration & sep>ation ( ! residues 0 p]=m$ 9 ! *emical works1 & !re foll[$ a l>ge am\nt ( lab\r 9 purification & conc5tration4 ,9 ?is mann]1 ! ,curies 7 able to obta9 a small quantity ( radium :i* 0 enorm\sly active comp>$ ) uranium4 ,no def9ite results h yet be5 giv5 on ! activity ( pure radium1 b ! ,curies e/imate t x is ab\t "o million times t ( uranium1 & may possibly be /ill high]4 ,! difficulty ( mak+ a num]ical e/imate = su* an int5sely active body is v great4 ,9 ! electric me?od1 ! activities are comp>$ by not+ ! relative /r5g? ( ! maximum or saturation curr5t betwe5 two p>allel plates1 on "o ( :i* ! active sub/ance is spread4 ,on acc\nt ( ! int5se ionization ( ! gas betwe5 ! plates1 x is n possible to rea* ! saturation curr5t unless v high voltages are appli$4 ,approximate comp>isons c be made by ! use ( metal scre5s to cut d[n ! int5sity ( ! radiations1 if ! proportion ( ! radiation transmitt$ by su* a scre5 has be5 det]m9$ by direct exp]im5t on impure mat]ial ( easily measurable activity4 ,! value ( ! activity ( radium comp>$ ) t ( uranium w h[ev] v>y to "s ext5t accord+ to :i* ( ! ?ree types ( rays is tak5 z a basis ( comp>ison4 ,x is ?us difficult to control ! f9al /ages ( ! purification ( radium by measurem5ts ( its activity alone4 ,moreov] ! activity ( radium imm$iately aft] its prep>ation is only ab\t "o-f\r? ( its f9al value2 x gradually rises to a maximum aft] ! radium salt has be5 kept 9 ! dry /ate = ab\t a mon?4 ,= control exp]im5ts 9 purification1 x is advisable to measure ! initial r ?an ! f9al activity4 ,mme ,curie has utiliz$ ! coloration ( ! cry/als ( radif]\s b>ium z a means ( controll+ ! f9al process ( purification4 ,! cry/als ( salts ( radium & b>ium deposit$ f acid solutions are indi/+ui%able by ! eye4 ,! cry/als ( radif]\s b>ium are at fir/ col\rless1 b1 9 ! c\rse ( a few h\rs1 become yell[1 pass+ to orange & sometimes to a beautiful rose col\r4 ,! rapidity ( ?is coloration dep5ds on ! am\nt ( b>ium pres5t4 ,pure radium cry/als d n col\r1 or at any rate n z rapidly z ^? conta9+ b>ium4 ,! coloration is a maximum = a def9ite proportion ( radium1 & ?is fact c be utiliz$ z a means ( te/+ ! am\nt ( b>ium pres5t4 ,:5 ! cry/als are dissolv$ 9 wat] ! coloration disappe>s4 ,giesel#ah has obs]v$ t pure radium bromide gives a beautiful c>m9e col\r to ! ,buns5 flame4 ,if b>ium be pres5t 9 any quantity1 only ! gre5 col\r due to b>ium is obs]v$1 & a spectroscopic exam9ation %[s only ! b>ium l9es4 ,?is c>m9e coloration ( ! ,buns5 flame is a good indication ( ! purity ( ! radium4 ,s9ce ! prelim9>y ann\ncem5t ( ! discov]y ( radium1 ,giesel#ai has devot$ a great deal ( att5tion to ! sep>ation ( radium1 polonium & o!r active bodies f pit*bl5de4 ,he 0 indebt$ = 8 work+ mat]ial to ! firm ( ,p4 de ,ha51 ( ,hanov]1 :o pres5t$ him ) a ton ( pit*bl5de residues4 ,us+ ! me?od ( fractional cry/allization ( ! bromide in/ead ( ! *loride1 he has be5 able to prep>e consid]able quantities ( pure radium4 ,by ?is means ! lab\r ( f9al purification ( radium has be5 mu* r$uc$4 ,he /ates t six or eight cry/allizations ) ! bromide are suffici5t to free ! radium almo/ completely f ! b>ium4 #ac4 ,spectrum ( radium4 ,x 0 ( great importance to settle z soon z possible :e!r radium 0 9 reality modifi$ b>ium or a new elem5t ) a def9ite spectrum4 ,= ?is purpose ! ,curies prep>$ "s specim5s ( radium *loride1 & submitt$ !m = exam9ation ( _! spectrum to ,dem>ay1 an au?ority on t subject4 ,! fir/ specim5 ( radium *loride exam9$ by ,dem>ay#bj 0 n v active1 b %[$1 besides ! l9es due to b>ium1 a v /rong new l9e 9 ! ultra-violet4 ,9 ano!r sample ( great] activity1 ! l9e 0 /ill /rong] & o!rs also appe>$1 :ile ! int5sity ( ! new l9es 0 comp>able ) ^? pres5t due to b>ium4 ,) a /ill m active specim5 :i* 0 probably ne>ly pure1 only ?ree /rong l9es ( b>ium appe>$1 :ile ! new spectrum 0 v bright4 ,! foll[+ table %[s ! wave-l5g? ( ! new l9es obs]v$ = radium4 ,! wave l5g?s are express$ 9 ng/rm units & ! int5sity ( ea* ray is d5ot$ by a numb]1 ! ray ( maximum int5sity be+ #af4 ,wave l5g? ,int5sity ,wave l5g? ,int5sity #dhbfc #aj #dfjjc #c #dgbfi #e #decce #i #dfiif #c #ddcfa #f #dfiba #g #dcdjf #ab #dfhcj #ad #chadg #af #dfdai #d #cfdif #ab ,! l9es are all %>ply def9$1 & ?ree or f\r ( !m h an int5sity comp>able ) any kn[n l9es ( o!r sub/ances4 ,!re are also pres5t 9 ! spectrum two /rong nebul\s b&s4 ,9 ! visible "p ( ! spectrum1 :i* has n be5 photograph$1 ! only noticeable ray has a wave l5g? #effe1 :i* is1 h[ev]1 v feeble comp>$ ) t ( wave l5g? #dhbfc4 ,! g5]al aspect ( ! spectrum is simil> to t ( ! alkal9e e>?s2 x is kn[n t ^! metals h /rong l9es accompani$ by nebul\s b&s4 ,! pr9cipal l9e due to radium c be di/+ui%$ 9 impure radium ( activity #ej times t ( uranium4 ,by ! electrical me?od x is easy to di/+ui% ! pres5ce ( radium 9 a body :i* has an activity only ( uranium4 ,) a m s5sitive electromet] ( ! activity ( uranium c\ld be obs]v$4 ,= ! detection ( radium1 ! exam9ation ( ! radio-activity is ?us a process ne>ly a million times m s5sitive ?an spectrum analysis4 ,lat] obs]vations on ! spectrum ( radium h be5 made by ,runge#ba1 ,exn] & ,has*ek#bb1 ) specim5s ( radium prep>$ by ,giesel4 ,crookes#bc has photograph$ ! spectrum ( radium 9 ! ultra-violet1 :ile ,runge & ,pre*t#bd1 us+ a highly purifi$ sample ( radium1 obs]v$ a numb] ( new l9es 9 ! sp>k spectrum4 ,x has be5 m5tion$ already t ! bromide ( radium gives a *>act]i/ic pure c>m9e-r$ coloration to ! ,buns5 flame4 ,! flame spectrum %[s two broad bright b&s 9 ! orange-r$1 n obs]v$ 9 ,dem>ay's spectrum4 ,9 addition !re is a l9e 9 ! blue-gre5 & two feeble l9es 9 ! violet4 #ad4 ,atomic weight ( radium4 ,mme ,curie has made successive det]m9ations ( ! atomic weight ( ! new elem5t ) specim5s ( /eadily increas+ purity4 ,9 ! fir/ obs]vation ! radium 0 l>gely mix$ ) b>ium1 & ! atomic weight obta9$ 0 ! same z t ( b>ium1 #acge4 ,9 successive obs]vations ) specim5s ( increas+ purity ! atomic weights ( ! mixture 7 #adf & #age4 ,! f9al value obta9$ rec5tly 0 #bbe1 :i* may be tak5 z ! atomic weight ( radium on ! assumption t x is dival5t4 ,9 ^! exp]im5ts ab\t #ja gram ( pure radium *loride 0 obta9$ by successive fractionations4 ,! difficulty involv$ 9 prep>+ a quantity ( pure radium *loride l>ge en\gh to te/ ! atomic weight may be gaug$ f ! fact t only a few c5tigrams ( fairly pure radium1 or a few decigrams ( less conc5trat$ mat]ial1 are obta9$ f ! treatm5t ( ab\t #b tons ( ! m9]al f :i* x is d]iv$4 ,runge & ,pre*t#be h exam9$ ! spectrum ( radium 9 a magnetic field1 & h %[n ! exi/5ce ( s]ies analog\s to ^? obs]v$ = calcium1 b>ium1 & /rontium4 ,^! s]ies are connect$ ) ! atomic weights ( ! elem5ts 9 "q1 & ,runge & ,pre*t h calculat$ by ^! means t ! atomic weight ( radium %\ld be #beh--;a numb] consid]ably great] ?an ! numb] #bbe obta9$ by ,mme ,curie by means ( *emical analysis4 ,m>%all ,watts#bf1 on ! o!r h&1 us+ ano!r relation betwe5 ! l9es ( ! spectrum1 d$uc$ ! value obta9$ by ,mme ,curie4 ,runge#bg has criticis$ ! me?od ( d$uction employ$ by ,m>%all ,watts on ! gr\nd t ! l9es us$ = comp>ison 9 ! diff]5t spectra 7 n homolog\s4 ,consid]+ t ! numb] f\nd by ,mme ,curie agrees ) t requir$ by ! p]iodic sy/em1 x is advisable 9 ! pres5t /ate ( our k to accept ! exp]im5tal numb] r ?an ! "o d$uc$ by ,runge & ,pre*t f spectroscopic evid5ce4 ,!re is no d\bt t radium is a new elem5t possess+ rem>kable physical prop]ties4 ,! detection & sep>ation ( ?is sub/ance1 exi/+ 9 su* m9ute proportions 9 pit*bl5de1 has be5 due entirely to ! *>act]i/ic prop]ty we are consid]+1 & is ! fir/ notable triumph ( ! /udy ( radio-activity4 ,z we %all see lat]1 ! prop]ty ( radio-activity c be us$1 n only z a means ( *emical rese>*1 b also z an extraord9>ily delicate me?od ( detect+ *emical *anges ( a v special k9d4 #ae4 ,radiations f radium4 ,on acc\nt ( its enorm\s activity1 ! radiations f radium are v int5se3 a scre5 ( z9c sulphide1 br\ght ne> a few c5tigrams ( radium bromide1 is light$ up q brightly 9 a d>k room1 :ile brilliant fluoresc5ce is produc$ on a scre5 ( plat9o-b>ium cyanide4 ,an electroscope br\ght ne> ! radium salt is dis*>g$ almo/ in/antly1 :ile a photographic plate is imm$iately affect$4 ,at a di/ance ( "o metre1 a day's exposure to ! radium rays w\ld produce a /rong impression4 ,! radiations f radium are analog\s to ^? ( uranium1 & consi/ ( ?ree types ( rays3 easily absorb$1 p5etrat+1 & v p5etrat+4 ,radium also gives rise to an emanation simil> to t ( ?orium1 b ) a v mu* sl[] rate ( decay4 ,! radium emanation reta9s its activity = sev]al weeks1 :ile t ( ?orium la/s only a few m9utes4 ,! emanation obta9$ f a few c5tigrams ( radium illum9ates a scre5 ( z9c sulphide ) great brilliancy4 ,! v p5etrat+ rays ( radium are able to light up an ,x ray scre5 9 a d>k room1 aft] passage ?r\gh sev]al c5timetres ( lead & sev]al in*es ( iron4 ,z 9 ! case ( uranium or ?orium1 ! photographic action is ma9ly due to ! p5etrat+ or ca?odic rays4 ,! radiographs obta9$ ) radium are v simil> to ^? obta9$ ) ,x rays1 b lack ! %>pness & detail ( ! latt]4 ,! rays are unequally absorb$ by diff]5t k9ds ( matt]1 ! absorption v>y+ approximately z ! d5sity4 ,9 photographs ( ! h& ! bones d n /& out z 9 ,x ray photographs4 ,curie & ,laborde h %[n t ! comp\nds ( radium possess ! rem>kable prop]ty ( always keep+ _! temp]ature sev]al degrees above ! temp]ature ( ! surr\nd+ air4 ,ea* gram ( radium radiates an am\nt ( en]gy correspond+ to #ajj gram-calories p] h\r4 ,?is & o!r prop]ties ( radium are discuss$ 9 detail 9 *apt]s ,v & ,,xii4 #af4 ,comp\nds ( radium4 ,:5 fir/ prep>$ 9 ! solid /ate1 all ! salts ( radium--! *loride1 bromide1 acetate1 sulphate1 & c>bonate--are v simil> 9 appe>ance to ! correspond+ salts ( b>ium1 b 9 "t !y gradually become col\r$4 ,9 *emical prop]ties ! salts ( radium are practically ! same z ^? ( b>ium1 ) ! exception t ! *loride & bromide ( radium are less soluble 9 wat] ?an ! correspond+ salts ( b>ium4 ,all ! salts ( radium are naturally phosphoresc5t4 ,! phosphoresc5ce ( impure radium prep>ations is 9 "s cases v m>k$4 ,all ! radium salts possess ! prop]ty ( caus+ rapid colorations ( ! glass vessel :i* conta9s !m4 ,= feebly active mat]ial ! col\r is usually violet1 = m active mat]ial a yell[i%-br[n1 & f9ally black4 #ag4 ,act9ium4 ,! discov]y ( radium 9 pit*bl5de gave a great impetus to ! *emical exam9ation ( uranium residues1 & a sy/ematic se>* e>ly l$ to ! detection ( sev]al new radio-active bodies4 ,al?\gh ^! %[ di/9ctive radio-active prop]ties1 s f> none ( !m h be5 purifi$ suffici5tly to give a def9ite spectrum z 9 ! case ( radium4 ,"o ( ! mo/ int]e/+ & important ( ^! sub/ances 0 discov]$ by ,debi]ne#bh :ile work+ up ! uranium residues1 obta9$ by ,m4 & ,mme ,curie f ! ,au/rian gov]nm5t1 & 0 call$ by him act9ium4 ,?is active sub/ance is precipitat$ ) ! iron gr\p1 & appe>s to be v closely alli$ 9 *emical prop]ties to ?orium1 ?\gh x is _m ?\s& times m active4 ,x is v difficult to sep>ate f ?orium & ! r>e e>?s4 ,debi]ne has made use ( ! foll[+ me?ods = p>tial sep>ation3 7#a7 ,precipitation 9 hot solutions1 slightly acidulat$ ) hydro*loric acid1 by excess ( hyposulphite ( soda4 ,! active matt] is pres5t almo/ entirely 9 ! precipitate4 7#b7 ,action ( hydr(luoric acid ^u ! hydrates fre%ly precipitat$1 & held 9 susp5sion 9 wat]4 ,! portion dissolv$ is only slightly active4 ,by ?is me?od titanium may be sep>at$4 7#c7 ,precipitation ( neutral nitrate solutions by oxyg5at$ wat]4 ,! precipitate c>ries d[n ! active body4 7#d7 ,precipitation ( insoluble sulphates4 ,if b>ium sulphate1 = example1 is precipitat$ 9 ! solution conta9+ ! active body1 ! b>ium c>ries d[n ! active matt]4 ,! ?orium & act9ium are fre$ f ! b>ium by conv]sion ( ! sulphate into ! *loride & precipitation by ammonia4 ,9 ?is way ,debi]ne has obta9$ a sub/ance comp>able 9 activity ) radium4 ,! sep>ation1 :i* is difficult & labori\s1 has n yet be5 c>ri$ f> en\gh to br+ out any new l9es 9 ! spectrum4 #ah4 ,aft] ! initial ann\ncem5t ( ! discov]y ( act9ium1 sev]al ye>s elaps$ be=e any def9ite results ^u x 7 publi%$ by ,debi]ne4 ,9 ! meantime1 ,giesel#bi _h indep5d5tly obta9$ a radio-active sub/ance f pit*bl5de :i* seem$ simil> 9 _m respects to ! act9ium ( ,debi]ne4 ,! active sub/ance belongs to ! gr\p ( c]ium e>?s & is precipitat$ ) !m4 ,by a succession ( *emical op]ations1 ! active sub/ance is sep>at$ mix$ ) lan?anum4 ,:ile int5sely active 9 comp>ison ) ?orium1 ! new active sub/ance closely resembles x 9 radio-active prop]ties1 al?\gh1 f ! me?od ( sep>ation ?orium _c be pres5t except 9 m9ute quantity4 ,giesel e>ly obs]v$ t ! sub/ance gave (f a radio-active emanation4 ,on acc\nt ( ! int5sity ( ! emanation x emits1 he t]m$ x ! 8emanat+ sub/ance40 ,rec5tly ?is "n has be5 *ang$ to 8emanium10 & "u ?is title prep>ations ( ! active sub/ance prep>$ by ,giesel h be5 plac$ on ! m>ket4 ,giesel f\nd t ! activity ( ?is sub/ance 0 p]man5t & seem$ to increase dur+ ! six mon?s' int]val aft] sep>ation4 ,9 ?is respect x is simil> to radium comp\nds1 = ! activity ( radium1 measur$ by ! electric me?od1 increases 9 ! c\rse ( a mon?'s int]val to f\r times its initial value at sep>ation4 ,!re c be no d\bt t ! 8act9ium0 ( ,debi]ne & ! 8emanium0 ( ,giesel conta9 ! same radio-active con/itu5t1 = rec5t "w#cj has %[n t !y exhibit id5tical radio-active prop]ties4 ,ea* gives out easily absorb$ & p5etrat+ rays1 & emits a *>act]i/ic emanation ( :i* ! rate ( decay is ! same = bo? sub/ances4 ,! rate ( decay ( ! emanation is ! simple/ me?od ( di/+ui%+ act9ium f ?orium1 :i* x resembles s closely 9 radio-active z well z 9 *emical prop]ties4 ,! emanation ( act9ium loses its radiat+ p[] f> m rapidly ?an t ( ?orium1 ! "t tak5 = ! activity to fall to half value be+ 9 ! two cases #cg seconds & #eb seconds respectively4 ,! rapid & cont9u\s emission ( ?is %ort-liv$ emanation is ! mo/ /rik+ radio-active prop]ty possess$ by act9ium4 ,9 /ill air1 ! radio-active effects ( ?is emanation are conf9$ to a di/ance ( a few c5timetres f ! active mat]ial1 z x is only able to diffuse a %ort di/ance ?r\gh ! air be=e los+ its radiat+ p[]4 ,) v active prep>ations ( act9ium1 ! mat]ial appe>s to be surr\nd$ by a lum9\s haze produc$ by ! emanation4 ,! radiations produce /rong lum9osity 9 "s sub/ances1 = example1 z9c sulphide1 willemite & plat9ocyanide ( b>ium4 ,! lum9osity is especially m>k$ on scre5s ( z9c sulphide4 ,mu* ( ?is effect is due to ! emanation1 =1 on g5tly bl[+ a curr5t ( air ov] ! sub/ance1 ! lum9osity is displac$ at once 9 ! direction ( ! curr5t4 ,) a z9c sulphide scre51 act9ium %[s ! ph5om5a ( 8sc9tillations0 to an ev5 m m>k$ degree ?an radium itself4 ,! prep>ations ( emanium are 9 "s cases lum9\s1 & a spectroscopic exam9ation ( ?is light has %[n a numb] ( bright l9es#ca4 ,! di/9ctive "* ( ! emanation ( act9ium1 z well z ( ! o!r radio-active products to :i* x gives rise1 c\pl$ ) ! p]man5ce ( its activity1 r5d]s x v probable t act9ium w prove to be a new radio-active elem5t ( v great activity4 ,al?\gh v active prep>ations ( act9ium h be5 obta9$1 x has n yet be5 f\nd possible to free x f impurities4 ,consequ5tly1 no def9ite obs]vations h be5 made on its *emical prop]ties1 & no new spectrum l9es h be5 obs]v$4 ,a m complete discussion ( ! radio-active & o!r prop]ties ( act9ium is giv5 9 lat] *apt]s4 #ai4 ,polonium4 ,polonium 0 ! fir/ ( ! active sub/ances obta9$ f pit*bl5de4 ,x has be5 inve/igat$ 9 detail by its discov]] ,mme ,curie#cb4 ,! pit*bl5de 0 dissolv$ 9 acid & sulphurett$ hydrog5 add$4 ,! precipitat$ sulphides conta9$ an active sub/ance1 :i*1 aft] sep>ation ( impurities1 0 f\nd associat$ ) bismu?4 ,?is active sub/ance1 :i* has be5 nam$ polonium1 is s closely alli$ 9 *emical prop]ties to bismu? t x has s f> be5 f\nd impossible to effect a complete sep>ation4 ,p>tial sep>ation ( polonium c be made by successive fractionations bas$ on "o ( ! foll[+ modes ( proc$ure3 7#a7 ,sublimation 9 a vacuum4 ,! active sulphide is m volatile ?an t ( bismu?4 ,x is deposit$ z a black sub/ance at ^? p>ts ( ! tube1 :]e ! temp]ature is betwe5 #bej & #cjj ,c4 ,9 ?is way polonium ( activity #gjj times t ( uranium 0 obta9$4 7#b7 ,precipitation ( nitric acid solutions by wat]4 ,! precipitat$ sub-nitrate is mu* m active ?an ! "p t rema9s 9 solution4 7#c7 ,precipitation by sulphurett$ hydrog5 9 a v acid hydro*loric acid solution4 ,! precipitat$ sulphides are mu* m active ?an ! salt :i* rema9s 9 solution4 ,= conc5tration ( ! active sub/ance ,mme ,curie#cc has made use ( me?od 7#b74 ,! process is1 h[ev]1 v sl[ & t$i\s1 & is made /ill m complicat$ by ! t5d5cy to =m precipitates insoluble ei!r 9 /rong or weak acids4 ,aft] a l>ge numb] ( fractionations1 a small quantity ( matt] 0 obta9$1 enorm\sly active comp>$ ) uranium4 ,on exam9ation ( ! sub/ance spectroscopically1 only ! bismu? l9es 7 obs]v$4 ,a spectroscopic exam9ation ( ! active bismu? by ,dem>ay & by ,runge & ,exn] has l$ to ! discov]y ( no new l9es4 ,on ! o!r h& ,sir ,william ,crookes#cd /ates t he f\nd "o new l9e 9 ! ultra-violet1 :ile ,b]ndt#ce1 work+ ) polonium ( activity #cjj1 obs]v$ a l>ge numb] ( new l9es 9 ! ultra-violet4 ,^! results await fur!r confirmation4 ,! polonium prep>$ by ,mme ,curie diff]s f ! o!r radio-active bodies 9 sev]al p>ticul>s4 ,9 ! fir/ place ! radiations include only v easily absorbable rays4 ,! two p5etrat+ types ( radiation giv5 out by uranium1 ?orium1 & radium are abs5t4 ,9 ! second place ! activity does n rema9 con/ant1 b dim9i%es cont9u\sly ) ! "t4 ,mme ,curie /ates t diff]5t prep>ations ( polonium _h some:at diff]5t rates ( decay4 ,9 "s cases1 ! activity fell to half value 9 ab\t six mon?s1 & 9 o!rs1 ab\t half value 9 elev5 mon?s4 #bj4 ,! gradual dim9ution ( ! activity ( polonium ) "t seem$ at fir/ sight to diff]5tiate x f su* sub/ances z uranium & radium1 ! activity ( :i* appe>$ fairly p]man5t4 ,?is diff]5ce 9 behavi\r is1 h[ev]1 "o ( degree r ?an ( k9d4 ,we %all %[ lat] t !re is pres5t 9 pit*bl5de a numb] ( radio-active sub/ances1 ! activity ( :i* is n p]man5t4 ,! "t tak5 = ^! bodies to lose half ( _! activity v>ies 9 diff]5t cases f a few seconds to sev]al hundr$s ( ye>s4 ,9 fact1 ?is gradual loss ( activity is an ess5tial feature ( our !ory ( reg>d+ ! ph5om5a ( radio-activity4 ,no radio-active sub/ance1 left to itself1 c cont9ue to radiate indef9itely2 x mu/ ultimately lose its activity4 ,9 ! case ( bodies l uranium & radium1 ! loss ( activity is s sl[ t no s5sible alt]ation has be5 obs]v$ ov] a p]iod ( sev]al ye>s1 b x c be d$uc$ !oretically t ! activity ( radium w ev5tually decrease to half value 9 a p]iod ( ab\t #ajjj ye>s1 :ile 9 ! case ( a feebly radio-active sub/ance l uranium1 m ?an a #ajj million ye>s mu/ elapse be=e ! dim9ution ( ! activity becomes appreciable4 ,x may be ( int]e/ "h to consid] briefly ! sugge/ions advanc$ at v>i\s times to acc\nt = ! tempor>y "* ( ! activity ( polonium4 ,its association ) bismu? l$ to ! view t polonium 0 n a new active sub/ance1 b m]ely radio-active bismu?1 t is1 bismu? :i* 9 "s way _h be5 made active by admixture ) radio-active bodies4 ,x 0 kn[n t a body plac$ 9 ! vic9ity ( ?orium or radium became tempor>ily active4 ,! same action 0 suppos$ to take place :5 inactive matt] 0 9 solution ) active matt]4 ,! non-active matt] 0 suppos$ to acquire activity by 8induction10 z x 0 call$1 9 consequ5ce ( its intimate contact ) ! active mat]ial4 ,!re is no pro(1 h[ev]1 t su* is ! case4 ,! evid5ce po9ts r to ! conclusion t ! activity is due1 n to an alt]ation ( ! inactive body itself1 b to an admixture ) x ( a v small quantity ( int5sely active matt]4 ,?is active matt] is pres5t 9 pit*bl5de & is sep>at$ ) ! bismu? b diff]s f x 9 *emical prop]ties4 ,! subject _c be consid]$ ) advantage at ?is /age1 b w be discuss$ lat] 9 detail 9 *apt] ,,xi4 ,x w !re be %[n t polonium1 t is1 ! radio-active con/itu5t mix$ ) ! bismu?1 is a di/9ct *emical sub/ance1 :i* is alli$ 9 *emical prop]ties to bismu?1 b possesses "s di/9ct analytical prop]ties :i* all[ ( a p>tial sep>ation f x4 ,! polonium1 if obta9$ 9 a pure /ate1 %\ld initially be sev]al hundr$ times z active z pure radium4 ,?is activity1 h[ev]1 is n p]man5t2 x decays ) ! "t1 fall+ to half value 9 ab\t six mon?s4 ,! abs5ce ( any new l9es 9 ! spectrum ( radio-active bismu? is to be expect$1 =1 ev5 9 ! mo/ active bismu? prep>$1 ! active matt] exi/s 9 a v small proportion4 #ba4 ,! discussion ( ! nature ( polonium 0 r5ew$ by ! discov]y ( ,m>ckwald#cf t a sub/ance simil> to polonium c be sep>at$ f pit*bl5de2 ! activity ( ?is sub/ance1 he /at$1 did n decay appreciably ) ! "t4 ,! me?od ( sep>ation f ! bismu? *loride solution1 obta9$ f uranium residues1 0 v simple4 ,a rod ( bismu? or antimony1 dipp$ 9 ! active solution1 rapidly became coat$ ) a black deposit :i* 0 int5sely active4 ,?is process 0 cont9u$ until ! :ole ( ! activity 0 remov$ f ! solution4 ,! active deposit gave out only easily absorb$ rays1 & 9 t respect resembl$ ! polonium ( ,mme ,curie4 ,! active sub/ance 0 f\nd to consi/ ma9ly ( tellurium1 & = ?is reason ,m>ckwald gave x ! "n ( radio-tellurium4 ,9 lat] "w1 h[ev]1 ,m>ckwald#cg has %[n t ! active con/itu5t has no connection ) tellurium1 b c always be sep>at$ completely f x by a simple *emical process4 ,9 ord] to obta9 a l>ge am\nt ( ! active sub/ance1 #bjjj kilos4 ( pit*bl5de 7 work$ up4 ,?is yield$ #f kilos4 ( bismu? oxy*loride1 & f ?is 0 sep>at$ #ae grams ( radio-tellurium4 ,! tellurium pres5t 0 precipitat$ f a hydro*loric acid solution by hydraz9e hydro*loride4 ,! precipitat$ tellurium /ill %[$ "s activity1 b ?is 0 remov$ by repeat+ ! process4 ,! active matt] !n rema9$ 9 ! filtrate1 &1 aft] evaporation1 ! addition ( a few drops ( /ann\s *loride caus$ a small quantity ( a d>k precipitate :i* 0 int5sely active4 ,?is 0 collect$ on a filt] & weigh$ only #d milligrams4 ,:5 plates ( copp]1 t9 or bismu? 7 dipp$ into an hydro*loric acid solution ( ?is active sub/ance1 ! plates 7 f\nd to be cov]$ ) a v f9ely divid$ deposit4 ,^! plates 7 int5sely active1 & produc$ m>k$ photographic & phosphoresc5t action4 ,z an illu/ration ( ! enorm\s activity ( ?is deposit1 ,m>ckwald /at$ t a precipitate ( milligram on a copp] plate1 #d squ>e c5timetres 9 area1 illum9at$ a z9c sulphide scre5 s brightly t x c\ld be se5 by an audi5ce ( sev]al hundr$ p4 ,! active sub/ance ( ,m>ckwald is v closely alli$ 9 *emical & radio-active prop]ties to ! polonium ( ,mme ,curie4 ,bo? active sub/ances are sep>at$ ) bismu? & bo? give out only easily absorb$ rays4 ,! p5etrat+ rays1 su* z are giv5 out by uranium1 radium or ?orium1 are completely abs5t4 ,!re has be5 a consid]able am\nt ( discussion z to :e!r ! active sub/ance obta9$ by ,m>ckwald is id5tical ) t pres5t 9 ! polonium ( ,mme ,curie4 ,m>ckwald /at$ t 8 active sub/ance did n s5sibly dim9i% 9 activity 9 ! c\rse ( six mon?s1 b x is d\btful :e!r ! me?od ( measurem5t us$ 0 suffici5tly precise4 ,! writ] has f\nd t radio-tellurium ( mod]ate activity1 prep>$ aft] ,m>ckwald's me?od & sold by ,dr ,/ham] ( ,hamburg1 und\bt$ly loses its activity ) "t4 ,! radio-tellurium is obta9$ 9 ! =m ( a ?9 radio-active deposit on a poli%$ bismu? rod or plate4 ,a bismu? rod 0 f\nd to h lo/ half its activity 9 ab\t #aej days1 & a simil> result has be5 record$ by o!r obs]v]s4 ,! two sub/ances are ?us simil> 9 bo? radio-active & *emical prop]ties1 & !re c be no reasonable d\bt t ! active con/itu5t pres5t 9 ea* case is ! same4 ,! evid5ce is discuss$ 9 detail 9 *apt] ,,xi & x w !re be %[n t ! active sub/ance pres5t 9 ! radio-tellurium ( ,m>ckwald is a sl[ trans=mation product ( radium4 #bb4 ,radio-active lead4 ,sev]al obs]v]s e>ly notic$ t ! lead sep>at$ f pit*bl5de %[$ /rong radio-active prop]ties1 b consid]able diff]5ce ( op9ion 0 express$ 9 reg>d to ! p]man5ce ( its activity4 ,el/] & ,geitel#ch f\nd t lead sulphate obta9$ f pit*bl5de 0 v active1 b !y consid]$ t ! activity 0 probably due to an admixture ( radium or polonium ) ! lead1 &1 by suitable *emical treatm5t1 ! lead sulphate 0 obta9$ 9 an inactive /ate4 ,giesel#ci also sep>at$ "s radio-active lead b f\nd t its activity dim9i%$ ) ! "t4 ,on ! o!r h&1 ,h(mann & ,/rauss#dj obta9$ lead f pit*bl5de ^: activity seem$ fairly p]man5t4 ,!y /ate t ! radio-active lead resembl$ ord9>y lead 9 mo/ ( its reactions1 b %[$ diff]5ces 9 ! behavi\r ( ! sulphide & sulphate4 ,! sulphate 0 f\nd to be /rongly phosphoresc5t4 ,^! results ( ,h(mann & ,/rauss 7 subject$ at ! "t ( _! publication to consid]able criticism1 & !re is no d\bt t ! lead itself is n radio-active b conta9s a small quantity ( radio-active matt] :i* is sep>at$ ) x4 ,9 lat] "w#da1 x has be5 %[n t radio-lead conta9s sev]al radio-active con/itu5ts :i* c be remov$ tempor>ily f x by suitable *emical me?ods4 ,!re c be no d\bt t ! lead sep>at$ f pit*bl5de by c]ta9 me?ods does %[ consid]able activity & t ?is activity is fairly p]man5t4 ,! radio-active *anges occurr+ 9 radio-lead are complicat$ & _c be discuss$ ) advantage at ?is /age1 b w be consid]$ 9 detail 9 *apt] ,,xi4 ,x w !re be %[n t ! prim>y con/itu5t pres5t 9 lead is a sl[ trans=mation product ( radium4 ,?is sub/ance !n sl[ly *anges into ! active con/itu5t pres5t 9 polonium1 :i* gives out only easily absorb$ rays4 ,?is polonium c be sep>at$ tempor>ily f ! lead by suitable *emical me?ods1 b ! radio-lead /ill cont9ues to produce polonium1 s t a fre% supply may be obta9$ f x1 provid$ an int]val ( sev]al mon?s is all[$ to elapse4 ,x w be calculat$ lat] t 9 all probability ! radio-lead w\ld lose half ( its activity 9 an int]val ( #dj ye>s4 ,! con/itu5t pres5t 9 radio-lead has n yet be5 sep>at$1 b x w be %[n t1 9 ! pure /ate1 x %\ld h an activity consid]ably great] ?an t ( radium itself4 ,suffici5t att5tion has n yet be5 paid to ?is sub/ance1 =1 sep>at$ 9 a pure /ate1 x %\ld be z useful sci5tifically z radium4 ,9 addition1 s9ce x is ! p>5t ( polonium1 x %\ld be possible to obta9 f x at any "t a supply ( v active polonium1 9 ! same way t a supply ( ! radium emanation c be obta9$ at int]vals f radium4 ,h(mann & ,/rauss h obs]v$ a peculi> action ( ! ca?ode rays on ! active lead sulphate sep>at$ by !m4 ,!y /ate t ! activity dim9i%es ) "t1 b is recov]$ by exposure ( ! lead = a %ort "t to ! action ( ca?ode rays4 ,no su* action is %[n by ! active lead sulphide4 ,?is effect is due mo/ probably to ! action ( ! ca?ode rays 9 caus+ a /rong phosphoresc5ce ( ! lead sulphate & has no?+ to d ) ! radio-activity prop] ( ! sub/ance4 #bc4 ,is ?orium a radio-active elem5t8 ,! simil>ity ( ! *emical prop]ties ( act9ium & ?orium has l$ to ! sugge/ion at diff]5t times t ! activity ( ?orium is n due to ?orium itself1 b to ! pres5ce ( a slight trace ( act9ium4 ,9 view ( ! diff]5ce 9 ! rate ( decay ( ! emanations ( ?orium & act9ium1 ?is position is n t5able4 ,if ! activity ( ?orium 7 due to act9ium1 ! two emanations1 z well z ! o!r products obta9$ f ^! sub/ances1 %\ld h id5tical rates ( decay4 ,s9ce !re is n ! slighte/ evid5ce t ! rate ( decay ( activity ( ! v>i\s products c be alt]$ by *emical or physical ag5cies1 we may conclude ) confid5ce t :atev] radio-active sub/ance is responsible = ! activity ( ?orium1 x c]ta9ly is n act9ium4 ,?is diff]5ce 9 ! rate ( decay ( ! active products is ( f> m weight 9 decid+ ! "q :e!r two bodies conta9 ! same radio-active con/itu5t ?an diff]5ces 9 *emical behavi\r1 = x is q probable t ! active mat]ial 9 ea* case may exi/ only 9 m9ute quantity 9 ! matt] "u exam9ation1 &1 "u su* conditions1 a direct *emical exam9ation 9 ! fir/ place is ( little value4 ,rec5t "w ( ,h(mann & ,z]ban & ( ,bask]ville1 h[ev]1 c]ta9ly t5ds to %[ t ! elem5t ?orium is itself non-radio-active1 & t ! radio-activity obs]v$ 9 ord9>y ?orium comp\nds is due to ! admixture ) x ( an unkn[n radio-active elem5t4 ,h(mann & ,z]ban#db made a sy/ematic exam9ation ( ! radio-activity ( ?orium obta9$ f diff]5t m9]al s\rces4 ,!y f\nd g5]ally t ?orium1 obta9$ f m9]als conta9+ a l>ge p]c5tage ( uranium1 7 m active ?an ^? obta9$ f m9]als ne>ly free f uranium4 ,?is indicates t ! radio-activity obs]v$ 9 ?orium may possibly be due to a trans=mation product ( uranium :i* is closely alli$ *emically to ?orium & is always sep>at$ ) x4 ,a small quantity ( ?orium obta9$ f ! m9]al gadol9ite 0 f\nd by ,h(mann to be almo/ inactive1 :e!r te/$ by ! electric or by ! photographic me?od4 ,lat] ,bask]ville & ,z]ban#dc f\nd t ?orium obta9$ f a ,brazilian m9]al 0 practically devoid ( activity4 ,9 ?is connection ! rec5t "w ( ,bask]ville on ! complexity ( ord9>y ?orium is ( int]e/4 ,by special *emical me?ods1 he succe$$ 9 sep>at+ two new & di/9ct sub/ances f ?orium1 :i* he has nam$ c>ol9ium & b]zelium4 ,bo? ( ^! sub/ances are /rongly radio-active1 & x ?us seems probable t ! active con/itu5t obs]v$ 9 ord9>y ?orium may be due to "o ( ^! elem5ts4 ,if1 z we h sugge/$1 ?orium itself is n active1 x is c]ta9ly a matt] ( surprise t ord9>y comm]cial ?orium & ! pure/ *emical prep>ations %[ ab\t ! same activity4 ,su* a result indicates t ! me?ods ( purification h n remov$ any ( ! radio-active con/itu5t orig9ally pres5t4 ,:atev] ! radio-active con/itu5t 9 ?orium may ultimately prove to be1 x is und\bt$ly n radium nor act9ium nor any ( ! kn[n radio-active sub/ances4 ,9 lat] *apt]s1 ! radio-activity ( ?orium w1 = simplicity1 be discuss$ on ! assumption t ?orium is itself a radio-active elem5t4 ,! analysis ( ! *anges :i* occur w ?us n ref] to ?orium itself b to ! prim>y radio-active sub/ance usually f\nd associat$ ) x4 ,! conclusions to be drawn f an exam9ation ( ! radio-active processes are = ! mo/ "p indep5d5t ( :e!r ?orium is itself radio-active or :e!r ! radio-activity is due to an unkn[n elem5t4 ,if ?orium is n radio-active itself1 x is n possible to draw any conclusions ^u ! "q ( ! duration ( ! prim>y radio-activity associat$ ) x4 ,su* a d$uction _c be made until ! quantity ( ! radio-active elem5t pres5t 9 ?orium has be5 def9itely det]m9$4 #bd4 ,if elem5ts heavi] ?an uranium exi/1 x is probable t !y w be radio-active4 ,! extreme delicacy ( radio-activity z a means ( *emical analysis w\ld enable su* elem5ts to be recogniz$ ev5 if pres5t 9 inf9itesimal quantities4 ,x is probable t consid]ably m ?an ! ?ree or f\r radio-elem5ts at pres5t recogniz$ exi/ 9 m9ute quantity1 & t ! numb] at pres5t kn[n w be augm5t$ 9 ! future4 ,9 ! fir/ /age ( ! se>*1 a purely *emical exam9ation is ( little value1 = x is n probable t ! new elem5t %\ld exi/ 9 suffici5t quantity to be detect$ by *emical or spectroscopic analysis4 ,! ma9 crit]ia ( importance are ! exi/5ce or abs5ce ( di/9ctive radiations or emanations1 & ! p]man5ce ( ! radio-activity4 ,! discov]y ( a radio-active emanation ) a rate ( decay diff]5t f ^? already kn[n w\ld af=d /rong evid5ce t a new radio-active body 0 pres5t4 ,! pres5ce ( ei!r ?orium or radium 9 matt] c v readily be detect$ by obs]v+ ! rate ( decay ( ! emanations giv5 out by !m4 ,:5 once ! exi/5ce ( a new radio-elem5t has be5 inf]r$ by an exam9ation ( its radio-active prop]ties1 *emical me?ods ( sep>ation c be devis$1 ! radiat+ or emanat+ prop]ty be+ us$ z a guide 9 qualitative & quantitative analysis4 ,footnote #a3 ,niew5gl[ski1 ,c4 ,r4 #abb1 p4 #che1 #ahif4 ,footnote #b3 ,becqu]el1 ,c4 ,r4 #abb1 p4 #eei1 #ahif4 ,footnote #c3 ,troo/1 ,c4 ,r4 #abb1 p4 #efd1 #ahif4 ,footnote #d3 ,arnold1 ,annal4 d4 ,phys4 #fa1 p4 #caf1 #ahig4 ,footnote #e3 ,le ,bon1 ,c4 ,r4 #abb1 pp4 #ahh1 #bcc1 #chf1 #dfb1 #ahif4 ,footnote #f3 ,becqu]el1 ,c4 ,r4 #abb1 pp4 #dbj1 #eja1 #eei1 #fhi1 #gfb1 #ajhf1 #ahif4 ,footnote #g3 ,mme ,curie1 ,?se prs5te la ,facult des ,sci5ces de ,p>is1 #aijc4 ,footnote #h3 ,nature1 #ef1 #ahig2 ,phil4 ,mag4 #dc1 p4 #dah1 #ahig2 #de1 p4 #bgg1 #ahih4 ,footnote #i3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #ahii4 ,footnote #aj3 ,ibid4 ,footnote #aa3 ,le ,bon1 ,c4 ,r4 #acj1 p4 #hia1 #aijj4 ,footnote #ab3 ,l5>d1 ,annal4 d4 ,phys4 #a1 p4 #dih2 #c1 p4 #bih1 #aijj4 ,footnote #ac3 ,s*midt1 ,annal4 d4 ,phys4 #fe1 p4 #ada1 #ahih4 ,footnote #ad3 ,mme ,curie1 ,c4 ,r4 #abf1 p4 #aaja1 #ahih4 ,footnote #ae3 ,ow5s1 ,phil4 ,mag4 ,oct4 #ahii4 ,footnote #af3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #aijj4 ,footnote #ag3 ,m4 & ,mme ,curie & ,g4 ,bemont1 ,c4 ,r4 #abg1 p4 #abae1 #ahih4 ,footnote #ah3 ,giesel1 ,phys4 ,zeit4 #c1 ,no4 #bd1 p4 #egh1 #aijb4 ,footnote #ai3 ,giesel1 ,annal4 d4 ,phys4 #fi1 p4 #ia1 #ahij4 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #cfjh1 #aijb4 ,footnote #bj3 ,dem>ay1 ,c4 ,r4 #abg1 p4 #abah1 #ahih2 #abi1 p4 #gaf1 #ahii2 #aca1 p4 #beh1 #aijj4 ,footnote #ba3 ,runge1 ,a/rophys4 ,j\rnal1 p4 #a1 #aijj4 ,annal4 d4 ,phys4 ,no4 #aj1 p4 #djg1 #aijc4 ,footnote #bb3 ,exn] & ,has*ek1 ,wi54 ,b]4 ,july #d1 #aija4 ,footnote #bc3 ,crookes1 ,proc4 ,roy4 ,soc4 #gb1 p4 #bie1 #aijd4 ,footnote #bd3 ,runge & ,pre*t1 ,annal4 d4 ,phys4 ,,xiv4 #b1 p4 #dah1 #aijd4 ,footnote #be3 ,runge & ,pre*t1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #bf3 ,watts1 ,phil4 ,mag4 ,july1 #aijc2 ,augu/1 #aijd4 ,footnote #bg3 ,runge1 ,phil4 ,mag4 ,decemb]1 #aijc4 ,footnote #bh3 ,debi]ne1 ,c4 ,r4 #abi1 p4 #eic1 #ahii2 #acj1 p4 #bjf1 #aijj4 ,footnote #bi3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #cfjh1 #aijb2 p4 #cdb1 #aijc4 ,footnote #cj3 ,debi]ne1 ,c4 ,r4 #aci1 p4 #ech1 #aijd4 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,giesel1 ,phys4 ,zeit4 #e1 p4 #hbb1 #aijd4 ,jahrbu*4 d4 ,radioaktivitt1 no4 #d1 p4 #cde1 #aijd4 ,footnote #ca3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 #cg1 p4 #afif1 #aijd2 ,h>tmann1 ,phys4 ,zeit4 #e1 ,no4 #ah1 p4 #egj1 #aijd4 ,footnote #cb3 ,mme ,curie1 ,c4 ,r4 #abg1 p4 #age1 #ahih4 ,footnote #cc3 ,mme ,curie1 ,?se1 ,p>is1 #aijc4 ,footnote #cd3 ,crookes1 ,proc4 ,roy4 ,soc4 ,may1 #aijj4 ,footnote #ce3 ,b]ndt1 ,phys4 ,zeit4 #b1 p4 #ahj1 #aijj4 ,footnote #cf3 ,m>ckwald1 ,phys4 ,zeit4 #d1 ,no4 #a b1 p4 #ea4 ,footnote #cg3 ,m>ckwald1 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #bffb1 ,no4 #ab1 #aijc4 ,footnote #ch3 ,el/] & ,geitel1 ,annal4 d4 ,phys4 #fi1 p4 #hc1 #ahii4 ,footnote #ci3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #cgge1 #aija4 ,footnote #dj3 ,h(mann & ,/rauss1 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #cjce1 #aija4 ,footnote #da3 ,h(mann1 ,gond] & ,wlfl1 ,annal4 d4 ,phys4 ,no4 #ac1 p4 #fae1 #aijd4 ,footnote #db3 ,h(mann & ,z]ban1 ,b]4 d4 ,d4 ,*em4 ,ges4 ,no4 #ab1 p4 #cjic1 #aijc4 ,footnote #dc3 ,bask]ville & ,z]ban1 ,am]4 ,*em4 ,soc4 #bf1 p4 #afdb1 #aijd4 ,,*apt] ,,ii4 ,,ionization ,,!ory ,,( ,,gases4 #be4 ,ionization ( gases by radiation4 ,! mo/ important prop]ty possess$ by ! radiations f radio-active bodies is _! p[] ( dis*>g+ bodies :e!r positively or negatively electrifi$4 ,z ?is prop]ty has be5 made ! basis ( a me?od = an accurate quantitative analysis & comp>ison ( ! radiations1 ! v>iation ( ! rate ( dis*>ge "u diff]5t conditions & ! processes und]ly+ x w be consid]$ 9 "s detail4 ,9 ord] to expla9 ! simil> dis*>g+ p[] ( ,rntg5 rays1 ! !ory#dd has be5 put =w>d t ! rays produce positively & negatively *>g$ c>ri]s ?r\gh\t ! volume ( ! gas surr\nd+ ! *>g$ body1 & t ! rate ( production is proportional to ! int5sity ( ! radiation4 ,^! c>ri]s1 or ions#de z !y h be5 t]m$1 move ) a uni=m velocity ?r\gh ! gas "u a con/ant electric field1 & _! velocity v>ies directly z ! /r5g? ( ! field4 ,illu/ration3 ,fig4 #a4 ,suppose we h a gas betwe5 two metal plates ,a & ,b 7,fig4 #a7 expos$ to ! radiation1 & t ! plates are kept at a con/ant diff]5ce ( pot5tial4 ,a def9ite numb] ( ions w be produc$ p] second by ! radiation1 & ! numb] produc$ w dep5d 9 g5]al ^u ! nature & pressure ( ! gas4 ,9 ! electric field ! positive ions travel t[>ds ! negative plate1 & ! negative ions t[>ds ! positive1 & consequ5tly a curr5t w pass ?r\gh ! gas4 ,"s ( ! ions w also recomb9e1 ! rate ( recomb9ation be+ proportional to ! squ>e ( ! numb] pres5t4 ,= a giv5 int5sity ( radiation1 ! curr5t pass+ ?r\gh ! gas w increase at fir/ ) ! pot5tial diff]5ce betwe5 ! plates1 b x w rea* a limit :5 all ! ions are remov$ by ! electric field be=e any recomb9ation occurs4 ,?is !ory acc\nts also = all ! *>act]i/ic prop]ties ( gases made conduct+ by ! rays f active sub/ances1 ?\gh !re are c]ta9 diff]5ces obs]v$ betwe5 ! conductivity ph5om5a produc$ by active sub/ances & by ,x rays4 ,^! diff]5ces are = ! mo/ "p ! result ( unequal absorption ( ! two types ( rays4 ,unlike ,rntg5 rays1 a l>ge proportion ( ! radiation f active bodies consi/s ( rays :i* are absorb$ 9 _! passage ?r\gh a few c5timetres ( air4 ,! ionization ( ! gas is ?us n uni=m1 b falls (f rapidly ) increase ( di/ance f ! active sub/ance4 #bf4 ,v>iation ( ! curr5t ) voltage4 ,suppose t a lay] ( radio-active matt] is spread uni=mly on ! l[] ( two horizontal plates ,a & ,b 7,fig4 #a74 ,! l[] plate ,a is connect$ ) "o pole ( a batt]y ( cells ! o!r pole ( :i* is connect$ ) e>?4 ,! plate ,b is connect$ ) "o pair ( quadrants ( an electromet]1 ! o!r pair be+ connect$ ) e>?4 ,! curr5t#df betwe5 ! plates1 det]m9$ by ! rate ( movem5t ( ! electromet] ne$le1 is obs]v$ at fir/ to increase rapidly ) ! voltage1 !n m sl[ly1 f9ally rea*+ a value :i* increases v slightly ) a l>ge increase 9 ! voltage4 ,?is1 z we h indicat$1 is simply expla9$ on ! ionization !ory4 ,! radiation produces ions at a con/ant rate1 &1 be=e ! electric field is appli$1 ! numb] p] unit volume increases until ! rate ( production ( fre% ions is exactly balanc$ by ! recomb9ation ( ! ions already produc$4 ,on application ( a small electric field1 ! positive ions travel to ! negative electrode & ! negative to ! positive4 ,s9ce ! velocity ( ! ions betwe5 ! plates is directly proportional to ! /r5g? ( ! electric field1 9 a weak field ! ions take s long to travel betwe5 ! electrodes t mo/ ( !m recomb9e on ! way4 ,! curr5t obs]v$ is consequ5tly small4 ,) increase ( ! voltage !re is an increase ( spe$ ( ! ions & a small] numb] recomb9e4 ,! curr5t consequ5tly increases1 & w rea* a maximum value :5 ! electric field is suffici5tly /rong to remove all ! ions be=e appreciable recomb9ation has occurr$4 ,! value ( ! curr5t w !n rema9 con/ant ev5 ?\gh ! voltage is l>gely increas$4 ,?is maximum curr5t w be call$ ! 8saturation0 curr5t1 & ! value ( ! pot5tial diff]5ce requir$ to give ?is maximum curr5t1 ! 8saturation ,p4,d40#dg ,! g5]al %ape ( ! curr5t-voltage curve is %[n 9 ,fig4 #b1 :]e ! ord9ates repres5t curr5t & ! abscissae volts4 ,illu/ration3 ,fig4 #b4 ,al?\gh ! v>iation ( ! curr5t ) voltage dep5ds only on ! velocity ( ! ions & _! rate ( recomb9ation1 ! full ma!matical analysis is intricate1 & ! equations1 express+ ! relation betwe5 curr5t & voltage1 are only integrable = ! case ( uni=m ionization4 ,! "q is complicat$ by ! inequality 9 ! velocity ( ! ions & by ! di/urbance ( ! pot5tial gradi5t betwe5 ! plates by ! movem5t ( ! ions4 ,j4 ,j4 ,?omson#dh has work$ out ! case = uni=m production ( ions betwe5 two p>allel plates1 & has f\nd t ! relation betwe5 ! curr5t i & ! pot5tial diff]5ce ,v appli$ is express$ by ,ai ,bi ,v :]e ,a & ,b are con/ants = a def9ite int5sity ( radiation & a def9ite di/ance betwe5 ! plates4 ,illu/ration3 ,fig4 #c4 ,9 c]ta9 cases ( unsymmetrical ionization1 :i* arise 9 ! /udy ( ! radiations f active bodies1 ! relation betwe5 curr5t & voltage is v diff]5t f t express$ by ! above equation4 ,"s ( ^! cases w be consid]$ 9 section #dg4 #bg4 ,! g5]al %ape ( ! curr5t-voltage curves = gases expos$ to ! radiations f active bodies is %[n 9 ,fig4 #c4 ,?is curve 0 obta9$ = #de grams ( impure radium *loride1 ( activity #ajjj times t ( uranium1 spread ov] an area ( #cc sq4 cms4 on ! l[] ( two l>ge p>allel plates1 #de cms4 ap>t4 ,! maximum value ( ! curr5t obs]v$1 :i* is tak5 z #ajj1 0 #ab #aj amp]es1 ! curr5t = l[ voltages 0 ne>ly proportional to ! voltage1 & ab\t #fjj volts betwe5 ! plates 0 requir$ to ensure approximate saturation4 ,9 deal+ ) slightly active bodies l uranium or ?orium1 approximate saturation is obta9$ = mu* l[] voltages4 ,tables ,i4 & ,,ii4 %[ ! results = ! curr5t betwe5 two p>allel plates di/ant #je cms4 & #be cms4 ap>t respectively1 :5 "o plate 0 cov]$ ) a ?9 uni=m lay] ( uranium oxide4 ,,table ,i4 #je cms4 ap>t ,volts ,curr5t #abe #ah #be #cf #e #ee #a #fg #b #gb #d #gi #h #he #af #hh #ajj #id #cce #ajj ,,table ,,ii4 #be cms4 ap>t ,volts ,curr5t #e #gc #a #ad #b #bg #d #dg #h #fd #af #gc #cge #ha #aab #ij #cge #ig #hjj #ajj ,! results are %[n graphically 9 ,fig4 #d4 ,illu/ration3 ,fig4 #d4 ,f ! above tables x is se5 t ! curr5t at fir/ increases ne>ly 9 proportion to ! voltage4 ,!re is no evid5ce ( complete saturation1 al?\gh ! curr5t increases v sl[ly = l>ge increases ( voltage4 ,= example1 9 ,table ,i4 a *ange ( voltage f #abe to #be volts increases ! curr5t f #ah to #cf ( ! maximum1 :ile a *ange ( voltage f #ajj to #cce volts increases ! curr5t only #f4 ,! v>iation ( ! curr5t p] volt 7assum$ uni=m betwe5 ! range ( voltages consid]$7 is ?us ab\t #ejjj times great] = ! =m] *ange4 ,tak+ into consid]ation ! e>ly "p ( ! curves1 ! curr5t does n rea* a practical maximum z soon z w\ld be expect$ on ! simple ionization !ory4 ,x seems probable t ! sl[ increase ) ! l>ge voltages is due ei!r to an action ( ! electric field on ! rate ( production ( ions1 or to ! difficulty ( remov+ ! ions produc$ ne> ! surface ( ! uranium be=e recomb9ation4 ,x is possible t ! pres5ce ( a /rong electric field may assi/ 9 ! sep>ation ( ions :i* o!rwise w\ld n initially escape f ! sph]e ( "o ano!r's attraction4 ,f ! data obta9$ by ,t[ns5d = ! conditions ( production ( fre% ions at l[ pressures by ! movem5t ( ions ?r\gh ! gas1 x seems t ! increase ( curr5t _c be ascrib$ to an action ( ! mov+ ions 9 ! fur!r ionization ( ! gas4 #bh4 ,! equation express+ ! relation betwe5 ! curr5t & ! voltage is v complicat$ ev5 9 ! case ( a uni=m rate ( production ( ions betwe5 ! plates4 ,an approximate !ory1 :i* is ( utility 9 int]pret+ ! exp]im5tal results1 c h[ev] be simply d$uc$ if ! di/urbance ( ! pot5tial gradi5t is disreg>d$1 & ! ionization assum$ uni=m betwe5 ! plates4 ,suppose t ! ions are produc$ at a con/ant rate q p] cubic c5timetre p] second 9 ! gas betwe5 p>allel plates di/ant l cms4 f ea* o!r4 ,:5 no electric field is appli$1 ! numb] ,n pres5t p] c4c41 :5 !re is equilibrium betwe5 ! rates ( production & recomb9ation1 is giv5 by q ,n1 :]e is a con/ant4 ,if a small pot5tial diff]5ce ,v is appli$1 :i* gives only a small fraction ( ! maximum curr5t1 & consequ5tly has n mu* effect on ! value ( ,n1 ! curr5t i p] sq4 cm4 ( ! plate1 is giv5 by ,neu,v i ----- l :]e u is ! sum ( ! velocity ( ! ions = unit pot5tial gradi5t1 & e is ! *>ge c>ri$ by an ion4 u,v ---- l is ! velocity ( ! ions 9 ! electric field ( /r5g? ,v --- l ,! numb] ( ions produc$ p] second 9 a prism ( l5g? l & unit area ( cross-section is ql4 ,! maximum or saturation curr5t ,i p] sq4 cm4 ( ! plate is obta9$ :5 all ( ^! ions are remov$ to ! electrodes be=e any recomb9ation has occurr$4 ,?us ,i q 4 l 4 e1 & fraci,i frac,nu,vql#b fracu,vl#bsqrtqalpha ,?is equation expresses ! fact previ\sly not$ t1 = small voltages1 ! curr5t i is proportional to ,v4 ,let i_/,i 1 !n ,v frac rho l#b sqrt qalpha u ,n[ ! great] ! value ( ,v requir$ to obta9 a giv5 value ( 7suppos$ small comp>$ ) unity71 ! great] ! pot5tial requir$ to produce saturation4 ,x ?us foll[s f ! equation t3 7#a7 ,= a giv5 int5sity ( radiation1 ! saturation ,p4,d4 increases ) ! di/ance betwe5 ! plates4 ,9 ! equation1 = small values ( 1 ,v v>ies z l4 ,?is is f\nd to be ! case = uni=m ionization1 b x only holds approximately = non-uni=m ionization4 7#b7 ,= a giv5 di/ance betwe5 ! plates1 ! saturation ,p4,d4 is great]1 ! great] ! int5sity ( ionization betwe5 ! plates4 ,?is is f\nd to be ! case = ! ionization produc$ by radio-active sub/ances4 ,) a v active sub/ance l radium1 ! ionization produc$ is s int5se t v l>ge voltages are requir$ to produce approximate saturation4 ,on ! o!r h&1 only a fraction ( a volt p] cm4 is necess>y to produce saturation 9 a gas :]e ! ionization is v slight1 = example1 9 ! case ( ! natural ionization obs]v$ 9 a clos$ vessel1 :]e no radio-active sub/ances are pres5t4 ,= a giv5 int5sity ( radiation1 ! saturation ,p4,d4 decreases rapidly ) ! l[]+ ( ! pressure ( ! gas4 ,?is is due to two causes op]at+ 9 ! same direction1 viz4 a decrease 9 ! int5sity ( ! ionization & an increase 9 ! velocity ( ! ions4 ,! ionization v>ies directly z ! pressure1 :ile ! velocity v>ies inv]sely z ! pressure4 ,?is w obvi\sly h ! effect ( caus+ m rapid saturation1 s9ce ! rate ( recomb9ation is sl[] & ! "t tak5 = ! ions to travel betwe5 ! electrodes is less4 ,! saturation curves obs]v$ = ! gases hydrog5 & c>bon dioxide#di are v simil> 9 %ape to ^? obta9$ = air4 ,= a giv5 int5sity ( radiation1 saturation is m readily obta9$ 9 hydrog5 ?an 9 air1 s9ce ! ionization is less ?an 9 air :ile ! velocity ( ! ions is great]4 ,c>bon dioxide on ! o!r h& requires a great] ,p4,d4 to produce saturation ?an does air1 s9ce ! ionization is m int5se & ! velocity ( ! ions less ?an 9 air4 #bi4 ,t[ns5d#ej has %[n t1 = l[ pressures1 ! v>iation ( ! curr5t ) ! voltage is v diff]5t f t obs]v$ at atmosph]ic pressure4 ,if ! increase ( curr5t ) ! voltage is det]m9$ = gases1 expos$ to ,rntg5 rays1 at a pressure ( ab\t #a mm4 ( m]cury1 x is f\nd t = small voltages ! ord9>y saturation curve is obta9$2 b :5 ! voltage appli$ increases beyond a c]ta9 value1 dep5d+ on ! pressure & nature ( ! gas & ! di/ance betwe5 ! electrodes1 ! curr5t comm5ces to increase sl[ly at fir/ b v rapidly z ! voltage is rais$ to ! sp>k+ value4 ,! g5]al %ape ( ! curr5t curve is %[n 9 ,fig4 #e4 ,illu/ration3 ,fig4 #e4 ,! portion ,,oab ( ! curve corresponds to ! ord9>y saturation curve4 ,at ! po9t ,b ! curr5t comm5ces to increase4 ,?is increase ( curr5t has be5 %[n to be due to ! action ( ! negative ions at l[ pressures 9 produc+ fre% ions by collision ) ! molecules 9 _! pa?4 ,! increase ( curr5t is n obs]v$ 9 air at a pressure above #cj mms4 until ! ,p4,d4 is increas$ ne>ly to ! value requir$ to produce a sp>k4 ,?is production ( ions by collision is consid]$ 9 m detail 9 section #da4 #cj4 ,rate ( recomb9ation ( ! ions4 ,a gas ioniz$ by ! radiation pres]ves its conduct+ p[] = "s "t aft] x is remov$ f ! pres5ce ( ! active body4 ,a curr5t ( air bl[n ov] an active body w ?us dis*>ge an electrifi$ body "s di/ance away4 ,! duration ( ?is aft] conductivity c be exam9$ v conv5i5tly 9 an app>atus simil> to t %[n 9 ,fig4 #f4 ,illu/ration3 ,fig4 #f4 ,a dry curr5t ( air or any o!r gas is pass$ at a con/ant rate ?r\gh a long metal tube ,,tl4 ,aft] pass+ ?r\gh a quantity ( cotton-wool to remove du/ p>ticles1 ! curr5t ( air passes ov] a vessel ,t conta9+ a radio-active body su* z uranium1 :i* does n give (f a radio-active emanation4 ,by means ( insulat$ electrodes ,a & ,b1 *>g$ to a suitable pot5tial1 ! curr5t betwe5 ! tube & "o ( ^! electrodes c be te/$ at v>i\s po9ts along ! tube4 ,a gauze scre51 plac$ ov] ! cross-section ( ! tube at ,d1 s]ves to prev5t any direct action ( ! electric field 9 ab/ract+ ions f ! neighb\rhood ( ,t4 ,if ! electric field is suffici5tly /rong1 all ! ions travel 9 to ! electrodes at ,a1 & no curr5t is obs]v$ at ! electrode ,b4 ,if ! curr5t is obs]v$ successively at diff]5t di/ances along ! tube1 all ! electrodes except ! "o "u consid]ation be+ connect$ to e>?1 x is f\nd t ! curr5t dim9i%es ) ! di/ance f ! active body4 ,if ! tube is ( fairly wide bore1 ! loss ( ! ions due to diffusion is small1 & ! decrease 9 conductivity ( ! gas is due to recomb9ation ( ! ions alone4 ,on ! ionization !ory1 ! numb] dn ( ions p] unit volume :i* recomb9e 9 ! "t dt is proportional to ! squ>e ( ! numb] pres5t4 ,?us dn ---- n1 dt :]e is a con/ant4 ,integrat+ ?is equation1 #a #a --- --- t1 n ,n if ,n is ! initial numb] ( ions1 & n ! numb] aft] a "t t4 ,! exp]im5tal results obta9$#ea h be5 %[n to agree v well ) ?is equation4 ,9 an exp]im5t simil> to t illu/rat$ 9 ,fig4 #f1 us+ uranium oxide z a s\rce ( ionization1 x 0 f\nd t half ! numb] ( ions pres5t 9 ! gas recomb9$ 9 #bd seconds1 & t at ! end ( #h seconds "o-f\r? ( ! ions 7 /ill uncomb9$4 ,s9ce ! rate ( recomb9ation is proportional to ! squ>e ( ! numb] pres5t1 ! "t tak5 = half ( ! ions pres5t 9 ! gas to recomb9e decreases v rapidly ) ! int5sity ( ! ionization4 ,if radium is us$1 ! ionization is s int5se t ! rate ( recomb9ation is extremely rapid4 ,x is on acc\nt ( ?is rapidity ( recomb9ation t l>ge voltages are necess>y to produce saturation 9 ! gases expos$ to v active prep>ations ( radium4 ,! value ( 1 :i* may be t]m$ ! coeffici5t ( recomb9ation1 has be5 det]m9$ 9 absolute measure by ,t[ns5d#eb1 ,mc,clung#ec & ,langev9#ed by diff]5t exp]im5tal me?ods b ) v concordant results4 ,suppose1 = example1 ) ! app>atus ( ,fig4 #f1 ! "t ,t1 tak5 = half ! ions to recomb9e aft] pass+ by ! electrode ,a1 has be5 det]m9$ exp]im5tally4 ,!n #a --- ,t1 ,n :]e ,n is ! numb] ( ions p] c4c4 pres5t at ,a4 ,if ! saturation curr5t i is det]m9$ at ! electrode ,a1 i ,n,ve1 :]e e is ! *>ge on an ion & ,v is ! volume ( uni=mly ioniz$ gas c>ri$ by ! electrode ,a p] second4 ,!n ,ve ----- 4 i,t ,! foll[+ table %[s ! value ( obta9$ = diff]5t gases4 ,value ( 4 ,gas ,t[ns5d ,mc,clung ,langev9 ,air #cdbj e #cchd e #cbjj e ,c>bon #cejj e #cdib e #cdjj e ,dioxide ,hydrog5 #cjbj e ,! late/ det]m9ation ( ! value ( e 7see section #cf7 is #cd #aj ,e4,s4 units2 ?us #aa #aj4 ,us+ ?is value1 x c readily be %[n f ! equation ( recomb9ation t1 if #aj ions are pres5t p] c4c41 half ( !m recomb9e 9 ab\t #ji sec4 & #ii 9 #ij secs4 ,mc,clung 7loc4 cit47 %[$ t ! value ( 0 approximately indep5d5t ( ! pressure betwe5 #abe & ?ree atmosph]es4 ,9 lat] obs]vations1 ,langev9 has f\nd t ! value ( decreases rapidly :5 ! pressure is l[]$ bel[ ! limits us$ by ,mc,clung4 #ca4 ,9 exp]im5ts on recomb9ation x is ess5tial t ! gas %\ld be free f du/ or o!r susp5d$ p>ticles4 ,9 du/y air1 ! rate ( recomb9ation is mu* m rapid ?an 9 du/-free air1 z ! ions diffuse rapidly to ! comp>atively l>ge du/ p>ticles di/ribut$ ?r\gh\t ! gas4 ,! effect ( ! susp5sion ( small p>ticles 9 a conduct+ gas is v well illu/rat$ by an exp]im5t ( ,ow5s#ee4 ,if tobacco smoke is bl[n betwe5 two p>allel plates z 9 ,fig4 #a1 ! curr5t at once dim9i%es to a small fraction ( its =m] value1 al?\gh a ,p4,d4 is appli$ suffici5t to produce saturation "u ord9>y conditions4 ,a mu* l>g] voltage is !n necess>y to produce saturation4 ,if ! smoke p>ticles are remov$ by a /ream ( air1 ! curr5t returns at once to its orig9al value4 #cb4 ,mobility ( ! ions4 ,det]m9ations ( ! mobility ( ! ions1 i4e4 ! velocity ( ! ions "u a pot5tial gradi5t ( #a volt p] cm41 h be5 made by ,ru!r=d#ef1 ,zel5y#eg1 & ,langev9#eh = gases expos$ to ,rntg5 rays4 ,al?\gh widely diff]5t me?ods h be5 employ$1 ! results h be5 v concordant1 & fully support ! view t ! ions move ) a velocity proportional to ! /r5g? ( ! field4 ,on ! application ( an electric field1 ! ions almo/ in/antly atta9 ! velocity correspond+ to ! field & !n move ) a uni=m spe$4 ,zel5y#ei fir/ drew att5tion to ! fact t ! positive & negative ions _h diff]5t velocities4 ,! velocity ( ! negative ion is always great] ?an t ( ! positive1 & v>ies ) ! am\nt ( wat] vap\r pres5t 9 ! gas4 ,! results1 previ\sly discuss$1 ( ! v>iation ( ! curr5t ) voltage & ( ! rate ( recomb9ation ( ! ions d n ( !mselves imply t ! ions produc$ 9 gases by ! radiations f active bodies are ( ! same size z ^? produc$ by ,rntg5 rays "u simil> conditions4 ,!y m]ely %[ t ! conductivity "u v>i\s conditions c be satisfactorily expla9$ by ! view t *>g$ ions are produc$ ?r\gh\t ! volume ( ! gas4 ,! same g5]al relations w\ld be obs]v$ if ! ions diff]$ consid]ably 9 size & velocity f ^? produc$ by ,rntg5 rays4 ,! mo/ satisfactory me?od ( det]m9+ :e!r ! ions are id5tical 9 ! two cases is to det]m9e ! velocity ( ! ions "u simil> conditions4 ,9 ord] to comp>e ! velocity ( ! ions#fj1 ! writ] has us$ an app>atus simil> to t %[n 9 ,fig4 #f on p4 #dj4 ,! ions 7 c>ri$ ) a rapid con/ant /ream ( air pa/ ! *>g$ electrode ,a1 & ! conductivity ( ! gas te/$ imm$iately aft]w>ds at an electrode ,b1 :i* 0 plac$ close to ,a4 ,! insulat$ electrodes ,a & ,b 7 fix$ c5trally 9 ! metal tube ,l1 :i* 0 connect$ ) e>?4 ,= conv5i5ce ( calculation1 x is assum$ t ! electric field betwe5 ! cyl9d]s is ! same z if ! cyl9d]s 7 inf9itely long4 ,let a & b be ! radii ( ! electrode ,a1 & ( ! tube ,l respectively1 & let ,v pot5tial ( ,a4 ,! electromotive int5sity ,x 7)\t reg>d to sign7 at a di/ance r f ! c5tre ( ! tube is giv5 by ,x frac ,v r loge frac b a ,let u & u be ! velocities ( ! positive & negative ions = a pot5tial gradi5t ( #a volt p] cm4 ,if ! velocity is proportional to ! electric =ce at any po9t1 ! di/ance dr trav]s$ by ! negative ion 9 ! "t dt is giv5 by dr ,xu dt1 or dt frac loge frac ba r dr ,vu#b ,let r be ! greate/ di/ance measur$ f ! axis ( ! tube f :i* ! negative ion c j rea* ! electrode ,a 9 ! "t t tak5 = ! air to pass along ! electrode4 ,!n t frac r#bb a#b #b ,vu#b loge frac ba ,if be ! ratio ( ! numb] ( ! negative ions t rea* ! electrode ,a to ! total numb] pass+ by1 !n rho#b frac r#bb a#b b#b a#b ,!re=e u#b frac rho#b 7b#b a#b7 loge frac ba #b ,vt ,simil>ly ! ratio ( ! numb] ( positive ions t give up _! *>ge to ! ext]nal cyl9d] to ! total numb] ( positive ions is giv5 by u#a frac rho#a 7b#b a#b7 loge frac ba #b ,vt ,9 ! above equations x is assum$ t ! curr5t ( air is uni=m ov] ! cross-section ( ! tube1 & t ! ions are uni=mly di/ribut$ ov] ! cross-section2 also1 t ! movem5t ( ! ions does n appreciably di/urb ! electric field4 ,s9ce ! value ( t c be calculat$ f ! velocity ( ! curr5t ( air & ! l5g? ( ! electrode1 ! values ( ! velocities ( ! ions "u unit pot5tial gradi5t c at once be det]m9$4 ,! equation 7#a7 %[s t is proportional to ,v1--i4e4 t ! rate ( dis*>ge ( ! electrode ,a v>ies directly z ! pot5tial ( ,a1 provid$ t ! value ( ,v is n l>ge en\gh to remove all ! ions f ! gas z x passes by ! electrode4 ,?is 0 f\nd exp]im5tally to be ! case4 ,9 ! comp>ison ( ! velocities1 ! pot5tial ,v 0 adju/$ to su* a value t 0 ab\t "o half1 :5 uranium oxide 0 plac$ 9 ! tube at ,l4 ,! active sub/ance 0 !n remov$1 & an alum9ium cyl9d] sub/itut$ = ! brass tube4 ,x rays 7 all[$ to fall on ! c5tre ( ?is alum9ium cyl9d]1 & ! /r5g? ( ! rays adju/$ to give ab\t ! same conductivity to ! gas z ! uranium _h done4 ,"u ^! conditions ! value ( 0 f\nd to be ! same z = ! fir/ exp]im5t4 ,?is exp]im5t %[s conclusively t ! ions produc$ by ,rntg5 rays & by uranium move ) ! same velocity & are probably id5tical 9 all respects4 ,! me?od describ$ above is n v suitable = an accurate det]m9ation ( ! velocities1 b gave values = ! positive ions ( ab\t #ad cms4 p] second p] volt p] c5timetre1 & slightly great] values = ! negative ions4 #cc4 ,! mo/ accurate det]m9ations ( ! mobility ( ! ions produc$ by ,rntg5 rays h be5 made by ,zel5y#fa & ,langev9#fb4 ,zel5y us$ a me?od simil> 9 pr9ciple to t expla9$ above4 ,8 results are %[n 9 ! foll[+ table1 :]e ,k is ! mobility ( ! positive ion & ,k t ( ! negative ion4 ,gas ,k ,k ,k_/,k ,temp]ature ,air1 dry #acf #ahg #acge #ace ,c4 moi/ #acg #aea #aaj #ad ,oxyg51 dry #acf #ahj #acb #ag moi/ #abi #aeb #aah #af ,c>bon dioxide1 #jgf #jha #ajg #age dry #jha #jge #jiae #ag moi/ ,hydrog51 dry #fgj #gie #aae #bj moi/ #ecj #efj #aje #bj ,langev9 det]m9$ ! velocity ( ! ions by a direct me?od 9 :i* ! "t tak5 = ! ion to travel ov] a kn[n di/ance 0 obs]v$4 ,! foll[+ table %[s ! comp>ative values obta9$ = air & c>bon dioxide4 ,air ,k ,air ,k ,air ,,co ,k ,,co ,k ,,co ,k_/,k ,k_/,k ,direct #adj #agj #abb #jhf #jij #aje me?od 7,langev97 ,curr5t ( #acf #ahg #acge #jgf #jha #ajg gas 7,zel5y7 ,^! results %[ t = all gases except ,,co1 !re is a m>k$ increase 9 ! velocity ( ! negative ion ) ! dryness ( ! gas1 & t1 ev5 9 moi/ gases1 ! velocity ( ! negative ions is always great] ?an t ( ! positive ions4 ,! velocity ( ! positive ion is n mu* affect$ by ! pres5ce ( moi/ure 9 ! gas4 ,! velocity ( ! ions v>ies inv]sely z ! pressure ( ! gas4 ,?is has be5 %[n by ,ru!r=d#fc = ! negative ions produc$ by ultra-violet light fall+ on a negatively *>g$ surface1 & lat] by ,langev9#fd = bo? ! positive & negative ions produc$ by ,rntg5 rays4 ,langev9 has %[n t ! velocity ( ! positive ion increases m sl[ly ) ! dim9ution ( pressure ?an t ( ! negative ion4 ,x appe>s z if ! negative ion1 especially at pressures ( ab\t #aj mm4 ( m]cury1 beg9s to dim9i% 9 size4 #cd4 ,cond5sation exp]im5ts4 ,"s exp]im5ts w n[ be describ$ :i* h v]ifi$ 9 a direct way ! !ory t ! conductivity produc$ 9 gases by ! v>i\s types ( radiation is due to ! production ( *>g$ ions ?r\gh\t ! volume ( ! gas4 ,"u c]ta9 conditions1 ! ions =m nuclei = ! cond5sation ( wat]1 & ?is prop]ty all[s u to %[ ! pres5ce ( ! individual ions 9 ! gas1 & also to c\nt ! numb] pres5t4 ,x has long be5 kn[n t1 if air saturat$ ) wat]-vap\r be sudd5ly exp&$1 a cl\d ( small globules ( wat] is =m$4 ,^! drops are =m$ r\nd ! du/ p>ticles pres5t 9 ! gas1 :i* act z nuclei = ! cond5sation ( wat] ar\nd !m4 ,! exp]im5ts ( ,r4 von ,helmholtz & ,ri*>z#fe _h %[n t *emical reactions1 = example ! combu/ion ( flames1 tak+ place 9 ! neighb\rhood1 affect$ ! cond5sation ( a /eam-jet4 ,l5>d %[$ t a simil> action 0 produc$ :5 ultra-violet light fell on a negatively *>g$ z9c surface plac$ ne> ! /eam-jet4 ,^! results sugge/$ t ! pres5ce ( electric *>ges 9 ! gas facilitat$ cond5sation4 ,a v complete /udy ( ! conditions ( cond5sation ( wat] on nuclei has be5 made by ,c4 ,t4 ,r4 ,wilson#ff4 ,an app>atus 0 con/ruct$ :i* all[$ a v sudd5 expansion ( ! air ov] a wide range ( pressure4 ,! am\nt ( cond5sation 0 obs]v$ 9 a small glass vessel4 ,a beam ( light 0 pass$ into ! app>atus :i* all[$ ! drops =m$ to be readily obs]v$ by ! eye4 ,prelim9>y small expansions caus$ a cond5sation ( ! wat] r\nd ! du/ nuclei pres5t 9 ! air4 ,^! du/ nuclei 7 remov$ by all[+ ! drops to settle4 ,aft] a numb] ( successive small expansions1 ! air 0 completely fre$ f du/1 s t no cond5sation 0 produc$4 ,let v initial volume ( ! gas 9 ! vessel1 v volume aft] expansion4 ,if v_/v #abe no cond5sation is produc$ 9 du/-free air4 ,if h[ev] v_/v #abe & #ach1 a few drops appe>4 ,?is numb] is r\ghly con/ant until v_/v #ach1 :5 ! numb] sudd5ly increases & a v d5se cl\d ( f9e drops is produc$4 ,if ! radiation f an ,x ray tube or a radio-active sub/ance is n[ pass$ into ! cond5sation vessel1 a new s]ies ( ph5om5a is obs]v$4 ,z be=e1 if v_/v #abe no drops are =m$1 b if v_/v #abe !re is a sudd5 production ( a cl\d4 ,! wat] drops ( :i* ?is cl\d is =m$ are f9] & m num]\s ! great] ! int5sity ( ! rays4 ,! po9t at :i* cond5sation beg9s is v m>k$1 & a slight v>iation ( ! am\nt ( expansion causes ei!r a d5se cl\d or no cl\d at all4 ,x n[ rema9s to be %[n t ! =mation ( a cl\d by ! action ( ! rays is due to ! productions ( ions 9 ! gas4 ,if ! expansion vessel is provid$ ) two p>allel plates betwe5 :i* an electric field c be appli$1 x is se5 t ! numb] ( drops1 =m$ by ! expansion ) ! rays act+1 decreases ) increase ( ! electric field4 ,! /rong] ! field ! small] ! numb] ( drops =m$4 ,?is result is to be expect$ if ! ions are ! c5tres ( cond5sation2 = 9 a /rong electric field ! ions are c>ri$ at once to ! electrodes1 & ?us disappe> f ! gas4 ,if no electric field is act+1 a cl\d c be produc$ "s "t aft] ! rays h be5 cut (f2 b if a /rong electric field is appli$1 "u ! same conditions1 no cl\d is =m$4 ,?is is 9 agreem5t ) exp]im5ts %[+ ! "t requir$ = ! ions to disappe> by recomb9ation4 ,9 addition x c be %[n t ea* "o ( ! f9e drops c>ries an electric *>ge & c be made to move 9 a /rong uni=m electric field4 ,! small numb] ( drops produc$ )\t ! action ( ! rays :5 v_/v #abe is due to a v slight natural ionization ( ! gas4 ,t ?is ionization exi/s has be5 cle>ly %[n by electrical me?ods 7section #bhd74 ,! evid5ce is ?us complete t ! ions !mselves s]ve z c5tres = ! cond5sation ( wat] ar\nd !m4 ,^! exp]im5ts %[ conclusively t ! passage ( electricity ?r\gh a gas is due to ! pres5ce ( *>g$ ions di/ribut$ ?r\gh\t ! volume ( ! gas1 & v]ify 9 a rem>kable way ! hypo!sis ( ! discont9u\s /ructure ( ! electric *>ges c>ri$ by matt]4 ,?is prop]ty ( ! ions ( act+ z nuclei ( cond5sation gives a v delicate me?od ( detect+ ! pres5ce ( ions 9 ! gas4 ,if only an ion or two is pres5t p] c4c41 _! pres5ce aft] expansion is at once obs]v$ by ! drops =m$4 ,9 ?is way ! ionization due to a small quantity ( uranium held a y>d away f ! cond5sation vessel is at once made manife/4 #ce4 ,diff]5ce betwe5 ! positive & negative ions4 ,9 ! c\rse ( exp]im5ts to det]m9e ! *>ge c>ri$ by an ion1 ,j4 ,j4 ,?omson#fg obs]v$ t ! cl\d =m$ "u ! influ5ce ( ,x rays increas$ 9 d5sity :5 ! expansion 0 ab\t #aca1 & sugge/$ 9 explanation t ! positive & negative ions _h diff]5t cond5sation po9ts4 ,illu/ration3 ,fig4 #g4 ,?is diff]5ce 9 behavi\r ( ! positive & negative ions 0 inve/igat$ 9 detail by ,c4 ,t4 ,r4 ,wilson#fh 9 ! foll[+ way4 ,x rays 7 made to pass 9 a n>r[ beam on ei!r side ( a plate ,,ab 7,fig4 #g7 divid+ ! cond5sation vessel into two equal p>ts4 ,! opposite poles ( a batt]y ( cells 7 connect$ ) two p>allel plates ,c & ,d1 plac$ symmetrically ) reg>d to ,a4 ,! middle po9t ( ! batt]y & ! plate ,a 7 connect$ ) e>?4 ,if ! plate ,c is positively *>g$1 ! ions 9 ! space ,,ca at a %ort di/ance f ,a are all negative 9 sign4 ,^? to ! "r are all positive4 ,x 0 f\nd t cond5sation occurr$ only = ! negative ions 9 ,,ac :5 v_/v #abe b did n occur 9 ,,ad = ! positive ions until v_/v #aca4 ,?us ! negative acts m readily ?an ! positive ion z a c5tre ( cond5sation4 ,! great] effect ( ! negative ion 9 caus+ cond5sation has be5 sugge/$ z an explanation ( ! positive *>ge always obs]v$ 9 ! upp] atmosph]e4 ,! negative ions "u c]ta9 conditions become c5tres = ! =mation ( small drops ( wat] & are remov$ to ! e>? by ! action ( gravity1 :ile ! positive ions rema9 susp5d$4 ,) ! app>atus describ$ above1 x has be5 %[n t ! positive & negative ions are equal 9 numb]4 ,if ! expansion is l>ge en\gh to ensure cond5sation on bo? ions1 ! drops =m$ on ! "r & left ( ! vessel 9 ,fig4 #g are equal 9 numb] & fall at ! same rate1 i4e4 are equal 9 size4 ,s9ce ! ions are produc$ 9 equal numb]s f a gas electrically neutral1 ?is exp]im5t %[s t ! *>ges on positive & negative ions are equal 9 value b opposite 9 sign4 #cf4 ,*>ge c>ri$ by an ion4 ,= a kn[n sudd5 expansion ( a gas saturat$ ) wat] vap\r1 ! am\nt ( wat] precipitat$ on ! ions c be calculat$ readily4 ,! size ( ! drops c be det]m9$ by obs]v+ ! rate at :i* ! cl\d settles "u ! action ( gravity4 ,f ,/okes' equation1 ! t]m9al velocity u ( a small sph]e ( radius r & d5sity d fall+ ?r\gh a gas ( :i* ! coeffici5t ( viscosity is is giv5 by #b dgr u -------- #i :]e g is ! accel]ation due to gravity4 ,! radius ( ! drop & consequ5tly ! weight ( wat] 9 ea* drop c ?us be det]m9$4 ,s9ce ! total weight ( wat] precipitat$ is kn[n1 ! numb] ( drops pres5t is obta9$ at once4 ,?is me?od has be5 us$ by ,j4 ,j4 ,?omson#fi to det]m9e ! *>ge c>ri$ by an ion4 ,if ! expansion exce$s ! value #aca1 bo? positive & negative ions become c5tres ( cond5sation4 ,f ! rate ( fall x c be %[n t approximately ! drops are all ( ! same size4 ,! cond5sation vessel 0 simil> to t employ$ by ,c4 ,t4 ,r4 ,wilson4 ,two p>allel horizontal plates 7 fitt$ 9 ! vessel & ! radiation f an ,x ray tube or radio-active sub/ance ioniz$ ! gas betwe5 !m4 ,a diff]5ce ( pot5tial ,v1 small comp>$ ) t requir$ to saturate ! gas1 0 appli$ betwe5 ! p>allel plates di/ant l cms4 f ea* o!r4 ,! small curr5t i ?r\gh ! gas is giv5 7section #bh7 by ,nu,ve i ------ l :]e ,n numb] ( ions pres5t 9 ! gas1 e *>ge on ea* ion1 u sum ( ! velocities ( ! positive & negative ions4 ,s9ce ! value ( ,n is ! same z ! numb] ( drops1 & ! velocity u is kn[n1 ! value ( e c be det]m9$4 ,9 8 la/ det]m9ation ,j4 ,j4 ,?omson f\nd t e #cd #aj electro/atic units4 ,a v concordant value1 namely1 #ca #aj1 has be5 obta9$ by ,h4 ,a4 ,wilson#gj1 by us+ a modifi$ me?od ( c\nt+ ! drops4 ,a *eck on ! size ( ! drops1 det]m9$ by _! rate ( fall1 0 made by obs]v+ ! rate at :i* ! drops mov$ 9 a /rong electric field1 arrang$ s z to act ) or aga9/ gravity4 ,j4 ,j4 ,?omson f\nd t ! *>ge on ! ions produc$ 9 hydrog5 & oxyg5 is ! same4 ,?is %[s t ! nature ( ! ionization 9 gases is di/9ct f t occurr+ 9 ! electrolysis ( solutions :]e ! oxyg5 ion always c>ries twice ! *>ge ( ! hydrog5 ion4 #cg4 ,diffusion ( ! ions4 ,e>ly exp]im5ts ) ioniz$ gases %[$ t ! conductivity 0 remov$ f ! gas by passage ?r\gh a f9ely divid$ sub/ance l cotton-wool1 or by bubbl+ ?r\gh wat]4 ,?is loss ( conductivity is due to ! fact t ! ions 9 pass+ ?r\gh n>r[ spaces diffuse to ! sides ( ! b\nd>y1 to :i* !y ei!r adh]e or give up _! *>ge4 ,a direct det]m9ation ( ! coeffici5t ( diffusion ( ! ions produc$ 9 gases by ,rntg5 rays or by ! rays f active sub/ances has be5 made by ,t[ns5d#ga4 ,! g5]al me?od employ$ 0 to pass a /ream ( ioniz$ gas ?r\gh a diffusion vessel made up ( a numb] ( f9e metal tubes arrang$ 9 p>allel4 ,"s ( ! ions 9 _! passage ?r\gh ! tubes diffuse to ! sides1 ! proportion be+ great] ! sl[] ! motion ( ! gas & ! n>r[] ! tube4 ,obs]vations 7 made ( ! conductivity ( ! gas be=e & aft] passage ?r\gh ! tubes4 ,9 ?is way1 correct+ if necess>y = ! recomb9ation dur+ ! "t tak5 to pass ?r\gh ! tubes1 ! proportion ,r ( ei!r positive or negative ions :i* are ab/ract$ c be d$uc$4 ,! value ( ,r c be express$ ma!matically by ! foll[+ equation 9 t]ms ( ,k1 ! coeffici5t ( diffusion ( ! ions into ! gas ) :i* !y are mix$#gb1 ,r #d 7cdot#aie;e frac#c;cdot#ff,,kza#b,v cdot#jbdc;e frac#bb;cdot#c,,kza#b,v c47 :]e a radius ( ! tube1 ,z l5g? ( ! tube1 ,v mean velocity ( ! gas 9 ! tube4 ,only ! fir/ two t]ms ( ! s]ies ne$ be tak5 into acc\nt :5 n>r[ tubes are us$4 ,9 ?is equation ,r1 ,v1 & a are det]m9$ exp]im5tally1 & ,k c ?us be d$uc$4 ,! foll[+ table %[s ! results obta9$ by ,t[ns5d :5 ,x rays 7 us$4 ,almo/ id5tical results 7 obta9$ lat]1 :5 ! radiations f active sub/ances replac$ ! ,x rays4 ,coeffici5ts ( diffusion ( ions into gases4 ,gas ,k ,k ,mean ,ratio = = value ( ions ions ( ,k values ( ,k ,air1 dry #jbh #jdc #jcdg #aed moi/ #jcb #jce #jcce #aji ,oxyg51 dry #jbe #jcif #jcbc #aeh moi/ #jbhh #jceh #jcbc #abd ,c>bonic acid1 #jbc #jbf #jbde #aac dry #jbde #jbee #jbe #ajd moi/ ,hydrog51 dry #abc #aij #aef #aed moi/ #abh #adb #ace #aaa ,! moi/ gases 7 saturat$ ) wat] vap\r at a temp]ature ( #ae ,c4 ,x is se5 t ! negative ion 9 all cases diffuses fa/] ?an ! positive4 ,!ory %[s t ! coeffici5ts ( diffusion %\ld be directly proportional to ! velocities ( ! ions1 s t ?is result is 9 agreem5t ) ! obs]vations on ! great] velocity ( ! negative ion4 ,?is diff]5ce 9 ! rate ( diffusion ( ! ions at once expla9s an int]e/+ exp]im5tal result4 ,if ioniz$ gases are bl[n ?r\gh a metal tube1 ! tube ga9s a negative *>ge :ile ! gas itself reta9s a positive *>ge4 ,! numb] ( positive & negative ions pres5t 9 ! gas is orig9ally ! same1 b1 9 consequ5ce ( ! m rapid diffusion ( ! negative ions1 m ( ! negative ions ?an ( ! positive give up _! *>ges to ! tube4 ,! tube consequ5tly ga9s a negative & ! gas a positive *>ge4 #ch4 ,a v important result c be d$uc$ at once :5 ! velocities & coeffici5ts ( diffusion ( ! ions are kn[n4 ,t[ns5d 7loc4 cit47 has %[n t ! equation ( _! motion is express$ by ! =mula #a dp --- pu ---- n,xe1 ,k dx :]e e is ! *>ge on an ion1 n numb] ( ions p] c4c41 p _! p>tial pressure1 & u is ! velocity due to ! electric =ce ,x 9 ! direction ( ! axis ( x4 ,:5 a /eady /ate is rea*$1 dp n,xe,k ---- #j & u ----1 dx p ,let ,n be ! numb] ( molecules 9 a cubic c5timetre ( gas at ! pressure ,p & at ! temp]ature #ae ,c41 = :i* ! values ( u & ,k h be5 det]m9$4 ,!n ,n_/,p may be sub/itut$ = n_/p1 &1 s9ce ,p at atmosph]ic pressure is #aj1 #c #aju ,ne ---------- electro/atic units1 ,k :]e u is ! velocity = #a volt 7i4e4 ,e4 ,s4 unit7 p] cm4 ,x is kn[n t "o absolute electromagnetic unit ( electricity 9 pass+ ?r\gh wat] lib]ates #abc c4c4 ( hydrog5 at a temp]ature ( #ae ,c4 & /&>d pressure4 ,! numb] ( atoms 9 ?is volume is #bdf,n1 &1 if e is ! *>ge on ! hydrog5 atom 9 ! electrolysis ( wat]1 #bdf ,ne #c #aj ,e4 ,s4 units1 ,ne #abb #aj ,e4 ,s4 units4 e u ,?us --- #bdf #aj ---- e ,k ,= example1 sub/itut+ ! values ( u & ,k det]m9$ 9 moi/ air = ! positive ion1 e #bdf #acg --- ----- ----- #ajd4 e #ajj #jcb ,values ( ?is ratio1 n v diff]5t f unity1 are obta9$ = ! positive & negative ions ( ! gases hydrog51 oxyg51 & c>bon dioxide4 ,tak+ into consid]ation ! unc]ta9ty 9 ! exp]im5tal values ( u & ,k1 ^! results indicate t ! *>ge c>ri$ by an ion 9 all gases is ! same & is equal to t c>ri$ by ! hydrog5 ion 9 ! electrolysis ( liquids4 #ci4 ,numb] ( ! ions4 ,we h se5 t1 f exp]im5tal data1 ,t[ns5d has f\nd t ,n1 ! numb] ( molecules pres5t 9 #a c4c4 ( gas at #ae ,c4 & /&>d pressure1 is giv5 by ,ne #abb #aj4 ,n[ e1 ! *>ge on an ion1 is equal to #cd #aj ,e4 ,s4 units2 ?us ,n #cf #aj4 ,if ,i is ! saturation curr5t ?r\gh a gas1 & q ! total rate ( production ( ions 9 ! gas1 ,i q --- 4 e ,! saturation curr5t ?r\gh air 0 f\nd to be #ab #aj amp]es1 i4e4 #cf ,e4,s4 units1 = p>allel plates #de cms4 ap>t1 :5 #de gramme ( radium ( activity #ajjj times t ( uranium 0 spread ov] an area ( #cc sq4 cms4 ( ! l[] plate4 ,?is corresponds to a production ( ab\t #aj ions p] second4 ,assum+1 = ! purpose ( illu/ration1 t ! ionization 0 uni=m betwe5 ! plates1 ! volume ( air act$ on by ! rays 0 ab\t #adh c4c41 & ! numb] ( ions produc$ p] c4c4 p] second ab\t #g #aj4 ,s9ce ,n #cf #aj1 we see t1 if "o molecule produces two ions1 ! proportion ( ! gas ioniz$ p] second is ab\t #aj ( ! :ole4 ,= uranium ! fraction is ab\t #aj1 & = pure radium1 ( activity "o million times t ( uranium1 ab\t #aj4 ,?us ev5 9 ! case ( pure radium1 only ab\t "o molecule ( gas is act$ on p] second 9 e #ajj millions4 ,! electrical me?ods are s delicate t ! production ( "o ion p] cubic c5timetre p] second c be detect$ readily4 ,?is corresponds to ! ionization ( ab\t "o molecule 9 e #aj pres5t 9 ! gas4 #dj4 ,size & nature ( ! ions4 ,an approximate e/imate ( ! mass ( an ion1 comp>$ ) ! mass ( ! molecule ( ! gas 9 :i* x is produc$1 c be made f ! kn[n data ( ! coeffici5t ,k ( int]-diffusion ( ! ions into gases4 ,! value ( ,k = ! positive ions 9 moi/ c>bon dioxide has be5 %[n to be #jbde1 :ile ! value ( ,k = ! int]-diffusion ( c>bon dioxide ) air is #ad4 ,! value ( ,k = diff]5t gases is approximately inv]sely proportional to ! squ>e root ( ! products ( ! masses ( ! molecules ( ! two int]-diffus+ gases2 ?us1 ! positive ion 9 c>bon dioxide behaves z if its mass 7 l>ge comp>$ ) t ( ! molecule4 ,simil> results hold = ! negative z well z = ! positive ion1 & = o!r gases besides c>bon dioxide4 ,?is has l$ to ! view t ! ion consi/s ( a *>g$ c5tre surr\nd$ by a clu/] ( molecules travell+ ) x1 :i* are kept 9 position r\nd ! *>g$ nucleus by electrical =ces4 ,a r\gh e/imate %[s t ?is clu/] consi/s ( ab\t #cj molecules ( ! gas4 ,?is idea is support$ by ! v>iation 9 velocity1 i4e4 ! v>iation ( ! size ( ! negative ion1 9 ! pres5ce ( wat] vap\r2 = ! negative ion und\bt$ly has a great] mass 9 moi/ ?an 9 dry gases4 ,at ! same "t x is possible t ! app>5tly l>ge size ( ! ion1 z det]m9$ by diffusion me?ods1 may be 9 "p a result ( ! *>ge c>ri$ by ! ion4 ,! pres5ce ( a *>ge on a mov+ body w\ld increase ! frequ5cy ( collision ) ! molecules ( ! gas1 & consequ5tly dim9i% ! rate ( diffusion4 ,! ion on ?is view may n actually be ( great] size ?an ! molecule f :i* x is produc$4 ,! negative & positive ions c]ta9ly diff] 9 size1 & ?is diff]5ce becomes v pron\nc$ = l[ pressures ( ! gas4 ,at atmosph]ic pressure1 ! negative ion1 produc$ by ! action ( ultra-violet light on a negatively *>g$ body1 is ( ! same size z ! ion produc$ by ,x rays1 b at l[ pressures ,j4 ,j4 ,?omson has %[n t x is id5tical ) ! corpuscle or electron1 :i* has an app>5t mass ( ab\t ( ! mass ( ! hydrog5 atom4 ,a simil> result has be5 %[n by ,t[ns5d to hold = ! negative ion produc$ by ,x rays at a l[ pressure4 ,x appe>s t ! negative ion at l[ pressure %$s its att5dant clu/]4 ,! result ( ,langev91 t ! velocity ( ! negative ion increases m rapidly ) ! dim9ution ( pressure ?an t ( ! positive ion1 %[s t ?is process ( removal ( ! clu/] is q appreciable at a pressure ( #aj mms4 ( m]cury4 ,we mu/ suppose t ! process ( ionization 9 gases consi/s 9 a removal ( a negative corpuscle or electron f ! molecule ( ! gas4 ,at atmosph]ic pressure ?is corpuscle imm$iately becomes ! c5tre ( an aggregation ( molecules :i* moves ) x & is ! negative ion4 ,aft] removal ( ! negative ion ! molecule reta9s a positive *>ge1 & probably also becomes ! c5tre ( a clu/] ( new molecules4 ,! t]ms electron & ion z us$ 9 ?is "w may !re=e be def9$ z foll[s3-- ,! electron or corpuscle is ! body ( smalle/ mass yet kn[n to sci5ce4 ,x c>ries a negative *>ge ( value #cd #aj electro/atic units4 ,its pres5ce has only be5 detect$ :5 9 rapid motion1 :51 = spe$s up to ab\t #aj cms4 a second1 x has an app>5t mass m giv5 by e_/m #ahf #aj electromagnetic units4 ,?is app>5t mass increases ) ! spe$ z ! velocity ( light is approa*$ 7see section #hb74 ,! ions :i* are produc$ 9 gases at ord9>y pressure h an app>5t size1 z det]m9$ f _! rates ( diffusion1 l>ge comp>$ ) ! molecule ( ! gas 9 :i* !y are produc$4 ,! negative ion consi/s ( an electron ) a clu/] ( molecules atta*$ to & mov+ ) x2 ! positive ion consi/s ( a molecule f :i* an electron has be5 expell$1 ) a clu/] ( molecules atta*$4 ,at l[ pressures "u ! action ( an electric field ! electron does n =m a clu/]4 ,! positive ion is always atomic 9 size1 ev5 at l[ pressures ( ! gas4 ,ea* ( ! ions c>ries a *>ge ( value #cd #aj electro/atic units4 #da4 ,ions produc$ by collision4 ,! great] "p ( ! radiation f ! radio-active bodies consi/s ( a /ream ( *>g$ p>ticles travell+ ) great velocity4 ,9 ?is radiation1 ! p>ticles1 :i* cause mo/ ( ! ionization obs]v$ 9 ! gas1 consi/ ( positively *>g$ bodies project$ ) a velocity ab\t "o-t5? ! velocity ( light4 ,! rays consi/ ( negatively *>g$ p>ticles1 :i* are id5tical ) ! ca?ode rays g5]at$ 9 a vacuum tube1 & travel ) a spe$ ab\t "o-half ! velocity ( light 7*apt] ,,iv474 ,ea* ( ^! project$ p>ticles1 9 virtue ( its great k9etic en]gy1 sets free a l>ge numb] ( ions by collision ) ! gas molecules 9 its pa?4 ,no def9ite exp]im5tal evid5ce has yet be5 obta9$ ( ! numb] ( ions produc$ by a s+le p>ticle1 or ( ! way 9 :i* ! ionization v>ies ) ! spe$1 b !re is no d\bt t ea* project$ body gives rise to _m ?\s& ions 9 its pa? be=e its en]gy ( motion is de/roy$4 ,x has already be5 m5tion$ 7section #bi7 t at l[ pressures ions mov+ "u ! action ( an electric field are able to produce fre% ions by collision ) ! molecules ( ! gas4 ,at l[ pressures ! negative ion is id5tical ) ! electron set free 9 a vacuum tube1 or emitt$ by a radio-active sub/ance4 ,! mean free pa? ( ! ion is inv]sely proportional to ! pressure ( ! gas4 ,consequ5tly1 if an ion moves 9 an electric field1 ! velocity acquir$ betwe5 collisions increases ) dim9ution ( ! pressure4 ,t[ns5d has %[n t fre% ions are occasionally produc$ by collision :5 ! negative ion moves freely betwe5 two po9ts diff]+ 9 pot5tial by #aj volts4 ,if ! diff]5ce be ab\t ,v #bj volts1 fre% ions arise at ea* collision#gc4 ,n[ ! en]gy ,w1 acquir$ by an ion ( *>ge e mov+ freely betwe5 two po9ts at a diff]5ce ( pot5tial ,v1 is giv5 by ,w ,ve4 ,tak+ ,v #bj volts ,e4 ,s4 units1 & e #cd #aj1 ! en]gy ,w requir$ 9 ! case ( a negative ion to produce an ion by collision is giv5 by ,w #bc #aj ergs4 ,! velocity u acquir$ by ! ion ( mass m j be=e a collision is giv5 by #a --- mu ,ve1 #b & u sqrtfrac#b,vem ,n[ e_/m #ahf #aj electromagnetic units = ! electron at sl[ spe$s 7section #hb74 ,tak+ ,v #bj volts1 we f9d t u #bg #aj cms4 p] sec4 ,?is velocity is v great comp>$ ) ! velocity ( agitation ( ! molecules ( ! gas4 ,9 a weak electric field1 ! negative ions only produce ions by collision4 ,! positive ion1 ^: mass is at lea/ #ajjj times great] ?an ! electron1 does n acquire a suffici5t velocity to g5]ate ions by collision until an electric field is appli$ ne>ly suffici5t to cause a sp>k ?r\gh ! gas4 ,an e/imate ( ! en]gy requir$ = ! production ( an ion by ,x rays has be5 made by ,ru!r=d & ,mc,clung4 ,! en]gy ( ! rays 0 measur$ by _! heat+ effect1 & ! total numb] ( ions produc$ det]m9$4 ,on ! assumption t all ! en]gy ( ! rays is us$ up 9 produc+ ions1 x 0 f\nd t ,v #age volts--a value consid]ably great] ?an t obs]v$ by ,t[ns5d f data ( ionization by collision4 ,! ionization 9 ! two cases1 h[ev]1 is produc$ "u v diff]5t conditions1 & x is impossible to e/imate h[ mu* ( ! en]gy ( ! rays is dissipat$ 9 ! =m ( heat4 #db4 ,v>iations are f\nd 9 ! saturation curr5t ?r\gh gases1 expos$ to ! radiations f active bodies1 :5 ! pressure & nature ( ! gas & ! di/ance betwe5 ! electrodes are v>i$4 ,"s cases :i* are ( special importance 9 measurem5ts w n[ be consid]$4 ,) unscre5$ active mat]ial ! ionization ( ! gas is1 to a l>ge ext5t1 due to ! rays1 :i* are absorb$ 9 _! passage ?r\gh a few c5timetres ( air4 ,9 consequ5ce ( ?is rapid absorption1 ! ionization decreases rapidly f ! surface ( ! active body1 & ?is gives rise to conductivity ph5om5a diff]5t 9 "* f ^? obs]v$ ) ,rntg5 rays1 :]e ! ionization is 9 mo/ cases uni=m4 #dc4 ,v>iation ( ! curr5t ) di/ance betwe5 ! plates4 ,x has be5 f\nd exp]im5tally#gd t ! int5sity ( ! ionization1 due to a l>ge plane surface ( active matt]1 falls (f approximately 9 an expon5tial law ) ! di/ance f ! plate4 ,on ! assumption t ! rate ( production ( ions at any po9t is a measure ( ! int5sity ,i ( ! radiation1 ! value ( ,i at t po9t is giv5 by frac ii #a e- x :]e is a con/ant1 x ! di/ance f ! plate1 & ,i ! int5sity ( ! radiation at ! surface ( ! plate4 ,:ile ! expon5tial law1 9 "s cases1 approximately repres5ts ! v>iation ( ! ionization ) di/ance1 9 o!rs ! div]g5ce f x is wide4 ,! ionization1 due to a plane surface ( polonium1 = example1 falls (f m rapidly ?an ! expon5tial law indicates4 ,! rays f an active sub/ance l radium are highly complex2 ! law ( v>iation ( ! ionization due to !m is by no means simple & dep5ds ^u a v>iety ( conditions4 ,! di/ribution ( ionization is q diff]5t accord+ z a ?ick lay] or a v ?ick film ( radio-active matt] is employ$4 ,! "q is fully consid]$ at ! end ( *apt] ,,iv41 b = simplicity1 ! expon5tial law is assum$ 9 ! foll[+ calculations4 ,consid] two p>allel plates plac$ z 9 ,fig4 #a1 "o ( :i* is cov]$ ) a uni=m lay] ( radio-active matt]4 ,if ! di/ance d betwe5 ! plates is small comp>$ ) ! dim5sions ( ! plates1 ! ionization ne> ! c5tre ( ! plates w be s5sibly uni=m ov] any plane p>allel to ! plates & ly+ betwe5 !m4 ,if q be ! rate ( production ( ions at any di/ance x & q t at ! surface1 !n q qe-x4 ,! saturation curr5t i p] unit area is giv5 by i intd qe' dx 1 :]e e is ! *>ge on an ion1 qe' intd e- x dx fracqe' 7#a - e- d7 h5ce1 :5 d is small1 i4e4 :5 ! ionization betwe5 ! plates is ne>ly con/ant1 i qed4 ,! curr5t is ?us proportional to ! di/ance betwe5 ! plates4 ,:5 d is l>ge1 ! saturation curr5t i is equal to qe_/1 & is indep5d5t ( fur!r increase 9 ! value ( d4 ,9 su* a case ! radiation is completely absorb$ 9 produc+ ions betwe5 ! plates1 & frac ii #a e- d ,= example1 9 ! case ( a ?9 lay] ( uranium oxide spread ov] a l>ge plate1 ! ionization is mo/ly produc$ by rays ! int5sity ( :i* is r$uc$ to half value 9 pass+ ?r\gh #dc mms4 ( air1 i4e4 ! value ( is #af4 ,! foll[+ table is an example ( ! v>iation ( i ) ! di/ance betwe5 ! plates4 ,di/ance ,saturation ,curr5t #be mms4 #cb #e #ee #ge #gb #aj #he #abe #if #ae #ajj ,?us ! increase ( curr5t = equal increm5ts ( di/ance betwe5 ! plates decreases rapidly ) ! di/ance trav]s$ by ! radiation4 ,! di/ance ( #ae mms4 0 n suffici5t to completely absorb all ! radiation1 s t ! curr5t _h n rea*$ its limit+ value4 ,:5 m ?an "o type ( radiation is pres5t1 ! saturation curr5t betwe5 p>allel plates is giv5 by i ,a 7#a e d7 ,a#a 7#a e-#a d7 c4 :]e ,a1 ,a are con/ants1 & 1 ! absorption con/ants ( ! radiations 9 ! gas4 ,s9ce ! radiations are unequally absorb$ 9 diff]5t gases1 ! v>iation ( curr5t ) di/ance dep5ds on ! nature ( ! gas betwe5 ! plates4 #dd4 ,v>iation ( ! curr5t ) pressure4 ,! rate ( production ( ions by ! radiations f active sub/ances is directly proportional to ! pressure ( ! gas4 ,! absorption ( ! radiation 9 ! gas also v>ies directly z ! pressure4 ,! latt] result necess>ily foll[s if ! en]gy requir$ to produce an ion is indep5d5t ( ! pressure4 ,9 cases :]e ! ionization is uni=m betwe5 two p>allel plates1 ! curr5t w v>y directly z ! pressure2 :5 h[ev] ! ionization is n uni=m1 on acc\nt ( ! absorption ( ! radiation 9 ! gas1 ! curr5t does n decrease directly z ! pressure until ! pressure is r$uc$ s f> t ! ionization is s5sibly uni=m4 ,consid] ! v>iation ) pressure ( ! saturation curr5t i betwe5 two l>ge p>allel plates1 "o ( :i* is cov]$ ) a uni=m lay] ( active matt]4 ,let absorption con/ant ( ! radiation 9 ! gas = unit pressure4 ,= a pressure p1 ! int5sity ,i at any po9t x is giv5 by frac ,i ,i e- p #a x ,! saturation curr5t i is ?us proportional to intd p,i dx intd p,ie-p#a x dx frac,i#a 7,i ep,a#a;d7 ,if r be ! ratio ( ! saturation curr5ts = ! pressures p & p1 r frac #a e-p#aa d #a e-p#ba d ,! ratio is ?us dep5d5t on ! di/ance d betwe5 ! plates & ! absorption ( ! radiation by ! gas4 ,! diff]5ce 9 ! %ape ( ! pressure-curr5t curves#ge is well illu/rat$ 9 ,fig4 #h1 :]e curves are giv5 = hydrog51 air1 & c>bonic acid = plates #ce cms4 ap>t4 ,illu/ration3 ,fig4 #h4 ,= ! purpose ( comp>ison1 ! curr5t at atmosph]ic pressure & temp]ature 9 ea* case is tak5 z unity4 ,! actual value ( ! curr5t 0 greate/ 9 c>bonic acid & lea/ 9 hydrog54 ,9 hydrog51 :]e ! absorption is small1 ! curr5t ov] ! :ole range is ne>ly proportional to ! pressure4 ,9 c>bonic acid1 :]e ! absorption is l>ge1 ! curr5t dim9i%es at fir/ sl[ly ) ! pressure1 b is ne>ly proportional to x bel[ ! pressure ( #bce mms4 ( m]cury4 ,! curve = air occupies an int]m$iate position4 ,9 cases :]e ! di/ance betwe5 ! plates is l>ge1 ! saturation curr5t w rema9 con/ant ) dim9ution ( pressure until ! absorption is s r$uc$ t ! radiation rea*es ! o!r plate4 ,an int]e/+ result foll[s f ! rapid absorption ( radiation by ! gas4 ,if ! curr5t is obs]v$ betwe5 two fix$ p>allel plates1 di/ant d & d respectively f a l>ge plane surface ( active matt]1 ! curr5t at fir/ increases ) dim9ution ( pressure1 passes ?r\gh a maximum value1 & !n dim9i%es4 ,9 su* an exp]im5tal case ! l[] plate ?r\gh :i* ! radiations pass is made ei!r ( op5 gauze or ( ?9 metal foil to all[ ! radiation to pass ?r\gh readily4 ,! saturation curr5t i is obvi\sly proportional to intd#a;d#b p,ie-p#a d 1 i4e4 to frac,i#a 7e-p#a d#a e-p#a d#b7 ,?is is a function ( ! pressure1 & is a maximum :5 loge fracd#a;d#b p#a 7d#b d#a7 ,= example1 if ! active matt] is uranium1 p #af = ! rays at atmosph]ic pressure4 ,if d #c1 & d #a1 ! saturation curr5t rea*es a maximum :5 ! pressure is r$uc$ to ab\t ( an atmosph]e4 ,?is result has be5 v]ifi$ exp]im5tally4 #de4 ,conductivity ( diff]5t gases :5 act$ on by ! rays4 ,= a giv5 int5sity ( radiation1 ! rate ( production ( ions 9 a gas v>ies = diff]5t gases & increases ) ! d5sity ( ! gas4 ,/rutt#gf has made a v complete exam9ation ( ! relative conductivity ( gases expos$ to ! diff]5t types ( rays emitt$ by active sub/ances4 ,to avoid correction = any diff]5ce ( absorption ( ! radiation 9 ! v>i\s gases1 ! pressure ( ! gas 0 always r$uc$ until ! ionization 0 directly proportional to ! pressure1 :51 z we h se5 above1 ! ionization mu/ ev]y:]e be uni=m ?r\gh\t ! gas4 ,= ea* type ( rays1 ! ionization ( air is tak5 z unity4 ,! curr5ts ?r\gh ! gases 7 det]m9$ at diff]5t pressures1 & 7 r$uc$ to a common pressure by assum+ t ! ionization 0 proportional to ! pressure4 ,) unscre5$ active mat]ial1 ! ionization is almo/ entirely due to rays4 ,:5 ! active sub/ance is cov]$ ) a lay] ( alum9ium #ja cm4 9 ?ickness1 ! ionization is ma9ly due to ! or ca?odic rays1 & :5 cov]$ ) #a cm4 ( lead1 ! ionization is solely due to ! or v p5etrat+ rays4 ,exp]im5ts on ! rays ( radium 7 made by obs]v+ ! rate ( dis*>ge ( a special gold-leaf electroscope fill$ ) ! gas "u exam9ation & expos$ to ! action ( ! rays4 ,! foll[+ table gives ! relative conductivities ( gases expos$ to v>i\s k9ds ( ioniz+ radiations4 ,gas ,relative ,rntg5 ,d5sity rays rays rays rays ,hydrog5 #jjfic #jbbf #jaeg #jafi #jaad ,air #ajj #ajj #ajj #ajj #ajj ,oxyg5 #aaa #aaf #aba #aag #aci ,c>bon dioxide #aec #aed #aeg #aec #afj ,cyanog5 #ahf #aid #ahf #aga #aje ,sulphur dioxide #bai #bjd #bca #bac #gig ,*lor(orm #dcb #ddd #dhi #dhh #cai ,me?yl iodide #eje #cea #eah #dhj #gbj ,c>bon #eca #ecd #ehc #efg #dec tetra*loride ,) ! exception ( hydrog51 x w be se5 t ! ionization ( gases is approximately proportional to _! d5sity = ! 1 1 rays ( radium4 ,! results obta9$ by ,/rutt = ,rntg5 rays are q diff]5t2 = example1 ! relative conductivity produc$ by !m 9 me?yl iodide 0 m ?an #ad times z great z t due to ! rays ( radium4 ,! relative conductivities ( gases expos$ to ,x rays has be5 rec5tly re-exam9$ by ,mc,clung#gg & ,eve#gh1 :o h f\nd t ! conductivity dep5ds ^u ! p5etrat+ p[] ( ! ,x rays employ$4 ,! results obta9$ by !m w be discuss$ lat] 7section #ajg74 ,?is diff]5ce ( conductivity 9 gases is due to unequal absorptions ( ! radiations4 ,! writ] has %[n#gi t ! total numb] ( ions produc$ by ! rays = uranium1 :5 completely absorb$ by diff]5t gases1 is n v diff]5t4 ,! foll[+ results 7 obta9$3 ,gas ,total ,ionization ,air #ajj ,hydrog5 #ie ,oxyg5 #ajf ,c>bonic acid #if ,hydro*loric acid gas #ajb ,ammonia #aja ,! numb]s1 ?\gh only approximate 9 "*1 seem to %[ t ! en]gy requir$ to produce an ion is probably n v diff]5t = ! v>i\s gases4 ,assum+ t ! en]gy requir$ to produce an ion 9 diff]5t gases is ab\t ! same1 x foll[s t ! relative conductivities are proportional to ! relative absorption ( ! radiations4 ,a simil> result has be5 f\nd by ,mc,lennan = ca?ode rays4 ,he prov$ t ! ionization 0 directly proportional to ! absorption ( ! rays 9 ! gas1 ?us %[+ t ! same en]gy is requir$ to produce an ion 9 all ! gases exam9$4 #df4 ,pot5tial ,gradi5t4 ,! normal pot5tial gradi5t betwe5 two *>g$ electrodes is always di/urb$ :5 ! gas is ioniz$ 9 ! space betwe5 !m4 ,if ! gas is uni=mly ioniz$ betwe5 two p>allel plates1 ,*ild & ,zel5y h %[n t !re is a sudd5 drop ( pot5tial ne> ! surface ( bo? plates1 & t ! electric field is s5sibly uni=m = ! int]m$iate space betwe5 !m4 ,! di/urbance ( ! pot5tial gradi5t dep5ds ^u ! diff]5ce ( pot5tial appli$1 & is diff]5t at ! surface ( ! two plates4 ,9 mo/ measurem5ts ( radio-activity ! mat]ial is spread ov] "o plate only4 ,9 su* a case ! ionization is to a l>ge ext5t conf9$ to ! volume ( ! air close to ! active plate4 ,! pot5tial gradi5t 9 su* a case is %[n 9 ,fig4 #i4 ,! dott$ l9e %[s ! v>iation ( pot5tial at any po9t betwe5 ! plates :5 no ionization is produc$ betwe5 ! plates2 curve ,a = weak ionization1 su* z is produc$ by uranium1 curve ,b = ! int5se ionization produc$ by a v active sub/ance4 ,9 bo? cases ! pot5tial gradi5t is lea/ ne> ! active plate1 & greate/ ne> ! opposite plate4 ,= v int5se ionization x is v small ne> ! active surface4 ,! pot5tial gradi5t v>ies slightly accord+ z ! active plate is *>g$ positively or negatively4 ,illu/ration3 ,fig4 #i4 #dg4 ,v>iation ( curr5t ) voltage = surface ionization4 ,"s v int]e/+ results1 giv+ ! v>iation ( ! curr5t ) voltage1 are obs]v$ :5 ! ionization is int5se1 & conf9$ to ! space ne> ! surface ( "o ( two p>allel plates betwe5 :i* ! curr5t is measur$4 ,! !ory ( ?is subject has be5 work$ out indep5d5tly by ,*ild#hj & ,ru!r=d#ha4 ,let ,v be ! pot5tial diff]5ce betwe5 two p>allel plates at a di/ance d ap>t4 ,suppose t ! ionization is conf9$ to a ?9 lay] ne> ! surface ( ! plate ,a 7see ,fig4 #a7 :i* is *>g$ positively4 ,:5 ! electric field is act+1 !re is a di/ribution ( positive ions betwe5 ! plates ,a & ,b4 ,let n numb] ( positive ions p] unit volume at a di/ance x f ! plate ,a1 ,k mobility ( ! positive ions1 e *>ge on an ion4 ,! curr5t i p] squ>e c5timetre ?r\gh ! gas is con/ant = all values ( x1 & is giv5 by i#a ,k#an#a;e fracd,vdx ,by ,poisson's equation frac d#b ,v da#b #dpi n#a e ,!n i#a frac ,k#a #dpi frac d,v dx frac d#b ,v dx#b ,integrat+ 7frac d,v dx7#b frac #hpi i#ax ,k#a ,a :]e ,a is a con/ant4 ,n[ ,a is equal to ! value ( d,v ---- dx :5 x #j4 ,by mak+ ! ionization v int5se1 ! value ( d,v ---- dx c be made extremely small4 ,putt+ ,a #j1 we see t frac d,v dx pm sqrt frac #hpi i#a x ,k#a ,?is gives ! pot5tial gradi5t betwe5 ! plates = diff]5t values ( x4 ,integrat+ betwe5 ! limits #j & d1 ,v pm frac#bc sqrt frac #hpi i#a ,k#a d rac#cb or i#a frac #i,v#b #cbpi d#c ,k#a ,if i is ! value ( ! curr5t :5 ! electric field is rev]s$1 & ,k ! velocity ( ! negative ion1 i#b frac #i,v#b #cb pi d#c ,k#b & i ,k ---- ---- 4 i ,k ,! curr5t 9 ! two directions is ?us directly proportional to ! velocities ( ! positive & negative ions4 ,! curr5t %\ld v>y directly z ! squ>e ( ! pot5tial diff]5ce appli$1 & inv]sely z ! cube ( ! di/ance betwe5 ! plates4 ,! !oretical condition ( surface ionization _c be fulfill$ by ! ionization due to active sub/ances1 z ! ionization ext5ds "s c5timetres f ! active plate4 ,if1 h[ev]1 ! di/ance betwe5 ! plates is l>ge comp>$ ) ! di/ance ov] :i* ! ionization ext5ds1 ! results w be 9 r\gh agreem5t ) ! !ory4 ,us+ an active prep>ation ( radium1 ! writ] has made "s exp]im5ts on ! v>iation ( curr5t ) voltage betwe5 p>allel plates di/ant ab\t #aj cms4 f ea* o!r#hb4 ,! results %[$ 7#a7 ,t ! curr5t ?r\gh ! gas = small voltages increas$ m rapidly ?an ! pot5tial diff]5ce appli$1 b n z rapidly z ! squ>e ( t pot5tial diff]5ce4 7#b7 ,! curr5t ?r\gh ! gas dep5d$ on ! direction ( ! electric field2 ! curr5t 0 always small] :5 ! active plate 0 *>g$ positively on acc\nt ( ! small] mobility ( ! positive ion4 ,! diff]5ce betwe5 i & i 0 greate/ :5 ! gas 0 dry1 :i* is ! condition = ! greate/ diff]5ce betwe5 ! velocities ( ! ions4 ,an int]e/+ result foll[s f ! above !ory4 ,= giv5 values ( ,v & d1 ! curr5t _c exce$ a c]ta9 def9ite value1 h[ev] mu* ! ionization may be increas$4 ,9 a simil> way1 :5 an active prep>ation ( radium is us$ z a s\rce ( surface ionization1 x is f\nd t1 = a giv5 voltage & di/ance betwe5 ! plates1 ! curr5t does n increase beyond a c]ta9 value h[ev] mu* ! activity ( ! mat]ial is increas$4 #dh4 ,magnetic field produc$ by an ion 9 motion4 ,x w be %[n lat] t ! two mo/ important k9ds ( rays emitt$ by radio-active sub/ances consi/ ( electrifi$ p>ticles1 spontane\sly project$ ) great velocity4 ,! easily absorb$ rays1 kn[n z rays1 are positively electrifi$ atoms ( matt]2 ! p5etrat+ rays1 kn[n z rays1 c>ry a negative *>ge1 & h be5 f\nd to be id5tical ) ! ca?ode rays produc$ by ! electric dis*>ge 9 a vacuum tube4 ,! me?ods adopt$ to det]m9e ! "* ( ^! rays are v simil> to ^? fir/ us$ by ,j4 ,j4 ,?omson to %[ t ! ca?ode rays consi/$ ( a /ream ( negatively electrifi$ p>ticles project$ ) great velocity4 ,! pro( t ! ca?ode rays 7 corpuscul> 9 "*1 & consi/$ ( *>g$ p>ticles ^: mass 0 v small comp>$ ) t ( ! hydrog5 atom1 m>k$ an important epo* 9 physical sci5ce3 = x n only op5$ up new & f]tile fields ( rese>*1 b also pr(\ndly modifi$ our previ\s conceptions ( ! con/itution ( matt]4 ,a brief acc\nt w accord+ly be giv5 ( ! effects produc$ by a mov+ *>g$ body1 & also ( "s ( ! exp]im5tal me?ods :i* h be5 us$ to det]m9e ! mass & velocity ( ! p>ticles ( ! ca?ode /ream#hc4 ,consid] an ion ( radius a1 c>ry+ a *>ge ( electricity e1 & mov+ ) a velocity u1 small comp>$ ) ! velocity ( light4 ,9 consequ5ce ( ! motion1 a magnetic field is set up ar\nd ! *>g$ ion1 :i* is c>ri$ ) x4 ,! *>g$ ion 9 motion con/itutes a curr5t elem5t ( magnitude eu1 & ! magnetic field ,h at any po9t di/ant r f ! sph]e is giv5 by eu s9 ,h --------- r :]e is ! angle ! radius vector makes ) ! direction ( motion4 ,! l9es ( magnetic =ce are circles ar\nd ! axis ( motion4 ,:5 ! ion is mov+ ) a velocity small comp>$ ) ! velocity ( light1 ! l9es ( electric =ce are ne>ly radial1 b z ! spe$ ( light is approa*$1 !y t5d to leave ! axis ( motion & to b5d t[>ds ! equator4 ,:5 ! spe$ ( ! body is v close to t ( light1 ! magnetic & electric field is conc5trat$ to a l>ge ext5t 9 ! equatorial plane4 ,! pres5ce ( a magnetic field ar\nd ! mov+ body implies t magnetic en]gy is /or$ up 9 ! m$ium surr\nd+ x4 ,! am\nt ( ?is en]gy c be calculat$ v simply = sl[ spe$s4 ,9 a magnetic field ( /r5g? ,h1 ! magnetic en]gy /or$ up 9 unit volume ( ! m$ium ( unit p]meability is giv5 by ,h ---- #h ,integrat+ ! value ( ?is expression ov] ! region ext]ior to a sph]e ( radius a1 ! total magnetic en]gy due to ! motion ( ! *>g$ body is giv5 by intainfty frac,h#bhpi d7vol7 frace#b u#bhpi int#bpi intpi intainfty fracs9#b !tar#d r s9 !ta dphi rd!ta dr frace#b u#bd intpi intainfty frac7#a;cos#b !ta7r#b s9 !ta d!ta 4 dr frace#b u#bc intainfty fracdrr#b frace#b u#bc;a ,! magnetic en]gy1 due to ! motion1 is analog\s to k9etic en]gy1 = x dep5ds ^u ! squ>e ( ! velocity ( ! body4 ,9 consequ5ce ( ! *>ge c>ri$ by ! ion1 additional k9etic en]gy is associat$ ) x4 ,if ! velocity ( ! ion is *ang$1 electric & magnetic =ces are set up t5d+ to /op ! *ange ( motion1 & m "w is done dur+ ! *ange ?an if ! ion 7 un*>g$4 ,! ord9>y k9etic en]gy ( ! body is #a --- mu #b ,9 consequ5ce ( its *>ge1 ! k9etic en]gy associat$ ) x is increas$ by eu ------ #c;a ,x ?us behaves z if x possess$ a mass m m :]e m is ! electrical mass1 ) ! value #b;e ---- #c;a ,we h s f> only consid]$ ! electrical mass ( a *>g$ ion mov+ ) a velocity small comp>$ ) t ( light4 ,z ! spe$ ( light is approa*$1 ! magnetic en]gy c no long] be express$ by ! equation already giv54 ,! g5]al values ( ! electrical mass ( a *>g$ body = spe$ 7 fir/ work$ out by ,j4 ,j4 ,?omson#hd 9 #ahhg4 ,a m complete exam9ation 0 made 9 #ahhi by ,heaviside#he1 :ile ,se>le#hf work$ out ! case = a *>g$ ellipsoid4 ,rec5tly1 ! "q 0 aga9 attack$ by ,abraham#hg4 ,slightly diff]5t expressions = ! v>iation ( electrical mass ) spe$ h be5 obta9$1 dep5d+ ^u ! conditions assum$ = ! di/ribution ( ! electricity on ! sph]e4 ,! expression f\nd by ,abraham1 :i* has be5 utiliz$ by ,kaufmann to %[ t ! mass ( ! electron is electromagnetic 9 orig91 is giv5 lat] 9 section #hb4 ,all ! calculations agree 9 %[+ t ! electrical mass is practically con/ant = sl[ spe$s1 b increases z ! spe$ ( light is approa*$1 & is !oretically inf9ite :5 ! spe$ ( light is rea*$4 ,! ne>] ! velocity ( light is approa*$1 ! great] is ! resi/+ =ce to a *ange ( motion4 ,an inf9ite =ce w\ld be requir$ to make an electron actually atta9 ! velocity ( light1 s t1 accord+ to ! pres5t !ory1 x w\ld be impossible = an electron to move fa/] ?an light1 i4e4 fa/] ?an an electromagnetic di/urbance travels 9 ! e!r4 ,! importance ( ^! d$uctions lies 9 ! fact t an electric *>ge 9 motion1 q indep5d5tly ( any mat]ial nucleus1 possesses an app>5t mass 9 virtue ( its motion1 & t ?is mass is a function ( ! spe$4 ,inde$1 we %all see lat] 7see section #hb7 t ! app>5t mass ( ! p>ticles con/itut+ ! ca?ode /ream c be expla9$ 9 virtue ( _! *>ge1 )\t ! necessity ( assum+ a mat]ial body 9 :i* ! *>ge is di/ribut$4 ,?is has l$ to ! sugge/ion t all mass may be electrical 9 orig91 & due purely to electricity 9 motion4 #di4 ,action ( a magnetic field on a mov+ ion4 ,let u consid] ! case ( an ion ( mass m c>ry+ a *>ge e & mov+ freely ) a velocity u4 ,if u is small comp>$ ) ! velocity ( light1 ! ion 9 motion corresponds to a curr5t elem5t ( magnitude eu4 ,if ! ion moves 9 an ext]nal magnetic field ( /r5g? ,h1 x is act$ on by a =ce at "r angles bo? to ! direction ( motion1 & to t ( ! magnetic =ce & equal 9 magnitude to ,heu s9 1 :]e is ! angle betwe5 ! direction ( ! magnetic =ce & ! direction ( motion4 ,s9ce ! =ce due to ! magnetic field is always p]p5dicul> to ! direction ( motion1 x has no effect ^u ! velocity ( ! p>ticle1 b c only alt] ! direction ( its pa?4 ,if is ! radius ( curvature ( ! pa? ( ! ion1 ! =ce along ! normal is equal to mu -----1 & ?is is balanc$ by ! =ce ,heu s9 4 ,if ---1 #b i4e4 if ! ion is mov+ at "r angles to ! direction ( ! magnetic field mu ,heu ----- or m ,h ---- u e ,s9ce u is con/ant1 is also con/ant1 i4e4 ! p>ticle describes a circul> orbit ( radius 4 ,! radius ( ! circul> orbit is ?us directly proportional to u1 & inv]sely proportional to ,h4 ,if ! ion is mov+ at an angle ) ! direction ( ! magnetic field1 x describes a curve :i* is comp\nd$ ( a motion ( a p>ticle ( velocity u s9 p]p5dicul> to ! field & u cos 9 ! direction ( ! field4 ,! =m] describes a circul> orbit ( radius 1 giv5 by m ,h --- u s9 2 e ! latt] is unaffect$ by ! magnetic field & moves uni=mly 9 ! direction ( ! magnetic field ) a velocity u cos 4 ,! motion ( ! p>ticle is 9 consequ5ce a helix1 trac$ on a cyl9d] ( radius mu s9 ----------1 e,h ^: axis is 9 ! direction ( ! magnetic field4 ,?us an ion project$ obliquely to ! direction ( a uni=m magnetic field always moves 9 a helix ^: axis is p>allel to ! l9es ( magnetic =ce#hh4 #ej4 ,det]m9ation ( e_/m = ! ca?ode /ream4 ,! ca?ode rays1 fir/ obs]v$ by ,v>ley1 7 inve/igat$ 9 detail by ,crookes4 ,^! rays are project$ f ! ca?ode 9 a vacuum tube at l[ pressure4 ,!y travel 9 /raight l9es1 & are readily deflect$ by a magnet1 & produce /rong lum9osity 9 a v>iety ( sub/ances plac$ 9 _! pa?4 ,! rays are deflect$ by a magnetic field 9 ! same direction z w\ld be expect$ = a negatively *>g$ p>ticle project$ f ! ca?ode4 ,9 ord] to expla9 ! peculi> prop]ties ( ^! rays ,crookes suppos$ t !y consi/$ ( negatively electrifi$ p>ticles1 mov+ ) great velocity & con/itut+1 z he appropriately t]m$ x1 8a new or f\r? /ate ( matt]40 ,! nature ( ^! rays 0 = tw5ty ye>s a subject ( mu* controv]sy1 = :ile "s upheld _! mat]ial "*1 o!rs consid]$ t !y 7 a special =m ( wave motion 9 ! e!r4 ,p]r9 & ,j4 ,j4 ,?omson %[$ t ! rays always c>ri$ ) !m a negative *>ge1 :ile ,l5>d made ! important discov]y t ! rays pass$ ?r\gh ?9 metal foil & o!r sub/ances opaque to ord9>y light4 ,us+ ?is prop]ty1 he s5t ! rays ?r\gh a ?9 w9d[ & exam9$ ! prop]ties ( ! rays outside ! vacuum tube 9 :i* !y 7 produc$4 ,! absorption ( ! rays by matt] 0 %[n to be ne>ly proportional to ! d5sity ov] a v wide range1 & to be indep5d5t ( its *emical con/itution4 ,! nature ( ^! rays 0 successfully demon/rat$ by ,j4 ,j4 ,?omson#hi 9 #ahig4 ,if ! rays consi/$ ( negatively electrifi$ p>ticles1 !y %\ld be deflect$ 9 _! passage ?r\gh an electric z well z ?r\gh a magnetic field4 ,su* an exp]im5t _h be5 tri$ by ,h]tz1 b ) negative results4 ,j4 ,j4 ,?omson1 h[ev]1 f\nd t ! rays 7 deflect$ by an electric field 9 ! direction to be expect$ = a negatively *>g$ p>ticle1 & %[$ t ! failure ( ,h]tz to detect ! same 0 due to ! mask+ ( ! electric field by ! /rong ionization produc$ 9 ! gas by ! ca?ode /ream4 ,?is effect 0 got rid ( by r$uc+ ! pressure ( ! gas 9 ! tube4 ,! exp]im5tal arrangem5t us$ = ! electric deflection ( ! rays is %[n 9 ,fig4 #aj4 ,! ca?ode rays are g5]at$ at ! ca?ode ,c1 & a n>r[ p5cil ( rays is obta9$ by pass+ ! rays ?r\gh a p]=at$ disc ,,ab4 ,! rays !n pass$ midway betwe5 two p>allel insulat$ plates ,d & ,e1 d c5timetres ap>t1 & ma9ta9$ at a con/ant diff]5ce ( pot5tial ,v4 ,! po9t ( incid5ce ( ! p5cil ( rays 0 m>k$ by a lum9\s pat* produc$ on a phosphoresc5t scre5 plac$ at ,,pp4 ,! p>ticle c>ry+ a negative *>ge e 9 pass+ betwe5 ! *>g$ plates1 is act$ on by a =ce ,xe direct$ t[>ds ! positive plate1 :]e ,x1 ! /r5g? ( ! electric field1 is giv5 by ,v ---- 4 d ,illu/ration3 ,fig4 #aj4 ,! application ( ! electric field ?us causes ! lum9\s pat* to move 9 ! direction ( ! positive plate4 ,if n[ a uni=m magnetic field is appli$ at ! plates ,d & ,e1 p]p5dicul> to ! p5cil ( rays1 & p>allel to ! plane ( ! plates1 & 9 su* a direction t ! electric & magnetic =ces are oppos$ to "o ano!r1 ! pat* ( light c be br\ght back to its undi/urb$ position by adju/+ ! /r5g? ( ! magnetic field4 ,if ,h is ! /r5g? ( ! magnetic field1 ! =ce on ! p>ticle due to ! magnetic field is ,heu1 & :5 a balance is obta9$ ,heu ,xe1 or ,x u --- 7#a74 ,h ,n[ if ! magnetic field ,h is act+ alone1 ! curvature ( ! pa? ( ! rays betwe5 ! plates c be d$uc$ f ! deflection ( ! lum9\s pat*4 ,b we h se5 t mu ,h ----- 7#b74 e ,f equations 7#a7 & 7#b71 ! value ( u & e_/m = ! p>ticle c be det]m9$4 ,! velocity u is n con/ant1 b dep5ds ^u ! pot5tial diff]5ce betwe5 ! electrodes1 & ?is 9 turn dep5ds ^u ! pressure & nature ( ! residual gas 9 ! tube4 ,by alt]+ ^! factors1 ! ca?ode p>ticles may be made to acquire velocities v>y+ betwe5 ab\t #aj & #aj cms4 p] second4 ,?is velocity is enorm\s comp>$ ) t :i* c be impress$ ord9>ily ^u matt] by me*anical means4 ,on ! o!r h&1 ! value ( e_/m = ! p>ticles is s5sibly con/ant = diff]5t velocities4 ,z a result ( a s]ies ( exp]im5ts ! mean value e_/m #gg #aj 0 obta9$4 ,! value ( e_/m is indep5d5t ( ! nature or pressure ( ! gas 9 ! vacuum tube & indep5d5t ( ! metal us$ z ca?ode4 ,a simil> value ( e_/m 0 obta9$ by ,l5>d#ij & o!rs4 ,kaufmann#ia & ,simon#ib us$ a diff]5t me?od to det]m9e ! value ( e_/m4 ,! pot5tial diff]5ce ,v betwe5 ! t]m9als ( ! tube 0 measur$4 ,! "w done on ! *>g$ p>ticle 9 mov+ f "o end ( ! tube to ! o!r is ,ve1 & ?is mu/ be equal to ! k9etic en]gy #a -- mu #b acquir$ by ! mov+ p>ticle4 ,?us e u --- ---- 7#c74 m #b,v ,by comb9ation ( ?is equation ) 7#b7 obta9$ by measurem5t ( ! magnetic deflexion1 bo? u & e_/m c be det]m9$4 ,simon f\nd by ?is me?od t e --- #ahfe #aj4 m ,x w be se5 lat] 7section #hb7 t a simil> value 0 d$uc$ by ,kaufmann = ! electrons project$ f radium4 ,^! results1 :i* h be5 bas$ on ! effect ( a magnetic & electric field on a mov+ ion1 7 confirm$ by ,wei*]t1 :o det]m9$ by a direct me?od ! "t requir$ = ! p>ticle to trav]se a kn[n di/ance4 ,! p>ticles :i* make up ! ca?ode /ream 7 t]m$ 8corpuscles0 by ,j4 ,j4 ,?omson4 ,! "n 8electron10 fir/ employ$ by ,john/one ,/oney1 has also be5 appli$ to !m & has come into g5]al use#ic4 ,! me?ods above describ$ d n give ! mass ( ! electron1 b only ! ratio ( ! *>ge to ! mass4 ,a direct comp>ison c1 h[ev]1 be made betwe5 ! ratio e_/m = ! electron & ! correspond+ value = ! hydrog5 atoms set free 9 ! electrolysis ( wat]4 ,ea* ( ! hydrog5 atoms is suppos$ to c>ry a *>ge e1 & x is kn[n t #if1jjj c\lombs ( electricity1 or1 9 r\nd numb]s1 #aj electromagnetic units ( quantity are requir$ to lib]ate "o gram ( hydrog54 ,if ,n is ! numb] ( atoms 9 "o gram ( hydrog51 !n ,ne #aj4 ,b if m is ! mass ( a hydrog5 atom1 !n ,nm #a4 ,divid+ "o by ! o!r e_/m #aj4 ,we h se5 already t a gase\s ion c>ries ! same *>ge z a hydrog5 atom1 :ile indirect evid5ce %[s t ! electron c>ries ! same *>ge z an ion1 & consequ5tly ! same *>ge z ! atom ( hydrog54 ,h5ce we may conclude t ! app>5t mass ( ! electron is only ab\t ( ! mass ( ! hydrog5 atom4 ,! electron ?us behaves z ! smalle/ body kn[n to sci5ce4 ,9 lat] exp]im5ts ,j4 ,j4 ,?omson %[$ t ! negative ions set free at l[ pressures by an inc&esc5t c>bon filam5t1 & also ! negative ions lib]at$ f a z9c plate expos$ to ! action ( ultra-violet light1 _h ! same value = e_/m z ! electrons produc$ 9 a vacuum tube4 ,x ?us seem$ probable t ! electron 0 a con/itu5t ( all matt]4 ,?is view receiv$ /rong support f measurem5ts ( q a diff]5t "*4 ,zeeman 9 #ahig f\nd t ! l9es ( ! spectrum f a s\rce ( light expos$ 9 a /rong magnetic field 7 displac$ & d\bl$4 ,lat] "w has %[n t ! l9es 9 "s cases are trebl$1 9 o!rs sextupl$1 :ile1 9 a few cases1 ! multiplication is /ill great]4 ,^! results receiv$ a g5]al explanation on ! radiation !ories previ\sly advanc$ by ,lor5z & ,l>mor4 ,! radiation1 emitt$ f any s\rce1 0 suppos$ to result f ! orbital or oscillatory motion ( ! *>g$ p>ts con/itut+ ! atom4 ,s9ce a mov+ ion is act$ on by an ext]nal magnetic field1 ! motion ( ! *>g$ ions is di/urb$ :5 ! s\rce ( light is expos$ betwe5 ! poles ( a /rong magnet4 ,!re results a small *ange 9 ! p]iod ( ! emitt$ light1 & a bright l9e 9 ! spectrum is1 9 consequ5ce1 displac$ by ! action ( ! magnetic field4 ,accord+ to !ory1 ! small *ange 9 ! wave-l5g? ( ! emitt$ light dep5ds ^u ! /r5g? ( ! magnetic field & on ! ratio e_/m ( ! *>ge c>ri$ by ! ion to its mass4 ,by comp>ison ( ! !ory ) ! exp]im5tal results1 x 0 d$uc$ t ! mov+ ion c>ri$ a negative *>ge1 & t ! value ( e_/m 0 ab\t #aj4 ,! *>g$ ion1 responsible = ! radiation f a lum9\s body1 is ?us id5tical ) ! electron set free 9 a vacuum tube4 ,x ?us seems reasonable to suppose t ! atoms ( all bodies are complex & are built up1 9 "p at lea/1 ( electrons1 ^: app>5t mass is v small comp>$ ) t ( ! hydrog5 atom4 ,! prop]ties ( su* disembodi$ *>ges has be5 exam9$ ma!matically among o!rs by ,l>mor1 :o sees 9 ?is conception ! ultimate basis ( a !ory ( matt]4 ,j4 ,j4 ,?omson & ,"l ,kelv9 h inve/igat$ ma!matically c]ta9 arrangem5ts ( a numb] ( electrons :i* are /able = small di/urbances4 ,?is "q w be discuss$ m 9 detail 9 section #bgj4 #ea4 ,canal rays4 ,if a dis*>ge is pass$ ?r\gh a vacuum tube provid$ ) a p]=at$ ca?ode1 )9 c]ta9 limits ( pressure1 lum9\s /reams are obs]v$ to pass ?r\gh ! holes & to em]ge on ! side ( ! ca?ode remote f ! anode4 ,^! rays 7 fir/ obs]v$ by ,gold/e9#id & 7 call$ by him ! 8,canal-/rahl540 ,^! rays travel 9 /raight l9es & produce phosphoresc5ce 9 v>i\s sub/ances4 ,wi5#ie %[$ t ! canal rays 7 deflect$ by /rong magnetic & electric fields1 b ! am\nt ( deflection 0 v small comp>$ ) t ( ! ca?ode rays "u simil> conditions4 ,! deflection 0 f\nd to be opposite 9 direction to ! ca?ode rays1 & ?is indicates t ! canal rays consi/ ( positive ions4 ,wi5 det]m9$ _! velocity & ! ratio e_/m1 by measur+ ! am\nt ( _! magnetic & electric deflection4 ,! value ( e_/m 0 f\nd to be v>iable1 dep5d+ ^u ! gas 9 ! tube1 b ! maximum value obs]v$ 0 #aj4 ,?is %[s t ! positive ion1 9 no case1 has a mass less ?an t ( ! hydrog5 atom4 ,x seems probable t ! canal rays consi/ ( positive ions1 d]iv$ ei!r f ! gas or ! electrodes1 :i* travel t[>ds ! ca?ode1 & h suffici5t velocity to pass ?r\gh ! holes ( ! ca?ode & to appe> 9 ! gas beyond4 ,x is rem>kable t1 s f>1 no case has be5 obs]v$ :]e ! c>ri] ( a positive *>ge has an app>5t mass less ?an t ( ! hydrog5 atom4 ,positive electricity always appe>s to be associat$ ) bodies atomic 9 size4 ,we h se5 t ! process ( ionization 9 gases is suppos$ to consi/ ( ! expulsion ( an electron f ! atom4 ,! correspond+ positive *>ge rema9s beh9d on ! atom & travels ) x4 ,?is diff]5ce betwe5 positive & negative electricity appe>s to be fundam5tal1 & no explanation ( x has1 z yet1 be5 =?com+4 #eb4 ,radiation ( en]gy4 ,if an electron moves uni=mly 9 a /raight l9e ) con/ant velocity1 ! magnetic field1 :i* travels ) x1 rema9s con/ant1 & !re is no loss ( en]gy f x by radiation4 ,if1 h[ev]1 its motion is ha/5$ or ret>d$1 ! magnetic field is alt]$1 & !re results a loss ( en]gy f ! electron 9 ! =m ( electromagnetic radiation4 ,! rate ( loss ( en]gy f an accel]at$ electron 0 fir/ calculat$ by ,l>mor#if & %[n to be #b;e ---- 7accel]ation71 #c,v :]e e is ! *>ge on ! electron 9 electromagnetic units1 & ,v ! velocity ( light4 ,any alt]ation 9 ! velocity ( a mov+ *>ge is ?us always accompani$ by a radiation ( en]gy f x4 ,s9ce ! electron1 set free 9 a vacuum tube1 increases 9 velocity 9 pass+ ?r\gh ! electric field1 en]gy mu/ be radiat$ f x dur+ its passage f ca?ode to anode4 ,x c1 h[ev]1 readily be calculat$ t1 9 ord9>y cases1 ?is loss ( en]gy is small comp>$ ) ! k9etic en]gy acquir$ by ! electron 9 pass+ ?r\gh ! electric field4 ,an electron mov+ 9 a circul> orbit is a p[]ful radiator ( en]gy1 s9ce x is con/antly accel]at$ t[>ds ! c5tre4 ,an electron mov+ 9 an orbit ( radius equal to ! radius ( an atom 7ab\t #aj cms47 w\ld lose mo/ ( its k9etic en]gy ( motion 9 a small fraction ( a second1 ev5 ?\gh its velocity 0 orig9ally ne>ly equal to ! velocity ( light4 ,if1 h[ev]1 a numb] ( electrons are arrang$ at equal angul> int]vals on ! circumf]5ce ( a circle & move ) con/ant velocity r\nd ! r+1 ! radiation ( en]gy is mu* less ?an = a s+le electron1 & rapidly dim9i%es ) an increase 9 ! numb] ( electrons r\nd ! r+4 ,?is result1 obta9$ by ,j4 ,j4 ,?omson1 w be discuss$ 9 m detail lat] :5 ! /ability ( sy/ems compos$ ( rotat+ electrons is "u consid]ation4 ,s9ce ! radiation ( en]gy is proportional to ! squ>e ( ! accel]ation1 ! proportion ( ! total en]gy radiat$ dep5ds ^u ! sudd5ness ) :i* an electron is />t$ or /opp$4 ,n[ "s ( ! ca?ode ray p>ticles are /opp$ abruptly :5 !y imp+e on ! metal ca?ode1 &1 9 consequ5ce1 give up a fraction ( _! k9etic en]gy 9 ! =m ( electromagnetic radiation4 ,/okes & ,wei*]t sugge/$ t ?is radiation con/itut$ ! ,x rays1 :i* are kn[n to h _! orig9 at ! surface on :i* ! ca?ode rays imp+e4 ,! ma!matical !ory has be5 work$ out by ,j4 ,j4 ,?omson#ig4 ,if ! motion ( an electron is sudd5ly arre/$1 a ?9 sph]ical pulse 9 :i* ! magnetic & electric =ces are v int5se travels out f ! po9t ( impact ) ! velocity ( light4 ,! m sudd5ly ! electron is /opp$1 ! ?9n] & m int5se is ! pulse4 ,on ?is view ! ,x rays are n corpuscul> l ! ca?ode rays1 :i* produce !m1 b consi/ ( transv]se di/urbances 9 ! e!r1 ak9 9 "s respects to light waves ( %ort wave-l5g?4 ,! rays are ?us made up ( a numb] ( pulses1 :i* are non-p]iodic 9 "*1 & :i* foll[ "o ano!r at irregul> int]vals4 ,on ?is !ory ( ! nature ( ! ,x rays1 ! abs5ce ( direct deflection1 refraction1 or pol>ization is to be expect$1 if ! ?ickness ( ! pulse is small comp>$ ) ! diamet] ( an atom4 ,x also expla9s ! non-deflection ( ! pa? ( ! rays by a magnetic or electric field4 ,! int5sity ( ! electric & magnetic =ce 9 ! pulse is s great t x is able to cause a removal ( an electron f "s ( ! atoms ( ! gas1 ov] :i* ! pulse passes1 & ?us causes ! ionization obs]v$4 ,! ca?ode rays produce ,x rays1 & ^! 9 turn give rise to a second>y radiation :5ev] !y imp+e on a solid body4 ,?is second>y radiation is emitt$ equally 9 all directions1 & consi/s p>tly ( a radiation ( ! ,x ray type & also ( electrons project$ ) consid]able velocity4 ,?is second>y radiation gives rise to a t]ti>y radiation & s on4 ,b>kla#ih has %[n t ! second>y radiation emitt$ f a gas ?r\gh :i* ! rays pass consi/s 9 "p ( scatt]$ ,x rays ( ab\t ! same p5etrat+ p[] z ! prim>y rays z well z "s easily absorb$ rays4 ,"p ( ! ca?ode rays is diffusely reflect$ on /rik+ ! ca?ode4 ,^! scatt]$ rays consi/ 9 "p ( electrons ( ! same spe$ z 9 ! prim>y beam1 b also include "s o!rs ( mu* less velocity4 ,! am\nt ( diffuse reflection dep5ds ^u ! nature ( ! ca?ode & ! angle ( incid5ce ( ! rays4 ,we %all see lat] 7*apt] ,,iv47 t simil> effects are produc$ :5 ! rays f radio-active sub/ances imp+e ^u solid bodies4 99 99 99 99 99 ,9 ?is *apt] an acc\nt ( ! ionization !ory ( gases has be5 giv5 to ! ext5t t is necess>y = ! int]pretation ( ! measurem5ts ( radio-activity by ! electric me?od4 ,x w\ld be out ( place "h to discuss ! developm5t ( t !ory 9 detail1 to expla9 ! passage ( electricity ?r\gh flames & vap\rs1 ! dis*>ge ( electricity f hot bodies1 & ! v complicat$ ph5om5a obs]v$ 9 ! passage ( electricity ?r\gh a vacuum tube4 ,= fur!r in=mation on ?is important subject1 ! read] is ref]r$ to ,j4 ,j4 ,?omson's ,conduction ( ,electricity ?r\gh ,gases1 9 :i* ! :ole subject is treat$ 9 a full & complete mann]4 ,a simple acc\nt ( ! effect ( mov+ *>ges & ! electronic !ory ( matt] 0 giv5 by ! same au?or 9 ! ,silliman ,lectures ( ,yale ,univ]sity & publi%$ "u ! title ,electricity & ,matt] 7,scribn]1 ,new ,york1 #aijd74 ,footnote #dd3 ,j4 ,j4 ,?omson & ,ru!r=d1 ,phil4 ,mag4 ,nov4 #ahif4 ,footnote #de3 ,! ^w ion has n[ be5 g5]ally adopt$ 9 ! lit]ature ( ! subject4 ,9 us+ ?is ^w1 x is n assum$ t ! ions 9 gases are ! same z ! correspond+ ions 9 ! electrolysis ( solutions4 ,footnote #df3 ,a m9ute curr5t is obs]v$ betwe5 ! plates ev5 if no radio-active matt] be pres5t4 ,?is has be5 f\nd to be due ma9ly to a slight natural radio-activity ( ! matt] compos+ !m4 7,see *apt] ,,xiv47 ,footnote #dg3 ,?is nom5clature has aris5 f ! simil>ity ( ! %ape ( ! curr5t-voltage curves to ! magnetization curves = iron4 ,s9ce1 on ! ionization !ory1 ! maximum curr5t is a result ( ! removal ( all ! ions f ! gas1 be=e recomb9ation occurs1 ! t]ms are n v suitable4 ,!y h h[ev] n[ come into g5]al use & w be reta9$ ?r\gh\t ?is "w4 ,footnote #dh3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 #dg1 p4 #bec1 #ahii2 ,conduction ( ,electricity ?r\gh ,gases1 p4 #gc1 #aijc4 ,footnote #di3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #ahii4 ,footnote #ej3 ,t[ns5d1 ,phil4 ,mag4 ,feb4 #aija4 ,footnote #ea3 ,ru!r=d1 ,phil4 ,mag4 ,nov4 #ahig1 p4 #add1 ,jan4 #ahii4 ,footnote #eb3 ,t[ns5d1 ,phil4 ,trans4 ,a1 p4 #aeg1 #ahii4 ,footnote #ec3 ,mc,clung1 ,phil4 ,mag4 ,m>*1 #aijb4 ,footnote #ed3 ,langev91 ,?se prs5te la ,facult des ,sci5ces1 p4 #aea1 ,p>is1 #aijb4 ,footnote #ee3 ,ow5s1 ,phil4 ,mag4 ,oct4 #ahii4 ,footnote #ef3 ,ru!r=d1 ,phil4 ,mag4 p4 #dbi1 ,nov4 #ahig4 ,footnote #eg3 ,zel5y1 ,phil4 ,trans4 ,a1 p4 #aic1 #aija4 ,footnote #eh3 ,langev91 ,c4 ,r4 #acd1 p4 #fdf1 #aijb4 ,footnote #ei3 ,zel5y1 ,phil4 ,mag4 ,july1 #ahih4 ,footnote #fj3 ,ru!r=d1 ,phil4 ,mag4 ,feb4 #ahii4 ,footnote #fa3 ,zel5y1 ,phil4 ,trans4 #aie1 p4 #aic1 #aijj4 ,footnote #fb3 ,langev91 ,c4 ,r4 #acd1 p4 #fdf1 #aijb1 & ,!sis1 p4 #aia1 #aijb4 ,footnote #fc3 ,ru!r=d1 ,proc4 ,camb4 ,phil4 ,soc4 #i1 p4 #daj1 #ahih4 ,footnote #fd3 ,langev91 ,!sis1 p4 #aij1 #aijb4 ,footnote #fe3 ,helmholtz & ,ri*>z1 ,annal4 d4 ,phys4 #dj1 p4 #afa1 #ahij4 ,footnote #ff3 ,wilson1 ,phil4 ,trans4 p4 #bfe1 #ahig2 p4 #djc1 #ahii2 p4 #bhi1 #aijj4 ,footnote #fg3 ,?omson1 ,phil4 ,mag4 p4 #ebh1 ,dec4 #ahih4 ,footnote #fh3 ,wilson1 ,phil4 ,trans4 ,a1 #aic1 p4 #bhi1 #ahii4 ,footnote #fi3 ,?omson1 ,phil4 ,mag4 p4 #ebh1 ,dec4 #ahih1 & ,m>*1 #aijc4 ,conduction ( ,electricity ?r\gh ,gases1 ,camb4 ,univ4 ,press1 #aijc1 p4 #aba4 ,footnote #gj3 ,wilson1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #ga3 ,t[ns5d1 ,phil4 ,trans4 ,a1 p4 #abi1 #ahii4 ,footnote #gb3 ,t[ns5d1 loc4 cit4 p4 #aci4 ,footnote #gc3 ,"s diff]5ce ( op9ion has be5 express$ z to ! value ( ,v requir$ to produce ions at ea* collision4 ,t[ns5d consid]s x to be ab\t #bj volts2 ,langev9 #fj volts & ,/>k ab\t #ej volts4 ,footnote #gd3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #ahii4 ,footnote #ge3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #ahii4 ,footnote #gf3 ,/rutt1 ,phil4 ,trans4 ,a1 p4 #ejg1 #aija & ,proc4 ,roy4 ,soc4 p4 #bjh1 #aijc4 ,footnote #gg3 ,mc,clung1 ,phil4 ,mag4 ,sept4 #aijd4 ,footnote #gh3 ,eve1 ,phil4 ,mag4 ,dec4 #aijd4 ,footnote #gi3 ,ru!r=d1 ,phil4 ,mag4 p4 #acg1 ,jan4 #ahii4 ,footnote #hj3 ,*ild1 ,phys4 ,rev4 ,vol4 #ab1 #aija4 ,footnote #ha3 ,ru!r=d1 ,phil4 ,mag4 p4 #baj1 ,augu/1 #aija2 ,phys4 ,rev4 ,vol4 #ac1 #aija4 ,footnote #hb3 ,ru!r=d1 ,phil4 ,mag4 ,aug4 #aija4 ,footnote #hc3 ,a simple & excell5t acc\nt ( ! effects produc$ by ! motion ( a *>g$ ion & also ( ! electronic !ory ( matt] 0 giv5 by ,sir ,oliv] ,lodge 9 #aijc 9 a pap] entitl$ 8,electrons0 7,proce$+s ( ! ,in/itution ( ,electrical ,eng9e]s1 ,"p #aei1 ,vol4 #cb1 #aijc74 ,see also ,j4 ,j4 ,?omson's ,electricity & ,matt] 7,scribn]1 ,new ,york1 #aijd74 ,footnote #hd3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 ,april1 #ahhg4 ,footnote #he3 ,heaviside1 ,collect$ ,pap]s1 ,vol4 ,,ii4 p4 #ead4 ,footnote #hf3 ,se>le1 ,phil4 ,mag4 ,oct4 #ahig4 ,footnote #hg3 ,abraham1 ,phys4 ,zeit4 #d1 ,no4 #a b1 p4 #eg1 #aijb4 ,footnote #hh3 ,a full acc\nt ( ! pa? describ$ by a mov+ ion "u v>i\s conditions is giv5 by ,j4 ,j4 ,?omson1 ,conduction ( ,electricity 9 ,gases 7,camb4 ,univ4 ,press1 #aijc71 pp4 #gi-ij4 ,footnote #hi3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 p4 #bic1 #ahig4 ,footnote #ij3 ,l5>d1 ,annal4 d4 ,phys4 #fd1 p4 #bgi1 #ahih4 ,footnote #ia3 ,kaufmann1 ,annal4 d4 ,phys4 #fa1 p4 #edd2 #fb1 p4 #eif1 #ahig2 #fe1 p4 #dca1 #ahih4 ,footnote #ib3 ,simon1 ,annal4 d4 ,phys4 #fi1 p4 #ehi1 #ahii4 ,footnote #ic3 ,a complete discussion ( ! v>i\s me?ods employ$ to measure ! velocity & mass ( electrons & also ( ! !ory on :i* !y are bas$ w be f\nd 9 ,j4 ,j4 ,?omson's ,conduction ( ,electricity ?r\gh ,gases4 ,footnote #id3 ,gold/e91 ,b]l9 ,sitzb]4 #ci1 p4 #fia1 #ahif2 ,annal4 d4 ,phys4 #fd1 p4 #de1 #ahih4 ,footnote #ie3 ,wi51 ,annal4 d4 ,phys4 #fe1 p4 #ddj1 #ahih4 ,footnote #if3 ,l>mor1 ,phil4 ,mag4 #dd1 p4 #eic1 #ahig4 ,footnote #ig3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 ,feb4 #ahig4 ,footnote #ih3 ,b>kla1 ,phil4 ,mag4 ,june1 #aijc4 ,,*apt] ,,iii4 ,,me?ods ,,( ,,measurem5t4 #ec4 ,me?ods ( ,measurem5t4 ,?ree g5]al me?ods h be5 employ$ = exam9ation ( ! radiations f radio-active bodies1 dep5d+ on 7#a7 ,! action ( ! rays on a photographic plate4 7#b7 ,! ioniz+ action ( ! rays on ! surr\nd+ gas4 7#c7 ,! fluoresc5ce produc$ by ! rays on a scre5 ( plat9ocyanide ( b>ium1 z9c sulphide1 or simil> sub/ance4 ,! ?ird me?od is v re/rict$ 9 its application1 & c only be employ$ = int5sely active sub/ances l radium or polonium4 ,! photographic me?od has be5 us$ v widely1 especially 9 ! e>li] developm5t ( ! subject1 b has gradually be5 displac$ by ! electrical me?od1 z a quantitative det]m9ation ( ! radiations became m & m necess>y4 ,9 c]ta9 directions1 h[ev]1 x possesses di/9ct advantages ov] ! electrical me?od4 ,= example1 x has prov$ a v valuable means ( inve/igat+ ! curvature ( ! pa? ( ! rays1 :5 deflect$ by a magnetic or electric field1 & has all[$ u to det]m9e ! con/ants ( ^! rays ) consid]able accuracy4 ,on ! o!r h&1 z a g5]al me?od ( /udy ( ! radiations1 x is op5 to _m objections4 ,a day's exposure is g5]ally requir$ to produce an appreciable d>k5+ ( ! s5sitive film :5 expos$ to a weak s\rce ( radiation l uranium & ?orium4 ,x _c1 9 consequ5ce1 be employ$ to inve/igate ! radiations ( ^? active products :i* rapidly lose _! activity4 ,moreov]1 ,w4 ,j4 ,russell has %[n t ! d>k5+ ( a photographic plate c be produc$ by _m ag5ts :i* d n give out rays l ^? ( ! radio-active bodies4 ,?is d>k5+ ( ! plate is produc$ "u ! mo/ v>i$ conditions1 & v special precautions are necess>y :5 long exposures to a weak s\rce ( radiation are requir$4 ,! ma9 objection to ! photographic me?od1 h[ev]1 lies 9 ! fact t ! radiations :i* produce ! /ronge/ electrical effect are v weak photographically4 ,= example1 ,soddy#ii has %[n t ! photographic action ( uranium is due almo/ entirely to ! m p5etrat+ rays1 & t ! easily absorb$ rays produce 9 comp>ison v little effect4 ,speak+ g5]ally1 ! p5etrat+ rays are ! mo/ active photographically1 &1 "u ord9>y conditions1 ! action on ! plate is almo/ entirely due to !m4 ,mo/ ( ! en]gy radiat$ f active bodies is 9 ! =m ( easily absorb$ rays :i* are comp>atively inactive photographically4 ,^! rays are difficult to /udy by ! photographic me?od1 z ! lay] ( black pap] :i*1 9 _m cases1 is requir$ 9 ord] to absorb ! phosphoresc5t light f active sub/ances1 cuts (f at ! same "t mo/ ( ! rays "u exam9ation4 ,^! easily absorb$ rays w be %[n to play a f> m important "p 9 ! processes occurr+ 9 radio-active bodies ?an ! p5etrat+ rays :i* are m active photographically4 ,! electrical me?od1 on ! o!r h&1 (f]s a rapid & accurate me?od ( quantitatively exam9+ ! radiations4 ,x c be us$ z a means ( measurem5t ( all ! types ( radiation emitt$1 exclud+ light waves1 & is capable ( accurate measurem5t ov] an extremely wide range4 ,) prop] precautions x c be us$ to measure effects produc$ by radiations ( extremely small int5sity4 #ed4 ,electrical ,me?ods4 ,! electrical me?ods employ$ 9 /udy+ radio-activity are all bas$ on ! prop]ty ( ! radiation 9 "q ( ioniz+ ! gas1 i4e4 ( produc+ positively & negatively *>g$ c>ri]s ?r\gh\t ! volume ( ! gas4 ,! discussion ( ! application ( ! ionization !ory ( gases to measurem5ts ( radio-activity has be5 giv5 9 ! la/ *apt]4 ,x has be5 %[n !re t ! ess5tial condition to be fulfill$ = comp>ative measurem5ts ( ! int5sity ( ! radiations is t ! electrical field %all 9 all cases be /rong en\gh to obta9 ! maximum or saturation curr5t ?r\gh ! gas4 ,! electric field requir$ to produce practical saturation v>ies ) ! int5sity ( ! ionization & consequ5tly ) ! activity ( ! prep>ations to be exam9$4 ,= prep>ations :i* h an activity n m ?an #ejj times t ( uranium1 "u ord9>y conditions1 a field ( #ajj volts p] cm4 is suffici5t to produce a practical saturation curr5t4 ,= v active samples ( radium1 x is (t5 impossible to obta9 conv5i5tly a high en\gh electromotive =ce to give ev5 approximate saturation4 ,"u su* conditions comp>ative measurem5t c be made by measur+ ! curr5t "u dim9i%$ pressure ( ! gas1 :5 saturation is m readily obta9$4 ,! me?od to be employ$ 9 ! measurem5t ( ?is ionization curr5t dep5ds l>gely on ! int5sity ( ! curr5t to be measur$4 ,if "s v active radium is spread on ! l[] ( two insulat$ plates z 9 ,fig4 #a1 & a saturat+ electric field appli$1 ! curr5t may readily be measur$ by a s5sitive galvanomet] ( high resi/ance4 ,= example1 a weight ( #de gr4 ( radium *loride ( activity #ajjj times t ( uranium oxide1 spread ov] a plate ( area #cc sq4 cms41 gave a maximum curr5t ( #aa #aj amp]es :5 ! plates 7 #de cms4 ap>t4 ,9 ?is case ! diff]5ce ( pot5tial to be appli$ to produce practical saturation 0 ab\t #fjj volts4 ,s9ce mo/ ( ! ionization is due to rays :i* are absorb$ 9 pass+ ?r\gh a few c5timetres ( air1 ! curr5t is n mu* increas$ by wid5+ ! di/ance betwe5 ! two plates4 ,9 cases :]e ! curr5t is n q l>ge en\gh = direct deflection1 ! curr5t may be det]m9$ by connect+ ! upp] insulat$ plate ) a well insulat$ cond5s]4 ,aft] *>g+ = a def9ite "t1 say "o or m m9utes1 ! cond5s] is dis*>g$ ?r\gh ! galvanomet]1 & ! curr5t c readily be d$uc$4 #ee4 ,9 mo/ cases1 h[ev]1 :5 deal+ ) less active sub/ances l uranium or ?orium1 or ) small am\nts ( active mat]ial1 x is necess>y to employ me?ods = measur+ mu* small] curr5ts ?an c be detect$ conv5i5tly by an ord9>y galvanomet]4 ,! mo/ conv5i5t app>atus to employ = ?is purpose is "o ( ! num]\s types ( quadrant electromet] or an electroscope ( special design4 ,= _m obs]vations1 especially :]e ! activity ( ! two sub/ances is to be comp>$ "u con/ant conditions1 an electroscope (f]s a v c]ta9 & easy me?od ( measurem5t4 ,z an example ( a simple app>atus ( ?is k9d1 a brief description w be giv5 ( ! electroscope us$ by ,m4 & ,mme ,curie 9 _m ( _! e>li] obs]vations4 ,illu/ration3 ,fig4 #aa4 ,! connections are cle>ly se5 f ,fig4 #aa4 ,! active mat]ial is plac$ on a plate laid on top ( ! fix$ circul> plate ,p1 connect$ ) ! case ( ! in/rum5t & ) e>?4 ,! upp] insulat$ plate ,p is connect$ ) ! insulat$ gold-leaf sy/em ,,ll4 ,s is an insulat+ support & ,l ! gold-leaf4 ,! sy/em is fir/ *>g$ to a suitable pot5tial by means ( ! rod ,c4 ,! rate ( movem5t ( ! gold-leaf is obs]v$ by means ( a microscope4 ,9 comp>isons ( ! activity ( two specim5s1 ! "t tak5 by ! gold leaf to pass ov] a c]ta9 numb] ( divisions ( ! micromet] scale 9 ! eye-piece is obs]v$4 ,s9ce ! capacity ( ! *>g$ sy/em is con/ant1 ! av]age rate ( movem5t ( ! gold-leaf is directly proportional to ! ionization curr5t betwe5 ,p & ,p1 i4e4 to ! int5sity ( ! radiation emitt$ by ! active sub/ance4 ,unless v active mat]ial is be+ exam9$1 ! diff]5ce ( pot5tial betwe5 ,p & ,p c easily be made suffici5t to produce saturation4 ,:5 necess>y1 a correction c be made = ! rate ( leak :5 no active mat]ial is pres5t4 ,9 ord] to avoid ext]nal di/urbances1 ! plates ,,pp & ! rod ,c are surr\nd$ by metal cyl9d]s1 ,e & ,f1 connect$ ) e>?4 #ef4 ,a modifi$ =m ( ! gold-leaf electroscope c be us$ to det]m9e extraord9>ily m9ute curr5ts ) accuracy1 & c be employ$ 9 cases :]e a s5sitive electromet] is unable to detect ! curr5t4 ,a special type ( electroscope has be5 us$ by ,el/] & ,geitel1 9 _! exp]im5ts on ! natural ionization ( ! atmosph]e4 ,a v conv5i5t type ( electroscope to measure ! curr5t due to m9ute ionization ( ! gas is %[n 9 ,fig4 #ab4 ,illu/ration3 ,fig4 #ab4 ,?is type ( in/rum5t 0 fir/ us$ by ,c4 ,t4 ,r4 ,wilson#ajj 9 8 exp]im5ts ( ! natural ionization ( air 9 clos$ vessels4 ,a brass cyl9drical vessel is tak5 ( ab\t #a litre capacity4 ,! gold-leaf sy/em1 consi/+ ( a n>r[ /rip ( gold-leaf ,l atta*$ to a flat rod ,r1 is insulat$ inside ! vessel by ! small sulphur bead or piece ( amb] ,s1 support$ f ! rod ,p4 ,9 a dry atmosph]e a clean sulphur bead or piece ( amb] is almo/ a p]fect insulator4 ,! sy/em is *>g$ by a light b5t rod ,,cc pass+ ?r\gh an ebonite cork#aja4 ,! rod ,c is connect$ to "o t]m9al ( a batt]y ( small accumulators ( #bjj to #cjj volts4 ,if ^! are abs5t1 ! sy/em c be *>g$ by means ( a rod ( seal+-wax4 ,! *>g+ rod ,,cc is !n remov$ f contact ) ! gold-leaf sy/em4 ,! rods ,p & ,c & ! cyl9d] are !n connect$ ) e>?4 ,! rate ( movem5t ( ! gold-leaf is obs]v$ by a read+ microscope ?r\gh two holes 9 ! cyl9d]1 cov]$ ) ?9 mica4 ,9 cases :]e ! natural ionization due to ! enclos$ air 9 ! cyl9d] is to be measur$ accurately1 x is advisable to enclose ! support+ & *>g+ rod & sulphur bead inside a small metal cyl9d] ,m connect$ to e>?1 s t only ! *>g$ gold-leaf sy/em is expos$ 9 ! ma9 volume ( ! air4 ,9 an app>atus ( ?is k9d ! small leakage ov] ! sulphur bead c be elim9at$ almo/ completely by keep+ ! rod ,p *>g$ to ! av]age pot5tial ( ! gold-leaf sy/em dur+ ! obs]vation4 ,?is me?od has be5 us$ ) great success by ,c4 ,t4 ,r4 ,wilson 7loc4 cit474 ,su* ref9em5ts1 h[ev]1 are g5]ally unnecess>y1 except 9 inve/igations ( ! natural ionization ( gases at l[ pressures1 :5 ! conduction leak ov] ! sulphur bead is comp>able ) ! dis*>ge due to ! ioniz$ gas4 #eg4 ,! electric capacity ,c ( a gold-leaf sy/em ab\t #d cms4 long is usually ab\t #a electro/atic unit4 ,if ,v is ! decrease ( pot5tial ( ! gold-leaf sy/em 9 t seconds1 ! curr5t i ?r\gh ! gas is giv5 by ,,cv i ---- t4 ,) a well clean$ brass electroscope ( volume #a litre1 ! fall ( pot5tial due to ! natural ionization ( ! air 0 f\nd to be ab\t #f volts p] h\r4 ,s9ce ! capacity ( ! gold-leaf sy/em 0 ab\t #a electro/atic unit #f i #a ---------- #ef #aj ,e4,s4 units #ai #aj amp]es4 #cfjj #cjj ,) special precautions a rate ( dis*>ge ( or ev5 ( ?is am\nt c be measur$ accurately4 ,! numb] ( ions produc$ 9 ! gas c be calculat$ if ! *>ge on an ion is kn[n4 ,j4 ,j4 ,?omson has %[n t ! *>ge e on an ion is equal to #cd #aj electro/atic units or #aac #aj c\lombs4 ,let q numb] ( ions produc$ p] second p] cubic c5timetre ?r\gh\t ! volume ( ! electroscope1 ,s volume ( electroscope 9 cubic c5timetres4 ,if ! ionization be uni=m1 ! saturation curr5t i is giv5 by i q,se4 ,n[ = an electroscope ) a volume ( #ajjj c4c41 i 0 equal to ab\t #ai #aj amp]es4 ,sub/itut+ ! values giv5 above q #ag ions p] cubic c5timetre p] second4 ,) suitable precautions an electroscope c ?us readily measure an ionization curr5t correspond+ to ! production ( #a ion p] cubic c5timetre p] second4 ,! great advantage ( an app>atus ( ?is k9d lies 9 ! fact t ! curr5t measur$ is due to ! ionization inside ! vessel & is n influ5c$ by ! ionization ( ! ext]nal air or by electro/atic di/urbances#ajb4 ,su* an app>atus is v conv5i5t = inve/igat+ ! v p5etrat+ radiations f ! radio-elem5ts1 s9ce ^! rays pass readily ?r\gh ! walls ( ! electroscope4 ,:5 ! electroscope is plac$ on a lead plate #c or #d mms4 ?ick1 ! ionization 9 ! electroscope1 due to a radio-active body plac$ "u ! lead1 is due entirely to ! v p5etrat+ rays1 s9ce ! o!r two types ( rays are completely absorb$ 9 ! lead plate4 ,if a circul> op5+ is cut 9 ! base ( ! electroscope & cov]$ ) ?9 alum9ium ( suffici5t ?ickness to absorb ! rays1 measurem5ts ( ! int5sity ( ! rays f an active sub/ance plac$ "u x1 c be made ) ease & c]ta9ty4 #eh4 ,a modifi$ =m ( electroscope1 :i* promises to be ( great utility = measur+ curr5ts ev5 m m9ute ?an ^? to be obs]v$ ) ! type ( in/rum5t already describ$1 has rec5tly be5 devis$ by ,c4 ,t4 ,r4 ,wilson#ajc4 ,! con/ruction ( ! app>atus is %[n 9 ,fig4 #ac4 ,! case consi/s ( a rectangul> brass box #d cms4 #d cms4 #c cms4 ,a n>r[ gold-leaf ,l is atta*$ to a rod ,r pass+ ?r\gh a clean sulphur cork4 ,opposite ! gold-leaf is fix$ an insulat$ brass plate ,p1 plac$ ab\t #a mm4 f ! wall ( ! box4 ,! movem5t ( ! gold-leaf is obs]v$ ?r\gh two small w9d[s by means ( a microscope provid$ ) a micromet] scale4 ,! plate ,p is ma9ta9$ at a con/ant pot5tial 7g5]ally ab\t #bjj volts74 ,! electromet] case is plac$ 9 an incl9$ position z %[n 9 ! figure1 ! angle ( incl9ation & ! pot5tial ( ! plate be+ adju/$ to give ! desir$ s5sitiv5ess4 ,! gold-leaf is initially connect$ to ! case1 & ! microscope adju/$ s t ! gold-leaf is se5 9 ! c5tre ( ! scale4 ,= a giv5 pot5tial ( ! plate1 ! s5sitiv5ess dep5ds on ! angle ( tilt ( ! case4 ,!re is a c]ta9 critical incl9ation bel[ :i* ! gold-leaf is un/able4 ,! mo/ s5sitive position lies j above ! critical angle4 ,9 a p>ticul> exp]im5t ,wilson f\nd t ) an angle ( tilt ( #cj & ) ! plate at a con/ant pot5tial ( #bjg volts1 ! gold-leaf1 :5 rais$ to a pot5tial ( "o volt above ! case1 mov$ ov] #bjj scale divisions ( ! eye-piece1 #ed divisions correspond+ to "o millimetre4 ,illu/ration3 ,fig4 #ac4 ,9 use1 ! rod ,r is connect$ ) ! ext]nal insulat$ sy/em ^: rise or fall ( pot5tial is to be measur$4 ,on acc\nt ( ! small capacity ( ! sy/em & ! l>ge movem5t ( ! gold-leaf = a small diff]5ce ( pot5tial1 ! electroscope is able to measure extraord9>ily m9ute curr5ts4 ,! app>atus is portable4 ,if ! plate ,p be connect$ to "o pole ( a dry pile ! gold-leaf is /ret*$ out t[>ds ! plate1 & 9 ?is position c be c>ri$ )\t risk ( injury4 #ei4 ,electromet]s4 ,al?\gh ! electroscope c be us$ ) advantage 9 special cases1 x is limit$ 9 its application4 ,! mo/ g5]ally conv5i5t app>atus = measurem5t ( ionization curr5ts ?r\gh gases is "o ( ! num]\s types ( quadrant electromet]4 ,) ! help ( auxili>y capacities1 ! electromet] c be us$ to measure curr5ts ) accuracy ov] a wide range1 & c be employ$ = practically e k9d ( measurem5t requir$ 9 radio-activity4 ,! elem5t>y !ory ( ! symmetrical quadrant electromet] z giv5 9 ! text-books is v imp]fect4 ,x is d$uc$ t ! s5sibility ( ! electromet]--measur$ by ! deflection ( ! ne$le = #a volt ,p4,d4 betwe5 ! quadrants--v>ies directly z ! pot5tial ( ! *>g$ ne$le1 provid$ t ?is pot5tial is high comp>$ ) ! ,p4,d4 betwe5 ! quadrants4 ,9 mo/ electromet]s h[ev]1 ! s5sibility rises to a maximum1 & !n decreases ) increase ( pot5tial ( ! ne$le4 ,= electromet]s 9 :i* ! ne$le lies close to ! quadrants1 ?is maximum s5sibility is obta9$ = a comp>atively l[ pot5tial ( ! ne$le4 ,a !ory ( ! quadrant electromet]1 acc\nt+ = ?is action1 has be5 rec5tly giv5 by ,g4 ,w4 ,walk]#ajd4 ,! effect appe>s to be due to ! pres5ce ( ! air space t necess>ily exi/s betwe5 adjo9+ quadrants4 ,illu/ration3 ,fig4 #ad4 ,suppose t x is requir$ to measure ) an electromet] ! ionization curr5t betwe5 two horizontal metal plates ,a & ,b 7,fig4 #ad7 on ! l[] ( :i* "s active mat]ial has be5 spread4 ,if ! saturation curr5t is requir$1 ! insulat$ plate ,a is connect$ ) "o pole ( a batt]y ( suffici5t ,e4,m4,f4 to produce saturation1 ! o!r pole be+ connect$ to e>?4 ,! insulat$ plate ,b is connect$ ) "o pair ( quadrants ( ! electromet]1 ! o!r pair be+ e>!d4 ,by means ( a suitable key ,k1 ! plate ,b & ! pair ( quadrants connect$ ) x may be ei!r insulat$ or connect$ ) e>?4 ,:5 a measurem5t is to be tak51 ! e>? connection is brok54 ,if ! positive pole ( ! batt]y is connect$ ) ,a1 ! plate ,b & ! electromet] connections imm$iately beg9 to be *>g$ positively1 & ! pot5tial1 if all[$1 w /eadily rise until x is v ne>ly equal to ! pot5tial ( ,a4 ,z soon z ! pot5tial ( ! electromet] sy/em beg9s to rise1 ! electromet] ne$le comm5ces to move at a uni=m rate4 ,obs]vations ( ! angul> movem5t ( ! ne$le are made ei!r by ! telescope & scale or by ! movem5t ( ! spot ( light on a scale 9 ! usual way4 ,if ! ne$le is damp$ s z to give a uni=m motion ov] ! scale1 ! rate ( movem5t ( ! ne$le1 i4e4 ! numb] ( divisions ( ! scale pass$ ov] p] second1 may be tak5 z a measure ( ! curr5t ?r\gh ! gas4 ,! rate ( movem5t is mo/ simply obta9$ by obs]v+ ) a /op-wat* ! "t tak5 = ! spot ( light1 aft] ! motion has become /eady1 to pass ov] #ajj divisions ( ! scale4 ,z soon z ! obs]vation is made1 ! plate ,b is aga9 connect$ ) e>?1 & ! electromet] ne$le returns to its orig9al position4 ,9 mo/ exp]im5ts on radio-activity1 only comp>ative measurem5ts ( saturation curr5ts are requir$4 ,if ^! measurem5ts are to ext5d ov] weeks or mon?s1 z is sometimes ! case1 x is necess>y to adopt "s me?od ( /&>diz+ ! electromet] f day to day1 s z to correct = v>iation 9 its s5sibility4 ,?is is done mo/ simply by comp>+ ! curr5t to be measur$ ) t due to a /&>d sample ( uranium oxide1 :i* is plac$ 9 a def9ite position 9 a small te/+ vessel1 always kept 9 connection ) ! electromet]4 ,uranium oxide is a v con/ant s\rce ( radiation1 & ! saturation curr5t due to x is ! same f day to day4 ,by ?is me?od ( comp>ison accurate obs]vations may be made on ! v>iation ( activity ( a sub/ance ov] long int]vals ( "t1 al?\gh ! s5sibility ( ! electromet] may v>y widely betwe5 successive measurem5ts4 #fj4 ,con/ruction ( electromet]s4 ,z ! quadrant electromet] has ga9$ ! reputation ( be+ a difficult & unc]ta9 in/rum5t = accurate measurem5ts ( curr5t1 x may be ( value to give "s p>ticul> details 9 reg>d to ! be/ me?od ( con/ruction & insulation4 ,9 mo/ ( ! old] types ( quadrant electromet]s ! ne$le sy/em 0 made unnecess>ily heavy4 ,9 consequ5ce ( ?is1 if a s5sibility ( ! ord] ( #ajj mms4 deflection = #a volt 0 requir$1 x 0 necess>y to *>ge ! ,leyd5 j> connect$ to ! ne$le to a fairly high pot5tial4 ,?is at once introduc$ difficulties1 = at a high pot5tial x is n easy to insulate ! ,leyd5 j> satisfactorily1 or to *>ge x to ! same pot5tial f day to day4 ,?is drawback is to a l>ge ext5t avoid$ 9 ! ,:ite patt]n ( ! ,kelv9 electromet]1 :i* is provid$ ) a repl5i%] & attract$ disc = keep+ ! pot5tial ( ! ne$le at a def9ite value4 ,if suffici5t tr\ble is tak5 9 insulat+ & sett+ up ?is type ( electromet]1 x proves a v useful in/rum5t ( mod]ate s5sibility1 & w cont9ue 9 good work+ ord] = a ye> or m )\t mu* att5tion4 ,simpl] types ( electromet] ( great] s5sibility c h[ev] be readily con/ruct$ to give accurate results4 ,! old type ( quadrant electromet]1 to be f\nd 9 e laboratory1 c readily be modifi$ to prove a useful & tru/wor?y in/rum5t4 ,a light ne$le c be made ( ?9 alum9ium1 ( silv]$ pap] or ( a ?9 plate ( mica1 cov]$ ) gold-leaf to make x conduct+4 ,! alum9ium wire & mirror atta*$ %\ld be made z light z possible4 ,! ne$le %\ld be support$ ei!r by a f9e qu>tz fibre or a long bifil> susp5sion ( silk4 ,a v f9e phosphor bronze wire ( "s l5g? is also v satisfactory4 ,a magnetic control is n v suitable1 z x is di/urb$ by coils or dynamos work+ 9 ! neighb\rhood4 ,9 addition1 ! z]o po9t ( ! ne$le is n z /eady z ) ! qu>tz or bifil> susp5sion4 ,:5 an electromet] is us$ to measure a curr5t by not+ ! rate ( movem5t ( ! ne$le1 x is ess5tial t ! ne$le %\ld be damp$ suffici5tly to give a uni=m motion ( ! spot ( light ov] ! scale4 ,! damp+ requires fairly accurate adju/m5t4 ,if x is too little1 ! ne$le has an oscillatory movem5t sup]impos$ on ! /eady motion2 if x is too great1 x moves too sluggi%ly f re/ & takes "s "t to atta9 a /ate ( uni=m motion4 ,) a light ne$le1 v little1 if any1 extra damp+ is requir$4 ,a light plat9um wire ) a s+le loop dipp+ 9 sulphuric acid is g5]ally suffici5t = ! purpose4 ,) light ne$le sy/ems & delicate susp5sions1 x is only necess>y to *>ge ! ne$le to a pot5tial ( a few hundr$ volts to give a s5sibility ( sev]al ?\s& divisions = a volt4 ,) su* l[ pot5tials1 ! difficulty ( insulation ( ! cond5s]1 ) :i* ! ne$le is 9 electrical connection1 is mu* r$uc$4 ,x is conv5i5t to use a cond5s] su* t ! pot5tial ( ! ne$le does n fall m ?an a few p] c5t4 p] day4 ,! ord9>y %ort glass j> p>tly fill$ ) sulphuric acid is1 9 mo/ cases1 n easy to insulate to ?is ext5t4 ,x is bett] to replace x by an ebonite 7or sulphur7 cond5s]#aje su* z is %[n 9 ,fig4 #ae4 ,illu/ration3 ,fig4 #ae4 ,a circul> plate ( ebonite ab\t #a cm4 ?ick is turn$ d[n until x is n m ?an mm4 ?ick 9 ! c5tre4 ,into ?is circul> recess a brass plate ,b fits loosely4 ,! ebonite plate re/s on ano!r brass plate ,c connect$ ) e>?4 ,! cond5s] ?us =m$ has a consid]able capacity & reta9s a *>ge = a long "t4 ,9 ord] to make connection ) ! ne$le1 a small glass vessel ,d1 p>tly fill$ ) sulphuric acid1 is plac$ on ! plate ,b & put 9 connection ) ! ne$le by means ( a f9e plat9um wire4 ,! plat9um wire f ! ne$le dips into ! acid1 & s]ves to damp ! ne$le4 ,9 a dry atmosph]e1 a cond5s] ( ?is k9d w n lose m ?an #bj p] c5t4 ( its *>ge 9 a week4 ,if ! insulation det]iorates1 x c readily be made good by rubb+ ! edge ( ! ebonite ,a ) s&-pap]1 or remov+ its surface 9 a la!4 ,if a suffici5t & /eady ,e4,m4,f4 is available1 x is mu* bett] to keep ! batt]y con/antly connect$ ) ! ne$le1 & to avoid ! use ( ! cond5s] altoge!r4 ,if a batt]y ( small accumulators is us$1 _! pot5tial c be kept at a con/ant value1 & ! electromet] always has a con/ant s5sibility4 #fa4 ,a v useful electromet] ( great s5sibility has be5 devis$ by ,dolezalek#ajf4 ,x is ( ! ord9>y quadrant type ) a v light ne$le ( silv]$ pap]1 sp9dle %ap$1 :i* lies fairly close to ! quadrants4 ,a v f9e qu>tz susp5sion is employ$4 ,9 consequ5ce ( ! lightness ( ! ne$le & its ne>ness to ! quadrants1 x acts z its own damp]4 ,?is is a great advantage1 = difficulties always arise :5 ! wire dips into sulphuric acid1 on acc\nt ( ! ?9 film :i* collects aft] "s "t on ! surface ( ! acid4 ,?is film ob/ructs ! motion ( ! plat9um wire dipp+ into ! acid1 & has to be remov$ at regul> int]vals4 ,^! in/rum5ts c readily be made to give a s5sibility ( sev]al ?\s& divisions = a volt :5 ! ne$le is *>g$ to ab\t "o hundr$ volts4 ,! s5sibility ( ! electromet] passes ?r\gh a maximum z ! pot5tial ( ! ne$le is increas$4 ,x is always advisable to *>ge ! ne$le to ab\t ! value ( ?is critical pot5tial4 ,! capacity ( ! electromet] is 9 g5]al high 7ab\t #ej electro/atic units7 b ! increas$ s5sibility m ?an comp5sates = ?is4 ,! ne$le may ei!r be *>g$ by lightly t\*+ x ) "o t]m9al ( a batt]y1 or x may be kept *>g$ to a con/ant pot5tial ?r\gh ! qu>tz susp5sion4 ,dolezalek /ates t ! fibre c be made suffici5tly conduct+ = ! purpose by dipp+ x into a dilute solution ( calcium *loride or phosphoric acid4 ,i h n f\nd ?is me?od satisfactory 9 dry climates z 9 _m cases ! fibre practically loses its conductivity aft] a few days exposure to dry air4 ,9 addition to its great s5sibility1 ! advantage ( ?is in/rum5t is 9 ! /ead9ess ( ! z]o & 9 ! self-damp+4 ,a s5sibility ( #aj1jjj millimetre divisions p] volt c be readily obta9$ ) ?is electromet]1 if a v f9e fibre be us$4 ,! use ( su* high s5sibilities _c1 h[ev]1 be recomm5d$ except = v special exp]im5ts4 ,! p]iod ( sw+ ( ! ne$le "u ^! conditions is sev]al m9utes & ! natural leak ( ! te/+ vessels employ$1 z well z electro/atic & o!r di/urbances1 make !mselves only too manife/4 ,if measurem5ts ( m9ute curr5ts are requir$1 an electroscope ( ! type describ$ 9 ,section #ef is mu* to be pref]r$ to a v s5sitive electromet]4 ,! electroscope read+s 9 su* a case are m accurate ?an simil> measurem5ts made by an electromet]4 ,= mo/ measurem5ts 9 radio-activity1 an electromet] :i* has a s5sibility ( #ajj divisions p] volt is v suitable1 & no advantage is ga9$ by us+ an electromet] ( great] s5sibility4 ,if /ill small] effects require to be measur$1 ! s5sibility may be increas$ to sev]al ?\s& divisions p] volt4 #fb4 ,adju/m5t & scre5+4 ,9 adju/+ an electromet]1 x is important to arrange t ! ne$le %all lie symmetrically ) reg>d to ! quadrants4 ,?is is be/ te/$ by obs]v+ :e!r ! ne$le is deflect$ on *>g+1 ! quadrants all be+ e>!d4 ,9 mo/ electromet]s !re is an adju/able quadrant1 ! position ( :i* may be alt]$ until ! ne$le is n displac$ on *>g+4 ,:5 ?is condition is fulfill$1 ! z]o read+ ( ! electromet] rema9s unalt]$ z ! ne$le loses its *>ge1 & ! deflection on bo? sides ( ! z]o %\ld be ! same = equal & opposite quantities ( electricity4 ,! supports ( ! quadrants require to be well insulat$4 ,ebonite rods are z a rule m satisfactory = ?is purpose ?an glass4 ,9 te/+ = ! insulation ( ! quadrants & ! connections atta*$1 ! sy/em is *>g$ to give a deflection ( ab\t #bjj scale divisions4 ,if ! ne$le does n move m ?an "o or two divisions aft] /&+ = "o m9ute1 ! insulation may be consid]$ q satisfactory4 ,:5 a suitable desiccator is plac$ inside ! tight-fitt+ electromet] case1 ! insulation ( ! quadrants %\ld rema9 good = mon?s4 ,if ! insulation ( ! ebonite det]iorates1 x c easily be made good by remov+ ! surface ( ! ebonite 9 a la!4 ,9 work+ ) a s5sitive in/rum5t l ! ,dolezalek electromet]1 x is ess5tial t ! electromet] & ! te/+ app>atus %\ld be completely enclos$ 9 a scre5 ( wire-gauze connect$ ) e>?1 9 ord] to avoid electro/atic di/urbances4 ,if an app>atus is to be te/$ at "s di/ance f ! electromet]1 ! wires lead+ to x %\ld be insulat$ 9 metal cyl9d]s connect$ ) e>?4 ,! size ( ! insulators us$ at v>i\s po9ts %\ld be made z small z possible1 9 ord] to avoid di/urbances due to _! electrification4 ,9 damp climates1 p>aff91 amb]1 or sulphur insulates bett] ?an ebonite4 ,! objection to p>aff9 z an insulator = s5sitive electromet]s lies 9 ! difficulty ( gett+ entirely rid ( any electrification on its surface4 ,:5 p>aff9 has be5 once *>g$1 ! residual *>ge1 aft] diselectrify+ x ) a flame1 cont9ues to leak out = a long int]val4 ,all insulators %\ld be diselectrifi$ by means ( a _s-lamp or /ill bett] by leav+ "s uranium ne> !m4 ,c>e %\ld be tak5 n to t\* ! insulation :5 once diselectrifi$4 ,9 accurate "w x is advisable to avoid ! use ( gas jets or ,buns5 flames 9 ! neighb\rhood ( ! electromet]1 z ! flame gases are /rongly ioniz$ & take "s "t to lose _! conductivity4 ,if radio-active sub/ances are pres5t 9 ! room1 x is necess>y to enclose ! wires lead+ to ! electromet] 9 fairly n>r[ tubes1 connect$ ) e>?4 ,if ?is is n done1 x w be f\nd t ! ne$le does n move at a con/ant rate1 b rapidly approa*es a /eady deflection :]e ! rate ( loss ( *>ge ( ! electromet] & connections1 due to ! ionization ( ! air ar\nd !m1 is balanc$ by ! curr5t to be measur$4 ,?is precaution mu/ always be tak5 :5 obs]vations are made on ! v p5etrat+ rays f active sub/ances4 ,^! rays readily pass ?r\gh ord9>y scre5s1 & ionize ! air ar\nd ! electromet] & connect+ wires4 ,= ?is reason x is impossible to make accurate measurem5ts ( small curr5ts 9 a room :i* is us$ = ! prep>ation ( radio-active mat]ial4 ,9 c\rse ( "t ! walls ( ! room become radio-active ow+ to ! dissem9ation ( du/ & ! action ( ! radio-active emanations#ajg4 #fc4 ,electromet] key4 ,= "w ) electromet]s ( high s5sibility1 a special key is necess>y to make & break f a di/ance ! connection ( ! quadrants ) e>? 9 ord] to avoid electro/atic di/urbances at ! mom5t ! curr5t is to be measur$4 ,! simple key %[n 9 ,fig4 #af has be5 f\nd v satisfactory = ?is purpose4 ,a small brass rod ,,bm1 to :i* a /r+ is atta*$1 c be mov$ v]tically up & d[n 9 a brass tube ,a1 :i* is rigidly atta*$ to a b5t metal support connect$ ) e>?4 ,:5 ! /r+ is releas$1 ?is rod makes contact ) ! m]cury ,m1 :i* is plac$ 9 a small metal vessel re/+ on a block ( ebonite ,p4 ,! electromet] & te/+ vessel are connect$ ) ! m]cury4 ,:5 ! /r+ is pull$1 ! rod ,,bm is remov$ f ! m]cury & ! e>? connection ( ! electromet] sy/em is brok54 ,on release ( ! /r+1 ! rod ,,bm falls & ! electromet] is aga9 e>!d4 ,by means ( ?is key1 :i* may be op]at$ at any di/ance f ! electromet]1 ! e>? connection may be made & brok5 at def9ite int]vals )\t any appreciable di/urbance ( ! ne$le4 ,illu/ration3 ,fig4 #af4 #fd4 ,te/+ app>atus4 ,! arrangem5t %[n 9 ,fig4 #ag is v conv5i5t = _m measurem5ts 9 radio-activity4 ,two p>allel insulat$ metal plates ,a & ,b are plac$ inside a metal vessel ,v1 provid$ ) a side door4 ,! plate ,a is connect$ ) "o t]m9al ( a batt]y ( small /orage cells1 ! o!r pole ( :i* is e>!d2 ! plate ,b ) ! electromet]1 & ! vessel ,v ) e>?4 ,! %ad$ areas 9 ! figure indicate ! position ( ebonite insulators4 ,! active mat]ial to be te/$ is spread uni=mly 9 a %all[ groove 7ab\t #e cms4 squ>e & #b mms4 deep7 9 ! brass plate ,a4 ,9 ord] to avoid break+ ! batt]y connection e "t ! plate ,a is remov$1 ! wire f ! batt]y is p]man5tly connect$ ) ! metal block ,n re/+ on ! ebonite support4 ,9 ?is arrangem5t !re is no possibility ( a conduction leak f ! plate ,a to ,b1 s9ce ! e>?-connect$ vessel ,v int]v5es4 ,illu/ration3 ,fig4 #ag4 ,an app>atus ( ?is k9d is v conv5i5t = te/+ ! absorption ( ! radiations by solid scre5s1 z well z = mak+ comp>ative /udies ( ! activity ( diff]5t bodies4 ,unless v active prep>ations ( radium are employ$1 a batt]y ( #cjj volts is suffici5t to ensure saturation :5 ! plates are n m ?an #e c5timetres ap>t4 ,if sub/ances :i* give (f a radio-active emanation are be+ te/$1 ! effect ( ! emanation c be elim9at$ by pass+ a /eady curr5t ( air f a gas bag betwe5 ! plates4 ,?is removes ! emanation z fa/ z x is produc$4 ,if a clean plate is put 9 ! place ( ,a1 a small movem5t ( ! electromet] ne$le is always obs]v$4 ,if !re is no radio-active sub/ance 9 ! neighb\rhood1 ?is effect is due to ! small natural ionization ( ! air4 ,we c correct = ?is natural leak :5 necess>y4 #fe4 ,we h (t5 to measure ! activity due to ! emanations ( ?orium or radium1 or ! excit$ activity produc$ by ^? emanations on rods or wires4 ,a conv5i5t app>atus = ?is purpose is %[n 9 ,fig4 #ah4 ,! cyl9d] ,b is connect$ ) ! batt]y 9 ! usual way1 & ! c5tral conductor ,a ) ! electromet]4 ,?is c5tral rod is insulat$ f ! ext]nal cyl9d] by an ebonite cork1 :i* is divid$ into two p>ts by a metal r+ ,,cc connect$ to e>?4 ,?is r+ acts ! "p ( a gu>d-r+1 & prev5ts any conduction leak betwe5 ,b & ,a4 ,! ebonite is ?us only requir$ to insulate satisfactorily = ! small rise ( pot5tial produc$ on ,a dur+ ! exp]im5t4 ,9 all accurate measurem5ts ( curr5t 9 radio-activity ! gu>d-r+ pr9ciple %\ld always be us$ to ensure good insulation4 ,?is is easily secur$ :5 ! ebonite is only requir$ to insulate = a fraction ( a volt1 in/ead ( = sev]al hundr$ volts1 z is ! case :5 ! gu>d-r+ is abs5t4 ,illu/ration3 ,fig4 #ah4 #ff4 ,= measurem5ts ( radio-activity ) an electromet]1 a /eady s\rce ( ,e4,m4,f4 ( at lea/ #cjj volts is necess>y4 ,?is is be/ obta9$ by a batt]y ( small cells simply made by imm]s+ /rips ( lead 9 dilute sulphuric acid1 or by a batt]y ( small accumulators ( ! usual con/ruction4 ,small accumulators ( capacity ab\t "o-half amp]e-h\r c n[ be obta9$ at a mod]ate price1 & are m con/ant & require less att5tion ?an simple lead cells4 ,9 ord] to measure curr5ts ov] a wide range1 a graduat$ s]ies ( capacities is requir$4 ,! capacity ( an electromet] & te/+ app>atus is usually ab\t #ej electro/atic units or #jjjjef micr(>ads4 ,subdivid$ cond5s]s ( mica are con/ruct$ 9 :i* capacities v>y+ f #jja to #b micr(>ads are provid$4 ,) su* a cond5s]1 ano!r extra capacity is requir$ to bridge ov] ! gap betwe5 ! capacity ( ! electromet] & ! l[e/ capacity ( ! cond5s]4 ,?is capacity ( value ab\t #bjj electro/atic units c readily be made by us+ p>allel plates or /ill bett] conc5tric cyl9d]s4 ,) ?is s]ies ( capacities1 curr5ts may be measur$ betwe5 #c #aj & #c #aj amp]es--a range ( ov] "o million4 ,/ill l>g] curr5ts c be measur$ if ! s5sibility ( ! electromet] is r$uc$1 or if l>g] capacities are available4 ,9 a room devot$ to electromet] measurem5ts ( radio-activity1 x is desirable to h no radio-active matt] pres5t except t to be te/$4 ,! room %\ld also be z free f du/ z possible4 ,! pres5ce ( a l>ge quantity ( du/ 9 ! air 7see section #ca7 is a v di/urb+ factor 9 all radio-active measurem5ts4 ,a l>g] ,e4,m4,f4 is requir$ to produce saturation on acc\nt ( ! diffusion ( ! ions to ! du/ p>ticles4 ,! pres5ce ( du/ 9 ! air also leads to unc]ta9ty 9 ! di/ribution ( excit$ activity 9 an electric field 7see section #aha74 #fg4 ,measurem5t ( ,curr5t4 ,9 ord] to det]m9e ! curr5t 9 ! electromet] circuit by measur+ ! rate ( movem5t ( ! ne$le1 x is necess>y to "k bo? ! capacity ( ! circuit & ! s5sibility ( ! electromet]4 ,let ,c capacity ( electromet] & its connections 9 ,e4,s4 units1 d numb] ( divisions ( ! scale pass$ ov] p] second1 ,d s5sibility ( ! electromet] measur$ 9 scale divisions = #a volt ,p4,d4 betwe5 ! quadrants4 ,! curr5t i is giv5 by ! product ( ! capacity ( ! sy/em & ! rate ( rise ( pot5tial4 ,?us ,cd i ----- ,e4,s4 units1 #cjj;,d ,cd ----------- amp]es4 #i #aj ,d ,suppose1 = example1 ,c #ej1 d #e1 ,d #ajjj2 !n i #bh #aj amp]es4 ,s9ce ! electromet] c readily measure a curr5t correspond+ to a movem5t ( half a scale division p] second1 we see t an electromet] c measure a curr5t ( #c #aj amp]es1 :i* is consid]ably bel[ ! range ( ! mo/ s5sitive galvanomet]4 ,! capacity ( ! electromet] itself mu/ n be consid]$ z equal to t ( ! pair ( quadrants & ! ne$le :5 9 a position ( re/4 ,! actual capacity is v mu* l>g] ?an ?is1 on acc\nt ( ! motion ( ! *>g$ ne$le4 ,suppose1 = example1 t ! ne$le is *>g$ to a high negative pot5tial1 & kept at ! z]o position by an ext]nal con/ra9t4 ,if a quantity ,q ( positive electricity is giv5 to ! electromet] & its connections1 ! :ole sy/em is rais$ to a pot5tial ,v1 su* t ,q ,,cv1 :]e ,c is ! capacity ( ! sy/em4 ,:5 h[ev] ! ne$le is all[$ to move1 x is attract$ into ! *>g$ pair ( quadrants4 ,?is corresponds to ! introduction ( a negatively *>g$ body betwe5 ! quadrants1 & 9 consequ5ce ! pot5tial ( ! sy/em is l[]$ to ,v4 ,! actual capacity ,c ( ! sy/em :5 ! ne$le moves is ?us great] ?an ,c1 & is giv5 by ,c,v ,,cv4 ,?us ! capacity ( ! electromet] is n a con/ant1 b dep5ds on ! pot5tial ( ! ne$le1 i4e4 on ! s5sibility ( ! electromet]4 ,an int]e/+ result ( practical importance foll[s f ! v>iation ( ! capacity ( ! electromet] ) ! pot5tial ( ! ne$le4 ,if ! ext]nal capacity atta*$ to ! electromet] is small comp>$ ) t ( ! electromet] itself1 ! rate ( movem5t ( ! ne$le = a con/ant curr5t is1 9 "s cases1 indep5d5t ( ! s5sibility4 ,an electromet] may be us$ = sev]al days or ev5 weeks to give ne>ly equal deflections = a con/ant curr5t1 )\t re*>g+ ! ne$le1 al?\gh its pot5tial has be5 /eadily fall+ dur+ ! int]val4 ,9 su* a case ! decrease 9 s5sibility is ne>ly proportional to ! decrease 9 capacity ( ! electromet]1 s t ! deflection = a giv5 curr5t is only slightly alt]$4 ,! !ory ( ?is action has be5 giv5 by ,j4 ,j4 ,?omson#ajh4 #fh4 ,! capacity ( ! electromet] & its connections _c be measur$ by any ( ! commutator me?ods us$ = ! det]m9ation ( small capacities1 = 9 su* cases ! ne$le does n move1 & ! capacity measur$ is n t ( ! electromet] sy/em :5 9 actual use4 ,! value ( ! capacity may1 h[ev]1 be det]m9$ by ! me?od ( mixtures4 ,let ,c capacity ( electromet] & connections1 ,c capacity ( a /&>d cond5s]4 ,! electromet] & its connections are *>g$ to a pot5tial ,v by a batt]y1 & ! deflection d ( ! ne$le is not$4 ,by means ( an insulat$ key1 ! capacity ( ! /&>d cond5s] is add$ 9 p>allel ) ! electromet] sy/em4 ,let ,v be ! pot5tial ( ! sy/em1 & d ! new deflection4 ,!n ,,cv 7,c ,c7 ,v1 ,c ,c ,v d -------- ---- ----- ,c ,v d d & ,c ,c ---------- d d ,illu/ration3 ,fig4 #ai4 ,a simple /&>d capacity = ?is purpose c be con/ruct$ ( two conc5tric brass tubes ! diamet]s ( :i* c be accurately measur$4 ,! ext]nal cyl9d] ,d 7,fig4 #ai7 is m\nt$ on a wood5 base1 :i* is cov]$ ) a %eet ( metal or t9foil connect$ to e>?4 ,! tube ,c is support$ c5trally on ebonite rods at ea* end4 ,! capacity is giv5 approximately by ! =mula ,c frac l #b loge frac b a 1 :]e b is ! int]nal diamet] ( ,d1 a ! ext]nal diamet] ( ,c1 & l ! l5g? ( ! tubes4 ,! foll[+ me?od c be us$ 9 "s cases ) advantage4 ,:ile a te/+ vessel is 9 connection ) ! electromet]1 a sample ( uranium is plac$ on ! l[] plate ,a4 ,let d & d be ! numb] ( divisions pass$ ov] p] second by ! ne$le ) & )\t ! /&>d capacity 9 connection4 ,c ,c d ,!n ---------- ----1 ,c d d & ,c ,c --------- d d ,?is me?od has ! advantage t ! relative capacities are express$ 9 t]ms ( ! motion ( ! ne$le "u ! actual conditions ( measurem5t4 #fi4 ,/eady deflection me?od4 ,! me?ods ( measurem5t previ\sly describ$ dep5d ^u ! rate ( angul> movem5t ( a susp5d$ gold-leaf or ( an electromet] ne$le4 ,! galvanomet] c only be employ$ = measurem5ts ) int5sely active matt]4 ,a ne$1 h[ev]1 has long be5 felt = a me?od 9 :i* ord9>y ionization curr5ts c be measur$ by means ( a /eady deflection ( an electromet] ne$le4 ,?is is especially ! case1 :]e measurem5ts h to be made ) active sub/ances ^: activity alt]s rapidly 9 ! c\rse ( a few m9utes4 ,?is c obvi\sly be secur$ if ! electromet] sy/em 7"o pair ( quadrants be+ e>!d7 is connect$ to e>? ?r\gh a suitable high resi/ance4 ,a /eady deflection ( ! electromet] ne$le w be obta9$ :5 ! rate ( supply ( electricity to ! electromet] sy/em is balanc$ by ! loss due to conduction ?r\gh ! resi/ance4 ,if ! high resi/ance obeys ,ohm's law1 ! deflection %\ld be proportional to ! ionization curr5t to be measur$4 ,a simple calculation %[s t ! resi/ance requir$ is v great4 ,suppose1 = example1 t a curr5t is to be measur$ correspond+ to a rate ( movem5t ( ! ne$le ( #e divisions p] second1 ) a s5sibility ( #ajjj divisions p] volt1 & :]e ! capacity ( ! electromet] sy/em is #ej electro/atic units4 ,?is curr5t is equal to #bh #aj amp]es4 ,if a /eady deflection ( #aj divisions is requir$1 :i* corresponds to a rise ( pot5tial ( ! sy/em ( ( a volt1 ! resi/ance %\ld be #cf1jjj megohms4 ,= a deflection ( #ajj divisions1 ! resi/ance %\ld be #aj times z l>ge4 ,dr ,bronson#aji1 work+ 9 ! laboratory ( ! writ]1 has rec5tly made "s exp]im5ts 9 ord] to devise a practical me?od = measurem5ts ( ?is "*4 ,x is difficult to obta9 suffici5tly high & con/ant resi/ances to answ] ! purpose4 ,tubes ( xylol _h too great a resi/ance1 :ile special c>bon resi/ances 7 n suffici5tly con/ant4 ,! difficulty 0 f9ally got ov] by ! use ( :at may be call$ an 8air resi/ance40 ,! arrangem5t ( ! exp]im5t is %[n 9 ,fig4 #bj4 ,illu/ration3 ,fig4 #bj4 ,! electromet] sy/em 0 connect$ ) ! upp] ( two insulat$ p>allel plates ,,ab1 on ! l[] ( :i* 0 spread a lay] ( a v active sub/ance4 ,an active bismu? plate1 coat$ ) radio-tellurium1 :i* _h be5 obta9$ f ,/ham] ( ,hamburg1 prov$ v conv5i5t = ?is purpose4 ,! l[] plate ,b 0 connect$ to e>?4 ,! *>ge communicat$ to ! upp] plate ( ! te/+ vessel ,,cd & ! electromet] sy/em leak$ away 9 consequ5ce ( ! /rong ionization betwe5 ! plates ,,ab1 & a /eady deflection 0 obta9$ :5 ! rate ( supply 0 equal to ! rate ( dis*>ge4 ,?is air resi/ance obey$ ,ohm's law ov] a consid]able range1 i4e4 ! /eady deflection 0 proportional to ! curr5t4 ,x is advisable1 9 su* an arrangem5t1 to te/ :e!r ! deflection is proportional to ! ionization curr5t ov] ! range requir$ = measurem5t4 ,?is c readily be done by ! use ( a numb] ( metal vessels fill$ ) a con/ant radio-active sub/ance l uranium oxide4 ,! effect ( ^!1 :5 plac$ 9 ! te/+ vessel1 c be te/$ sep>ately & 9 gr\ps1 & 9 ?is way ! scale c be calibrat$ accurately4 ,! plates ,,ab 7 plac$ inside a clos$ vessel to avoid air curr5ts4 ,! contact diff]5ce ( pot5tial betwe5 ! plates ,,ab1 :i* %[s itself by a /eady deflection :5 no radio-active matt] is pres5t 9 ,,cd1 0 = ! mo/ "p elim9at$ by cov]+ ! surface ( ! plates ,a & ,b ) v ?9 alum9ium foil4 ,?is me?od prov$ v accurate & conv5i5t = measurem5t ( rapid *anges 9 activity1 & possesses _m advantages ov] ! ord9>y rate-me?od ( use ( an electromet]4 ,a ?9 lay] ( radium ( mod]ate activity w\ld probably s]ve 9 place ( ! radio-tellurium1 b ! emanation & ! & rays emitt$ f x w\ld be a possible s\rce ( di/urbance to ! measurem5ts4 ,! deflection ( ! electromet] ne$le 9 ?is arrangem5t is indep5d5t ( ! capacity ( ! electromet] sy/em1 & ?us comp>ative measurem5ts ( curr5t c be made )\t ! necessity ( det]m9+ ! capacity 9 ea* case4 #gj4 ,qu>tz piezo-electrique4 ,9 measurem5ts ( ! /r5g? ( curr5ts by electromet]s1 x is always necess>y to det]m9e ! s5sibility ( ! in/rum5t & ! capacity ( ! electromet] & ! app>atus atta*$ !reto4 ,by means ( ! qu>tz piezo-electrique devis$ by ! bro!rs ,,mm4 ,j4 & ,p4 ,curie#aaj1 measurem5ts ( ! curr5t c be made ) rapidity & accuracy ov] a wide range4 ,^! measurem5ts are q indep5d5t ( ! capacity ( ! electromet] & ext]nal circuit4 ,! ess5tial "p ( ?is in/rum5t consi/s ( a plate ( qu>tz :i* is cut 9 a special mann]4 ,:5 ?is plate is plac$ "u t5sion1 !re is a lib]ation ( electricity equal 9 am\nt b opposite 9 sign on ! two sides ( ! plate4 ,! plate ( qu>tz ,,ab 7,fig4 #ba7 is hung v]tically & weights are add$ to ! l[] end4 ,! plate is cut s t ! optic axis ( ! cry/al is horizontal & at "r angles to ! plane ( ! pap]4 ,illu/ration3 ,fig4 #ba4 ,! two faces ,a & ,b are normal to "o ( ! b9>y axes 7or electrical axes7 ( ! cry/al4 ,! t5sion mu/ be appli$ 9 a direction normal to ! optic & electric axes4 ,! two faces ,a & ,b are silv]$1 b ! ma9 portion ( ! plate is electrically insulat$ by remov+ a n>r[ /rip ( ! silv]+ ne> ! upp] & l[] ends ( ! plate4 ,"o side ( ! plate is connect$ ) ! electromet] & ) ! conductor1 ! rate ( leak ( :i* is to be measur$4 ,! quantity ( electricity set free on "o face ( ! plate is accurately giv5 by ,l ,q #jfc ---- ,f b :]e ,l is ! l5g? ( ! insulat$ portion ( ! plate1 b ! ?ickness ,,ab1 & ,f ! weight atta*$ 9 kilogrammes4 ,q is !n giv5 9 electro/atic units4 ,suppose1 = example1 t x is requir$ to measure ! curr5t betwe5 ! plates ,,cd 7,fig4 #ba7 due to "s radio-active mat]ial on ! plate ,c1 = a giv5 diff]5ce ( pot5tial betwe5 ,c & ,d4 ,at a giv5 in/ant ! connection ( ! quadrants ( ! electromet] ) ! e>? is brok54 ,! weight is atta*$ to ! qu>tz plate1 & is held 9 ! h& s z to apply ! t5sion gradually4 ,?is causes a release ( electricity opposite 9 sign to t giv5 to ! plate ,d4 ,! electromet] ne$le is kept at ! position ( re/ z ne>ly z possible by adju/+ ! t5sion by h&4 ,! t5sion be+ fully appli$1 ! mom5t ! ne$le comm5ces to move /eadily f z]o is not$4 ,! curr5t betwe5 ! plates ,,cd is !n giv5 by ,q_/t :]e t is ! "t ( ! obs]vation4 ,! value ( ,q is kn[n f ! weight atta*$4 ,9 ?is me?od ! electromet] is only us$ z a detector to %[ t ! sy/em is kept at z]o pot5tial4 ,no k ( ! capacity ( ! insulat$ sy/em is requir$4 ,) practice1 measurem5ts ( ! curr5t c be made 9 ?is way ) rapidity & c]ta9ty4 ,footnote #ii3 ,soddy1 ,trans4 ,*em4 ,soc4 ,vol4 #ha1 p4 #hfj1 #aijb4 ,footnote #ajj3 ,wilson1 ,proc4 ,roy4 ,soc4 ,vol4 #fh1 p4 #aeb1 #aija4 ,footnote #aja3 ,if ! app>atus is requir$ to be air-tight1 ! gold-leaf sy/em c be *>g$ by means ( a piece ( magnetiz$ /eel wire1 :i* is made to t\* ! rod ,r by ! approa* ( a magnet4 ,footnote #ajb3 ,x is sometimes obs]v$ t ! motion ( ! gold-leaf1 imm$iately aft] *>g+1 is irregul>4 ,9 _m cases1 ?is c be trac$ to air curr5ts set up 9 ! electroscope 9 consequ5ce ( unsymmetrical heat+ by ! s\rce ( light us$ = illum9ation4 ,footnote #ajc3 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 ,vol4 #ab1 ,"p ,,ii4 #aijc4 ,footnote #ajd3 ,walk]1 ,phil4 ,mag4 ,aug4 #aijc4 ,footnote #aje3 ,/rutt1 ,phil4 ,trans4 ,a1 p4 #ejg1 #aija4 ,footnote #ajf3 ,dolezalek1 ,in/rum5t5kunde1 p4 #cde1 ,dec4 #aija4 ,footnote #ajg3 ,x is v desirable t c>e %\ld be tak5 n to release l>ge quantities ( ! radium emanation inside a laboratory4 ,?is emanation has a sl[ rate ( decay & is c>ri$ by curr5ts ( air ?r\gh\t ! :ole build+ & f9ally leaves beh9d an active deposit ( v sl[ rate ( *ange 7see *apt] ,,xi474 ,eve 7,nature1 ,m>* #af1 #aije7 has drawn att5tion to ! difficulty ( mak+ ref9$ radio-active measurem5ts "u su* conditions4 ,footnote #ajh3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 #df1 p4 #ecg1 #ahih4 ,footnote #aji3 ,bronson1 ,am]4 ,j\rn4 ,sci5ce1 ,feb4 #aije4 ,footnote #aaj3 ,j4 & ,p4 ,curie1 ,c4 ,r4 #ia1 pp4 #ch & #bid1 #ahhj4 ,see also ,fri$el & ,j4 ,curie1 ,c4 ,r4 #if1 pp4 #abfb & #achi1 #ahhc1 & ,"l ,kelv91 ,phil4 ,mag4 #cf1 pp4 #cca1 #cdb1 #chd1 #dad1 #dec1 #ahic4 ,,*apt] ,,iv4 ,,nature ,,( ,,! ,,radiations4 ,,"p ,i4 ,comp>ison ( ! ,radiations4 #ga4 ,! ,?ree ,types ( ,radiation4 ,all ! radio-active sub/ances possess 9 common ! p[] ( act+ on a photographic plate & ( ioniz+ ! gas 9 _! imm$iate neighb\rhood4 ,! int5sity ( ! radiations may be comp>$ by means ( _! photographic or electrical action2 &1 9 ! case ( ! /rongly radio-active sub/ances1 by ! p[] !y possess ( light+ up a phosphoresc5t scre54 ,su* comp>isons1 h[ev]1 d n ?r[ any light on ! "q :e!r ! radiations are ( ! same or ( diff]5t k9ds1 = x is well kn[n t su* diff]5t types ( radiations z ! %ort waves ( ultra-violet light1 ,rntg5 & ca?ode rays1 all possess ! prop]ty ( produc+ ions ?r\gh\t ! volume ( a gas1 light+ up a fluoresc5t scre51 & act+ on a photographic plate4 ,nei!r c ! ord9>y optical me?ods be employ$ to exam9e ! radiations "u consid]ation1 z !y %[ no trace ( regul> reflection1 refraction1 or pol>ization4 ,two g5]al me?ods c be us$ to di/+ui% ! types ( ! radiations giv5 out by ! same body1 & also to comp>e ! radiations f ! diff]5t active sub/ances4 ,^! me?ods are z foll[s3 7#a7 ,by obs]v+ :e!r ! rays are appreciably deflect$ 9 a magnetic field4 7#b7 ,by comp>+ ! relative absorption ( ! rays by solids & gases4 ,exam9$ 9 ^! ways1 x has be5 f\nd t !re are ?ree diff]5t types ( radiation emitt$ f radio-active bodies1 :i* = brevity & conv5i5ce h be5 t]m$ by ! writ] ! 1 1 & rays4 7i7 ,! rays are v readily absorb$ by ?9 metal foil & by a few c5timetres ( air4 ,!y h be5 %[n to consi/ ( positively *>g$ bodies project$ ) a velocity ( ab\t ! velocity ( light4 ,!y are deflect$ by int5se magnetic & electric fields1 b ! am\nt ( deviation is m9ute 9 comp>ison ) ! deviation1 "u ! same conditions1 ( ! ca?ode rays produc$ 9 a vacuum tube4 7ii7 ,! rays are f> m p5etrat+ 9 "* ?an ! rays1 & consi/ ( negatively *>g$ bodies project$ ) velocities ( ! same ord] z ! velocity ( light4 ,!y are f> m readily deflect$ ?an ! rays1 & are 9 fact id5tical ) ! ca?ode rays produc$ 9 a vacuum tube4 7iii7 ,! rays are extremely p5etrat+1 & non-deviable by a magnetic field4 ,_! true nature is n def9itely settl$1 b !y are analog\s 9 mo/ respects to v p5etrat+ ,rntg5 rays4 ,! ?ree be/ kn[n radio-active sub/ances1 uranium1 ?orium1 & radium1 all give out ^! ?ree types ( rays1 ea* 9 an am\nt approximately proportional to its relative activity measur$ by ! rays4 ,polonium /&s alone 9 giv+ only ! or easily absorb$ rays#aaa4 #gb4 ,deflection ( ! rays4 ,! rays emitt$ f ! active bodies ?us pres5t a v close analogy ) ! rays :i* are produc$ 9 a highly exhau/$ vacuum tube :5 an electric dis*>ge passes ?r\gh x4 ,! rays correspond to ! canal rays1 discov]$ by ,gold/e91 :i* h be5 %[n by ,wi5 to consi/ ( positively *>g$ bodies project$ ) great velocity 7see section #ea74 ,! rays are ! same z ! ca?ode rays1 :ile ! rays resemble ! ,rntg5 rays4 ,9 a vacuum tube1 a l>ge am\nt ( electric en]gy is exp5d$ 9 produc+ ! rays1 b1 9 ! radio-active bodies1 ! rays are emitt$ spontane\sly1 & at a rate un9flu5c$ by any *emical or physical ag5cy4 ,! & rays f ! active bodies are project$ ) mu* great] velocity ?an ! correspond+ rays 9 a vacuum tube1 :ile ! rays are ( mu* great] p5etrat+ p[] ?an ,rntg5 rays4 ,! effect ( a magnetic field on a p5cil ( rays f a radio-active sub/ance giv+ out ! ?ree k9ds ( rays is v well illu/rat$ 9 ,fig4 #bbaab4 ,illu/ration3 ,fig4 #bb4 ,"s radium is plac$ 9 ! bottom ( a n>r[ cyl9drical lead vessel ,r4 ,a n>r[ p5cil ( rays consi/+ ( 1 1 & rays escapes f ! op5+4 ,if a /rong uni=m magnetic field is appli$ at "r angles to ! plane ( ! pap]1 & direct$ t[>ds ! pap]1 ! ?ree types ( rays are sep>at$ f "o ano!r4 ,! rays cont9ue 9 a /raight l9e )\t any deviation4 ,! rays are deflect$ to ! "r1 describ+ circul> orbits ! radii ( :i* v>y )9 wide limits4 ,if ! photographic plate ,,ac is plac$ "u ! radium vessel1 ! rays produce a diffuse photographic impression on ! "r ( ! vessel ,r4 ,! rays are b5t 9 ! direction opposite to t ( ! rays1 & describe a portion ( ! arc ( a circle ( l>ge radius1 b !y are rapidly absorb$ aft] trav]s+ a di/ance ( a few c5timetres f ! vessel ,r4 ,! am\nt ( ! deviation ( ! rays comp>$ ) t ( ! rays is mu* exagg]at$ 9 ! figure4 #gc4 ,ioniz+ & p5etrat+ p[] ( ! rays4 ,( ! ?ree k9ds ( rays1 ! rays produce mo/ ( ! ionization 9 ! gas & ! rays ! lea/4 ,) a ?9 lay] ( unscre5$ active mat]ial spread on ! l[] ( two p>allel plates #e cms4 ap>t1 ! am\nt ( ionization due to ! 1 1 & rays is ( ! relative ord] #aj1jjj1 #ajj1 & #a4 ,^! numb]s are only r\gh approximations1 & ! diff]5ces become less m>k$ z ! ?ickness ( ! radio-active lay] increases4 ,! av]age p5etrat+ p[] ( ! rays is %[n bel[4 ,9 ! fir/ column is giv5 ! ?ickness ( ! alum9ium1 :i* cuts ea* radiation d[n to half its value1 & 9 ! second ! relative p[] ( p5etration ( ! rays4 ,radiation ,?ickness ( ,relative ,alum9ium 9 cms4 p[] ( :i* cuts (f half p5etration ! radiation rays #jjjje cms4 #a #jje cms4 #ajj #h cms4 #ajjjj ,! relative p[] ( p5etration is ?us approximately inv]sely proportional to ! relative ionization4 ,^! numb]s1 h[ev]1 only indicate ! ord] ( relative p5etrat+ p[]4 ,?is p[] v>ies consid]ably = ! diff]5t active bodies4 ,! rays f uranium & polonium are ! lea/ p5etrat+1 & ^? f ?orium ! mo/4 ,! radiations f ?orium & radium are v complex1 & consi/ ( rays widely diff]5t 9 p5etrat+ p[]4 ,"s ( ! rays f ^! sub/ances are mu* less & o!rs mu* m p5etrat+ ?an ^? f uranium1 :i* gives out fairly homog5e\s rays4 #gd4 ,difficulties ( comp>ative measurem5ts4 ,x is difficult to make quantitative or ev5 qualitative measurem5ts ( ! relative int5sity ( ! ?ree types ( rays f active sub/ances4 ,! ?ree g5]al me?ods employ$ dep5d ^u ! action ( ! rays 9 ioniz+ ! gas1 9 act+ on a photographic plate1 & 9 caus+ phosphoresc5t or fluoresc5t effects 9 c]ta9 sub/ances4 ,9 ea* ( ^! me?ods ! fraction ( ! rays :i* is absorb$ & trans=m$ into ano!r =m ( en]gy is diff]5t = ea* type ( ray4 ,ev5 :5 "o specific k9d ( ray is "u obs]vation1 comp>ative measurem5ts are r5d]$ difficult by ! complexity ( t type ( rays4 ,= example1 ! rays f radium consi/ ( negatively *>g$ p>ticles project$ ) a wide range ( velocity1 &1 9 consequ5ce1 !y are absorb$ 9 diff]5t am\nts 9 pass+ ?r\gh a def9ite ?ickness ( matt]4 ,9 ea* case1 only a fraction ( ! en]gy absorb$ is trans=m$ into ! p>ticul> type ( en]gy1 :e!r ionic1 *emical1 or lum9\s1 :i* s]ves z a means ( measurem5t4 ,! rays :i* are ! mo/ active electrically are ! lea/ active photographically4 ,"u ord9>y conditions1 mo/ ( ! photographic action ( uranium1 ?orium1 & radium1 is due to ! or ca?odic rays4 ,! rays f uranium & ?orium1 on acc\nt ( _! weak action1 h n yet be5 detect$ photographically4 ,) active sub/ances l radium & polonium1 ! rays readily produce a photographic impression4 ,s f> ! rays h be5 detect$ photographically f radium only4 ,t no photographic action ( ^! rays has yet be5 e/abli%$ = uranium & ?orium is probably due m]ely to ! fact t ! effect s\ght = is v small1 & dur+ exposures = long int]vals x is v difficult to avoid fogg+ ( ! plates ow+ to o!r causes4 ,consid]+ ! simil>ity ( ! radiations 9 o!r respects1 !re c be little d\bt t ! rays d produce "s photographic action1 ?\gh x is too small to obs]ve ) c]ta9ty4 ,^! diff]5ces 9 ! photographic & ioniz+ prop]ties ( ! radiations mu/ always be tak5 into acc\nt 9 comp>+ results obta9$ by ! two me?ods4 ,! app>5t contradiction ( results obta9$ by diff]5t obs]v]s us+ ^! two me?ods is f\nd to be due to _! diff]5ces 9 relative photographic & ioniz+ action4 ,= example1 ) ! unscre5$ active mat]ial1 ! ionization obs]v$ by ! electrical me?od is due almo/ entirely to rays1 :ile ! photographic action "u ! same condition is due almo/ entirely to ! rays4 ,x is (t5 conv5i5t to "k :at ?ickness ( matt] is suffici5t to absorb a specific type ( radiation4 ,a ?ickness ( alum9ium or mica ( #ja cms4 or a %eet ( ord9>y writ+-pap] is suffici5t to absorb completely all ! rays4 ,) su* a scre5 ov] ! active mat]ial1 ! effects are due only to ! & rays1 :i* pass ?r\gh ) a v slight absorption4 ,mo/ ( ! rays are absorb$ 9 #e mms4 ( alum9ium or #b mms4 ( lead4 ,! radiation pass+ ?r\gh su* scre5s consi/s v l>gely ( ! rays4 ,z a r\gh work+ rule1 x may be tak5 t a ?ickness ( matt] requir$ to absorb any type ( rays is inv]sely proportional to ! d5sity ( ! sub/ance1 i4e4 ! absorption is proportional to ! d5sity4 ,?is rule holds approximately = light sub/ances1 b1 9 heavy sub/ances l m]cury & lead1 ! radiations are ab\t twice z readily absorb$ z ! d5sity rule w\ld lead u to expect4 ,,"p ,,ii4 ,! or ,ca?odic ,rays4 #ge4 ,discov]y ( ! rays4 ,a discov]y :i* gave a great impetus to ! /udy ( ! radiations f active bodies 0 made 9 #ahii1 almo/ simultane\sly 9 ,g]many1 ,france1 & ,au/ria4 ,x 0 obs]v$ t prep>ations ( radium gave out "s rays :i* 7 deviable by a magnetic field1 & v simil> 9 "* to ! ca?ode rays produc$ 9 a vacuum tube4 ,! obs]vation ( ,el/] & ,geitel t a magnetic field alt]$ ! conductivity produc$ 9 air by radium rays1 l$ ,giesel#aac to exam9e ! effect ( a magnetic field on ! radiations4 ,9 8 exp]im5ts1 ! radio-active prep>ation 0 plac$ 9 a small vessel betwe5 ! poles ( an electromagnet4 ,! vessel 0 arrang$ to give a p5cil ( rays :i* 0 approximately p]p5dicul> to ! field4 ,! rays caus$ a small fluoresc5t pat* on ! scre54 ,on excit+ ! electromagnet1 ! fluoresc5t zone 0 obs]v$ to broad5 out on "o side4 ,on rev]s+ ! field1 ! ext5sion ( ! zone 0 9 ! opposite direction4 ,! deviation ( ! rays ?us indicat$ 0 9 ! same direction & ( ! same ord] ( magnitude z t = ca?ode rays4 ,s4 ,mey] & ,s*weidl]#aad also obta9$ simil> results4 ,!y %[$1 9 addition1 ! deviation ( ! rays by ! alt]ation ( ! conductivity ( ! air :5 a magnetic field 0 appli$4 ,becqu]el#aae1 a little lat]1 %[$ ! magnetic deflection ( ! radium rays by us+ ! photographic me?od4 ,p4 ,curie#aaf1 by ! electrical me?od1 %[$ fur!rmore t ! rays f radium consi/$ ( two k9ds1 "o app>5tly non-deviable & easily absorb$ 7n[ kn[n z ! rays71 & ! o!r p5etrat+ & deviable by a magnetic field 7n[ kn[n z ! rays74 ,! ionization effect due to ! rays 0 only a small fraction ( t due to ! rays4 ,at a lat] date ,becqu]el1 by ! photographic me?od1 %[$ t uranium gave out "s deflectable rays4 ,x _h be5 %[n previ\sly#aag t ! rays f uranium consi/$ ( & rays4 ,! deflect$ rays 9 ,becqu]el's exp]im5t consi/$ entirely ( rays1 z ! rays f uranium produce no appreciable photographic action4 ,ru!r=d & ,gri]#aah1 us+ ! electric me?od1 %[$ t comp\nds ( ?orium1 l ^? ( uranium1 gave out1 besides rays1 "s p5etrat+ rays1 deviable 9 a magnetic field4 ,z 9 ! case ( radium1 ! ionization due to ! rays ( uranium & ?orium is l>ge comp>$ ) t due to ! rays4 #gf4 ,exam9ation ( ! magnetic deviation by ! photographic me?od4 ,becqu]el has made a v complete /udy1 by ! photographic me?od1 ( ! rays f radium1 & has %[n t !y behave 9 all respects l ca?ode rays1 :i* are kn[n to be negatively *>g$ p>ticles mov+ ) a high velocity4 ,! motion ( a *>g$ ion act$ on by a magnetic field has be5 discuss$ 9 section #di4 ,x has be5 %[n t if a p>ticle ( mass m & *>ge e is project$ ) a velocity u1 at an angle ) ! direction ( a uni=m field ( /r5g? ,h1 x w describe a helix r\nd ! magnetic l9es ( =ce4 ,?is helix is w\nd on a cyl9d] ( radius ,r1 ) ! axis p>allel to ! field1 :]e ,r is giv5 by mu ,r ---- s9 4 ,he ,:5 _/#b1 i4e4 :5 ! rays are project$ normally to ! field1 ! p>ticles describe circles ( radius mu ,r ---- ,he ,! planes ( ^! circles are normal to ! field4 ,?us1 = a p>ticul> velocity u1 ! value ( ,r v>ies inv]sely z ! /r5g? ( ! field4 ,9 a uni=m field ! rays project$ normally to ! field describe circles1 & _! directions ( projection are ! tang5ts at ! orig94 ,?is conclusion has be5 v]ifi$ exp]im5tally by ,becqu]el = ! rays ( radium1 by an arrangem5t simil> to t %[n 9 ,fig4 #bc4 ,illu/ration3 ,fig4 #bc4 ,a photographic plate ,p1 ) ! film d[nw>ds1 is envelop$ 9 black pap] & plac$ horizontally 9 ! uni=m horizontal magnetic field ( an electromagnet4 ,! magnetic field is suppos$ to be uni=m1 &1 9 ! figure1 is at "r angles to ! plane ( ! pap]4 ,! plate 0 cov]$ ) a %eet ( lead1 & on ! edge ( ! plate1 9 ! c5tre ( ! magnetic field1 is plac$ a small lead vessel ,r conta9+ ! radio-active matt]4 ,on excit+ ! magnet1 s t ! rays are b5t to ! left ( ! figure1 x is obs]v$ t a photographic impression is produc$ directly bel[ ! s\rce ( ! rays1 :i* h be5 b5t r\nd by ! magnetic field4 ,! active matt] s5ds out rays equally 9 all directions4 ,! rays p]p5dicul> to ! field describe circles1 :i* /rike ! plate imm$iately "u ! s\rce4 ,a few ( ^! rays1 ,a1 ,a1 ,a1 are %[n 9 ! figure4 ,! rays1 normal to ! plate1 /rike ! plate almo/ normally1 :ile ! rays ne>ly p>allel to ! plate /rike ! plate at graz+ incid5ce4 ,! rays1 incl9$ to ! direction ( ! field1 describe spirals & produce effects on an axis p>allel to ! field pass+ ?r\gh ! s\rce4 ,9 consequ5ce ( ?is1 any opaque scre5 plac$ 9 ! pa? ( ! rays has its %ad[ ?r[n ne> ! edge ( ! photographic plate4 #gg4 ,complexity ( ! rays4 ,! deviable rays f radium are complex1 i4e4 !y are compos$ ( a flight ( p>ticles project$ ) a wide range ( velocity4 ,9 a magnetic field e ray describes a pa?1 ( :i* ! radius ( curvature is directly proportional to ! velocity ( projection4 ,! complexity ( ! radiation has be5 %[n v cle>ly by ,becqu]el#aai 9 ! foll[+ way4 ,an uncov]$ photographic plate1 ) ! film upw>ds1 0 plac$ horizontally 9 ! horizontal uni=m magnetic field ( an electromagnet4 ,a small1 op51 lead box1 conta9+ ! radio-active matt]1 0 plac$ 9 ! c5tre ( ! field1 on ! photographic plate4 ,! light1 due to ! phosphoresc5ce ( ! radio-active matt]1 !re=e1 c\ld n rea* ! plate4 ,! :ole app>atus 0 plac$ 9 a d>k room4 ,! impression on ! plate took ! =m ( a l>ge1 diffuse1 b cont9u\s b&1 elliptic 9 %ape1 produc$ on "o side ( ! plate4 ,su* an impression is to be expect$ if ! rays are s5t out 9 all directions1 ev5 if _! velocities ( projection are ! same1 = x c readily be %[n !oretically1 t ! pa? ( ! rays is conf9$ )9 an ellipse ^: m9or axis1 :i* is at "r angles to ! field1 is equal to #b,r1 & ^: major axis is equal to ,r4 ,if1 h[ev]1 ! active matt] is plac$ 9 ! bottom ( a deep lead cyl9d] ( small diamet]1 ! rays h practically all ! same direction ( projection1 & 9 t case ea* "p ( ! plate is act$ on by rays ( a def9ite curvature4 ,9 ?is case also1 a diffuse impression is obs]v$ on ! plate1 giv+1 s to speak1 a cont9u\s spectrum ( ! rays & %[+ t ! radiation is compos$ ( rays ( widely diff]5t curvatures4 ,fig4 #bd %[s a photograph ( ?is k9d obta9$ by ,becqu]el1 ) /rips ( pap]1 alum9ium1 & plat9um plac$ on ! plate4 ,illu/ration3 ,fig4 #bd4 ,if scre5s ( v>i\s ?ickness are plac$ on ! plate1 x is obs]v$ t ! plate is n appreciably affect$ )9 a c]ta9 di/ance f ! active matt]1 & t ?is di/ance increases ) ! ?ickness ( ! scre54 ,?is di/ance is obvi\sly equal to twice ! radius ( curvature ( ! pa? ( ! rays1 :i* are j able to produce an impression ?r\gh ! scre54 ,^! exp]im5ts %[ v cle>ly t ! mo/ deviable rays are ^? mo/ readily absorb$ by matt]4 ,by obs]vations ( ?is k9d ,becqu]el has det]m9$ approximately ! inf]ior limit ( ! value ( ,,hr = rays :i* are transmitt$ ?r\gh diff]5t ?icknesses ( matt]4 ,! results are giv5 9 ! table bel[3 ,sub/ance ,?ickness ,inf]ior limit 9 mms4 ( ,,hr = transmitt$ rays ,black pap] #jjfe #fej ,alum9ium #jjaj #cej #jajj #ajjj #jbjj #adhj ,mica #jjbe #ebj ,glass #jaee #aacj ,plat9um #jjcj #acaj ,copp] #jjhe #agdj ,lead #jacj #bfaj ,if e_/m is a con/ant = all ! rays1 ! value ( ,,hr is proportional to ! velocity ( ! rays1 & x foll[s f ! table t ! velocity ( ! rays :i* j produce an effect on ! plate ?r\gh #ac mms4 ( lead is ab\t #g times t ( ! rays :i* j produce an impression ?r\gh #ja mm4 ( alum9ium4 ,x w be %[n1 h[ev]1 9 section #hb1 t e_/m is n a con/ant = all spe$s1 b decreases ) increase ( velocity ( ! rays4 ,! diff]5ce 9 velocity betwe5 ! rays is 9 consequ5ce n z great z ?is calculation w\ld indicate4 ,on exam9ation ( ! rays f uranium1 ,becqu]el f\nd t ! radiation is n z complex z t f radium1 b consi/s :olly ( rays = :i* ! value ( ,,hr is ab\t #bjjj4 #gh4 ,exam9ation ( ! rays by ! electric me?od4 ,! pres5ce ( easily deviable rays giv5 (f f an active sub/ance c mo/ readily be %[n by ! photographic me?od1 b x is necess>y1 9 addition1 to %[ t ! p5etrat+ rays :i* produce ! ionization 9 ! gas are ! same z ^? :i* cause ! photographic action4 ,?is c be conv5i5tly te/$ 9 an arrangem5t simil> to t %[n 9 ,fig4 #be4 ,illu/ration3 ,fig4 #be4 ,! radio-active matt] ,a is plac$ on a lead block ,b betwe5 ! two p>allel lead plates ,,bb4 ,! rays pass betwe5 ! p>allel plates & ionize ! gas betwe5 ! plates ,,pp ( ! te/+ vessel4 ,! magnetic field is appli$ at "r angles to ! plane ( ! pap]4 ,! dott$ rectangle ,,eeee repres5ts ! position ( ! pole piece4 ,if a comp\nd ( radium or ?orium is "u inve/igation1 a /ream ( air is requir$ to prev5t ! diffusion ( ! radio-active emanations into ! te/+ vessel4 ,:5 a lay] ( uranium1 ?orium or radium comp\nd is plac$ at ,a1 ! ionization 9 ! te/+ vessel is due ma9ly to ! action ( ! & rays4 ,! rays are cut (f by add+ a lay] ( alum9ium #ja cm4 ?ick ov] ! active mat]ial4 ,:5 ! lay] ( active matt] is n m ?an a few millimetres ?ick1 ! ionization due to ! rays is small comp>$ ) t produc$ by ! rays1 & may be neglect$4 ,on ! application ( a magnetic field at "r angles to ! mean direction ( ! rays1 ! ionization 9 ! te/+ vessel due to ! rays /eadily decreases z ! /r5g? ( ! field increases1 & 9 a /rong field x is r$uc$ to a v small fraction ( its orig9al value4 ,9 ?is case ! rays are b5t s t none ( !m ent] ! te/+ vessel4 ,exam9$ 9 ?is way1 x has be5 f\nd t ! rays ( uranium1 ?orium1 & radium consi/ entirely ( rays readily deflect$ by a magnetic field4 ,! rays f polonium consi/ entirely ( rays1 ! deviation ( :i* c be detect$ only 9 v int5se magnetic fields4 ,:5 ! scre5 cov]+ ! active mat]ial is remov$1 9 a /rong magnetic field1 ! ionization 9 ! vessel is ma9ly due to ! rays4 ,on acc\nt ( ! slight deviation ( ! rays "u ord9>y exp]im5tal conditions1 a /ill great] increase ( ! magnetic field does n appreciably alt] ! curr5t due to !m 9 ! te/+ vessel4 ,! action ( a magnetic field on a v active sub/ance l radium is easily %[n by ! electrical me?od1 z ! ionization curr5t due to ! deviable rays is l>ge4 ,) sub/ances ( small activity l uranium & ?orium1 ! ionization curr5t due to ! deviable rays is v small1 & a s5sitive electromet] or an electroscope is requir$ to det]m9e ! v>iation1 9 a magnetic field1 ( ! v small curr5t involv$4 ,?is is especially ! case = ?orium oxide1 :i* gives out only ab\t ( ! am\nt ( deviable rays giv5 out by ! same weight ( uranium oxide4 #gi4 ,exp]im5ts ) a fluoresc5t scre54 ,! rays f a few milligrams ( pure radium bromide produce int5se fluoresc5ce 9 b>ium plat9ocyanide & o!r sub/ances :i* c be made lum9\s "u ! influ5ce ( ! ca?ode rays4 ,us+ a c5tigram ( radium bromide1 ! lum9osity on a scre51 plac$ ^u x1 is bright en\gh to be obs]v$ 9 daylight4 ,) ! aid ( su* a scre5 9 a d>k room _m ( ! prop]ties ( ! rays may be simply illu/rat$ & _! complex nature cle>ly %[n4 ,a small quantity ( radium is plac$ 9 ! bottom ( a %ort1 n>r[1 lead tube op5 at "o end4 ,?is is plac$ betwe5 ! pole pieces ( an electromagnet1 & ! scre5 plac$ bel[ x4 ,) no magnetic field1 a fa9t lum9osity ( ! scre5 is obs]v$ due to ! v p5etrat+ rays :i* readily pass ?r\gh ! lead4 ,:5 ! magnetic field is put on1 ! scre5 is brightly light$ up on "o side ov] an area elliptical 9 %ape 7section #gg74 ,! direction ( deviation is rev]s$ by rev]sal ( ! field4 ,! broad ext5t ( ! illum9ation %[s ! complex nature ( ! rays4 ,on plac+ a metallic object at v>i\s po9ts above ! scre51 ! trajectory ( ! rays c readily be trac$ by notic+ ! position ( ! %ad[ ca/ ^u ! scre54 ,by obs]v+ ! d5sity ( ! %ad[1 x c be se5 t ! rays mo/ easily deviat$ are ! lea/ p5etrat+4 ,comp>ison ( ! rays ) ca?ode rays4 #hj4 ,means ( comp>ison4 ,9 ord] to prove ! id5tity ( ! rays f active bodies ) ! ca?ode rays produc$ 9 a vacuum tube1 x is necess>y to %[ 7#a7 ,t ! rays c>ry ) !m a negative *>ge2 7#b7 ,t !y are deviat$ by an electric z well z by a magnetic field2 7#c7 ,t ! ratio e_/m is ! same z = ! ca?ode rays4 ,electric *>ge c>ri$ by ! rays4 ,! exp]im5ts ( ,p]r9 & ,j4 ,j4 ,?omson h %[n t ! ca?ode rays c>ry ) !m a negative *>ge4 ,9 addition1 ,l5>d has %[n t ! rays /ill c>ry a *>ge aft] trav]s+ ?9 lay]s ( matt]4 ,:5 ! rays are absorb$1 !y give up _! *>ge to ! body :i* absorbs !m4 ,! total am\nt ( *>ge c>ri$ by ! rays f ev5 a v active prep>ation ( radium is1 9 g5]al1 small comp>$ ) t c>ri$ by ! :ole ( ! ca?ode rays 9 a vacuum tube1 & c be detect$ only by delicate me?ods4 99 99 99 99 99 ,suppose t a lay] ( v active radium is spread on a metal plate connect$ to e>?1 & t ! rays are absorb$ by a p>allel plate connect$ ) an electromet]4 ,if ! rays are negatively *>g$1 ! top plate %\ld receive a negative *>ge increas+ ) ! "t4 ,on acc\nt1 h[ev]1 ( ! great ionization produc$ by ! rays betwe5 ! plates1 any *>ge giv5 to "o ( !m is almo/ in/antly dissipat$4 ,9 _m cases1 ! plate does become *>g$ to a def9ite positive or negative pot5tial dep5d+ on ! metal1 b ?is is due to ! contact diff]5ce ( pot5tial betwe5 ! plates1 & w\ld be produc$ :e!r ! rays 7 *>g$ or n4 ,! ionization ( ! gas is greatly dim9i%$ by plac+ ov] ! active mat]ial a metal scre5 :i* absorbs ! rays1 b all[s ! rays to pass ?r\gh ) little absorption4 ,! rapid loss ( any *>ge communicat$ to ! top plate c be v mu* r$uc$1 ei!r by dim9i%+ ! pressure ( ! gas surr\nd+ x or by enclos+ ! plate ) suitable insulators4 ,9 _! exp]im5ts to det]m9e ! am\nt ( *>ge c>ri$ by ! radium rays1 ,m4 & ,mme ,curie#abj us$ ! second me?od4 ,a metal disc ,,mm 7,fig4 #bf7 is connect$ ) an electromet] by ! wire ,t4 ,! disc & wire are completely surr\nd$ by insulat+ matt] ii4 ,! :ole is surr\nd$ by a metal envelope ,,eeee connect$ ) e>?4 ,on ! l[] side ( ! disc1 ! insulator & ! metallic cov]+ are v ?94 ,?is side is expos$ to ! rays ( ! radium ,r plac$ 9 a depression 9 a lead plate ,,aa4 ,illu/ration3 ,fig4 #bf4 ,! rays ( ! radium pass ?r\gh ! metal cov] & insulator ) little absorption1 b !y are completely absorb$ by ! disc ,,mm4 ,x 0 obs]v$ t ! disc receiv$ a negative *>ge :i* increas$ uni=mly ) ! "t1 %[+ t ! rays c>ry ) !m a negative *>ge4 ,! curr5t obs]v$ 0 v small4 ,) an active prep>ation ( radium#aba1 =m+ a lay] #be sq4 cms4 9 area & #b mms4 ?ick1 a curr5t ( ! ord] ( #aj amp]es 0 obs]v$ aft] ! rays _h trav]s$ a lay] ( alum9ium #ja mm4 ?ick & a lay] ( ebonite #c mm4 ?ick4 ,! curr5t 0 ! same ) discs ( lead1 copp]1 & z9c1 & also :5 ! ebonite 0 replac$ by p>aff94 ,curie also obs]v$ 9 ano!r exp]im5t ( a simil> "* t ! radium itself acquir$ a positive *>ge4 ,?is necess>ily foll[s if ! rays c>ry ) !m a negative *>ge4 ,if ! rays alone c>ri$ ) !m a *>ge1 a pellet ( radium1 if p]fectly insulat$1 & surr\nd$ by a non-conduct+ m$ium1 w\ld 9 ! c\rse ( "t be rais$ to a high positive pot5tial4 ,s9ce1 h[ev]1 ! rays c>ry ) !m a *>ge opposite 9 sign to ! rays1 ! ratio ( ! *>ge c>ri$ (f by ! two types ( rays mu/ be det]m9$1 be=e x c be settl$ :e!r ! radium w\ld acquire a positive or a negative *>ge4 ,if1 h[ev]1 ! radium is plac$ 9 an insulat$ metal vessel ( a ?ickness suffici5t to absorb all ! rays1 b n too ?ick to all[ mo/ ( ! rays to escape1 ! vessel w acquire a positive *>ge 9 a vacuum4 ,an int]e/+ exp]im5tal result be>+ ^u ?is po9t has be5 describ$ by ,dorn#abb4 ,a small quantity ( radium 0 plac$ 9 a seal$ glass tube & left = sev]al mon?s4 ,on op5+ ! tube ) a file1 a bright electric sp>k 0 obs]v$ at ! mom5t ( fracture1 %[+ t !re 0 a l>ge diff]5ce ( pot5tial betwe5 ! inside ( ! tube & ! e>?4 ,9 ?is case ! rays 7 absorb$ 9 ! walls ( ! tube1 b a l>ge proportion ( ! rays escap$4 ,! inside ( ! tube ?us became *>g$1 9 ! c\rse ( "t1 to a high positive pot5tial2 a /eady /ate w\ld be rea*$ :5 ! rate ( escape ( negative electricity 0 balanc$ by ! leakage ( positive electricity ?r\gh ! walls ( ! tube4 ,! ext]nal surface ( ! glass w\ld be always practically at z]o pot5tial1 on acc\nt ( ! ionization ( ! air ar\nd x4 ,/rutt#abc has rec5tly describ$ a simple & /rik+ exp]im5t to illu/rate /ill m cle>ly t a radium prep>ation acquires a positive *>ge1 if x is enclos$ 9 an envelope ?ick en\gh to absorb all ! p>ticles1 b ?9 en\gh to all[ mo/ ( ! p>ticles to escape4 ,! exp]im5tal arrangem5t is cle>ly se5 9 ,fig4 #bg4 ,a seal$ tube ,,aa conta9+ ! radium1 0 atta*$ at "o end to a pair ( ?9 gold leaves 9 metallic connection ) ! radium1 & 0 insulat$ inside a l>g] tube by means ( a qu>tz rod ,b4 ,! inn] surface ( ! tube 0 coat$ ) t9foil ,,ee connect$ to e>?4 ,! glass surface ( ,,aa 0 made conduct+ by a ?9 coat+ ( phosphoric acid4 ,! air 9 ! out] tube 0 exhau/$ z completely z possible by means ( a m]cury pump1 9 ord] to r$uce ! ionization 9 ! gas1 & consequ5tly ! loss ( any *>ge ga9$ by ! gold leaves4 ,aft] an int]val ( #bj h\rs1 ! gold leaves 7 obs]v$ to div]ge to _! full ext5t1 indicat+ t !y _h acquir$ a l>ge positive *>ge4 ,9 ?is exp]im5t ,/rutt us$ gram ( radif]\s b>ium ( activity only #ajj times t ( uranium4 ,illu/ration3 ,fig4 #bg4 ,if ! tube is fill$ ) #cj mgrs4 ( pure radium bromide1 ! leaves div]ge to _! full ext5t 9 ! c\rse ( ab\t a m9ute4 ,if x is arrang$ t ! gold leaf1 at a c]ta9 angle ( div]g5ce1 comes 9 contact ) a piece ( metal connect$ ) e>?1 ! app>atus c be made to "w automatically4 ,! leaf div]ges1 t\*es ! metal1 & at once collapses1 & ?is p]iodic movem5t ( ! leaf w cont9ue1 if n indef9itely1 at any rate z long z ! radium la/s4 ,?is 8radium clock0 %\ld "w at a s5sibly uni=m rate = _m ye>s1 b1 f evid5ce consid]$ lat] 7,section #bfa71 !re is reason to believe t ! numb] ( p>ticles emitt$ w\ld decrease expon5tially ) ! "t1 fall+ to half value 9 ab\t #abjj ye>s4 ,! p]iod ( movem5t ( ! leaf %\ld ?us gradually increase ) ! "t1 & ultimately ! effect w\ld become too small to obs]ve4 ,! action ( ?is radium clock is ! ne>e/ approa* to an app>5t p]petual motion t has s f> be5 obs]v$4 ,a det]m9ation ( ! am\nt ( ! *>ge c>ri$ (f by ! rays ( radium has be5 made by ,wi5#abd4 ,a small quantity ( radium1 plac$ 9 a seal$ plat9um vessel1 0 hung by an insulat+ ?read inside a glass cyl9d]1 :i* 0 exhau/$ to a l[ pressure4 ,a connection betwe5 ! plat9um vessel & an electrode seal$ on to ! ext]nal glass cyl9d] c\ld be made1 :5 requir$1 by tilt+ ! tube4 ,wi5 f\nd t 9 a good vacuum ! plat9um vessel became *>g$ to ab\t #ajj volts4 ,! rate ( escape ( negative electricity f ! plat9um vessel conta9+ #d milligrams ( radium bromide correspond$ to #bia #aj amp]es4 ,if ! *>ge on ea* p>ticle is tak5 z #aa #aj electromagnetic units1 ?is corresponds to an escape ( #bff #aj p>ticles p] second4 ,f #a gram ( radium bromide ! correspond+ numb] w\ld be #ff #aj p] second4 ,s9ce "s ( ! rays are absorb$ 9 _! passage ?r\gh ! walls ( ! conta9+ vessel & ?r\gh ! radium itself1 ! actual numb] project$ p] second f #a gram ( radium bromide mu/ be great] ?an ! above value4 ,?is has be5 f\nd by ! writ] to be ! case4 ,! me?od employ$ r$uc$ ! absorption ( ! rays to a m9imum1 & ! total numb] emitt$ p] second by #a gram ( radium bromide 9 radio-active equilibrium 0 f\nd to be #da #aj1 or ab\t six times ! numb] f\nd by ,wi54 ,a detail$ acc\nt ( ! me?od employ$ _c be giv5 ) advantage at ?is /age1 b w be f\nd lat] 9 ,section #bec4 #ha4 ,det]m9ation ( e_/m4 ,we h se5 7,section #ej7 t1 9 _! passage betwe5 ! plates ( a cond5s]1 ! ca?ode rays are deflect$ t[>ds ! positive plate4 ,%ortly aft] ! discov]y ( ! magnetic deviation ( ! rays f radium1 ,dorn#abe & ,becqu]el#abf %[$ t !y also 7 deflect$ by an electric field4 ,by obs]v+ sep>ately ! am\nt ( ! electric & magnetic deviation1 ,becqu]el 0 able to det]m9e ! ratio ( e_/m & ! velocity ( ! project$ p>ticles4 ,two rectangul> copp] plates1 #cde cms4 high & #a cm4 ap>t1 7 plac$ 9 a v]tical plane & insulat$ on p>aff9 blocks4 ,"o plate 0 *>g$ to a high pot5tial by means ( an influ5ce ma*9e1 & ! o!r 0 connect$ ) e>?4 ,! active matt] 0 plac$ 9 a n>r[ groove cut 9 a lead plate p>allel to ! copp] plates & plac$ midway betwe5 !m4 ,! photographic plate1 envelop$ 9 black pap]1 0 plac$ horizontally above ! plate conta9+ ! active sub/ance4 ,! l>ge & diffuse p5cil ( rays ?us obta9$ 0 deflect$ by ! electric field1 b ! deviation am\nt$ to only a few millimetres & 0 difficult to measure4 ,! me?od f9ally adopt$ 0 to place v]tically above ! active matt] a ?9 scre5 ( mica1 :i* cut ! field into two equal p>ts4 ,?us1 9 ! abs5ce ( an electric field1 a n>r[ rectangul> %ad[ 0 produc$ on ! plate4 ,:5 ! electric field 0 appli$1 ! rays 7 deflect$ & a "p ( ! p5cil ( rays 0 /opp$ by ! mica scre54 ,a %ad[ 0 ?us ca/ on ! plate :i* %[$ ! direction ( deviation & correspond$ to ! lea/ deviable rays :i* gave an impression ?r\gh ! black pap]4 ,if a p>ticle ( mass m1 *>ge e1 & velocity u1 is project$ normally to an electric field ( /r5g? ,x1 ! accel]ation is 9 ! direction ( ! field1 & is giv5 by ,xe ----- 4 m ,s9ce ! p>ticle moves ) a con/ant accel]ation p>allel to ! field1 ! pa? ( ! p>ticle is ! same z t ( a body project$ horizontally f a height ) a con/ant velocity & act$ on by gravity4 ,! pa? ( ! p>ticle is ?us a p>abola1 ^: axis is p>allel to ! field & ^: apex is at ! po9t :]e ! p>ticle ent]s ! electric field4 ,! l9e> deviation d ( ! ray p>allel to ! field aft] trav]s+ a di/ance l is giv5 by #a ,xe l d -- -- ---- ---- 4 #b m u ,on leav+ ! electric field1 ! p>ticle travels 9 ! direction ( ! tang5t to ! pa? at t po9t4 ,if is ! angul> deviation ( ! pa? at t po9t e,xl tan ----- 4 mu ,! photographic plate 0 at a di/ance h above ! extremity ( ! field4 ,?us ! p>ticles /ruck ! plate at a di/ance d f ! orig9al pa? giv5 by d#b h tan !ta d#a frac ,xle mu#b 7frac l #b h7 ,9 ! exp]im5tal arrangem5t ! values 7 d #d cms42 ,x #ajb #aj2 l #cde cms42 h #ab cms4 ,if ! radius ,r ( curvature ( ! pa? ( ! same rays is obs]v$ 9 a magnetic field ( /r5g? ,h p]p5dicul> to ! rays1 e ,v --- ---- m ,,hr ,comb9+ ^! two equations we get u frac ,x 4 l 7frac l #b h7 ,h 4 ,r 4 d#b 4 ,a difficulty arose 9 id5tify+ ! "p ( ! complex p5cil ( rays = :i* ! electric & magnetic deviations 7 det]m9$4 ,becqu]el e/imat$ t ! value ( ,,hr = ! rays deflect$ by ! electric field 0 ab\t #afjj ,c4,g4,s4 units4 ,?us u #af #aj cms4 p] second1 & e ---- #aj4 m ,?us ^! rays _h a velocity m ?an half ! velocity ( light1 & an app>5t mass ab\t ! same z ! ca?ode ray p>ticles1 i4e4 ab\t ( ! mass ( ! hydrog5 atom4 ,! ray is !re=e analog\s 9 all respects to ! ca?ode ray1 except t x diff]s 9 velocity4 ,9 a vacuum tube ! ca?ode rays g5]ally h a velocity ( ab\t #b #aj cms4 p] sec4 ,9 special tubes ) /rong fields ! velocity may be increas$ to ab\t #aj cms4 p] sec4 ,^! p>ticles1 !n1 behave l isolat$ units ( negative electricity1 id5tical ) ! electrons set free by an electric dis*>ge 9 a vacuum tube4 ,! electrons project$ f radium h velocities v>y+ f ab\t #jb,v to at lea/ #jif,v1 :]e ,v is ! velocity ( light1 & ?us h an av]age spe$ consid]ably great] ?an t ( ! electrons produc$ 9 a vacuum tube4 ,^! mov+ electrons are able to pass ?r\gh mu* great] ?icknesses ( matt] be=e !y are absorb$ ?an ! sl[] electrons produc$ 9 a vacuum tube1 b ! diff]5ce is "o m]ely ( degree & n ( k9d4 ,s9ce electrons are cont9u\sly & spontane\sly expell$ f radium ) enorm\s velocities1 !y mu/ acquire _! en]gy ( motion f ! matt] itself4 ,x is difficult to avoid ! conclusion1 t ?is velocity has n be5 sudd5ly impress$ on ! electron4 ,su* a sudd5 ga9 ( velocity w\ld mean an imm5se & sudd5 conc5tration ( en]gy on a small p>ticle1 & x is m probable t ! electron be=e its expulsion has be5 9 rapid orbital or oscillatory motion 9 ! atom1 &1 by "s means1 sudd5ly escapes f its orbit4 ,accord+ to ?is view1 ! en]gy ( ! electron is n sudd5ly creat$ b is only made obvi\s by its escape f ! sy/em to :i* x belongs4 #hb4 ,v>iation ( e_/m ) ! velocity ( ! electron4 ,! fact t radium ?r[s (f electrons ) rates ( spe$ v>y+ f to ! velocity ( light has be5 utilis$ by ,kaufmann#abg to exam9e :e!r ! ratio e_/m ( ! electrons v>ies ) ! spe$4 ,we h se5 7,section #dh7 t1 accord+ to ! electromagnetic !ory1 a *>ge ( electricity 9 motion behaves z if x _h app>5t mass4 ,= small spe$s1 ?is additional electrical mass is equal to #b e -- ----1 #c a :]e a is ! radius ( ! body1 b x increases rapidly z ! spe$ ( light is approa*$4 ,x is v important to settle :e!r ! mass ( ! electron is due p>tly to me*anical & p>tly to electrical mass1 or :e!r x c be expla9$ by virtue ( electricity 9 motion indep5d5tly ( ! usual conception ( mass4 ,slightly diff]5t =mulae express+ ! v>iation ( mass ) spe$ h be5 develop$ by ,j4 ,j4 ,?omson1 ,heaviside1 & ,se>le4 ,to int]pret 8 results ,kaufmann us$ a =mula develop$ by ,m4 ,abraham#abh4 ,let m mass ( electron = sl[ spe$s2 m app>5t mass ( electron at any spe$2 u velocity ( electron2 ,v velocity ( light4 ,let u_/,v2 !n x c be %[n t frac m m frac #c #d psi 7beta7 7#a71 :]e psi 7beta7 frac #a;beta#b 7frac #a beta#b #b;beta log frac #a beta #a beta #a7 7#b74 ,! exp]im5tal me?od employ$ to det]m9e e_/m & u is simil> to ! me?od ( cross$ spectra4 ,"s /rongly active radium 0 plac$ at ! bottom ( a brass box4 ,! rays f ?is pass$ betwe5 two brass plates insulat$ & ab\t #ab mm4 ap>t4 ,^! rays fell on a plat9um diaphragm1 conta9+ a small tube ab\t #jb mm4 9 diamet]1 :i* all[$ a n>r[ bundle ( rays to pass4 ,! rays !n /ruck a photographic plate envelop$ 9 a ?9 lay] ( alum9ium4 ,9 ! exp]im5ts ! diaphragm 0 ab\t #b cms4 f ! active mat]ial & at ! same di/ance f ! photographic plate4 ,:5 ! :ole app>atus 0 plac$ 9 a vacuum1 a ,p4,d4 ( f #bjjj to #ejjj volts c\ld be appli$ betwe5 ! plates )\t a sp>k4 ,! rays 7 deflect$ 9 _! passage ?r\gh ! electric field1 & produc$ :at may be t]m$ an electric spectrum on ! plate4 ,illu/ration3 ,fig4 #bh4 ,if a magnetic field is sup]impos$ p>allel to ! electric field by means ( an electromagnet1 a magnetic spectrum is obta9$ p]p5dicul> to ! electric spectrum4 ,! comb9ation ( ! two spectra gives rise to a curv$ l9e on ! plate4 ,! d\ble trace obta9$ on ! photographic plate ) rev]sal ( ! magnetic field is %[n 9 ,fig4 #bh4 ,disreg>d+ "s small corrections1 x c readily be %[n t if y & z are ! electric & magnetic deviations respectively1 z ----- 7#c71 y & e z --- ---- 7#d74 m y ,f ^! two equations1 comb9$ ) 7#a71 we obta9 frac y z#b psi 7kappa#a frac z y7 kappa#b 444 7#e71 :]e 1 1 are con/ants4 ,equation 7#e7 gives ! curve t %\ld be obta9$ on ! plate accord+ to ! electromagnetic !ory4 ,?is is comp>$ by trial ) ! actual curve obta9$ on ! plate4 ,9 ?is way ,kaufmann#abi f\nd t ! value ( e_/m decreas$ ) ! spe$1 %[+ t1 assum+ ! *>ge con/ant1 ! mass ( ! electron increas$ ) ! spe$4 ,! foll[+ numb]s give "s ( ! prelim9>y results obta9$ by ?is me?od4 ,velocity ( electron e_/m #bcf #aj cms4 p] #aca #aj sec4 #bdh #aag #aj #bei #jig #aj #bgb #jgg #aj #bhe #jfc #aj ,= ! ca?ode rays ,s4 ,simon#acj obta9$ a value = e_/m ( #ahf #aj = an av]age spe$ ( ab\t #g #aj cms4 p] second4 ,9 a lat] pap]#aca ) "s v active radium1 m satisfactory photographs 7 obta9$1 :i* all[$ ( accurate measurem5t4 ,! giv5 equation ( ! curve 0 f\nd to agree satisfactorily ) exp]im5t4 ,! table giv5 bel[1 d$uc$ f ! results giv5 by ,kaufmann1 %[s ! agreem5t betwe5 ! !oretical & exp]im5tal values1 u be+ ! velocity ( ! electron & ,v t ( light4 ,! av]age p]c5tage error betwe5 ! obs]v$ & calculat$ value is ?us n mu* m ?an "o p] c5t4 ,x is rem>kable h[ ne>ly ! velocity ( ! electron has to approa* ! velocity ( light be=e ! value ( m_/m becomes l>ge4 ,?is is %[n 9 ! foll[+ table :i* gives ! calculat$ values ( m_/m = diff]5t velocities ( ! electron4 ,value ( ,obs]v$ value ,p]c5tage u_/,v ( m_/m diff]5ce f !oretical values ,small #a #gcb #acd #ae #geb #acg #ji #ggg #adb #jf #hja #adg #je #hcj #aede #je #hfj #afe #j #hhc #agc #bh #icc #bje #gh 8 #idi #bade #ab #ifc #bdb #jd ,value ( small #a #e #i #ii #iii #iiii #iiiiii u_/,v ,calculat$ #ajj #ajae #aab #aha #cbh #dif #ffh #aja value m_/m ,?us = velocities v>y+ f #j to ! velocity ( light1 ! mass ( ! electron is practically con/ant4 ,! increase ( mass becomes appreciable at ab\t half ! velocity ( light1 & increases /eadily z ! velocity ( light is approa*$4 ,!oretically ! mass becomes inf9ite at ! velocity ( light1 b ev5 :5 ! velocity ( ! electron only diff]s f t ( light by "o "p 9 a million1 its mass is only #aj times ! value = sl[ spe$s4 ,! above results are !re=e 9 agreem5t ) ! view t ! mass ( ! electron is altoge!r electrical 9 orig9 & c be expla9$ purely by electricity 9 motion4 ,! value ( e_/m1 = sl[ spe$s1 d$uc$ f ! results 0 #ahd #aj1 :i* is 9 v close agreem5t ) ! value obta9$ by ,simon = ! ca?ode rays1 viz4 #ahf #aj4 ,if ! electricity c>ri$ by ! electron is suppos$ to be di/ribut$ uni=mly ov] a sph]e ( radius a1 = spe$s sl[ comp>$ ) ! velocity ( light1 ! app>5t mass #b e m --- ---- #c a ,!re=e #b e a --- ---- 4 e #c m ,tak+ ! value ( e z #aac #aj1 a is #ad #aj cms4 ,?us ! diamet] ( an electron is m9ute comp>$ ) ! diamet] ( an atom4 #hc4 ,di/ribution ( velocity among/ ! p>ticles4 ,"s int]e/+ exp]im5ts h be5 rec5tly made by ,pas*5#acb to det]m9e ! relative numb] ( p>ticles :i* are expell$ f radium at ! diff]5t spe$s4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #bi4 ,illu/ration3 ,fig4 #bi4 ,a small ?9 silv]$ glass tube b1 conta9+ #ae mgrs4 ( radium bromide1 0 plac$ 9 ! axis ( a numb] ( lead vanes arrang$ r\nd a cyl9d] ( diamet] #b cms4 & l5g? #bb cms4 ,:5 no magnetic field 0 act+1 ! p>ticles f ! radium pass$ ?r\gh ! op5+s & 7 absorb$ 9 an out] conc5tric cyl9d] aa ( lead ( inn] diamet] #cg cms4 & ( ?ickness #ee mms4 ,?is out] cyl9d] 0 rigidly connect$ to ! inn] cyl9d] cc by qu>tz rods ii1 :i* also s]v$ to insulate x4 ,! cyl9d] c & ! radium 7 connect$ ) e>?4 ,a gold-leaf electroscope ,e 0 atta*$ to a1 & ! :ole app>atus 0 enclos$ 9 a glass vessel :i* 0 exhau/$ to a l[ vacuum by means ( a m]cury pump4 ,! glass vessel 0 plac$ 9 ! uni=m field ( a l>ge electromagnet1 s t ! axis ( ! lead cyl9d] 0 p>allel to ! l9es ( =ce4 ,! out] cyl9d] ga9s a negative *>ge on acc\nt ( ! p>ticles :i* are absorb$ 9 x4 ,?is negative *>ge1 :i* is indicat$ by ! movem5t ( ! gold-leaf1 t5ds to be dissipat$ by ! small ionization produc$ 9 ! residual gas by ! passage ( ! rays4 ,?is action ( ! gas c be elim9at$ by obs]v+ ! rate ( movem5t ( ! gold leaf :5 *>g$ alt]nately to an initial positive & negative pot5tial4 ,! mean ( ! two rates is proportional to ! numb] ( p>ticles :i* give up _! *>ge to ! lead cyl9d]4 ,?is is evid5tly ! case1 s9ce1 :5 ! *>ge is positive1 ! ionization ( ! gas assi/s ! rate ( movem5t ( ! gold-leaf1 &1 :5 negative1 dim9i%es x to an equal ext5t4 ,:5 a magnetic field is appli$1 ea* ( ! p>ticles describes a curv$ pa?1 ^: radius ( curvature dep5ds on ! velocity ( ! p>ticle4 ,= weak fields1 only ! p>ticles ( smalle/ velocity w be deflect$ suffici5tly n to /rike ! out] cyl9d]1 b1 z ! field is rais$1 ! numb] w increase until f9ally all ! p>ticles fail to rea* ! out] cyl9d]4 ,! decrease ( ! *>ge communicat$ to ! out] cyl9d] ) ! increase ( ! /r5g? ( ! magnetic field is %[n graphically 9 ,fig4 #cj1 ,curve ,i4 ,! ord9ates repres5t 9 arbitr>y units ! *>ge communicat$ to ! lead cyl9d] p] second1 & ?us s]ve z a measure ( ! numb] ( p>ticles :i* rea* ! cyl9d]4 ,kn[+ ! dim5sions ( ! app>atus1 & assum+ ! value e_/m f\nd by ,kaufmann1 ! velocity ( ! p>ticles :i* j fail to rea* ! lead cyl9d] c be d$uc$ f any /r5g? ( ! magnetic field4 ,curve ,,ii1 ,fig4 #cj is ! fir/ diff]5tial ( ,curve ,i1 & ! ord9ates repres5t ! relative numb] ( p>ticles :i* are project$ at ea* velocity4 ,illu/ration3 ,fig4 #cj4 ,f ! data giv5 by ,kaufmann 7see section #hb7 ,pas*5 d$uc$ t ! gr\p ( rays exam9$ by ! =m]1 :i* _h velocities ly+ betwe5 #bab #aj & #bij #aj cms4 p] second1 correspond$ to ! gr\p ( rays betwe5 ! po9ts ,a & ,b1 t is1 to ! gr\p ( rays :i* 7 completely deflect$ f ! lead cyl9d] betwe5 ! magnetic fields ( /r5g?s ( #ahge & #dica ,c4,g4,s4 units4 ,s9ce radium gives (f p>ticles :i* require a field ( /r5g? ov] #gjjj units to deflect !m1 ,pas*5 conclud$ t p>ticles are expell$ f radium ) /ill great] velocities ?an ! highe/ record$ by ,kaufmann4 ,pas*5 consid]$ t ! small *>ge obs]v$ 9 /ill high] fields 0 ma9ly due to ! rays4 ,! effect is small & is probably n due to an actual *>ge c>ri$ by ! rays b to a second>y effect produc$ by !m4 ,?is "q w be discuss$ 9 m detail 9 section #aab4 ,!re is a gr\p ( l[ velocity p>ticles emitt$ by radium 7see ,fig4 #cj7 :i* h ab\t ! same spe$ z ! electrons set free 9 a vacuum tube4 ,9 consequ5ce ( _! small velocity1 ^! probably produce a l>ge proportion ( ! ionization due to ! rays at %ort di/ances f ! radium1 = x w be %[n 7section #ajc7 t ! ionization produc$ by an electron p] unit l5g? ( pa? /eadily decreases ) increase ( its velocity above a small limit+ value4 ,?is obs]vation is confirm$ by exp]im5ts on ! absorption ( ! rays 9 pass+ ?r\gh matt]4 ,9 ,pas*5's exp]im5ts1 ! glass tube conta9+ ! radium 0 #e mms4 ?ick1 s t a consid]able proportion ( ! l[ velocity p>ticles mu/ h be5 /opp$ by x4 ,?is is borne out by "s lat] exp]im5ts ( ,seitz :i* w be describ$ 9 section #he4 #hd4 ,absorption ( ! rays by matt]4 ,! p>ticles produce ions 9 _! passage ?r\gh ! gas & _! en]gy ( motion is consequ5tly dim9i%$4 ,a simil> action takes place also :5 ! rays pass ?r\gh solid & liquid m$ia1 & ! me*anism ( absorption is probably simil> 9 all cases4 ,"s ( ! p>ticles 9 _! passage ?r\gh matt] are completely /opp$1 :ile o!rs h _! velocity r$uc$4 ,9 addition1 !re is a consid]able scatt]+ or diffuse reflection ( ! rays 9 trav]s+ matt]4 ,! am\nt ( ?is scatt]+ dep5ds ^u ! d5sity ( ! sub/ance & also ^u ! angle ( incid5ce ( ! rays4 ,?is scatt]+ ( ! rays w be discuss$ lat] 9 section #aaa4 ,!re are two g5]al me?ods ( det]m9+ ! absorption ( ! rays4 ,9 ! fir/ me?od1 ! v>iation ( ! ionization curr5t is obs]v$ 9 a te/+ vessel :5 ! active matt] is cov]$ by scre5s diff]+ 9 mat]ial & ?ickness4 ,?is ionization 9 ! vessel dep5ds ^u two quantities1 viz4 ! numb] ( p>ticles :i* pass ?r\gh ! matt] & also ^u ! numb] ( ions produc$ by !m p] unit pa?4 ,9 ! abs5ce ( any def9ite in=mation 9 reg>d to ! v>iation ( ionization by ! electron ) its velocity1 no v def9ite conclusions c be drawn f su* exp]im5ts4 ,! adv5t ( pure radium-bromide has made x possible to det]m9e ! actual numb] ( electrons :i* are absorb$ 9 _! passage ?r\gh a def9ite ?ickness ( matt]1 by measur+ ! negative *>ge c>ri$ by ! issu+ rays4 ,exp]im5ts ( ?is "* h be5 made by ,seitz & w be consid]$ lat]4 ,^! two me?ods ( det]m9+ ! absorption ( rays are q di/9ct 9 pr9ciple1 & x is n to be expect$ t ! values ( ! coeffici5ts ( absorption obta9$ 9 ! two cases %\ld be ! same4 ,! :ole "q ( ! absorption ( electrons by matt] is v complicat$1 & ! difficulty is /ill fur!r increas$ by ! complexity ( ! rays emitt$ by ! radio-active sub/ances4 ,_m ( ! results obta9$ by diff]5t me?ods1 :ile po9t+ to ! same g5]al conclusion1 are quantitatively 9 wide disagreem5t4 ,be=e any def9ite advance c be made to a bett] und]/&+ ( ! me*anism ( absorption1 x w be necess>y to det]m9e ! v>iation ( ! ionization ) ! spe$ ( ! electron ov] a v wide range4 ,"s "w has already be5 done 9 ?is direction b n betwe5 suffici5tly wide limits4 ,ionization me?od4 ,we %all fir/ consid] ! results obta9$ on ! absorption ( rays by measur+ ! v>iation ( ! ionization curr5t1 :5 scre5s ( diff]5t ?ickness are plac$ ov] ! active sub/ance4 ,:5 ! active matt] is cov]$ ) alum9ium foil ( ?ickness #a mm41 ! curr5t 9 a te/+ vessel su* z is %[n 9 ,fig4 #ag1 is due almo/ entirely to ! rays4 ,if a uranium comp\nd is us$1 x is f\nd t ! saturation curr5t decreases ) ! ?ickness ( matt] trav]s$ ne>ly accord+ to an expon5tial law4 ,tak+ ! saturation curr5t z a measure ( ! int5sity ( ! rays1 ! int5sity ,i aft] pass+ ?r\gh a ?ickness d ( matt] is giv5 by frac ,i ,i e- d 1 :]e is ! con/ant ( absorption ( ! rays & ,i is ! initial int5sity4 ,= uranium rays1 ! curr5t is r$uc$ to half its value aft] pass+ ?r\gh ab\t #e mm4 ( alum9ium4 ,if a comp\nd ( ?orium or radium is exam9$ 9 ! same way1 x is f\nd t ! curr5t does n decrease regul>ly accord+ to ! above equation4 ,results ( ?is k9d = radium rays h be5 giv5 by ,mey] & ,s*weidl]#acc4 ,! am\nt ( absorption ( ! rays by a c]ta9 ?ickness ( matt] decreases ) ! ?ickness trav]s$4 ,?is is exactly opposite to :at is obs]v$ = ! rays4 ,?is v>iation 9 ! absorption is due to ! fact t ! rays are made up ( rays :i* v>y greatly 9 p5etrat+ p[]4 ,! rays f uranium are fairly homog5e\s 9 "*1 i4e4 !y consi/ ( rays project$ ) ab\t ! same velocity4 ,! rays f radium & ?orium are complex1 i4e4 !y consi/ ( rays project$ ) a wide range ( velocity & consequ5tly ) a wide range ( p5etrat+ p[]4 ,! electrical exam9ation ( ! deviable rays ?us leads to ! same results z _! exam9ation by ! photographic me?od4 ,results on ! absorption ( ca?ode rays h be5 giv5 by ,l5>d#acd1 :o has %[n t ! absorption ( ca?ode rays is ne>ly proportional to ! d5sity ( ! absorb+ matt]1 & is indep5d5t ( its *emical /ate4 ,if ! deviable rays f active bodies are simil> to ca?ode rays1 a simil> law ( absorption is to be expect$4 ,/rutt#ace1 work+ ) radium rays1 has det]m9$ ! law ( absorption1 & has f\nd x r\ghly proportional to ! d5sity ( matt] ov] a range ( d5sities v>y+ f #jjda = sulphur dioxide to #bae = plat9um4 ,9 ! case ( mica & c>dbo>d1 ! values ( divid$ by ! d5sity 7 #cid & #chd respectively1 :ile ! value = plat9um 0 #gcd4 ,9 ord] to d$uce ! absorption coeffici5t1 he assum$ t ! radiation fell (f accord+ to an expon5tial law ) ! di/ance trav]s$4 ,z ! rays f radium are complex1 we h se5 t ?is is only approximately ! case4 ,s9ce ! rays f uranium are fairly homog5e\s1 & are at ! same "t p5etrat+ 9 "*1 !y are m suitable = su* a det]m9ation ?an ! complex rays ( radium4 ,i h 9 consequ5ce made "s exp]im5ts ) uranium rays to det]m9e ! dep5d5ce ( absorption on ! d5sity4 ,! results obta9$ are giv5 9 ! foll[+ table1 :]e is ! coeffici5t ( absorption4 ,sub/ance ,d5sity _/,d5sity ,glass #adj #bde #eg ,mica #adb #bgh #ea ,ebonite #fe #aad #eg ,wood #baf #dj #ed ,c>dbo>d #cg #gj #ec ,iron #dd #gh #ef ,alum9ium #adj #bfj #ed ,copp] #fj #hf #gj ,silv] #ge #aje #ga ,lead #abb #aae #ajh ,t9 #if #gc #acb ,x w be obs]v$ t ! value ( ! absorption con/ant divid$ by ! d5sity is v ne>ly ! same = su* diff]5t sub/ances z glass1 mica1 ebonite1 wood1 iron & alum9ium4 ,! div]g5ces f ! law are great1 h[ev]1 = ! o!r metals exam9$1 viz4 copp]1 silv]1 lead & t94 ,9 t9 ! value ( divid$ by ! d5sity is #be times its value = iron & alum9ium4 ,^! diff]5ces %[ t a law = ! absorption ( ! rays dep5d+ only on ! d5sity does n hold = all sub/ances4 ,) an exception 9 ! case ( t91 ! value ( divid$ by ! d5sity = ! metals increases 9 ! same ord] z _! atomic weights4 ,! absorption ( ! rays by matt] decreases v rapidly ) increase ( spe$4 ,= example1 ! absorption ( ca?ode rays 9 ,l5>d's exp]im5t 7loc4 cit47 is ab\t #ejj times z great z = ! uranium rays4 ,! velocity ( ! rays ( uranium 0 f\nd by ,becqu]el to be ab\t #af #aj cms4 p] sec4 ,! velocity ( ! ca?ode rays us$ 9 ,l5>d's exp]im5t 0 c]ta9ly n less ?an ( ?is1 s t1 = a decrease ( spe$ ( less ?an #aj times1 ! absorption has increas$ ov] #ejj times4 #he4 ,numb] ( electrons /opp$ by matt]4 ,an acc\nt w n[ be giv5 ( ! exp]im5ts made by ,seitz#acf1 to det]m9e ! relative numb] ( electrons :i* are /opp$ 9 _! passage ?r\gh diff]5t ?icknesses ( matt]4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #ca4 ,illu/ration3 ,fig4 #ca4 ,! radium 0 plac$ outside a glass vessel conta9+ an insulat$ brass plate ,p1 ! connection ( :i* ) a wire lead+ to ! electromet] c\ld be made or brok5 by a simple electromagnetic device4 ,! rays f ! radium ,r1 aft] pass+ ?r\gh op5+s 9 a brass plate ,a1 cov]$ ) ?9 alum9ium foil1 7 absorb$ 9 ! plate ,p4 ,! glass vessel 0 exhau/$1 & ! *>ge communicat$ to ,p by ! rays 0 measur$ by an electromet]4 ,9 a good vacuum1 ! magnitude ( ! curr5t obs]v$ is a measure ( ! numb] ( p>ticles absorb$ by ! upp] plate#acg4 ,! foll[+ table %[s ! results obta9$ :5 diff]5t ?icknesses ( t9 foil 7 plac$ ov] ! radium4 ,! second table gives ! ratio ,i_/,i :]e ,i is ! rate ( dis*>ge obs]v$ be=e ! absorb+ scre5 is introduc$4 ,! mean value ( ! absorption con/ant 0 d$uc$ f ! equation frac ,i ,i e- d :]e d is ! ?ickness ( matt] trav]s$4 ,! values includ$ 9 ! brackets h n ! same accuracy z ! o!rs4 ,!re is ?us a wide diff]5ce 9 p5etrat+ p[] ( ! p>ticles emitt$ f radium1 & "s ( !m are v readily absorb$4 ,:5 a lead scre5 #c mms4 ?ick 0 plac$ ov] ! radium--a ?ickness suffici5t to absorb all ! readily deflectable rays--a small negative *>ge 0 /ill giv5 to ! plate1 correspond+ to #bi p] c5t4 ( ! maximum4 ,?is is a v mu* small] value ?an 0 obs]v$ by ,pas*5 7see ,fig4 #cj74 ,?ickness ( ,i_/,i ,t9 9 mms4 #jjjhcd #hfi #age #jjaff #hjb #acbe #jjdba #fec #ajae #jjhah #dff #ice #jabd #cei #hbe #jaff #bhi #gdi #jbje #bcj #gae #jbgj #agj #fed #jeah #jfe #ec #jghi #jca #dd #aehe #jjei #cb #baf #jjdc #be ,?is diff]5ce may1 9 "p1 be due to ! fact t1 9 ,pas*5's exp]im5ts1 a l>ge proportion ( ! sl[ velocity electrons 7 absorb$ 9 ! glass tube ( #e mm4 ?ickness conta9+ ! radium4 ,seitz also det]m9$ ! relative ?ickness1 comp>$ ) t91 ( diff]5t sub/ances :i* r$uc$ ! negative *>ge communicat$ to ,p by a def9ite am\nt4 ,a few ( ! numb]s are giv5 bel[1 & express$ 9 t]ms ( t9 z unity4 ,sub/ance ,?ickness ,t9 #a ,lead #gde ,gold #hc ,plat9um #hd ,silv] #a ,/eel #abi ,alum9ium #aef ,wat] #aff ,p>aff9 #afi ,! ?ickness requir$ to /op a giv5 proportion ( ! rays ?us decreases ) ! d5sity1 b n ne>ly s fa/ z ! d5sity increases4 ,^! results are difficult to reconcile ) ! d5sity-law ( absorption f\nd by ,l5>d f ! ca?ode rays1 or ) ! results ( ! ionization me?od already consid]$4 ,a fur!r exp]im5tal exam9ation ( ! :ole "q is v mu* to be desir$4 #hf4 ,v>iation ( ! am\nt ( radiation ) ! ?ickness ( ! lay] ( radiat+ mat]ial4 ,! radiations are s5t out equally f all portions ( ! active mass1 b ! ionization ( ! gas :i* is measur$ is due only to ! radiations :i* escape into ! air4 ,! dep? f :i* ! radiations c rea* ! surface dep5ds on ! absorption ( ! radiation by ! active matt] itself4 ,let be ! absorption con/ant ( ! homog5e\s radiation by ! active mat]ial4 ,x c readily be %[n t ! int5sity ,i ( ! rays issu+ f a lay] ( active matt]1 ( ?ickness d1 is giv5 by frac ,i ,i#j #a e- d 1 :]e ,i is ! int5sity at ! surface due to a v ?ick lay]4 ,?is equation has be5 confirm$ exp]im5tally by obs]v+ ! curr5t due to ! rays = diff]5t ?icknesses ( uranium oxide4 ,9 ?is case ,i 77,i = a ?ickness ( oxide correspond+ to #aa gr4 p] sq4 cm4 ,?is gives a value ( divid$ by d5sity ( #fc4 ,?is is a value slightly great] ?an t obs]v$ = ! absorption ( ! same rays 9 alum9ium4 ,su* a result %[s cle>ly t ! sub/ance :i* gives rise to ! rays does n absorb !m to a mu* great] ext5t ?an does ord9>y matt] ( ! same d5sity4 ,! value ( w v>y1 n only = ! diff]5t active sub/ances1 b also = ! diff]5t comp\nds ( ! same sub/ance4 ,,"p ,,iii4 ,! ,rays4 #hg4 ,! rays4 ,! magnetic deviation ( ! rays 0 discov]$ t[>ds ! end ( #ahii1 at a comp>atively e>ly /age 9 ! hi/ory ( radio-activity1 b ?ree ye>s elaps$ be=e ! true "* ( ! rays 0 disclos$4 ,x 0 natural t great prom95ce %\ld h be5 giv5 9 ! e>ly /ages ( ! subject to ! rays1 on acc\nt ( _! great p5etrat+ p[] & m>k$ action 9 caus+ phosphoresc5ce 9 _m sub/ances4 ,! rays 71 9 comp>ison1 v little /udi$1 & _! importance 0 n g5]ally recogniz$4 ,x w1 h[ev]1 be %[n t ! rays play a f> m important "p 9 radio-active processes ?an ! rays1 & t ! great] portion ( ! en]gy emitt$ 9 ! =m ( ioniz+ radiations is due to !m4 #hh4 ,! nature ( ! rays4 ,! nature ( ! rays 0 difficult to det]m9e1 = a magnetic field suffici5t to cause consid]able deviation ( ! rays produc$ no appreciable effect on ! rays4 ,x 0 sugge/$ by sev]al obs]v]s t !y 71 9 reality1 second>y rays set up by ! or ca?ode rays 9 ! active matt] f :i* !y 7 produc$4 ,su* a view1 h[ev]1 fail$ to expla9 ! radio-activity ( polonium1 :i* gave out rays only4 ,lat] "w also %[$ t ! matt]1 :i* gave rise to ! rays f uranium1 c\ld be *emically sep>at$ f ! uranium1 :ile ! int5sity ( ! rays 0 unaffect$4 ,^! & o!r results %[ t ! & rays are produc$ q indep5d5tly ( "o ano!r4 ,! view t !y are an easily absorb$ type ( ,rntg5 rays fails to expla9 a *>act]i/ic prop]ty ( ! rays1 viz4 t ! absorption ( ! rays 9 a giv5 ?ickness ( matt]1 det]m9$ by ! electrical me?od1 increases ) ! ?ickness ( matt] previ\sly trav]s$4 ,x does n seem probable t su* an effect c\ld be produc$ by a radiation l ,x rays1 b ! result is to be expect$ if ! rays consi/ ( project$ bodies1 :i* fail to ionize ! gas :5 _! velocity is r$uc$ bel[ a c]ta9 value4 ,f obs]vations ( ! relative ionization produc$ 9 gases by ! & rays1 ,/rutt#ach sugge/$ 9 #aija t ! rays might consi/ ( positively *>g$ bodies project$ ) great velocity4 ,sir ,william ,crookes#aci1 9 #aijb1 advanc$ ! same hypo!sis4 ,f a /udy ( ! rays ( polonium ,mme4 ,curie#adj 9 #aijj sugge/$ ! probability t ^! rays consi/$ ( bodies1 project$ ) great velocity1 :i* lo/ _! en]gy by pass+ ?r\gh matt]4 ,! writ] 0 l$ indep5d5tly to ! same view by a mass ( indirect evid5ce :i* receiv$ an explanation only on ! hypo!sis t ! rays consi/$ ( matt] project$ ) great velocity4 ,prelim9>y exp]im5ts ) radium ( activity #ajjj %[$ t x 0 v difficult to det]m9e ! magnetic deviation ( ! rays4 ,:5 ! rays 7 pass$ ?r\gh slits suffici5tly n>r[ to enable a m9ute deviation ( ! rays to be detect$1 ! ioniz+ effect ( ! issu+ rays 0 too small to be measur$ ) c]ta9ty4 ,x 0 n until radium ( activity #ai1jjj 0 obta9$ t x 0 possible to detect ! deviation ( ^! rays 9 an int5se magnetic field4 ,h[ small ! magnetic deviation is may be judg$ f ! fact t ! rays1 project$ at "r angles to a magnetic field ( #aj1jjj ,c4,g4,s4 units1 describe ! arc ( a circle ( ab\t #ci cms4 radius1 :ile "u ! same conditions ! ca?ode rays produc$ 9 a vacuum tube w\ld describe a circle ( ab\t #ja cm4 radius4 ,x is !re=e n surpris+ t ! rays 7 = "s "t ?\ght to be non-deviable 9 a magnetic field4 #hi4 ,magnetic deviation ( ! rays4 ,! g5]al me?od employ$#ada to detect ! magnetic deviation ( ! rays 0 to all[ ! rays to pass ?r\gh n>r[ slits & to obs]ve :e!r ! rate ( dis*>ge ( an electroscope1 due to ! issu+ rays1 0 alt]$ by ! application ( a /rong magnetic field4 ,fig4 #cb %[s ! g5]al arrangem5t ( ! exp]im5t4 ,! rays f a ?9 lay] ( radium ( activity #ai1jjj pass$ upw>ds ?r\gh a numb] ( n>r[ slits ,g1 9 p>allel1 & !n ?r\gh a ?9 lay] ( alum9ium foil1 #jjjcd cm4 ?ick1 into ! te/+ vessel ,v4 ,! ionization produc$ by ! rays 9 ! te/+ vessel 0 measur$ by ! rate ( movem5t ( ! leaves ( a gold-leaf electroscope ,b4 ,! gold-leaf sy/em 0 insulat$ inside ! vessel by a sulphur bead ,c1 & c\ld be *>g$ by means ( a movable wire ,d1 :i* 0 aft]w>ds e>!d4 ,! rate ( movem5t ( ! gold-leaf 0 obs]v$ ?r\gh small mica w9d[s 9 ! te/+ vessel by means ( a microscope provid$ ) a micromet] eye-piece4 ,illu/ration3 ,fig4 #cb4 ,9 ord] to increase ! ionization 9 ! te/+ vessel1 ! rays pass$ ?r\gh #bj to #be slits ( equal wid?1 plac$ side by side4 ,?is 0 arrang$ by cutt+ grooves at regul> int]vals 9 side-plates into :i* brass plates 7 slipp$4 ,! wid? ( ! slit v>i$ 9 diff]5t exp]im5ts betwe5 #jdb cm4 & #a cm4 ,! magnetic field 0 appli$ p]p5dicul> to ! plane ( ! pap]1 & p>allel to ! plane ( ! slits4 ,! rays are ?us deflect$ 9 a direction p]p5dicul> to ! plane ( ! slits & a v small am\nt ( deviation is suffici5t to cause ! rays to imp+e on ! sides ( ! plate :]e !y are absorb$4 ,! te/+ vessel & sy/em ( plates 7 wax$ to a lead plate ,p s t ! rays ent]$ ! vessel ,v only ?r\gh ! alum9ium foil4 ,x is necess>y 9 ^! exp]im5ts to h a /eady /ream ( gas pass+ d[nw>ds betwe5 ! plates 9 ord] to prev5t ! diffusion ( ! emanation f ! radium upw>ds into ! te/+ vessel4 ,! pres5ce 9 ! te/+ vessel ( a small am\nt ( ?is emanation1 :i* is always giv5 out by radium1 w\ld produce great ionization & completely mask ! effect to be obs]v$4 ,= ?is purpose1 a /eady curr5t ( dry electrolytic hydrog5 ( ab\t #b c4c4 p] second 0 pass$ into ! te/+ vessel2 x !n /ream$ ?r\gh ! por\s alum9ium foil1 & pass$ betwe5 ! plates c>ry+ ! emanation ) x away f ! app>atus4 ,! use ( a /ream ( hydrog5 in/ead ( air greatly simplifies ! exp]im5t1 = x increases ! ionization curr5t due to ! rays 9 ! te/+ vessel1 & at ! same "t greatly dim9i%es t due to ! & rays4 ,?is is caus$ by ! fact t ! rays are mu* m readily absorb$ 9 air ?an 9 hydrog51 :ile ! rate ( production ( ions due to ! & rays is mu* less 9 hydrog5 ?an 9 air4 ,! int5sity ( ! rays aft] pass+ betwe5 ! plates is consequ5tly great] :5 hydrog5 is us$2 & s9ce ! rays pass ?r\gh a suffici5t di/ance ( hydrog5 9 ! te/+ vessel to be l>gely absorb$1 ! total am\nt ( ionization produc$ by !m is great] ) hydrog5 ?an ) air4 ,! foll[+ is an example ( an obs]vation on ! magnetic deviation3-- ,pole-pieces #aij #bej cms4 ,/r5g? ( field betwe5 pole-pieces #hcgj units4 ,app>atus ( #be p>allel plates ( l5g? #cgj cms41 wid? #gj cm41 ) an av]age air-space betwe5 plates ( #jdb cm4 ,di/ance ( radium bel[ plates #ad cm4 ,rate ( dis*>ge ( electroscope 9 volts p] m9ute 7#a7 ,)\t magnetic field #hcc 7#b7 ,) magnetic field #agb 7#c7 ,radium cov]$ ) ?9 lay] ( #jic mica to absorb all rays 7#d7 ,radium cov]$ ) mica & #jib magnetic field appli$ ,! mica plate1 #ja cm4 ?ick1 0 ( suffici5t ?ickness to absorb completely all ! rays1 :ile x all[$ ! rays & rays to pass ?r\gh )\t appreciable absorption4 ,! diff]5ce betwe5 7#a7 & 7#c71 #gdj volts p] m9ute1 gives ! rate ( dis*>ge due to ! rays alone2 ! diff]5ce betwe5 7#b7 & 7#c71 #jgi volts p] m9ute1 t due to ! rays n deviat$ by ! magnetic field employ$4 ,! am\nt ( rays n deviat$ by ! field is ?us ab\t #aa ( ! total4 ,! small diff]5ce betwe5 7#c7 & 7#d7 measures ! small ionization due to ! rays1 = !y w\ld be completely deviat$ by ! magnetic field2 7#d7 comprises ! effect ( ! rays toge!r ) ! natural leak ( ! electroscope 9 hydrog54 ,9 ?is exp]im5t !re 0 a good deal ( /ray magnetic field act+ on ! rays be=e !y rea*$ ! pole-pieces4 ,! dim9ution ( ! rate ( dis*>ge due to ! rays 0 f\nd to be proportional to ! /r5g? ( field betwe5 ! pole-pieces4 ,) a m p[]ful magnetic field1 ! :ole ( ! rays 7 deviat$1 %[+ t !y consi/$ entirely ( project$ *>g$ p>ticles4 ,9 ord] to det]m9e ! direction ( deviation ( ! rays1 ! rays 7 pass$ ?r\gh slits "o mm4 9 wid?1 ea* ( :i* 0 half cov]$ ) a brass /rip4 ,! dim9ution ( ! rate ( dis*>ge 9 ! te/+ vessel = a giv5 magnetic field 9 su* a case dep5ds ^u ! direction ( ! field4 ,9 ?is way x 0 f\nd t ! rays 7 deviat$ 9 ! opposite s5se to ! ca?ode rays4 ,s9ce ! latt] consi/ ( negatively *>g$ p>ticles1 ! rays mu/ consi/ ( positively *>g$ p>ticles4 ,^! results 7 soon aft] confirm$ by ,becqu]el#adb1 by ! photographic me?od1 :i* is v well adapt$ to det]m9e ! "* ( ! pa? ( ! rays act$ on by a magnetic field4 ,! radium 0 plac$ 9 a l9e> groove cut 9 a small block ( lead4 ,above ?is s\rce1 at a di/ance ( ab\t #a c5timetre1 0 plac$ a metallic scre51 =m$ ( two plates1 leav+ betwe5 !m a n>r[ op5+ p>allel to ! groove4 ,above ?is 0 plac$ ! photographic plate4 ,! :ole app>atus 0 plac$ 9 a /rong magnetic field p>allel to ! groove4 ,! /r5g? ( ! magnetic field 0 suffici5t to deflect ! rays completely away f ! plate4 ,:5 ! plate 0 p>allel to ! op5+1 !re 0 produc$ on x an impression1 due to ! rays alone1 :i* became m & m diffuse z ! di/ance f ! op5+ increas$4 ,?is di/ance %\ld n exce$ #a or #b c5timetres on acc\nt ( ! absorption ( ! rays 9 air4 ,if1 dur+ ! exposure1 ! magnetic field is rev]s$ = equal l5g?s ( "t1 on develop+ ! plate two images ( ! rays are obs]v$ :i* are deflect$ 9 opposite directions4 ,?is deviation1 ev5 9 a /rong field1 is small ?\gh q appreciable & is opposite 9 s5se to ! deviation obs]v$ = ! or ca?odic rays f ! same mat]ial4 ,m4 ,becqu]el#adc1 by ! same me?od1 f\nd t ! rays f polonium 7 deviat$ 9 ! same direction z ! rays f radium2 & ?us t !y also consi/ ( project$ positive bodies4 ,9 bo? cases1 ! photographic impressions 7 %>ply m>k$ & did n %[ ! same diffusion :i* always appe>s 9 photographs ( ! rays4 #ij4 ,electro/atic deviation ( ! rays4 ,if ! rays are *>g$ bodies1 !y %\ld be deflect$ 9 pass+ ?r\gh a /rong electric field4 ,?is 0 f\nd by ! writ] to be ! case1 b ! electric deviation is /ill m difficult to detect ?an ! magnetic deviation1 z ! int5sity ( ! electric field mu/ ( necessity be less ?an t requir$ to produce a sp>k 9 ! pres5ce ( radium4 ,! app>atus 0 simil> to t employ$ = ! magnetic deviation 7,fig4 #cb7 ) ?is exception1 t ! brass sides :i* held ! plates 9 position1 7 replac$ by ebonite4 ,alt]nate plates 7 connect$ toge!r & *>g$ to a high pot5tial by means ( a batt]y ( small accumulators4 ,! dis*>ge 9 ! electroscope1 due to ! rays1 0 f\nd to be dim9i%$ by application ( ! electric field4 ,) plates #jee cm4 ap>t & #de cms4 high1 ! dim9ution 0 only #g ) a ,p4,d4 ( #fjj volts betwe5 ! slits4 ,) a special arrangem5t ( plates1 ) slits only #ja cm4 ap>t1 ! dis*>ge 0 dim9i%$ ab\t #de ) an electric field correspond+ to #aj1jjj volts p] cm4 #ia4 ,det]m9ation ( ! con/ants ( ! rays4 ,if ! deviation ( ! rays 9 bo? an electric & magnetic field is kn[n1 ! values ( ! velocity ( ! rays1 & ! ratio e_/m ( ! *>ge ( ! p>ticle to its mass c be det]m9$ by ! me?od1 fir/ us$ by ,j4 ,j4 ,?omson = ! ca?ode rays1 :i* is describ$ 9 section #ej4 ,f ! equations ( a mov+ *>g$ body1 ! radius ( curvature ( ! pa? ( ! rays 9 a magnetic field ( /r5g? ,h p]p5dicul> to ! pa? ( ! rays is giv5 by m ,h ---- ,v 4 e ,if ! p>ticle1 aft] pass+ ?r\gh a uni=m magnetic field = a di/ance l1 is deviat$ ?r\gh a small di/ance d f its orig9al direction1 #b;d l or l e ,h d ----- ---- ---- 7#a74 #b m ,v ,if ! rays pass ?r\gh a uni=m electric field ( /r5g? ,x & l5g? l ) a deviation d1 #a ,xel d --- ------ 7#b71 #b m,v s9ce ,xe_/m is ! accel]ation ( ! p>ticle1 at "r angles to its direction1 & l_/,v is ! "t requir$ to travel ?r\gh ! electric field4 ,f equations 7#a7 & 7#b7 d l ,x ,v ---- ----- -----1 d l ,h & e #b;d ,v ---- ---- --- 4 m l ,h ,! values ( ,v & e_/m are ?us completely det]m9$ f ! comb9$ results ( ! electric & magnetic deviation4 ,x 0 f\nd t ,v #be #aj cms4 p] sec4 e_/m #f #aj4 ,on acc\nt ( ! difficulty ( obta9+ a l>ge electro/atic deviation1 ^! values are only approximate 9 "*4 ,! results on ! magnetic & electric deviation ( ! rays ( radium h be5 confirm$ by ,des ,c\dres#add1 by ! photographic me?od4 ,"s pure radium bromide 0 us$ z a s\rce ( radiation4 ,! :ole app>atus 0 enclos$ 9 a vessel :i* 0 exhau/$ to a l[ vacuum4 ,9 ?is way1 n only 0 he able to det]m9e ! photographic action ( ! rays at a mu* great] di/ance f ! s\rce1 b he 0 also able to apply a /rong] electric field )\t ! passage ( a sp>k4 ,he f\nd values ( ! con/ants giv5 by ,v #afe #aj cms4 p] sec4 e_/m #fd #aj4 ,^! values are 9 v good agreem5t ) ! numb]s f\nd by ! electric me?od4 ,! rays f radium are complex1 & probably consi/ ( a /ream ( positively *>g$ bodies project$ at velocities ly+ betwe5 c]ta9 limits4 ,! am\nt ( deviation ( ! p>ticles 9 a magnetic field w ?us diff] accord+ to ! velocity ( ! p>ticle4 ,! photographic results ( ,becqu]el seem to indicate t ! velocity ( ! rays ( radium c v>y only )9 fairly n>r[ limits1 s9ce ! trajectory ( ! rays 9 a magnetic field is %>ply m>k$ & n ne>ly z diffuse z 9 simil> exp]im5ts ) ! rays4 ,! evid5ce1 h[ev]1 discuss$ 9 ! foll[+ section1 %[s t ! velocities ( ! p>ticles f a ?ick lay] ( radium v>y ov] a consid]able range4 #ib4 ,becqu]el#ade has exam9$ ! am\nt ( magnetic deviation ( ! rays at diff]5t di/ances f ! s\rce ( ! rays 9 a v simple way4 ,a n>r[ v]tical p5cil ( ! rays1 aft] its passage ?r\gh a n>r[ slit1 fell on a photographic plate1 :i* 0 incl9$ at a small angle to ! v]tical & _h its l[] edge p]p5dicul> to ! slit4 ,! trajectory ( ! rays is %[n by a f9e l9e trac$ on ! plate4 ,if a /rong magnetic field is appli$ p>allel to ! slit1 ! trajectory ( ! rays is displac$ to ! "r or left accord+ to ! direction ( ! field4 ,if equal times ( exposure are giv5 = ! magnetic field 9 ! two directions1 on develop+ ! plate two f9e div]g+ l9es are f\nd trac$ on ! plate4 ,! di/ance betwe5 ^! l9es at any po9t is a measure ( twice ! av]age deviation at t po9t1 correspond+ to ! value ( ! magnetic field4 ,by measur+ ! di/ance betwe5 ! trajectories at v>i\s po9ts1 ,becqu]el f\nd t ! radius ( curvature ( ! pa? ( ! rays increas$ ) ! di/ance f ! slit4 ,! product ,h ( ! /r5g? ( ! field & ! radius ( curvature ( ! pa? ( ! rays is %[n 9 ! foll[+ table4 ,di/ance 9 mms4 ,h f ! slit #a #bia #aj #c #bii #e #cjf #g #cae #h #cbg #i #cda ,! writ] 7loc4 cit47 %[$ t ! maximum value ( ,h = complete deviation ( ! rays 0 #cij1jjj4 ,! results are ?us 9 good agreem5t4 ,s9ce m ,h ----- ,v e ^! results %[ t ! values ei!r ( ,v or ( e_/m = ! project$ p>ticles v>y at diff]5t di/ances f ! s\rce4 ,becqu]el consid]$ t ! rays 7 homog5e\s1 &1 9 ord] to expla9 ! results1 has sugge/$ t ! *>ge on ! project$ p>ticles may gradually decrease ) ! di/ance trav]s$1 s t ! radius ( curvature ( ! pa? /eadily increases ) ! di/ance f ! s\rce4 ,x1 h[ev]1 seems m probable t ! rays consi/ ( p>ticles project$ ) diff]5t velocities1 & t ! sl[] p>ticles are m quickly absorb$ 9 ! gas4 ,9 consequ5ce ( ?is1 only ! swift] p>ticles are pres5t "s di/ance f ! s\rce4 ,?is conclusion is borne out by "s rec5t exp]im5ts ( ,bragg & ,kleeman#adf on ! nature ( ! absorption ( p>ticles by matt]1 :i* are discuss$ 9 m detail 9 sections #ajc & #ajd4 ,!y f\nd t ! p>ticles f a ?ick lay] ( radium are complex1 & h a wide range ( p5etrat+ p[] & presumably ( velocity4 ,?is is due to ! fact t ! p>ticles emitt$ f ! radium come f diff]5t dep?s4 ,s9ce _! velocity is r$uc$ 9 _! transit ?r\gh matt]1 a p5cil ( rays w consi/ ( p>ticles :i* diff] consid]ably 9 spe$4 ,^? :i* are j able to em]ge f ! radium w be absorb$ 9 a v %ort dep? ( air1 :ile ^? t come f ! surface w be able to pass ?r\gh sev]al c5timetres ( air be=e !y lose _! p[] ( ioniz+ ! gas4 ,s9ce ! p>ticles h diff]5t velocities1 !y w be unequally deflect$ by ! magnetic field1 ! sl[] mov+ p>ticles describ+ a m curv$ pa? ?an ! swift] ones4 ,consequ5tly1 ! out] edge ( ! trace ( ! p5cil ( rays on ! photographic plate1 z obta9$ by ,becqu]el1 w be ! locus ( ! po9ts :]e ! photographic action ( ! p>ticles end4 ,x 0 f\nd t ! p>ticles are mo/ effici5t z ioniz]s ( ! gas j be=e _! p[] ( ioniz+ ends4 ,! loss ( ioniz+ p[] ( ! p>ticles seems to be fairly abrupt1 &1 = p>ticles ( ! same velocity1 to occur always aft] trav]s+ a def9ite di/ance 9 air4 ,on ! assumption t ! photographic z well z ! ioniz+ action is mo/ int5se j be=e ! p>ticles are /opp$1 & ceases fairly abruptly1 ,bragg has be5 able to acc\nt num]ically = ! measurem5ts 7see above table7 record$ by ,becqu]el4 ,q ap>t f ! special assumptions requir$ = su* a quantitative comp>ison ( !ory ) exp]im5t1 !re c be little d\bt t ! increase ( value ( ,h ) di/ance c be satisfactorily expla9$ z a consequ5ce ( ! complex "* ( ! p5cil ( rays#adg4 ,becqu]el /ates t ! am\nt ( deviation1 9 a giv5 magnetic field1 0 ! same = ! rays ( polonium & ( radium4 ,?is %[s t ! value ( m ---- ,v e is ! same = ! rays f ! two sub/ances4 ,s9ce ! rays f polonium are f> m readily absorb$ ?an ! rays f radium1 ?is result w\ld indicate t ! value ( m_/e is great] = ! p>ticles ( polonium ?an ( radium4 ,fur!r exp]im5tal evid5ce is requir$ on ?is important po9t4 #ic4 ,*>ge c>ri$ by ! rays4 ,we h se5 t ! negative *>ge c>ri$ by ! p>ticles has be5 readily measur$4 ,s9ce !re is reason to believe 7section #bbi7 t f\r p>ticles are expell$ f radium = ea* p>ticle1 x is to be expect$ t ! positive *>ge c>ri$ by ! p>ticles %\ld be det]m9$ /ill m readily4 ,all ! initial exp]im5ts1 h[ev]1 made to detect ?is *>ge1 gave negative results2 &1 be=e successful results 7 obta9$1 x 0 f\nd necess>y to elim9ate "s second>y actions1 :i* at fir/ completely mask$ ! effects to be look$ =4 ,9 consequ5ce ( ! importance ( ?is "q1 a brief acc\nt w be giv5 ( ! me?ods ( measurem5t adopt$ & ! special exp]im5tal difficulties :i* h aris54 ,9 ! fir/ place1 x mu/ be rememb]$ t only a small fraction ( ! rays1 emitt$ f a lay] ( p[d]$ radium bromide1 escape into ! surr\nd+ gas4 ,on acc\nt ( ! ease ) :i* ! rays are /opp$ 9 _! passage ?r\gh matt]1 only ^? escape :i* are expell$ f a sup]ficial lay]1 & ! re/ are absorb$ by ! radium itself4 ,on ! o!r h&1 a mu* l>g] proportion ( ! rays escape1 on acc\nt ( _! great] p[] ( p5etration4 ,9 ! second place1 ! p>ticle is a f> m effici5t ioniz] ( ! gas ?an ! p>ticle1 &1 9 consequ5ce1 if ! *>ge c>ri$ by ! rays is to be det]m9$ by me?ods simil> to ^? employ$ = ! rays 7see section #hj71 ! pressure ( ! gas surr\nd+ ! conductor to be *>g$ mu/ be v small 9 ord] to elim9ate1 z f> z possible1 ! loss ( *>ge result+ f ! ionization ( ! residual gas by ! rays#adh4 ,! exp]im5tal arrangem5t us$ by ! writ] is %[n 9 ,fig4 #cc4 ,a ?9 film ( radium 0 obta9$ on a plate ,a by evaporation ( a radium solution conta9+ a kn[n weight ( radium bromide4 ,"s h\rs aft] evaporation1 ! activity ( ! radium1 measur$ by ! rays1 is ab\t #be p] c5t4 ( its maximum value1 & ! rays are almo/ completely abs5t4 ,! activity measur$ by ! & rays is !n sl[ly rega9$1 & recov]s its orig9al value aft] ab\t a mon?'s int]val 7see *apt] ,,xi474 ,! exp]im5ts 7 made on ! active plate :5 its activity 0 a m9imum1 9 ord] to avoid complications due to ! pres5ce ( rays4 ,! film ( radium 0 s ?9 t only a v small fraction ( ! rays 0 absorb$4 ,illu/ration3 ,fig4 #cc4 ,! active plate ,a 0 insulat$ 9 a metal vessel ,d1 & 0 connect$ to "o pole ( ! batt]y1 ! o!r pole be+ e>!d4 ,! upp] electrode1 :i* 0 insulat$ & connect$ ) a ,dolezalek electromet]1 consi/$ ( a rectangul> copp] vessel ,,bc1 ! l[] "p ( :i* 0 cov]$ ) a ?9 %eet ( alum9ium foil4 ,! rays pass$ ?r\gh ! foil1 b 7 /opp$ by ! copp] sides ( ! vessel4 ,?is arrangem5t 0 f\nd to r$uce ! second>y ionization produc$ at ! surface ( ! upp] plate4 ,! outside vessel ,d c\ld be connect$ ) ei!r ,a or ,b or ) e>?4 ,by means ( a m]cury pump1 ! vessel 0 exhau/$ to a v l[ pressure4 ,if ! rays c>ry a positive *>ge1 ! curr5t betwe5 ! two plates measur$ by ! electromet] %\ld be great] :5 ,a is *>g$ positively4 ,no c]ta9 diff]5ce1 h[ev]1 betwe5 ! curr5ts 9 ! two directions 0 obs]v$1 ev5 :5 a v good vacuum 0 obta9$4 ,9 "s arrangem5ts1 x 0 f\nd t ! curr5t 0 ev5 great] :5 ! l[] plate 0 negative ?an :5 x 0 positive4 ,an unexpect$ exp]im5tal result 0 also notic$4 ,! curr5t betwe5 ! p>allel plates at fir/ dim9i%$ ) ! pressure1 b soon rea*$ a limit+ value :i* 0 n alt]$ h[ev] good a vacuum 0 produc$4 ,= example1 9 "o exp]im5t1 ! curr5t betwe5 ! two p>allel plates1 plac$ ab\t #c mms4 ap>t1 0 initially #fe #aj amp]es & fell (f directly z ! pressure4 ,! curr5t rea*$ a limit+ value ( ab\t #f #aj amp]es1 or ab\t ( ! value at atmosph]ic pressure4 ,! magnitude ( ?is limit+ curr5t 0 n mu* alt]$ if ! air 0 replac$ by hydrog54 ,exp]im5ts ( a simil> "* h be5 made by ,/rutt#adi & ,j4 ,j4 ,?omson#aej2 us+ an active bismu? plate coat$ ) radio-tellurium 7polonium7 aft] ,m>ckwald's me?od4 ,?is sub/ance emits only rays1 & is ?us especially suitable = exp]im5ts ( ?is k9d4 ,/rutt employ$ ! me?od us$ by him to %[ ! *>ge c>ri$ by ! rays 7,fig4 #bg74 ,he f\nd1 h[ev]1 t1 ev5 9 ! l[e/ possible vacuum1 ! electroscope rapidly lo/ its *>ge & at ! same rate :e!r x 0 *>g$ positively or negatively4 ,?is is 9 agreem5t ) ! results f\nd by ! writ] ) radium4 ,9 ! exp]im5ts ( ,j4 ,j4 ,?omson1 ! electroscope 0 atta*$ to a metal disc plac$ #c cms4 f ! plate ( radio-tellurium4 ,a v l[ vacuum 0 produc$ by ,dew>'s me?od by absorb+ ! residual gas 9 cocoanut *>coal imm]s$ 9 liquid air4 ,:5 ! electroscope 0 *>g$ negatively1 an extremely sl[ rate ( leak 0 obs]v$1 b :5 *>g$ positively ! leak 0 ab\t #ajj times great]4 ,?is %[$ t ! polonium gave out l>ge quantities ( negative electricity1 b n en\gh positive to be detect$4 ,by plac+ ! app>atus 9 a /rong magnetic field1 ! negative p>ticles 7 prev5t$ f rea*+ ! electroscope & ! positive leak 0 /opp$4 ,^! results indicate t ^! negative p>ticles are n project$ ) suffici5t velocity to move aga9/ ! repulsion ex]t$ by ! electrifi$ body1 & are b5t by a magnetic field4 ,!re ?us seems little d\bt t a /ream ( negative p>ticles 7electrons7 is project$ f ! active surface at a v sl[ spe$4 ,su* l[ velocity electrons are also project$ f uranium & radium4 ,x is probable t ^! electrons are a type ( second>y radiation1 set up at ! surfaces on :i* ! rays fall4 ,! p>ticles w\ld be extremely readily absorb$ 9 ! gas1 & _! pres5ce w\ld be difficult to detect except 9 l[ vacua4 ,j4 ,j4 ,?omson at fir/ obta9$ no evid5ce t ! p>ticles ( polonium 7 *>g$2 b 9 lat] exp]im5ts1 :]e ! plates 7 clos] toge!r1 ! electroscope indicat$ t ! rays did c>ry a positive *>ge4 ,9 ord] to see :e!r ! positive *>ge due to ! rays f radium c\ld be detect$ :5 ! sl[ mov+ ions 7 prev5t$ f escap+ by a magnetic field1 ,i plac$ ! app>atus ( ,fig4 #cc betwe5 ! pole-pieces ( a l>ge electromagnet1 s t ! magnetic field 0 p>allel to ! plane ( ! plates#aea4 ,a v m>k$ alt]ation 0 obs]v$ bo? on ! magnitude ( ! positive & negative curr5ts4 ,9 a good vacuum1 ! upp] plate receiv$ a positive *>ge1 indep5d5tly ( :e!r ! l[] plate 0 *>g$ positively or negatively or 0 connect$ ) e>?4 ,aft] ! magnetic field _h rea*$ a c]ta9 value1 a great increase 9 its /r5g? _h no appreciable effect on ! magnitude ( ! curr5t4 ,! foll[+ table illu/rates ! results obta9$ :5 ! two plates 7 #c mms4 ap>t1 & 7 bo? coat$ ) ?9 alum9ium foil4 ,pot5tial ,curr5t 9 arbitr>y units ( l[] plate ,)\t magnetic ,) magnetic field field #j -- #cf #b volts #bj #df #ci #b #be #cc #d #bh #dg #da #d #ce #ce #h #ca #ef #dc #h #dj #ca #hd #ce #gg #ej #hd #eb #bd ,let n be ! numb] ( p>ticles1 c>ry+ a *>ge e1 :i* are absorb$ 9 ! upp] plate4 ,let be ! curr5t due to ! slight ionization ( ! residual gas4 ,if only a small pot5tial is appli$ to ! l[] plate1 ?is curr5t %\ld be equal 9 magnitude b opposite 9 sign :5 ! pot5tial is rev]s$4 ,let be ! *>ge p] sec4 communicat$ to ! upp] electrode :5 ! l[] plate is *>g$ positively & ! value :5 *>g$ negatively4 ,!n ne1 ne2 add+ we get ne ------ 4 #b ,n[ 9 ! ?ird column ( ! above table x is se5 t 7 7_/#b has ! values #ci1 #da1 #dc = #b1 #d1 & #h volts respectively4 ,! numb]s are ?us 9 fairly good agreem5t4 ,simil> results 7 obta9$ :5 a brass plate 0 sub/itut$ = ! upp] electrode %[n 9 ! figure4 ,tak+ into consid]ation t ! magnitude ( ne is indep5d5t ( ! /r5g? ( ! magnetic field above a c]ta9 small value1 & ! good agreem5t ( ! numb]s obta9$ ) v>iation ( voltage1 ,i ?9k t !re c be no d\bt t ! positive *>ge communicat$ to ! upp] electrode 0 c>ri$ by ! p>ticles4 ,?is positive *>ge 0 n small1 = us+ a weight ( #dh mgrs4 radium bromide spread 9 a ?9 foil ov] an area ( ab\t #bj sq4 cms41 ! *>ge communicat$ by ! p>ticles correspond$ to a curr5t #hh #aj amp]es1 &1 ) ! ,dolezalek electromet] employ$1 x 0 necess>y to add a capacity ( #jjbd micr(>ads to ! electromet] sy/em4 ,9 ^! exp]im5ts1 ! film ( radium bromide 0 s ?91 t only a v small p]c5tage ( ! p>ticles 0 /opp$ by ! radium itself4 ,assum+ t ea* p>ticle c>ries ! same *>ge z an ion1 viz4 #aa #aj c\lombs1 & rememb]+ t half ( ! p>ticles are absorb$ 9 ! l[] plate1 ! total numb] ,n ( p>ticles expell$ p] second f "o gram ( radium bromide 7at its m9imum activity7 c be d$uc$4 ,9 two sep>ate exp]im5ts :]e ! am\nt ( radium us$ 0 #aid & #dhd mgrs4 respectively1 ! values ( ,n 7 9 close agreem5t & equal to #cf #aj4 ,n[ x w be %[n lat] t 9 radium !re are ?ree o!r products 9 radio-active equilibrium1 ea* ( :i* probably gives out ! same numb] ( p>ticles z radium itself4 ,if ?is is ! case1 ! total numb] ( p>ticles expell$ p] second f #a gram ( radium bromide 9 radio-active equilibrium is #d,n or #add #aj4 ,assum+ ! composition ( radium bromide z ,ra,br1 ! numb] p] second p] gram ( radium is #be #aj4 ,?is numb] w be f\nd to be 9 v good agreem5t ) t d$uc$ f indirect data 7*apt] ,,xiii474 ,! value ( ,n is ( great importance 9 det]m9+ ! magnitude ( v>i\s quantities 9 radio-active calculations4 #id4 ,mass & en]gy ( ! p>ticle4 ,x has be5 po9t$ out t ! rays f radium & polonium are analog\s to ! ,canal rays ( ,gold/e91 = bo? c>ry a positive *>ge & are difficult to deflect by a magnetic field4 ,! exp]im5ts ( ,wi5 h %[n t ! velocity ( projection ( ! canal rays v>ies ) ! gas 9 ! tube & ! int5sity ( ! electric field appli$1 b x is g5]ally ab\t ( ! velocity ( ! p>ticle f radium4 ,! value ( e_/m is also v>iable1 dep5d+ ^u ! gas 9 ! tube4 ,x has be5 %[n t = ! rays ( radium e ,v #be #aj & ---- #f #aj4 m ,n[ ! value ( e_/m = ! hydrog5 atom1 lib]at$ 9 ! electrolysis ( wat]1 is #aj4 ,assum+ ! *>ge c>ri$ by ! p>ticle to be ! same z t c>ri$ by ! hydrog5 atom1 ! mass ( ! p>ticle is ab\t twice t ( ! hydrog5 atom4 ,tak+ into consid]ation ! unc]ta9ty atta*+ to ! exp]im5tal value ( e_/m = ! p>ticle1 if ! p>ticle consi/s ( any kn[n k9d ( matt]1 ?is result indicates t x consi/s ei!r ( project$ helium or hydrog54 ,fur!r evid5ce on ?is important "q is giv5 9 section #bfj4 ,! rays f all ! radio-active sub/ances & _! products1 su* z ! radio-active emanations & ! matt] caus+ excit$ activity1 possess ! same g5]al prop]ties & d n v>y v mu* 9 p5etrat+ p[]4 ,x is ?us probable t 9 all cases ! rays f ! diff]5t radio-active sub/ances consi/ ( positively *>g$ bodies project$ ) great velocity4 ,s9ce ! rays f radium are made up 9 "p ( rays f ! emanation /or$ 9 ! radium1 & f ! excit$ activity :i* x produces1 ! rays f ea* ( ^! products mu/ consi/ ( positively *>g$ bodies2 = x has be5 %[n t all ! rays f radium are deviat$ 9 a /rong magnetic field4 ,! k9etic en]gy ( ea* project$ p>ticle is enorm\s1 comp>$ ) its mass4 ,! k9etic en]gy ( ea* p>ticle is #a #a m --- m,v -- --- ,ve #ei #aj ergs4 #b #b e ,tak+ ! velocity ( a rifle bullet z #aj cms4 p] second1 x is se5 t1 mass = mass1 ! en]gy ( motion ( ! rays is #f #aj times z great z t ( ! rifle bullet4 ,9 ?is projection ( bodies atomic 9 size ) great velocity probably lies ! pr9cipal cause ( ! heat+ effects produc$ by radium 7*apt] ,,xii74 #ie4 ,atomic dis9tegration4 ,! radio-activity ( ! radio-elem5ts is an atomic & n a molecul> prop]ty4 ,! rate ( emission ( ! radiations dep5ds only on ! am\nt ( ! elem5t pres5t & is indep5d5t ( its comb9ation ) inactive sub/ances4 ,9 addition1 x w be %[n lat] t ! rate ( emission is n affect$ by wide v>iations ( temp]ature1 or by ! application ( any kn[n *emical or physical =ces4 ,s9ce ! p[] ( radiat+ is a prop]ty ( ! radio-atoms1 & ! radiations consi/ = ! mo/ "p ( positively & negatively *>g$ masses project$ ) great velocity1 x is necess>y to suppose t ! atoms ( ! radio-elem5ts are und]go+ dis9tegration1 9 ! c\rse ( :i* p>ts ( ! atom escape f ! atomic sy/em4 ,x seems v improbable t ! & p>ticles c sudd5ly acquire _! enorm\s velocity ( projection by ! action ( =ces exi/+ inside or outside ! atom4 ,= example1 ! p>ticle w\ld h to travel f re/ betwe5 two po9ts diff]+ 9 pot5tial by #eb million volts 9 ord] to acquire ! k9etic en]gy ) :i* x escapes4 ,?us x seems probable t ^! p>ticles are n set sudd5ly 9 motion1 b t !y escape f an atomic sy/em 9 :i* !y 7 already 9 rapid oscillatory or orbital motion4 ,on ?is view1 ! en]gy is n communicat$ to ! project$ p>ticles1 b exi/s be=eh& 9 ! atoms f :i* !y escape4 ,! idea t ! atom is a complicat$ /ructure consi/+ ( *>g$ p>ts 9 rapid oscillatory or orbital motion has be5 develop$ by ,j4 ,j4 ,?omson1 ,l>mor & ,lor5tz4 ,s9ce ! p>ticle is atomic 9 size1 x is natural to suppose t ! atoms ( ! radio-active elem5ts consi/ n only ( ! electrons 9 motion1 b also ( positively *>g$ p>ticles ^: mass is ab\t ! same z t ( ! hydrog5 or helium atom4 ,x w be %[n lat] t only a m9ute fraction ( ! atoms ( ! radio-elem5t ne$ break up p] second 9 ord] to acc\nt = ! radiations ev5 ( an enorm\sly active elem5t l radium4 ,! "q ( ! possible causes :i* lead to ?is atomic dis9tegration & ! consequ5ces :i* foll[ f x w be discuss$ lat] 9 *apt] ,,xiii4 #if4 ,exp]im5ts ) a z9c sulphide scre54 ,a scre5 ( ,sidot's hexagonal bl5d 7phosphoresc5t cry/all9e z9c sulphide7 lights up brightly "u ! action ( ! rays ( radium & polonium4 ,if ! surface ( ! scre5 is exam9$ ) a magnify+ glass1 ! light f ! scre5 is f\nd n to be uni=mly di/ribut$ b to consi/ ( a numb] ( sc9tillat+ po9ts ( light4 ,no two fla%es succe$ "o ano!r at ! same po9t1 b !y are scatt]$ ov] ! surface1 com+ & go+ rapidly )\t any movem5t ( translation4 ,?is rem>kable action ( ! radium & polonium rays on a z9c sulphide scre5 0 discov]$ by ,sir ,william ,crookes#aeb1 & indep5d5tly by ,el/] & ,geitel#aec1 :o obs]v$ x ) ! rays giv5 out f a wire :i* has be5 *>g$ negatively ei!r 9 ! op5 air or 9 a vessel conta9+ ! emanation ( ?orium4 ,9 ord] to %[ ! sc9tillations ( radium on ! scre51 ,sir ,william ,crookes has devis$ a simple app>atus :i* he has call$ ! 8,sp9?>iscope40 ,a small piece ( metal1 :i* has be5 dipp$ 9 a radium solution1 is plac$ sev]al millimetres away f a small z9c sulphide scre54 ,?is scre5 is fix$ at "o end ( a %ort brass tube & is look$ at ?r\gh a l5s fix$ at ! o!r end ( ! tube4 ,view$ 9 ?is way1 ! surface ( ! scre5 is se5 z a d>k backgr\nd1 dott$ ) brilliant po9ts ( light :i* come & g ) great rapidity4 ,! numb] ( po9ts ( light p] unit area to be se5 at "o "t falls (f rapidly z ! di/ance f ! radium increases1 &1 at sev]al c5timetres di/ance1 only an occasional "o is se54 ,! exp]im5t is extremely beautiful1 & br+s vividly be=e ! obs]v] ! idea t ! radium is %oot+ out a /ream ( projectiles1 ! impact ( ea* ( :i* on ! scre5 is m>k$ by a fla% ( light4 ,! sc9tillat+ po9ts ( light on ! scre5 are ! result ( ! impact ( ! p>ticles on its surface4 ,if ! radium is cov]$ ) a lay] ( foil ( suffici5t ?ickness to absorb all ! rays ! sc9tillations cease4 ,!re is /ill a phosphoresc5ce to be obs]v$ on ! scre5 due to ! & rays1 b ?is lum9osity is n m>k$ by sc9tillations to any appreciable ext5t4 ,sir ,william ,crookes %[$ t ! numb] ( sc9tillations 0 ab\t ! same 9 vacuo z 9 air at atmosph]ic pressure4 ,if ! scre5 0 kept at a con/ant temp]ature1 b ! radium cool$ d[n to ! temp]ature ( liquid air1 no appreciable diff]5ce 9 ! numb] ( sc9tillations 0 obs]v$4 ,if1 h[ev]1 ! scre5 0 gradually cool$ to ! temp]ature ( liquid air1 ! sc9tillations dim9i%$ 9 numb] & f9ally ceas$ altoge!r4 ,?is is due to ! fact t ! scre5 loses to a l>ge ext5t its p[] ( phosphoresc5ce at su* a l[ temp]ature4 ,n only are sc9tillations produc$ by radium1 act9ium1 & polonium1 b also by ! emanations & o!r radio-active products :i* emit rays4 ,9 addition1 ,f4 ,h4 ,glew#aed has f\nd t !y c be obs]v$ f ! metal uranium1 ?orium comp\nds & v>i\s v>ieties ( pit*bl5de4 ,9 ord] to %[ ! sc9tillations produc$ by pit*bl5de1 a flat surface 0 gr\nd1 & a transp>5t scre51 ^: l[] surface 0 coat$ ) z9c sulphide1 plac$ ^u x4 ,glew has design$ a modifi$ & v simple =m ( sp9?>iscope4 ,a transp>5t scre51 coat$ on "o side ) a ?9 lay] ( z9c sulphide1 is plac$ 9 contact ) ! active mat]ial1 & ! sc9tillations obs]v$ by a l5s 9 ! usual way4 ,s9ce !re is no absorption 9 ! air1 ! lum9osity is a maximum4 ,! relative transp>5cy ( diff]5t sub/ances plac$ betwe5 ! active mat]ial & ! scre5 may1 9 ?is way1 be directly /udi$4 ,! production ( sc9tillations appe>s to be a g5]al prop]ty ( ! rays f all radio-active sub/ances4 ,! sc9tillations are be/ %[n ) a z9c sulphide scre52 b are also obs]v$ ) willemite 7z9c silicate71 p[d]$ diamond1 & potassium plat9ocyanide 7,glew1 loc4 cit474 ,if a scre5 ( b>ium plat9ocyanide is expos$ to ! rays f radium1 ! sc9tillations are difficult to obs]ve1 & ! lum9osity is f> m p]si/5t ?an = a z9c sulphide scre5 expos$ "u ! same conditions4 ,! duration ( ! phosphoresc5ce 9 ?is case probably acc\nts = ! abs5ce ( visible sc9tillations4 ,!re c be no d\bt t ! sc9tillations result f ! cont9u\s bomb>dm5t ( ! s5sitive scre5 by ! p>ticles4 ,ea* ( ^! p>ticles moves ) enorm\s velocity1 & has a consid]able en]gy ( motion4 ,on acc\nt ( ! ease ) :i* ^! p>ticles are /opp$1 mo/ ( ?is en]gy is giv5 up at ! surface ( ! scre51 & a portion ( ! en]gy is 9 "s way trans=m$ into light4 ,z9c sulphide is v s5sitive to me*anical %ocks4 ,lum9osity is obs]v$ if a p5knife is drawn across ! scre51 or if a curr5t ( air is direct$ on to ! scre54 ,! di/urbance effect$ by ! impact ( ! p>ticle ext5ds ov] a di/ance v l>ge comp>$ ) ! size ( ! imp++ p>ticle1 s t ! spots ( light produc$ h an appreciable area4 ,rec5tly ,becqu]el#aee has made an exam9ation ( ! sc9tillations produc$ by diff]5t sub/ances1 & has conclud$ t ! sc9tillations are due to irregul> cleavages 9 ! cry/als compos+ ! scre51 produc$ by ! action ( ! rays4 ,sc9tillations c be me*anically produc$ by cru%+ a cry/al4 ,tommas9a#aef f\nd t a z9c sulphide scre5 remov$ f ! action ( ! radium rays = sev]al days1 %[$ ! sc9tillations aga9 :5 an electrifi$ rod 0 br\ght ne> x4 ,! numb] ( sc9tillations produc$ 9 z9c sulphide dep5ds ^u ! pres5ce ( a slight am\nt ( impurity & on its cry/all9e /ate4 ,x c be %[n t ev5 ) ! mo/ s5sitive z9c sulphide scre5s1 ! numb] ( sc9tillations is probably only a small fraction ( ! total numb] ( p>ticles :i* fall ^u x4 ,x w\ld appe> t ! cry/als are 9 "s way alt]$ by ! bomb>dm5t ( ! p>ticles1 & t "s ( ! cry/als occasionally break up ) emission ( light#aeg4 ,al?\gh ! sc9tillations f a p>ticle ( pure radium bromide are v num]\s1 !y are n too num]\s to be c\nt$4 ,close to ! radium1 ! lum9osity is v bright1 b by us+ a high p[] microscope ! lum9osity c /ill be %[n to consi/ ( sc9tillations4 ,s9ce ! numb] ( sc9tillations probably be>s no close relation to ! numb] ( p>ticles emitt$1 a det]m9ation ( ! numb] ( sc9tillations w\ld h no special physical significance4 ,! relation betwe5 ! numb] ( p>ticles & ! numb] ( sc9tillations w\ld probably be v>iable1 dep5d+ greatly on ! exact *emical composition ( ! s5sitive sub/ance & also ^u its cry/all9e /ate4 #ig4 ,absorption ( ! rays by matt]4 ,! rays f ! diff]5t radio-active sub/ances c be di/+ui%$ f "o ano!r by ! relative am\nts ( _! absorption by gases or by ?9 scre5s ( solid sub/ances4 ,:5 exam9$ "u ! same conditions1 ! rays f ! active sub/ances c be arrang$ 9 a def9ite ord] ) ref]5ce to ! am\nt ( absorption 9 a giv5 ?ickness ( matt]4 ,9 ord] to te/ ! am\nt ( absorption ( ! rays = diff]5t ?icknesses ( matt]1 an app>atus simil> to t %[n 9 ,fig4 #ag1 p4 #ih1 0 employ$#aeh4 ,a ?9 lay] ( ! active mat]ial 0 spread uni=mly ov] an area ( ab\t #cj sq4 cms41 & ! saturation curr5t obs]v$ betwe5 two plates #ce cms4 ap>t4 ,) a ?9 lay]#aei ( active mat]ial1 ! ionization betwe5 ! plates is due almo/ entirely to ! rays4 ,! ionization due to ! & rays is g5]ally less ?an #a ( ! total4 ,! foll[+ table %[s ! v>iation ( ! saturation curr5t betwe5 ! plates due to ! rays f radium & polonium1 ) successive lay]s ( alum9ium foil int]pos$1 ea* #jjjcd cm4 9 ?ickness4 ,9 ord] to get rid ( ! ionization due to ! rays f radium1 ! radium *loride employ$ 0 dissolv$ 9 wat] & evaporat$4 ,?is r5d]s ! active comp\nd1 = ! "t1 ne>ly free f rays4 ,! initial curr5t ) #a lay] ( alum9ium ov] ! active mat]ial is tak5 z #ajj4 ,x w be obs]v$ t ! curr5t due ,polonium4 ,radium4 ,lay]s ( ,curr5t ,ratio ( ,lay]s ( ,curr5t ,ratio ( alum9ium decrease alum9ium decrease = ea* = ea* lay] lay] #j #ajj #j #ajj #da #dh #a #da #a #dh #ca #dh #b #abf #b #bc #ag #fj #c #ba #c #acf #jfg #dg #d #ad #d #fd #ci #e #j #e #be #cf #f #i #g #j to ! radium rays decreases v ne>ly by half its value = ea* additional ?ickness until ! curr5t is r$uc$ to ab\t #f ( ! maximum4 ,x !n decays m rapidly to z]o4 ,?us1 = radium1 ov] a wide range1 ! curr5t decreases approximately accord+ to an expon5tial law ) ! ?ickness ( ! scre51 or frac i i e d 1 :]e i is ! curr5t = a ?ickness d1 & i ! initial curr5t4 ,9 ! case ( polonium1 ! decrease is f> m rapid ?an w\ld be indicat$ by ! expon5tial law4 ,by ! fir/ lay]1 ! curr5t is r$uc$ to ! ratio #da4 ,! addition ( ! ?ird lay] cuts ! curr5t d[n to a ratio ( #ag4 ,= mo/ ( ! active bodies1 ! curr5t dim9i%es slightly fa/] ?an ! expon5tial law w\ld lead "o to expect1 especially :5 ! radiation is ne>ly all absorb$4 #ih4 ,! increase ( absorption ( ! rays ( polonium ) ! ?ickness ( matt] trav]s$ has be5 v cle>ly %[n 9 "s exp]im5ts made by ,mme ,curie4 ,! app>atus employ$ is %[n 9 ,fig4 #cd4 ,illu/ration3 ,fig4 #cd4 ,! saturation curr5t 0 measur$ betwe5 two p>allel plates ,,pp #c cms4 ap>t4 ,! polonium ,a 0 plac$ 9 ! metal box ,,cc1 & ! rays f x1 aft] pass+ ?r\gh an op5+ 9 ! l[] plate ,p1 cov]$ ) a lay] ( ?9 foil ,t1 ioniz$ ! gas betwe5 ! plates4 ,= a c]ta9 di/ance ,,at1 ( #d cms4 or m1 no appreciable curr5t 0 obs]v$ betwe5 ,p & ,p4 ,z ! di/ance ,,at 0 dim9i%$1 ! curr5t increas$ 9 a v sudd5 mann]1 s t = a small v>iation ( ! di/ance ,,at !re 0 a l>ge increase ( curr5t4 ,) /ill fur!r decrease ( di/ance ! curr5t increases 9 a m regul> mann]4 ,! results are %[n 9 ! foll[+ table1 :]e ! scre5 ,t consi/$ ( "o & two lay]s ( alum9ium foil respectively4 ,! curr5t due to ! rays1 )\t ! alum9ium scre51 is 9 ea* case tak5 z #ajj4 ,di/ance ,,at 9 cms4 #ce #be #ai #ade #je ,= #ajj rays #j #j #e #aj #be transmitt$ by "o lay] ,= #ajj rays #j #j #j #j #jg transmitt$ by two lay]s ,! metallic scre5 ?us cuts (f a great] proportion ( ! rays ! great] ! di/ance ( air :i* ! radiations trav]se4 ,! effects are /ill m m>k$ if ! plates ,,pp are close toge!r4 ,results simil> b n s m>k$ are f\nd if radium is sub/itut$ = ! polonium4 ,x foll[s f ^! exp]im5ts t ! ionization p] unit volume1 due to a l>ge plate uni=mly cov]$ ) ! radio-active matt]1 falls (f rapidly ) ! di/ance f ! plate4 ,at a di/ance ( #aj cms4 ! rays f uranium1 ?orium1 or radium h be5 completely absorb$ 9 ! gas1 & ! small ionization !n obs]v$ 9 ! gas is due to ! m p5etrat+ & rays4 ,! relative am\nt ( ! ionization obs]v$ at a di/ance f ! s\rce w increase ) ! ?ickness ( ! lay] ( active matt]1 b w rea* a maximum = a lay] ( a c]ta9 ?ickness4 ,! great] proportion ( ! ionization1 due to unscre5$ active matt]1 is ?us entirely conf9$ to a %ell ( air surr\nd+ x n m ?an #aj cms4 9 dep?4 ,illu/ration3 ,fig4 #ce4 #ii4 ,! rays f diff]5t comp\nds ( ! same active elem5t1 al?\gh diff]+ 9 am\nt1 h ab\t ! same av]age p5etrat+ p[]4 ,exp]im5ts on ?is po9t h be5 made by ! writ]#afj & by ,ow5s#afa4 ,?us 9 comp>+ ! relative p[] ( p5etration ( ! rays f ! diff]5t radio-elem5ts1 x is only necess>y to det]m9e ! p5etrat+ p[] = "o comp\nd ( ea* ( ! radio-elem5ts4 ,ru!r=d & ,miss ,brooks#afb h det]m9$ ! am\nt ( absorption ( ! rays f ! diff]5t active sub/ances 9 _! passage ?r\gh successive lay]s ( alum9ium foil #jjjcd cm4 ?ick4 ,! curves ( absorption are giv5 9 ,fig4 #ce4 ,= ! purpose ( comp>ison 9 ea* case1 ! initial curr5t ) ! b>e active comp\nd 0 tak5 z #ajj4 ,a v ?9 lay] ( ! active sub/ance 0 us$1 &1 9 ! case ( ?orium & radium1 ! emanations giv5 (f 7 remov$ by a sl[ curr5t ( air ?r\gh ! te/+ vessel4 ,a pot5tial diff]5ce ( #cjj volts 0 appli$ betwe5 ! plates1 :i* 0 suffici5t to give ! maximum curr5t 9 ea* case4 ,curves = ! m9]als organite & ?orite 7 v ne>ly ! same z = ?oria4 ,= comp>ison1 ! absorption curves ( ! excit$ radiations ( ?orium & radium are giv51 z well z ! curve = ! radio-elem5ts uranium1 ?orium1 radium1 & polonium4 ,! radiations may be arrang$ 9 ! foll[+ ord]1 z reg>ds _! p[] ( p5etration1 beg9n+ ) ! mo/ p5etrat+4 ,?orium ,radium excit$ radiation4 ,?orium4 ,radium4 ,polonium4 ,uranium4 ,! same ord] is obs]v$ = all ! absorb+ sub/ances exam9$1 viz41 alum9ium1 ,dut* metal1 t9foil1 pap]1 & air & o!r gases4 ,! diff]5ces 9 ! absorption ( ! rays f ! active bodies are ?us consid]able1 & mu/ be ascrib$ ei!r to a diff]5ce ( mass or ( velocity ( ! p>ticles or to a v>iation 9 bo? ^! quantities4 ,s9ce ! rays diff] ei!r 9 mass or velocity1 x foll[s t !y _c be ascrib$ to any s+le radio-active impurity common to all radio-active bodies4 #ajj4 ,absorption ( ! rays by gases4 ,! rays f ! diff]5t radio-active sub/ances are quickly absorb$ 9 _! passage ?r\gh a few c5timetres ( air at atmosph]ic pressure & temp]ature4 ,9 consequ5ce ( ?is1 ! ionization ( ! air1 due to ! rays1 is greate/ ne> ! surface ( ! radiat+ body & falls (f v rapidly ) ! di/ance 7see section #ih74 ,illu/ration3 ,fig4 #cf4 ,a simple me?od ( det]m9+ ! absorption 9 gases is %[n 9 ,fig4 #cf4 ,! maximum curr5t is measur$ betwe5 two p>allel plates ,a & ,b kept at a fix$ di/ance ( #b cms4 ap>t1 & !n mov$ by means ( a screw to diff]5t di/ances f ! radio-active surface4 ,! radiation f ?is active surface pass$ ?r\gh a circul> op5+ 9 ! plate ,a1 cov]$ ) ?9 alum9ium foil1 & 0 /opp$ by ! upp] plate4 ,= obs]vations on o!r gases besides air1 & = exam9+ ! effect at diff]5t pressures1 ! app>atus is enclos$ 9 an air-tight cyl9d]4 ,if ! radius ( ! active surface is l>ge comp>$ ) ! di/ance ( ! plate ,a f x1 ! int5sity ( ! radiation is approximately uni=m ov] ! op5+ 9 ! plate ,a1 & falls (f ) ! di/ance x trav]s$ accord+ to an expon5tial law4 ,?us frac ,i ,i e- x 1 :]e is ! 8absorption con/ant0 ( ! radiation = ! gas "u consid]ation#afc4 ,let x di/ance ( l[] plate f active mat]ial1 l di/ance betwe5 ! two fix$ plates4 ,! en]gy ( ! radiation at ! l[] plate is !n ,i e- x 1 & at ! upp] plate ,i e- 7l x7 4 ,! total numb] ( ions produc$ betwe5 ! p>allel plates ,a & ,b is !re=e proportional to e- x e- 7l x7 e- x 7#a - e- l7 4 ,s9ce ! factor #a e- l is a con/ant1 ! saturation curr5t betwe5 ,a & ,b v>ies z e- x 1 i4e4 x decreases accord+ to an expon5tial law ) ! di/ance trav]s$4 ,illu/ration3 ,fig4 #cg4 ,! v>iation ( ! curr5t betwe5 ,a & ,b ) ! di/ance f a ?9 lay] ( uranium oxide is %[n 9 ,fig4 #cg = diff]5t gases4 ,! initial measurem5ts 7 tak5 at a di/ance ( ab\t #ce mms4 f ! active surface4 ,! actual values ( ?is initial curr5t 7 diff]5t = ! diff]5t gases1 b1 = ! purposes ( comp>ison1 ! value is 9 ea* case tak5 z unity4 ,x w be se5 t ! curr5t falls (f ) ! di/ance approximately 9 a geometrical progression1 a result :i* is 9 agreem5t ) ! simple !ory giv5 above4 ,! di/ance ?r\gh :i* ! rays pass be=e !y are absorb$ is giv5 bel[ = diff]5t gases4 ,gas ,di/ance 9 mms4 to absorb half ( radiation ,c>bonic acid #c ,air #dc ,coal-gas #ge ,hydrog5 #af ,! results = hydrog5 are only approximate1 z ! absorption is small ov] ! di/ance exam9$4 ,! absorption is lea/ 9 hydrog5 & greate/ 9 c>bonic acid1 & foll[s ! same ord] z ! d5sities ( ! gases4 ,9 ! case ( air & c>bonic acid1 ! absorption is proportional to ! d5sity1 b ?is rule is widely dep>t$ f 9 ! case ( hydrog54 ,results = ! relative absorption by air ( ! rays f ! diff]5t active bodies are %[n 9 ,fig4 #ch4 ,illu/ration3 ,fig4 #ch4 ,! initial obs]vation 0 made ab\t #b mms4 f ! active surface1 & ! initial curr5t is 9 ea* case tak5 z #ajj4 ,! curr5t1 z 9 ! case ( uranium1 falls (f at fir/ approximately 9 geometrical progression ) ! di/ance4 ,! ?ickness ( air1 ?r\gh :i* ! radiation passes be=e ! int5sity is r$uc$ to half value1 is giv5 bel[4 ,di/ance 9 mms4 ,uranium #dc ,radium #ge ,?orium #aj ,excit$ radiation #afe f ,?orium & ,radium ,! ord] ( absorption by air ( ! radiations f ! active sub/ances is ! same z ! ord] ( absorption by ! metals & solid sub/ances exam9$4 #aja4 ,connection betwe5 absorption & d5sity4 ,s9ce 9 all cases ! radiations fir/ dim9i% approximately accord+ to an expon5tial law ) ! di/ance trav]s$1 ! int5sity ,i aft] pass+ ?r\gh a ?ickness x is giv5 by ,i ,i e- x :]e is ! absorption con/ant & ,i ! initial int5sity4 ,! foll[+ table %[s ! value ( ) diff]5t radiations = air & alum9ium4 ,radiation = = air alum9ium ,excit$ radiation #hcj #db ,?orium #abej #fi ,radium #afjj #ij ,uranium #bgej #af ,tak+ ! d5sity ( air at #bj ,c4 & #gfj mms4 z #jjjabj comp>$ ) wat] z unity1 ! foll[+ table %[s ! value ( divid$ by d5sity = ! diff]5t radiations4 ,radiation ,alum9ium ,air ,excit$ radiation #cbj #cej ,?orium #dhj #eej ,radium #fbj #gdj ,uranium #ajfj #acjj ,comp>+ alum9ium & air1 ! absorption is ?us r\ghly proportional to ! d5sity = all ! radiations4 ,! div]g5ce1 h[ev]1 betwe5 ! absorption-d5sity numb]s is l>ge :5 two metals l t9 & alum9ium are comp>$4 ,! value ( = t9 is n mu* great] ?an = alum9ium1 al?\gh ! d5sity is ne>ly ?ree times z great4 ,if ! absorption is proportional to ! d5sity1 ! absorption 9 a gas %\ld v>y directly z ! pressure1 & ?is is f\nd to be ! case4 ,"s results on ?is subject h be5 giv5 by ! writ] 7loc4 cit47 = uranium rays betwe5 pressures ( & #a atmosph]e4 ,ow5s 7loc4 cit47 exam9$ ! absorption ( ! radiation 9 air f ?oria betwe5 ! pressures ( #je to #c atmosph]es & f\nd t ! absorption v>i$ directly z ! pressure4 ,! v>iation ( absorption ) d5sity = ! project$ positive p>ticles is ?us v simil> to ! law = ! project$ negative p>ticles & = ca?ode rays4 ,! absorption1 9 bo? cases1 dep5ds ma9ly on ! d5sity1 b is n 9 all cases directly proportional to x4 ,s9ce ! absorption ( ! rays 9 gases is probably ma9ly due to ! exhau/ion ( ! en]gy ( ! rays by ! production ( ions 9 ! gas1 x seems probable t ! absorption 9 metals is due to a simil> cause4 #ajb4 ,relation betwe5 ionization & absorption 9 gases4 ,x has be5 %[n 7section #de7 t if ! rays are completely absorb$ 9 a gas1 ! total ionization produc$ is ab\t ! same = all ! gases exam9$4 ,s9ce ! rays are unequally absorb$ 9 diff]5t gases1 !re %\ld be a direct connection betwe5 ! relative ionization & ! relative absorption4 ,?is is se5 to be ! case if ! results ( ,/rutt 7section #de7 are comp>$ ) ! relative absorption con/ants 7section #ajj74 ,gas ,relative ,relative absorption ionization ,air #a #a ,hydrog5 #bg #bbf ,c>bon dioxide #adc #aec ,consid]+ ! difficulty ( obta9+ accurate det]m9ations ( ! absorption1 ! relative ionization 9 a gas is se5 to be directly proportional to ! relative absorption )9 ! limits ( exp]im5tal error4 ,?is result %[s t ! en]gy absorb$ 9 produc+ an ion is ab\t ! same 9 air1 hydrog51 & c>bon dioxide4 #ajc4 ,me*anism ( ! absorption ( rays by matt]4 ,! exp]im5ts1 already describ$1 %[ t ! ionization ( ! gas1 due to ! rays f a l>ge plane surface ( radio-active matt]1 falls (f 9 mo/ cases approximately accord+ to an expon5tial law1 until mo/ ( ! rays are absorb$1 :]eupon ! ionization decreases at a mu* fa/] rate4 ,9 ! case ( polonium1 ! ionization falls (f m rapidly ?an is to be expect$ on ! simple expon5tial law4 ,! ionization produc$ 9 ! gas is due to ! collision ( ! rapidly mov+ p>ticles ) ! molecules ( ! gas 9 _! pa?4 ,on acc\nt ( its l>ge mass1 ! p>ticle is a f> m effici5t ioniz] ?an ! p>ticle mov+ at ! same spe$4 ,x c be d$uc$ f ! results ( exp]im5t t ea* project$ p>ticle is able to produce ab\t #ajj1jjj ions 9 pass+ ?r\gh a few c5timetres ( ! gas be=e its velocity is r$uc$ to ! limit+ value1 bel[ :i* x no long] ionizes ! gas 9 its pa?4 ,en]gy is requir$ to ionize ! gas1 & ?is en]gy c only be obta9$ at ! exp5se ( ! k9etic en]gy ( ! project$ p>ticle4 ,?us x is to be expect$ t ! p>ticle %\ld gradually lose its velocity & en]gy ( motion 9 its passage ?r\gh ! gas4 ,s9ce ! rate ( absorption ( ! rays 9 gases is d$uc$ f measurem5ts ( ! ionization ( ! gas at diff]5t di/ances f ! s\rce ( radiation1 a k ( ! law ( v>iation ( ! ioniz+ p[] ( ! project$ p>ticle ) its spe$ is requir$ 9 ord] to int]pret ! results4 ,! exp]im5tal data on ?is "q are1 h[ev]1 too incomplete to be appli$ directly to a solution ( ?is "q4 ,t[ns5d#afd has %[n t a mov+ electron produces ions 9 ! gas aft] a c]ta9 limit+ velocity is rea*$4 ,! numb] ( ions produc$ p] c5timetre ( its pa? ?r\gh ! gas !n rises to a maximum1 & = /ill high] spe$s cont9u\sly decreases4 ,= example1 ,t[ns5d f\nd t ! numb] ( ions produc$ by an electron mov+ 9 an electric field 0 small at fir/ = weak fields1 b increas$ ) ! /r5g? ( ! electric field to a maximum correspond+ to ! production ( #bj ions p] cm4 ( pa? 9 air at a pressure ( #a mm4 ( m]cury4 ,durack#afe f\nd t ! electrons1 g5]at$ 9 a vacuum tube1 mov+ ) a velocity ( ab\t #e #aj cms4 p] second produc$ a pair ( ions e #e cms4 ( pa? at #a mm4 pressure4 ,9 a lat] pap]1 ,durack %[$ t = ! electrons f radium1 :i* are project$ ) a velocity great] ?an half ! velocity ( light1 a pair ( ions 0 produc$ e #aj cms4 ( pa?4 ,! high spe$ electron f radium is ?us a v ineffici5t ioniz] & produces only ab\t ( ! ionization p] unit pa? obs]v$ by ,t[ns5d = ! sl[ mov+ electron4 #ajd4 ,9 ! case ( ! p>ticle1 no direct measurem5ts h be5 made ^u ! v>iation ( ! ionization ) ! velocity ( ! p>ticle1 s t ! law ( absorption ( ! rays _c be d$uc$ directly4 ,an indirect attack ^u ! "q has1 h[ev]1 be5 made rec5tly by ,bragg & ,kleeman#aff :o h =mulat$ a simple !ory to acc\nt = ! exp]im5tal results :i* !y h obta9$ ^u ! absorption ( ! rays4 ,! p>ticles f ea* simple type ( radio-active matt] are suppos$ to be project$ ) ! same velocity1 & to pass ?r\gh a def9ite di/ance a 9 air at atmosph]ic pressure & temp]ature be=e !y are all absorb$4 ,z a fir/ approximation ! ionization p] unit pa? is suppos$ to be ! same ov] ! :ole l5g? trav]s$ be=e absorption1 & to cease fairly sudd5ly at a def9ite di/ance f ! s\rce ( radiation4 ,?is is 9 agreem5t ) ! obs]v$ fact t ! ionization betwe5 p>allel plates increases v rapidly :5 x approa*es ne>] ?an a c]ta9 di/ance to ! radiant s\rce4 ,! range a dep5ds ^u ! initial en]gy ( motion ( ! p>ticle & w ?us be diff]5t = diff]5t k9ds ( radio-active matt]4 ,if a ?ick lay] ( radio-active matt] is employ$1 only ! p>ticles f ! surface h a range a4 ,^? :i* rea* ! surface f a dep? d h _! range dim9i%$ by an am\nt d1 :]e is ! d5sity ( ! radio-active matt] comp>$ ) air4 ,?is is m]ely an expression ( ! fact t ! absorption ( ! rays is proportional to ! ?ickness & d5sity ( matt] trav]s$4 ,! rays f a ?ick lay] ( active matt] w ?us be complex1 & w consi/ ( p>ticles ( diff]5t velocity ^: ranges h all values betwe5 #j & a4 ,suppose t a n>r[ p5cil ( rays is emitt$ f a ?ick lay] ( radio-active mat]ial1 & conf9$ by metal /ops z 9 ,fig4 #ci4 ,illu/ration3 ,fig4 #ci4 ,! p5cil ( rays passes into an ionization vessel ,,ab ?r\gh a f9e wire gauze ,a4 ,! am\nt ( ionization is to be det]m9$ betwe5 ,a & ,b = diff]5t di/ances h f ! s\rce ( ! rays ,r to ! plate ,a4 ,all ! p>ticles com+ f a dep? x ( ! mat]ial giv5 by h a x w ent] ! ionization vessel4 ,! numb] ( ions produc$ 9 a dep? dh ( ! ionization vessel is equal to nxdh1 i4e4 to a h n --------- dh1 :]e n is a con/ant4 ,if ! dep? ( ! ionization vessel be b1 ! total numb] ( ions produc$ 9 ! vessel is inthhb n frac a-h rho dh frac nb rho 7a h - frac b #b7 4 ,?is supposes t ! /ream ( p>ticles passes completely across ! vessel4 ,if n1 ! expression becomes intha n frac a h rho dh frac n 7a h7#b #brho 4 ,if ! ionization 9 ! vessel ,,ab is measur$1 & a curve plott$ %[+ its relation to h1 ! curve 9 ! =m] case %\ld be a /raight l9e ^: slope is nb_/ & 9 ! latt] a p>abola4 ,?us if a ?9 lay] ( radio-active mat]ial is employ$ & a %all[ ionization vessel1 ! ionization w\ld be repres5t$ by a curve su* z ,,apm 7,fig4 #dj71 :]e ! ord9ates repres5t di/ances f ! s\rce ( radiation1 & ! abscissae ! ionization curr5t betwe5 ! plates ,,ab4 ,illu/ration3 ,fig4 #dj4 ,9 ?is case1 ,,pm is ! range ( ! p>ticles f ! l[e/ lay] ( ! radio-active matt]4 ,! curr5t %\ld be con/ant = all di/ances less ?an ,,pm4 ,= a ?ick lay] ( radio-active matt]1 ! curve %\ld be a /raight l9e su* z ,,apb4 ,curves ( ! above "* %\ld only be obta9$ :5 def9ite cones ( rays are employ$1 & :]e ! ionization vessel is %all[ & includes ! :ole cone ( rays4 ,9 su* a case ! inv]se squ>e law ne$ n be tak5 into acc\nt4 ,9 ! exp]im5ts previ\sly record$ 7sections #ii & #ajj71 ! ionization 0 measur$ betwe5 p>allel plates sev]al c5timetres ap>t = a l>ge area ( radio-active mat]ial4 ,su* an arrangem5t 0 necess>y at ! "t at :i* ! exp]im5ts 7 made1 z only weak radio-active mat]ial 0 available4 ,measurable electrical effects c\ld n !n be obta9$ ) n>r[ cones ( rays & %all[ ionization vessels1 b ?is disadvantage is remov$ by ! adv5t ( pure radium bromide z a s\rce ( radiation4 ,! int]e/+ exp]im5ts describ$ by ,bragg & ,kleeman %[ t ! !oretical curves are approximately realiz$ 9 practice4 ,! *ief difficulty exp]i5c$ 9 ! analysis ( ! exp]im5tal results 0 due to ! fact t radium is a complex radio-active sub/ance & conta9s f\r radio-active products ea* ( :i* gives rise to rays :i* h diff]5t ranges4 ,! g5]al "* ( ! results obta9$ f radium are %[n graphically 9 ,fig4 #da1 curves ,a1 ,b1 ,c1 ,d4 ,illu/ration3 ,fig4 #da4 ,! ord9ates repres5t ! di/ance betwe5 ! radium & ! gauze ( ! te/+ vessel2 ! abscissae ! curr5t 9 ! ionization vessel 9 arbitr>y units4 ,five milligrams ( radium bromide 7 us$1 & ! dep? ( ! ionization vessel 0 ab\t #e mms4 ,curve ,a is = a cone ( rays ( angle #bj4 ,! initial curr5t at a di/ance ( #g cms4 is due to ! & rays & natural leak4 ,?is curve is initially p>abolic1 & !n is made up ( two /raight l9es4 ,curve ,b is = a small] cone1 & %[s ! /raight l9e "* ( ! curve to )9 a %ort di/ance ( ! radium4 ,curve ,c 0 obta9$ "u ! same condition z curve ,a1 b ) a lay] ( gold beat]'s sk9 plac$ ov] ! radium4 ,! effect ( ?is is to r$uce all ! ord9ates ( curve ,a by ! same quantity4 ,?is is to be expect$ on ! simple !ory already consid]$4 ,curve ,d 0 obta9$ :5 ! radium 0 heat$ s z to get rid ( ! emanation & its products4 ,! p>ticles ( greate/ range are q abs5t & ! curve is simpl] 9 "*4 ,illu/ration3 ,fig4 #db4 ,! complex "* ( ! radium curves are m cle>ly br\ght out by a c>eful exam9ation ( a portion ( ! curve at di/ances betwe5 #b & #e cms4 f ! radium1 us+ an ionization vessel ( dep? only #b mms4 ,! results are %[n 9 ,fig4 #db1 :]e ! curve is se5 to consi/ approximately ( f\r /raight l9es ( diff]5t slopes repres5t$ by ,,pq1 ,,qr1 ,,rs1 ,,/4 ,su* a result is to be expect$1 = x w be %[n lat] t f\r di/9ct ray products exi/ 9 radium :5 9 radio-active equilibrium4 ,ea* ( ^! products ( radium emits an equal numb] ( p>ticles p] second1 b ! range ( ea* is diff]5t4 ,if a is ! range ( "o /ream1 a ( ano!r1 ! ionization 9 ! vessel ,,ab1 :5 two /reams ent] ! vessel1 %\ld be nb nb ---- 7a-h-b_/#b7 ----- 7a h b_/#b71 i4e4 nb ---- 7a a #b;h b7 4 ,?us ! slope ( ! curve %\ld 9 ?is case be #bnb_/1 :ile if only "o /ream ent]s1 x %\ld be nb_/4 ,:5 ?ree rea* x1 ! slope %\ld be #cnb_/ & = f\r #dnb_/4 ,^! results are realiz$ fairly closely 9 practice4 ,! curve 7,fig4 #db7 consi/s ( f\r p>ts1 ^: slopes are 9 ! proportion #af1 #cd1 #de1 #fe1 i4e4 v ne>ly 9 ! ratio #a1 #b1 #c1 #d4 ,exp]im5ts 7 also made ) v ?9 lay]s ( radium bromide1 :51 z we h se5 7,fig4 #dj7 a v diff]5t %ape ( curve is to be expect$4 ,an example ( ! results is %[n 9 ,fig4 #dc1 curves ,i41 ,,ii4 & ,,iii4 ,curve ,i4 is obta9$ f radium bromide :i* has be5 heat$ to drive (f ! emanation1 & curves ,,ii4 & ,,iii4 f ! same sub/ance sev]al days lat]1 :5 ! emanation 0 aga9 accumulat+4 ,! portion ,,pq1 :i* is abs5t 9 ! fir/ curve1 is probably due to ! 8excit$0 activity produc$ by ! emanation4 ,by c>eful exam9ation ( ! successive *anges 9 ! curves aft] ! radium has be5 heat$ to drive (f ! emanation1 x is possible to tell ! range ( ! rays f ea* ( ! diff]5t products1 & ?is has be5 done to "s ext5t by ,bragg & ,kleeman4 ,x w be se5 lat] t ! results "h obta9$ support 9 a novel way ! !ory ( radio-active *anges :i* has be5 advanc$ f data ( q a diff]5t "*4 ,! inw>d slope ( ! curve 9 ,fig4 #dc due to ! radium indicates t ! p>ticles become m effici5t ioniz]s z _! velocity decreases4 ,?is is 9 agreem5t ) obs]vations on ! rays4 ,9 "s cases ,bragg also obs]v$ t ! p>ticles are ! mo/ effici5t ioniz]s j be=e !y lose _! p[] ( ioniz+ ! gas4 ,illu/ration3 ,fig4 #dc4 ,?us we may conclude f ^! exp]im5ts t ! p>ticles f a simple radio-active sub/ance trav]se a def9ite di/ance 9 air1 at a def9ite pressure & temp]ature1 & t ! ionization ends fairly abruptly4 ,if ! rays trav]se a %eet ( metal1 ! effective range ( ionization is dim9i%$ by a di/ance correspond+ to d1 :]e is ! d5sity ( ! mat]ial comp>$ ) air & d its ?ickness4 ,! rays f a ?ick lay] ( a simple radio-active sub/ance consi/ ( p>ticles ( diff]5t velocities1 :i* h ranges 9 air ly+ betwe5 #j & ! maximum range4 ,! ionization ( ! p>ticles p] unit pa? is greate/ ne> ! end ( its range1 & decreases some:at z we approa* ! radiant s\rce4 ,a complex s\rce ( rays l radium gives out f\r types ( rays1 ea* ( :i* has a diff]5t b di/9ct range4 ,f ?is !ory x is possible to calculate approximately ! decrease ( curr5t to be obs]v$ :5 %eets ( metal foil are plac$ ov] a l>ge area ( radio-active sub/ance4 ,?is is ! me?od t has be5 employ$ to obta9 ! curves ( ,figs4 #ce & #ch4 ,suppose a v ?9 lay] ( simple radio-active matt] is employ$ 7= example a bismu? plate cov]$ ) radio-tellurium or a metal plate made active by exposure to ! pres5ce ( ! ?orium or radium emanations7 & t ! ionization vessel is ( suffici5t dep? to absorb ! rays completely4 ,let d be ! ?ickness ( ! metal plate1 its d5sity comp>$ ) air4 ,consid] a po9t ,p close to ! upp] side ( ! plate4 ,! range ( ! p>ticles mov+ f a po9t1 :5 ! pa? makes an angle ) ! normal at ,p1 is a d sec 1 :]e a is ! range 9 air4 ,! rays com+ f po9ts su* t ! pa?s make an angle ) ! normal great] ?an cos#a frac rho d a w ?us be absorb$ 9 ! plate4 ,by integrat+ ov] ! circul> area "u ! po9t ,p1 x is easy to %[ t ! total ionization 9 ! vessel is proportional to intcos#a frac rho d a #b pi s9 !ta cos !ta 7a rho d sec !ta7 d!ta frac pi 7a rho d7#b a 4 ,! curves %[+ ! relation betwe5 curr5t & di/ance ( metal trav]s$ %\ld ?us be p>abolic ) respect to d4 ,?is is approximately ! case = a simple sub/ance l radio-tellurium4 ,! curve = a ?ick lay] ( radium w\ld be difficult to calculate on acc\nt ( ! complexity ( ! rays1 b we "k f exp]im5t t x is approximately expon5tial4 ,an acc\nt ( "s rec5t inve/igations made to det]m9e ! range ( velocity ov] :i* ! p>ticle is able to ionize ! gas is giv5 9 ,app5dix ,a4 ,! results !re giv5 /rongly support ! !ory ( absorption ( ! rays discuss$ above4 ,,"p ,,iv4 ,! or v p5etrat+ ,rays4 #aje4 ,9 addition to ! & rays1 ! ?ree active sub/ances1 uranium1 ?orium1 & radium1 all give out a radiation ( an extraord9>ily p5etrat+ "*4 ,^! rays are consid]ably m p5etrat+ ?an ! ,x rays produc$ 9 a 8h>d0 vacuum tube4 ,_! pres5ce c readily be obs]v$ = an active sub/ance l radium1 b is difficult to detect = uranium & ?orium unless a l>ge quantity ( active mat]ial is us$4 ,vill>d#afg1 us+ ! photographic me?od1 fir/ drew att5tion to ! fact t radium gave out ^! v p5etrat+ rays1 & f\nd t !y 7 non-deviable by a magnetic field4 ,?is result 0 confirm$ by ,becqu]el#afh4 ,us+ a few milligrams ( radium bromide1 ! rays c be detect$ 9 a d>k room by ! lum9osity !y excite 9 ! m9]al willemite or a scre5 ( plat9ocyanide ( b>ium4 ,! & rays are completely absorb$ by plac+ a ?ickness ( #a c5timetre ( lead ov] ! radium1 & ! rays :i* !n pass ?r\gh ! lead consi/ entirely ( rays4 ,! v great p5etrat+ p[] ( ^! rays is easily obs]v$ by not+ ! slight dim9ution ( ! lum9osity ( ! scre5 :5 plates ( metal sev]al c5timetres ?ick are plac$ betwe5 ! radium & ! scre54 ,^! rays also produce ionization 9 gases & are be/ inve/igat$ by ! electrical me?od4 ,! pres5ce ( ! rays f #cj mgrs4 ( radium bromide c be obs]v$ 9 an electroscope aft] pass+ ?r\gh #cj cms4 ( iron4 #ajf4 ,absorption ( ! rays4 ,9 an exam9ation ( ! active sub/ances by ! electrical me?od1 ! writ]#afi f\nd t bo? uranium & ?orium gave out rays 9 am\nt r\ghly proportional to _! activity4 ,an electroscope ( ! type %[n 9 ,fig4 #ab 0 employ$4 ,?is 0 plac$ on a l>ge lead plate #fe cm4 ?ick1 ! active sub/ance be+ plac$ 9 a clos$ vessel b5ea?4 ,! dis*>ge due to ! natural ionization ( ! air 9 ! electroscope 0 fir/ obs]v$4 ,! additional ionization due to ! active sub/ance mu/ be t produc$ by rays :i* h pass$ ?r\gh ! lead plate & ! walls ( ! electroscope4 ,! foll[+ table %[s t ! dis*>ge due to ^! rays decreases approximately accord+ to an expon5tial law ) ! ?ickness ( lead trav]s$4 ,?ickness ( lead ,rate ( dis*>ge #fb cms4 #ajj #fd cms4 #fg #bhf #bc #ejh #h ,us+ #ajj grs4 ( uranium & ?orium1 ! dis*>ge due to ! rays ?r\gh #a cm4 ( lead 0 q appreciable1 & readily measur$4 ,! results %[$ t ! am\nt ( rays 0 ab\t ! same = equal weights ( ?orium & uranium oxides4 ,! p5etrat+ p[] 0 also ab\t ! same z = ! radium rays4 ,illu/ration3 ,fig4 #dd4 ,! writ] %[$ t ! absorption ( ! rays f radium 0 approximately proportional to ! d5sity ( ! sub/ance trav]s$4 ,a m detail$ exam9ation ( ! absorption ( ^! rays 9 v>i\s sub/ances has be5 rec5tly made by ,mc,clelland#agj4 ,! curve 7,fig4 #dd7 %[s ! decrease ( ! ionization curr5t 9 a te/+ vessel due to ! & rays ) successive lay]s ( lead4 ,x is se5 t ! rays are almo/ completely /opp$ by #d mms4 ( lead2 ! ionization is !n due entirely to ! rays4 ,9 ord] to leave no d\bt t all ! rays 7 absorb$1 ! radium 0 cov]$ ) a ?ickness ( #h mms4 ( lead1 & measurem5ts ( ! coeffici5t ( absorption 7 made = additional ?icknesses4 ,! av]age value ( 0 calculat$ f ! usual equation frac ,i ,i e- d 1 :]e d is ! ?ickness ( matt] trav]s$4 ,! foll[+ table %[s ! value ( 1 7,i7 = ! fir/ #be mms4 ( matt] trav]s$ 7aft] initially pass+ ?r\gh #h mms4 ( lead71 7,,ii7 = ! ?ickness #be to #e mms41 7,,iii7 = #e to #aj mms41 7,,iv7 #aj to #ae mms4 ,,table ,a4 ,sub/ance ,i ,,ii ,,iii ,,iv ,plat9um #aafg ,m]cury #gbf #ffa #ech #dic ,lead #fda #efc #dhj #ddj ,z9c #bhb #bff #bdh #bff ,alum9ium #ajd #ajd #ajd #ajd ,glass #jhg #jhg #jhg #jhg ,wat] #jcd #jcd #jcd #jcd ,9 ! above table1 ! absorption 9 alum9ium1 glass & wat] 0 too small to det]m9e ) accuracy ! v>iation ( ) di/ance trav]s$4 ,x w be obs]v$ t1 = ! d5s] sub/ances1 ! coeffici5t ( absorption decreases ) ! di/ance ?r\gh :i* ! rays h pass$4 ,?is indicates t ! rays are het]og5e\s4 ,! v>iation ( is m m>k$ 9 heavy sub/ances4 ,table ,b gives ! values ( divid$ by d5sity = ! above numb]s4 ,if ! absorption 7 directly proportional to ! d5sity1 ! quoti5t w\ld be ! same 9 all cases4 ,,table ,b4 divid$ by d5sity4 ,sub/ance ,i ,,ii ,,iii ,,iv ,plat9um #jed ,m]cury #jec #jdh #jci #jcf ,lead #jef #jdi #jdb #jcg ,z9c #jci #jcg #jcd #jcc ,alum9ium #jch #jch #jch #jch ,glass #jcd #jcd #jcd #jcd ,wat] #jcd #jcd #jcd #jcd ,! numb]s 9 column ,i v>y consid]ably1 b ! agreem5t becomes clos] 9 ! succe$+ columns1 until 9 column ,,iv ! absorption is v ne>ly proportional to ! d5sity4 ,x is se5 t ! absorption ( all ?ree types ( rays f radio-active sub/ances is approximately proportional to ! d5sity ( ! sub/ance trav]s$--a relation fir/ obs]v$ by ,l5>d = ! ca?ode rays4 ,?is law ( absorption ?us holds = bo? positively & negatively electrifi$ p>ticles project$ f ! radio-active sub/ances1 & also = ! electromagnetic pulses :i* are believ$ to con/itute ! rays2 al?\gh ! absorption ( ! rays1 = example1 is #aj1jjj times great] ?an = ! rays4 ,we h se5 9 section #hd t ! value ( ! absorption con/ant = lead is #abb = ! rays f uranium4 ,! value = ! rays f radium v>ies betwe5 #fd & #dd1 %[+ t ! rays are m ?an #bjj times z p5etrat+ z ! rays4 #ajg4 ,nature ( ! rays4 ,9 addition to _! great p5etrat+ p[]1 ! rays diff] f ! & rays 9 n be+ deflect$ to an appreciable degree by a magnetic or electric field4 ,9 a /rong magnetic field1 x c be %[n1 us+ ! photographic me?od1 t !re is an abrupt discont9uity betwe5 ! & rays1 = ! =m] are b5t completely away f ! latt]4 ,?is indicates t1 z reg>ds ! action ( a magnetic field1 !re is no gradual transition ( magnetic prop]ties betwe5 ! & rays4 ,pas*5#aga has exam9$ ! rays 9 a v int5se magnetic field1 &1 f ! abs5ce ( deflection ( ^! rays1 has calculat$ t1 if !y consi/ ( electrifi$ p>ticles c>ry+ an ionic *>ge1 & project$ ) a velocity approa*+ t ( light1 _! app>5t mass mu/ be at lea/ #de times great] ?an t ( ! hydrog5 atom4 ,x n[ rema9s = u to consid] :e!r ! rays are corpuscul> 9 "*1 or :e!r !y are a type ( electromagnetic pulse 9 ! e!r simil> to ,rntg5 rays4 ,!y resemble ,rntg5 rays 9 _! great p5etrat+ p[] & 9 _! abs5ce ( deflection 9 a magnetic field4 ,e>li] exp]im5ts seem$ to indicate an important diff]5ce betwe5 ! action ( & ,x rays4 ,x is well kn[n t ord9>y ,x rays produce mu* great] ionization 9 gases su* z sulphurett$ hydrog5 & hydro*loric acid gas1 ?an 9 air1 al?\gh ! diff]5ces 9 d5sity are n l>ge4 ,= example1 expos$ to ,x rays1 sulphurett$ hydrog5 has six times ! conductivity ( air1 :ile ) rays ! conductivity only slightly exce$s t ( air4 ,! results obta9$ by ,/rutt1 9 ?is connection1 h already be5 giv5 9 section #de4 ,x is !re %[n t ! relative conductivity ( gases expos$ to rays 7& also to & rays7 is1 9 mo/ cases1 ne>ly proportional to _! relative d5sities2 b1 "u ,x rays1 ! relative conductivity = "s gases & vap\rs is v mu* great] ?an = ! rays4 ,x mu/ be rememb]$1 h[ev]1 t ! results obta9$ by ,/rutt 7 = 8s(t ,x rays10 ^: p5etrat+ p[] 0 v mu* less ?an t ( ! rays4 ,9 ord] to see if ! relative conductivity ( gases produc$ by ,x rays dep5d$ ^u _! p5etrat+ p[]1 ,a4 ,s4 ,eve#agb made "s exp]im5ts ) a v 8h>d0 ,x ray bulb1 :i* gave an unusually p5etrat+ type ( rays4 ,! results ( ! measurem5ts are %[n 9 ! table bel[1 :]e ! conductivity = ea* type ( rays is express$ relative to air z unity4 ,! results obta9$ = 8s(t0 ,x rays by ,/rutt & by ,eve = rays are add$ = comp>ison4 ,x is se5 t ! h>d rays %[ a mu* clos] agreem5t ?an ! s(t rays ) ! d5sity law f\nd = ! rays4 ,! high values previ\sly obta9$ = ! vap\rs ( *lor(orm & c>bon tetra*loride are greatly r$uc$1 & are v ne>ly ! same z = ! rays4 ,on ! o!r h&1 ! vap\r ( me?yl iodide is an exception1 & /ill %[s a high conductivity4 ,! rays 71 h[ev]1 =ty times z p5etrat+ z ! h>d ,x rays1 & x is probable t ! value ( me?yl iodide w\ld be r$uc$ ) /ill m p5etrat+ ,x rays4 ,relative conductivities ( gases4 ,gas ,relative 8,s(t0 8,h>d0 rays ,d5sity ,x rays ,x rays ,hydrog5 #jg #aa #db #ai ,air #aj #aj #aj #aj ,sulphurett$ #ab #f #i #abc ,hydrog5 ,*lor(orm #dc #cb #df #dh ,me?yl ,iodide #ej #gb #ace #ef ,c>bon #ec #de #di #eb ,tetra*loride ,! h>d ,x rays 7 f\nd to give f> m second>y radiation ?an ! rays1 b ?is effect is probably also a function ( ! p5etrat+ p[] ( ! prim>y rays4 ,x w be se5 lat] 7section #aab7 t rays give rise to a second>y radiation ( ! ray type4 ,?is has also be5 obs]v$ = ! ,x rays4 ,consid]+ ! exp]im5tal evid5ce z a :ole1 !re is und\bt$ly a v m>k$ simil>ity betwe5 ! prop]ties ( & ,x rays4 ,! view t ! rays are a type ( v p5etrat+ ,x rays1 also receives support f !oretical consid]ations4 ,we h se5 7section #eb7 t ! ,x rays are believ$ to be electromagnetic pulses1 ak9 9 "s respects to %ort light waves1 :i* are set up by ! sudd5 /oppage ( ! ca?ode ray p>ticles4 ,conv]sely1 x is also to be expect$ t ,x rays w be produc$ at ! sudd5 />t+1 z well z at ! sudd5 /opp+1 ( electrons4 ,s9ce mo/ ( ! p>ticles f radium are eject$ f ! radium atom ) velocities mu* great] ?an ! ca?ode p>ticles 9 a vacuum tube1 ,x rays ( a v p5etrat+ "* w arise4 ,b ! /ronge/ argum5t 9 support ( ?is view is d]iv$ f an exam9ation ( ! orig9 & connection ( ! & rays f radio-active sub/ances4 ,x w be %[n lat] t ! ray activity obs]v$ 9 radium arises f sev]al dis9tegration products1 /or$ up 9 ! radium1 :ile ! & rays arise only f "o ( ^! products nam$ radium ,c4 ,x is f\nd1 too1 t ! activity measur$ by ! rays is always proportional to ! activity measur$ by ! rays1 al?\gh by sep>ation ( ! products ! activity ( ! latt] may be made to und]go great v>iations 9 value4 ,?us ! int5sity ( ! rays is always proportional to ! rate ( expulsion ( p>ticles1 & ?is result indicates t !re is a close connection betwe5 ! & rays4 ,su* a result is to be expect$ if ! p>ticle is ! p>5t ( ! ray1 = ! expulsion ( ea* electron f radium w give rise to a n>r[ sph]ical pulse travell+ f ! po9t ( di/urbance ) ! velocity ( light4 #ajh4 ,!re is ano!r possible hypo!sis 9 reg>d to ! nature ( ^! rays4 ,x has be5 %[n 7sections #dh & #hb7 t ! app>5t mass ( an electron increases z ! spe$ ( light is approa*$2 !oretically x %\ld be v great :5 ! velocity ( ! electron is exce$+ly close to ! velocity ( light4 ,9 su* a case1 a mov+ electron w\ld be difficult to deflect by a magnetic or electric field4 ,! view t ! rays are electrons c>ry+ a negative *>ge & mov+ ) a velocity ne>ly equal to t ( light has rec5tly be5 advocat$ by ,pas*5#agc4 ,he conclud$ f exp]im5t t ! rays l ! rays c>ri$ a negative *>ge4 ,we h se5 7section #he7 t ,seitz also obs]v$ t a small negative *>ge 0 communicat$ to bodies on :i* ! rays imp+$1 b ! magnitude ( ?is *>ge 0 mu* small] ?an t obs]v$ by ,pas*54 ,i d n ?9k t mu* weight c be atta*$ to obs]vations t a small positive or negative *>ge is communicat$ to bodies on :i* ! rays fall1 = x w be %[n lat] t a /rong second>y radiation1 consi/+ 9 "p ( electrons1 is set up dur+ ! passage ( ! rays ?r\gh matt]4 ,x is n improbable t ! small *>ge obs]v$ is n a direct result ( ! *>ge c>ri$ by ! rays1 b is an indirect effect due to ! second>y radiations emitt$ f ! surface ( bodies4 ,!re is no d\bt t a ?ick lead vessel1 completely enclos+ a quantity ( radium1 acquires a small positive *>ge1 b ?is result w\ld foll[ :e!r ! rays c>ry a *>ge or n1 s9ce ! second>y radiations f ! lead surface consi/ ( project$ p>ticles :i* c>ry ) !m a negative *>ge4 ,on ?is corpuscul> !ory ( ! nature ( ! rays1 ea* electron mu/ h a l>ge app>5t mass1 or o!rwise x w\ld be appreciably deflect$ by an int5se magnetic field4 ,! en]gy ( motion ( ! electron mu/1 9 consequ5ce1 be v great1 &1 if ! numb] ( ! electrons con/itut+ ! rays is ( ! same ord] ( magnitude z ! numb] ( ! p>ticles1 a l>ge heat+ effect is to be expect$ :5 ! rays are /opp$ 9 matt]4 ,pas*5#agd made "s exp]im5ts on ! heat emission ( radium due to ! rays2 he conclud$ t ! rays 7 responsible = m ?an half ( ! total heat emission ( radium & c>ri$ away en]gy at ! rate ( ov] #ajj gram calories p] h\r p] gram ( radium4 ,?is result 0 n confirm$ by lat] exp]im5ts ( ,ru!r=d & ,b>nes#age1 :o f\nd t ! heat+ effect ( ! rays c\ld n be m ?an a few p] c5t4 ( ! total heat emission ( radium4 ,^! results w be consid]$ lat] 9 *apt] ,,xii4 ,! weight ( evid5ce1 bo? exp]im5tal & !oretical1 at pres5t supports ! view t ! rays are ( ! same nature z ! ,x rays b ( a m p5etrat+ type4 ,! !ory t ! ,x rays consi/ ( non-p]iodic pulses 9 ! e!r1 set up :5 ! motion ( electrons is arre/$1 has f\nd mo/ fav\r1 al?\gh x is difficult to provide exp]im5tal te/s to decide def9itely ! "q4 ,! /ronge/ evid5ce 9 support ( ! wave nature ( ! ,x rays is d]iv$ f ! exp]im5ts ( ,b>kla#agf1 :o f\nd t ! am\nt ( second>y radiation set up by ! ,x rays on /rik+ a metallic surface dep5d$ on ! ori5tation ( ! ,x ray bulb4 ,! rays ?us %[$ evid5ce ( a "o-sid$ness or pol>ization :i* is only to be expect$ if ! rays consi/ ( a wave motion 9 ! e!r4 ,,"p ,v4 ,second>y ,rays4 #aji4 ,production ( second>y rays4 ,x has long be5 kn[n t ,rntg5 rays1 :5 !y imp+e on solid ob/acles1 produce second>y rays ( mu* less p5etrat+ p[] ?an ! incid5t rays4 ,?is 0 fir/ %[n by ,p]r9 & has be5 inve/igat$ 9 detail by ,sagnac1 ,langev91 ,t[ns5d & o!rs4 ,?us x is n surpris+ t simil> ph5om5a %\ld be obs]v$ = ! radiation f radio-active sub/ances4 ,by means ( ! photographic me?od1 ,becqu]el#agg has made a close /udy ( ! second>y radiations produc$ by radio-active sub/ances4 ,9 8 e>lie/ obs]vations1 he notic$ t radiographs ( metallic objects 7 always surr\nd$ by a diffuse bord]4 ,?is effect is due to ! second>y rays set up by ! incid5t rays at ! surface ( ! scre54 ,! second>y rays produc$ by ! rays are v feeble4 ,!y are be/ %[n by polonium1 :i* gives out only rays1 s t ! results are n complicat$ by ! action ( ! rays4 ,/rong second>y rays are set up at ! po9t ( impact ( ! or ca?odic rays4 ,becqu]el f\nd t ! magnitude ( ?is action dep5d$ greatly on ! velocity ( ! rays4 ,! rays ( l[e/ velocity gave ! mo/ int5se second>y action1 :ile ! p5etrat+ rays gave1 9 comp>ison1 sc>cely any second>y effect4 ,9 consequ5ce ( ! pres5ce ( ?is second>y radiation1 ! photographic impression ( a scre5 pi]c$ ) holes is n cle> & di/9ct4 ,9 ea* case !re is a d\ble photographic impression1 due to ! prim>y rays & ! second>y rays set up by !m4 ,^! second>y rays are deviable by a magnetic field1 & 9 turn produce t]ti>y rays & s on4 ,! second>y rays are 9 all cases m readily deviat$ & absorb$ ?an ! prim>y rays1 f :i* !y arise4 ,! v p5etrat+ rays give rise to second>y rays1 :i* cause int5se action on ! photographic plate4 ,:5 "s radium 0 plac$ 9 a cavity inside a deep lead block1 rectangul> 9 %ape1 besides ! impression due to ! direct rays ?r\gh ! lead1 ,becqu]el obs]v$ t !re 0 also a /rong impression due to ! second>y rays emitt$ f ! surface ( ! lead4 ,! action ( ^! second>y rays on ! plate is s /rong t ! effect on ! plate is1 9 _m cases1 increas$ by add+ a metal scre5 betwe5 ! active mat]ial & ! plate4 ,! comp>ative photographic action ( ! prim>y & second>y rays _c be tak5 z a relative measure ( ! int5sity ( _! radiations4 ,= example1 only a small portion ( ! en]gy ( ! rays is 9 g5]al absorb$ 9 ! s5sitive film4 ,s9ce ! second>y rays are f> m easily absorb$ ?an ! prim>y rays1 a f> great] proportion ( _! en]gy is exp5d$ 9 produc+ photographic action ?an 9 ! case ( ! prim>y rays4 ,x is ?us n surpris+ t ! second>y rays set up by ! & rays may 9 "s cases produce a photographic impression comp>able )1 if n great] ?an1 ! effect ( ! incid5t rays4 ,on acc\nt ( ^! second>y rays1 radiographs produc$ by ! rays ( radium 9 g5]al %[ a diffuse bord] r\nd ! %ad[ ( ! object4 ,= ?is reason radiographs ( ?is k9d lack ! %>pness ( outl9e ( ,x ray photographs4 #aaj4 ,second>y radiation produc$ by rays4 ,mme ,curie#agh has %[n by ! electric me?od t ! rays ( polonium produce second>y rays4 ,! me?od adopt$ 0 to comp>e ! ionization curr5t betwe5 two p>allel plates1 :5 two scre5s ( diff]5t mat]ial1 plac$ ov] ! polonium1 7 int]*ang$4 ,^! results %[ t ! rays ( polonium are modifi$ 9 pass+ ?r\gh matt]1 & t ! am\nt ( second>y rays set up v>ies ) scre5s ( diff]5t mat]ial4 ,mme ,curie1 us+ ! same me?od1 0 unable to obs]ve any su* effect = ! rays ( radium4 ,! production ( second>y rays by ! rays ( radium is1 h[ev]1 readily %[n by ! photographic me?od4 ,we h already se5 7section #ic7 t v l[ velocity electrons accompany ! rays f radium or radio-tellurium spread on a metal plate4 ,^! electrons are probably lib]at$ :5 ! rays escape f or imp+e ^u matt]1 & ! numb] emitt$ dep5ds ^u ! k9d ( matt] us$ z a scre54 ,! diff]5ces %[n 9 ! above table :5 ! scre5s 7 int]*ang$ are expla9$ simply 9 ?is way4 ,scre5s employ$ ,?ickness ,curr5t 9 mms4 obs]v$ ,alum9ium #jja ,c>dbo>d #jjje #agi ,c>dbo>d #jjje ,alum9ium #jja #fg ,alum9ium #jja ,t9 #jjje #aej ,t9 #jjje ,alum9ium #jja #abf ,t9 #jjje ,c>dbo>d #jjje #aci ,c>dbo>d #jjje ,t9 #jjje #dd ,illu/ration3 ,fig4 #de4 #aaa4 ,second>y rays produc$ by & rays4 ,an exam9ation ( ! am\nt & "* ( ! second>y radiation emitt$ by v>i\s sub/ances1 :5 expos$ to ! & rays ( radium1 has rec5tly be5 made by ,a4 ,s4 ,eve#agi4 ,! g5]al exp]im5tal me?od employ$ is %[n 9 ,fig4 #de4 ,! electroscope 7,fig4 #de7 0 plac$ beh9d a lead scre5 #de cms4 ?ick1 :i* /opp$ all ! rays & absorb$ ! great] proportion ( ! rays f ! radium tube plac$ at ,r4 ,on br++ ne> a plate ( matt] ,m1 ! prim>y rays fell ^u x & "s ( ! second>y rays1 emitt$ 9 all directions1 pass$ into ! side ( ! electroscope1 :i* 0 cov]$ ) alum9ium foil ( ?ickness #je mm4 ,be=e ! plate ,m 0 plac$ 9 position ! rate ( dis*>ge ( ! electroscope 0 due to ! natural leak & ! rays f ,r1 & ! second>y radiation f ! air4 ,on br++ ! radiator ,m into position1 ! rate ( dis*>ge 0 mu* increas$1 & ! diff]5ce betwe5 ! rate ( movem5t ( ! gold-leaf 9 ! two cases 0 tak5 z a measure ( ! am\nt ( second>y rays f ,m4 ,! absorption ( ! second>y rays 0 te/$ by plac+ an alum9ium plate #he mm4 ?ick be=e ! face ( ! electroscope4 ,! second>y rays 7 f\nd to be fairly homog5e\s1 = ! int5sity fell (f accord+ to an expon5tial law ) ! di/ance trav]s$4 ,! value ( ! absorption con/ant 0 det]m9$ f ! usual equation frac ,i ,i e- d 1 :]e d is ! ?ickness ( ! scre54 ,! table giv5 bel[ %[s ! results obta9$ :5 ?ick plates ( diff]5t sub/ances ( ! same dim5sions 7 plac$ 9 a def9ite position at ,m4 ,! second>y radiation f fluids 0 obta9$ by a slight alt]ation ( ! exp]im5tal arrangem5ts4 ,?irty milligrammes ( radium bromide 7 us$1 & ! results are express$ 9 t]ms ( ! numb] ( scale divisions pass$ ov] p] second by ! gold-leaf4 ,x w be notic$ t ! am\nt ( second>y radiation foll[s 9 mo/ cases ! same ord] z ! d5sities1 & is greate/ = m]cury4 ,! value ( 7second>y radiation7_/d5sity is n a con/ant1 b v>ies consid]ably1 be+ greate/ = light sub/ances4 ,! absorption con/ant ( ! second>y rays f diff]5t radiators is n v diff]5t1 ) ! exception ( sub/ances su* z granite1 brick1 & cem5t1 :i* give out second>y rays ( ne>ly twice ! p5etrat+ p[] ( o!r sub/ances4 & rays4 ,radiator ,d5sity ,second>y ,sec4 ,alum9ium ,radiation ,rad4 _/ #jhe cm4 ,d5sity ,m]cury #acf #adg #ajh ,lead #aad #ada #abd #ahe ,copp] #hh #gi #ij #bj ,brass #hd #ha #if #ba ,iron #gh #ge #if #bj 7wr\ght7 ,t9 #gd #gc #ii #bjc ,z9c #gj #gi #aac ,granite #bg #ed #bjj #abd ,slate #bf #ec #bjd #aba ,alum9ium #bf #db #afa #bd ,glass #be #dd #agf #bd ,cem5t #bd #dg #aif #ace ,brick #bb #di #bbc #acj ,ebonite #aa #cb #bia #bf ,wat] #aj #bd #bdj #ba ,ice #ib #bf #bhb ,p>aff9 #i #ag #ahh #ba solid liquid #he #af #ahh ,mahogany #ef #bad #chb #bc ,pap] #d8 #baj #eb #bb ,millbo>d #d8 #aid #dh #bje ,papi]-m* 444 #bai ,basswood #cf #bjg #eg #bb ,p9e #ce #bah #fb #ba ,x ray scre5 #geb #bcf ,! second>y radiation n only comes f ! surface ( ! radiator b f a consid]able dep?4 ,! am\nt ( second>y rays increases ) ! ?ickness ( ! radiator1 &1 9 ! case ( glass & alum9ium1 rea*es a practical maximum = a plate ab\t #c mms4 ?ick4 ,9 ! above table1 ! second>y radiation arises f bo? ! rays & rays toge!r4 ,:5 ! rays 7 cut (f by a lay] ( lead #fc mms4 ?ick1 plac$ betwe5 ! radium & ! radiator1 ! effect on ! electroscope 0 r$uc$ to less ?an #bj p] c5t4 ( its =m] value1 %[+ t ! rays suppli$ m ?an #hj p] c5t4 ( ! second>y radiation4 ,! foll[+ table %[s ! relative am\nt ( second>y rays f diff]5t sub/ances :5 expos$ to & rays toge!r & to rays alone4 ,! am\nt f lead 9 ea* case is tak5 z a /&>d & equal to #ajj4 ,! am\nt ( second>y radiation f\nd by ,t[ns5d f s(t ,x rays is add$ = comp>ison4 ,second>y ,radiations4 & ,rntg5 ,radiator rays rays ,lead #ajj #ajj #ajj ,copp] #eg #fa #bia ,brass #eh #ei #bfc ,z9c #eg 444 #bhb ,alum9ium #cj #cj #be ,glass #ca #ce #ca ,p>aff9 #ab #bj #abe ,x w be obs]v$ t ! relative am\nts are ab\t ! same = ! rays alone z = ! & rays toge!r4 ,on ! o!r h&1 ! am\nt ( second>y radiation set up by ,x rays is v diff]5t1 lead = example giv+ mu* less ?an brass or copp]4 ,! second>y rays f ! rays alone are slightly less p5etrat+ ?an = ! & rays toge!r1 b are f> m p5etrat+ ?an ! second>y radiation f ! ,x rays exam9$ by ,t[ns5d4 ,! am\nt ( second>y radiation set up by ! & rays is ma9ly indep5d5t ( ! /ate ( ! surface ( ! radiator4 ,ab\t ! same am\nt is obta9$ f iron z f iron fil+s2 f liquid z f solid p>aff92 & f ice z f wat]#ahj4 ,becqu]el has %[n t ! second>y rays set up by ! rays are deflect$ by a magnet & consi/ ( negatively *>g$ p>ticles 7electrons74 ,x has be5 po9t$ out 9 section #eb t ! ca?ode rays are diffusely reflect$ f ! metal on :i* !y fall4 ,^! second>y rays consi/ 9 "p ( electrons mov+ ) ab\t ! same velocity z ! prim>y1 & 9 "p ( "s electrons ) a mu* sl[] spe$4 ,! second>y rays set up by ! rays ( radium h on an av]age less p5etrat+ p[] ?an ! prim>y rays1 & consequ5tly less velocity ?an ! prim>y rays4 ,x mu/ be rememb]$ t ! rays f radium are v complex1 & consi/ ( electrons project$ ) a consid]able range ( velocities4 ,! second>y rays are1 on an av]age1 c]ta9ly m p5etrat+ ?an ! mo/ easily absorb$ rays emitt$ f radium1 & probably move ) a velocity ( ab\t half t ( light4 ,x is /ill unc]ta9 :e!r ! second>y rays are produc$ by ! action ( ! prim>y rays on matt]1 or :e!r !y consi/ ( a portion ( ! prim>y rays ^: direction ( motion has be5 deflect$ 9 _! passage ?r\gh matt]1 s t !y em]ge aga9 ) dim9i%$ velocity f ! surface4 #aab4 ,magnetic deflection ( second>y rays f rays4 ,x has be5 se5 t ! second>y rays set up by ! rays alone are v simil> 9 "* to ^? caus$ by ! rays4 ,?is result 0 /ill fur!r confirm$ by ,eve1 :o %[$ t ! second>y rays produc$ by ! rays are readily deflect$ by a magnetic field4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #df4 ,illu/ration3 ,fig4 #df4 ,a small electroscope 0 m\nt$ on "o side ( a lead plat=m #ab cms4 ?ick1 :i* re/$ on a lead cyl9d] #aj cms4 high & #aj cms4 9 diamet]4 ,! radium 0 plac$ at ! bottom ( a hole rea*+ to ! c5tre ( ! cyl9d]4 ,on apply+ a /rong magnetic field1 at "r angles to ! plane ( ! pap]1 s z to b5d ! second>y rays f ! plat=m t[>ds ! electroscope1 ! rate ( dis*>ge 0 mu* increas$4 ,on rev]s+ ! field1 ! effect 0 mu* dim9i%$4 ,s9ce ! rays are n !mselves deflect$ by a magnetic field1 ?is result %[s t ! second>y radiation is q diff]5t 9 "* f ! prim>y rays1 & consi/s ( electrons project$ ) a velocity 7d$uc$ f ! p5etrat+ p[]7 ( ab\t half ! velocity ( light4 ,we h already po9t$ out t ! emission ( electrons f a sub/ance trav]s$ by ! rays w acc\nt suffici5tly well = ! *>ge obs]v$ by ,pas*51 )\t ! necessity ( assum+ t ! rays c>ry a negative *>ge ( electricity4 ,! second>y radiation set up by ,rntg5 rays1 l t due to ! & rays1 consi/s 9 "p ( electrons project$ ) consid]able velocity4 ,^! ?ree types ( rays seem ab\t equally effici5t 9 caus+ ! expulsion ( electrons f ! sub/ance ?r\gh :i* !y pass4 ,we h se5 t ! ,x & rays are1 9 all probability1 electromagnetic pulses set up by ! sudd5 />t+ or /opp+ ( electrons1 &1 s9ce ^! rays 9 turn cause ! removal ( electrons1 ! process appe>s to be rev]sible4 ,s9ce ! rays pass ?r\gh "s ?ickness ( matt] be=e _! en]gy ( motion is arre/$1 !ory w\ld lead u to expect t a type ( s(t ,x rays %\ld be g5]at$ 9 ! absorb+ matt]4 ,,"p ,,vi4 #aac4 ,comp>ison ( ! ionization produc$ by ! & rays4 ,) unscre5$ active mat]ial ! ionization produc$ betwe5 two p>allel plates1 plac$ z 9 ,fig4 #ag1 is ma9ly due to ! rays4 ,on acc\nt ( ! slight p5etrat+ p[] ( ! rays1 ! curr5t due to !m practically rea*es a maximum ) a small ?ickness ( radio-active mat]ial4 ,! foll[+ saturation curr5ts 7 obs]v$#aha = diff]5t ?icknesses ( uranium oxide betwe5 p>allel plates suffici5tly f> ap>t = all ! rays to be absorb$ 9 ! gas betwe5 !m4 ,surface ( uranium oxide #ch sq4 cms4 ,weight ( uranium ,saturation curr5t oxide 9 grammes p] 9 amp]es p] sq4 sq4 cm4 ( surface cm4 ( surface #jjcf #ag #aj #jjif #cb #aj #jahi #dj #aj #jcej #dd #aj #jiee #dg #aj ,! curr5t rea*$ ab\t half its maximum value = a weight ( oxide #jjee gr4 p] sq4 cm4 ,if ! rays are cut (f by a metallic scre51 ! ionization is !n ma9ly due to ! rays1 s9ce ! ionization produc$ by ! rays is small 9 comp>ison4 ,= ! rays f uranium oxide x has be5 %[n 7section #hf7 t ! curr5t rea*es half its maximum value = a ?ickness ( #jaa gr4 p] sq4 cm4 ,mey] & ,s*weidl]#ahb h f\nd t ! radiation f a wat] solution ( uranium nitrate is v ne>ly proportional to ! am\nt ( uranium pres5t 9 ! solution4 ,on acc\nt ( ! diff]5ce 9 ! p5etrat+ p[] ( ! & rays1 ! ratio ( ! ionization curr5ts produc$ by !m dep5ds on ! ?ickness ( ! radio-active lay] "u exam9ation4 ,! foll[+ comp>ative values ( ! curr5t due to ! & rays 7 obta9$ = v ?9 lay]s ( active matt]#ahc4 ,a weight ( gramme ( f9e p[d]1 consi/+ ( uranium oxide1 ?orium oxide1 or radium *loride ( activity #bjjj1 0 spread z uni=mly z possible ov] an area ( #hj sq4 cms4 ,! saturation curr5t 0 obs]v$ betwe5 p>allel plates #eg cms4 ap>t4 ,?is di/ance 0 suffici5t to absorb mo/ ( ! rays f ! active sub/ances4 ,a lay] ( alum9ium #jji cm4 ?ick absorb$ all ! rays4 ,curr5t ,curr5t ,ratio ( due to due to curr5ts rays rays _/ ,uranium #a #a #jjgd ,?orium #a #bg #jjbj ,radium #bjjj #acej #jjcc ,9 ! above table ! saturation curr5t due to ! & rays ( uranium is1 9 ea* case1 tak5 z unity4 ,! ?ird column gives ! ratio ( ! curr5ts obs]v$ = equal weights ( sub/ance4 ,! results are only approximate 9 "*1 = ! ionization due to a giv5 weight ( sub/ance dep5ds on its f95ess ( division4 ,9 all cases1 ! curr5t due to ! rays is small comp>$ ) t due to ! rays1 be+ greate/ = uranium & lea/ = ?orium4 ,z ! ?ickness ( lay] increases1 ! ratio ( curr5ts _/ /eadily increases to a con/ant value4 #aad4 ,comp>ison ( ! en]gy radiat$ by ! & rays4 ,x has n yet be5 f\nd possible to measure directly ! en]gy ( ! & rays4 ,a comp>ison ( ! en]gy radiat$ 9 ! two =ms ( rays c1 h[ev]1 be made indirectly by two di/9ct me?ods4 ,if x be assum$ t ! same am\nt ( en]gy is requir$ to produce an ion by ei!r ! or ! ray1 & t ! same proportion ( ! total en]gy is us$ up 9 produc+ ions1 an approximate e/imate c be made ( ! ratio ( ! en]gy radiat$ by ! & rays by measur+ ! ratio ( ! total numb] ( ions produc$ by !m4 ,if is ! coeffici5t ( absorption ( ! rays 9 air1 ! rate ( production ( ions p] unit volume at a di/ance x f ! s\rce is q e- x :]e q is ! rate ( ionization at ! s\rce4 ,! total numb] ( ions produc$ by complete absorption ( ! rays is intinfty q e- x dx frac q 1 ,n[ is difficult to measure exp]im5tally = air1 b an approximate e/imate c be made ( its value f ! kn[n fact t ! absorption ( rays is approximately proportional to ! d5sity ( any giv5 sub/ance4 ,= rays f uranium ! value ( = alum9ium is ab\t #ad1 & divid$ by ! d5sity is #ed4 ,tak+ ! d5sity ( air z #jjab1 we f9d t = air #jjfe4 ,! total numb] ( ions produc$ 9 air is ?us #aedq :5 ! rays are completely absorb$4 ,n[ f ! above table ! ionization due to ! rays is #jjgd ( t produc$ by rays1 :5 ! rays pass$ ?r\gh a di/ance ( #eg cms4 ( air4 ,?us we h approximately ,total numb] ( ions produc$ by rays #jjgd ---------------------------------- ----- #aed #jbj4 ,total numb] ( ions produc$ by rays #eg ,!re=e ab\t ( ! total en]gy radiat$ into air by a ?9 lay] ( uranium is c>ri$ by ! rays or electrons4 ,! ratio = ?orium is ab\t & = radium ab\t 1 assum+ ! rays to h ab\t ! same av]age value ( 4 ,?is calculation takes into acc\nt only ! en]gy :i* is radiat$ out into ! surr\nd+ gas2 b on acc\nt ( ! ease ) :i* ! rays are absorb$1 ev5 ) a ?9 lay]1 ! great] proportion ( ! radiation is absorb$ by ! radio-active sub/ance itself4 ,?is is se5 to be ! case :5 x is recall$ t ! radiation ( ?orium or radium is r$uc$ to half value aft] pass+ ?r\gh a ?ickness ( ab\t #jjjje cm4 ( alum9ium4 ,tak+ into consid]ation ! great d5sity ( ! radio-active sub/ances1 x is probable t mo/ ( ! radiation :i* escapes into ! air is due to a ?9 sk9 ( ! p[d] n mu* m ?an #jjja cm4 9 ?ickness4 99 99 99 99 99 ,an e/imate1 h[ev]1 ( ! relative rate ( emission ( en]gy by ! & rays f a ?ick lay] ( mat]ial c be made 9 ! foll[+ way3--,= simplicity suppose a ?ick lay] ( radio-active sub/ance spread uni=mly ov] a l>ge plane area4 ,!re seems to be no d\bt t ! radiations are emitt$ uni=mly f ea* portion ( ! mass2 consequ5tly1 ! radiation1 :i* produces ! ioniz+ action 9 ! gas above ! radio-active lay]1 is ! sum total ( all ! radiation :i* rea*es ! surface ( ! lay]4 99 99 99 99 99 ,let be ! av]age coeffici5t ( absorption ( ! rays 9 ! radio-active sub/ance itself & ! specific gravity ( ! sub/ance4 ,let ,e be ! total en]gy radiat$ p] sec4 p] unit mass ( ! sub/ance :5 ! absorption ( ! rays 9 ! sub/ance itself is disreg>d$4 ,! en]gy p] sec4 radiat$ to ! upp] surface by a ?ickness dx ( a lay] ( unit area at a di/ance x f ! surface is giv5 by frac #a #b ,e#a sigma e-#a x dx 4 ,! total en]gy ,w p] unit area radiat$ to ! surface p] sec4 by a ?ickness d is giv5 by ,w#a frac #ab intd ,e#a sigma e-#a x dx frac ,e#a sigma #b #a 7#a e-#a d7 frac ,e#a sigma #b #a if d is l>ge4 99 99 99 99 99 ,9 a simil> way x may be %[n t ! en]gy ,w ( ! rays rea*+ ! surface is giv5 by ,w#b frac ,e#b sigma #b #b :]e ,e & are ! values = ! rays correspond+ to ,e & = ! rays4 ,?us x foll[s t ,e ,w ---- ------ ,e ,w & are difficult to det]m9e directly = ! radio-active sub/ance itself1 b x is probable t ! ratio _/ is n v diff]5t f ! ratio = ! absorption coeffici5ts = ano!r sub/ance l alum9ium4 ,?is foll[s f ! g5]al result t ! absorption ( bo? & rays is proportional to ! d5sity ( ! sub/ance2 = x has already be5 %[n 9 ! case ( ! rays f uranium t ! absorption ( ! rays 9 ! radio-active mat]ial is ab\t ! same z = non-radio-active matt] ( ! same d5sity4 ,) a ?ick lay] ( uranium oxide spread ov] an area ( #bb sq4 cms41 x 0 f\nd t ! saturation curr5t betwe5 p>allel plates #fa cms4 ap>t1 due to ! rays1 0 #abg times z great z ! curr5t due to ! rays4 ,s9ce ! rays 7 entirely absorb$ betwe5 ! plates & ! total ionization produc$ by ! rays is #aed times ! value at ! surface ( ! plates1 ,w total numb] ( ions due to rays ----- ---------------------------------- ,w total numb] ( ions due to rays #abg #fa ------ #je approximately4 #aed ,n[ ! value ( = alum9ium is #bgdj & ( = ! same metal #ad1 ?us ,e ,w ----- ---------- #ajj approximately ,e ,w ,?is %[s t ! en]gy radiat$ f a ?ick lay] ( mat]ial by ! rays is only ab\t #a p] c5t4 ( ! en]gy radiat$ 9 ! =m ( rays4 ,?is e/imate is confirm$ by calculations bas$ on indep5d5t data4 ,let m1 m be ! masses ( ! & p>ticles respectively & v1 v _! velocities4 frac ,en]gy ( "o alpha p>ticle ,en]gy ( "o beta p>ticle frac m#a v#ab m#b v#bb frac frac m#a e v#ab frac m#b e v#bb 4 ,n[ x has be5 %[n t = ! rays ( radium v #be #aj1 e ---- #f #aj4 m ,! velocity ( ! rays ( radium v>ies betwe5 wide limits4 ,tak+ = an av]age value v #ae #aj1 e ---- #ah #aj1 m x foll[s t ! en]gy ( ! p>ticle f radium is almo/ #hc times ! en]gy ( ! p>ticle4 ,if equal numb]s ( & p>ticles are project$ p] second1 ! total en]gy radiat$ 9 ! =m ( rays is ab\t #hc times ! am\nt 9 ! =m ( rays4 ,evid5ce w be giv5 lat] 7section #bec7 to %[ t ! numb] ( p>ticles project$ is probably f\r times ! numb] ( p>ticles2 s t a /ill great] proportion ( ! en]gy is emitt$ 9 ! =m ( rays4 ,^! results ?us lead to ! conclusion t1 f ! po9t ( view ( ! en]gy emitt$1 ! rays are f> m important ?an ! rays4 ,?is conclusion is support$ by o!r evid5ce :i* is discuss$ 9 *apt]s ,,xii & ,,xiii1 :]e x w be %[n t ! rays play by f> ! mo/ important "p 9 ! *anges occurr+ 9 radio-active bodies1 & t ! rays only appe> 9 ! latt] /ages ( ! radio-active processes4 ,f data bas$ on ! relative absorption & ionization ( ! & rays 9 air1 x c be %[n t ! rays c>ry (f ab\t ! same am\nt ( en]gy z ! rays4 ,^! conclusions are confirm$ by direct measurem5t ( ! heat+ effect ( radium1 :i* is discuss$ 9 detail 9 *apt] ,,xii4 ,footnote #aaa3 ,9 an exam9ation ( uranium ! writ] 7,phil4 ,mag4 p4 #aaf1 ,jan4 #ahii7 f\nd t ! rays f uranium consi/ ( two k9ds1 diff]+ greatly 9 p5etrat+ p[]1 :i* 7 call$ ! & rays4 ,lat]1 x 0 f\nd t simil> types ( rays 7 emitt$ by ?orium & radium4 ,on ! discov]y t v p5etrat+ rays 7 giv5 out by uranium & ?orium z well z by radium1 ! t]m 0 appli$ to !m by ! writ]4 ,! ^w 8ray0 has be5 reta9$ 9 ?is "w1 al?\gh x is n[ settl$ t ! & rays consi/ ( p>ticles project$ ) great velocity4 ,! t]m is ?us us$ 9 ! same s5se z by ,newton1 :o appli$ x 9 ! ,pr9cipia to ! /ream ( corpuscles :i* he believ$ to be responsible = ! ph5om5on ( light4 ,9 "s rec5t pap]s1 ! & rays h be5 call$ ! & 8emanations40 ,?is nom5clature _c fail to lead to confusion1 s9ce ! t]m 8radio-active emanation0 has already be5 g5]ally adopt$ 9 radio-activity z apply+ to ! mat]ial sub/ance :i* gradually diffuses f ?orium & radium comp\nds1 & itself emits rays4 ,footnote #aab3 ,?is me?od ( illu/ration is due to ,mme ,curie1 ,?se prs5te la ,facult des ,sci5ces de ,p>is1 #aijc4 ,footnote #aac3 ,giesel1 ,annal4 d4 ,phys4 #fi1 p4 #hcd1 #ahii4 ,footnote #aad3 ,mey] & ,s*weidl]1 ,phys4 ,zeit4 #a1 pp4 #ij1 #aac1 #ahii4 ,footnote #aae3 ,becqu]el1 ,c4 ,r4 #abi1 pp4 #iig1 #abje1 #ahii4 ,footnote #aaf3 ,curie1 ,c4 ,r4 #acj1 p4 #gc1 #aijj4 ,footnote #aag3 ,ru!r=d1 ,phil4 ,mag4 ,janu>y1 #ahii4 ,footnote #aah3 ,ru!r=d & ,gri]1 ,phil4 ,mag4 ,septemb]1 #aijb4 ,footnote #aai3 ,becqu]el1 ,c4 ,r4 #acj1 pp4 #bjf1 #cgb1 #haj1 #igi4 #aijj4 ,footnote #abj3 ,m4 & ,mme ,curie1 ,c4 ,r4 #acj1 p4 #fdg1 #aijj4 ,footnote #aba3 ,! activity ( ! radium prep>ation 0 n /at$ 9 ! pap]4 ,footnote #abb3 ,dorn1 ,phys4 ,zeit4 #d1 ,no4 #ah1 p4 #ejg1 #aijc4 ,footnote #abc3 ,/rutt1 ,phil4 ,mag4 ,nov4 #aijc4 ,footnote #abd3 ,wi51 ,phys4 ,zeit4 #d1 ,no4 #bc1 p4 #fbd1 #aijc4 ,footnote #abe3 ,dorn1 ,c4 ,r4 #acj1 p4 #aabi1 #aijj4 ,footnote #abf3 ,becqu]el1 ,c4 ,r4 #acj1 p4 #hji1 #aijj4 ,footnote #abg3 ,kaufmann1 ,phys4 ,zeit4 #d1 ,no4 #a b1 p4 #ed1 #aijb4 ,footnote #abh3 ,abraham1 ,phys4 ,zeit4 #d1 ,no4 #a b1 p4 #eg1 #aijb4 ,footnote #abi3 ,kaufmann1 ,na*ri*t5 d4 ,ges4 d4 ,wiss4 zu ,gtt41 ,nov4 #h1 #aija4 ,footnote #acj3 ,simon1 ,annal4 d4 ,phys4 p4 #ehi1 #ahii4 ,footnote #aca3 ,kaufmann1 ,phys4 ,zeit4 #d1 ,no4 #a b1 p4 #ed1 #aijb4 ,footnote #acb3 ,pas*51 ,annal4 d4 ,phys4 #ad1 p4 #chi1 #aijd4 ,footnote #acc3 ,mey] & ,s*weidl]1 ,phys4 ,zeit4 pp4 #ij1 #aac1 #bji1 #aijj4 ,footnote #acd3 ,l5>d1 ,annal4 d4 ,phys4 #ef1 p4 #bge1 #ahie4 ,footnote #ace3 ,/rutt1 ,nature1 p4 #eci1 #aijj4 ,footnote #acf3 ,seitz1 ,phys4 ,zeit4 #e1 ,no4 #ad1 p4 #cie1 #aijd4 ,footnote #acg3 ,x is presum$ t ! results 7 correct$1 if necess>y1 = ! dis*>g+ action due to ! ioniz$ gas1 al?\gh no direct m5tion ( ?is is made 9 ! pap] by ,seitz4 ,footnote #ach3 ,/rutt1 ,phil4 ,trans4 ,a1 p4 #ejg1 #aija4 ,footnote #aci3 ,crookes1 ,proc4 ,roy4 ,soc4 #aijb4 ,*em4 ,news1 #he1 p4 #aji1 #aijb4 ,footnote #adj3 ,mme ,curie1 ,c4 ,r4 #acj1 p4 #gf1 #aijj4 ,footnote #ada3 ,ru!r=d1 ,phil4 ,mag4 ,feb4 #aijc4 ,phys4 ,zeit4 #d1 p4 #bce1 #aijb4 ,footnote #adb3 ,becqu]el1 ,c4 ,r4 #acf1 p4 #aii1 #aijc4 ,footnote #adc3 ,becqu]el1 ,c4 ,r4 #acf1 p4 #dca1 #aijc4 ,footnote #add3 ,des ,c\dres1 ,phys4 ,zeit4 #d1 ,no4 #ag1 p4 #dhc1 #aijc4 ,footnote #ade3 ,becqu]el1 ,c4 ,r4 #acf1 p4 #aeag1 #aijc4 ,footnote #adf3 ,bragg1 ,phil4 ,mag4 ,dec4 #aijd2 ,bragg & ,kleeman1 ,phil4 ,mag4 ,dec4 #aijd4 ,footnote #adg3 ,fur!r exp]im5tal results be>+ on ?is important "q are giv5 9 an ,app5dix to ?is book4 ,footnote #adh3 ,bak]ian ,lecture1 ,phil4 ,trans4 ,a1 p4 #afi1 #aijd4 ,footnote #adi3 ,/rutt1 ,phil4 ,mag4 ,aug4 #aijd4 ,footnote #aej3 ,j4 ,j4 ,?omson1 ,proc4 ,camb4 ,phil4 ,soc4 #ac1 ,pt4 ,i4 p4 #ci1 #aije4 ,nature1 ,dec4 #ae1 #aijd4 ,footnote #aea3 ,ru!r=d1 ,nature1 ,m>* #b1 #aije4 ,j4 ,j4 ,?omson1 ,nature1 ,m>* #i1 #aije4 ,footnote #aeb3 ,crookes1 ,proc4 ,roy4 ,soc4 #ha1 p4 #dje1 #aijc4 ,footnote #aec3 ,el/] & ,geitel1 ,phys4 ,zeit4 ,no4 #ae1 p4 #dcg1 #aijc4 ,footnote #aed3 ,glew1 ,ar*4 ,rntg5 ,ray1 ,june #aijd4 ,footnote #aee3 ,becqu]el1 ,c4 ,r4 #acg1 ,oct4 #bg1 #aijc4 ,footnote #aef3 ,tommas9a1 ,c4 ,r4 #acg1 ,nov4 #i1 #aijc4 ,footnote #aeg3 ,an int]e/+ side-light is ?r[n on ?is "q by ! exp]im5ts describ$ 9 ,app5dix ,a ( ?is book4 ,footnote #aeh3 ,ru!r=d & ,miss ,brooks1 ,phil4 ,mag4 ,july #aijb4 ,footnote #aei3 ,9 ord] to obta9 a ?9 lay]1 ! comp\nd to be te/$ is gr\nd to a f9e p[d] & !n sift$ ?r\gh a f9e gauge uni=mly ov] ! area1 s t ! plate is only p>tially cov]$4 ,footnote #afj3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #ahii4 ,footnote #afa3 ,ow5s1 ,phil4 ,mag4 ,oct4 #ahii4 ,footnote #afb3 ,ru!r=d & ,miss ,brooks1 ,phil4 ,mag4 ,july1 #aijj4 ,footnote #afc3 ,s9ce ! ionization at any po9t above ! plate is ! resultant effect ( ! p>ticles com+ f all po9ts ( ! l>ge radio-active lay]1 is n ! same z ! coeffici5t ( absorption ( ! rays f a po9t s\rce4 ,x w h[ev] be proportional to x4 ,= ?is reason is call$ ! 8absorption con/ant40 ,footnote #afd3 ,t[ns5d1 ,phil4 ,mag4 ,feb4 #aija4 ,footnote #afe3 ,durack1 ,phil4 ,mag4 ,july #aijb1 ,may #aijc4 ,footnote #aff3 ,bragg & ,bragg & ,kleeman1 ,phil4 ,mag4 ,dec4 #aijd4 ,footnote #afg3 ,vill>d1 ,c4 ,r4 #acj1 pp4 #ajaj1 #aagh1 #aijj4 ,footnote #afh3 ,becqu]el1 ,c4 ,r4 #acj1 p4 #aaed1 #aijj4 ,footnote #afi3 ,ru!r=d1 ,phys4 ,zeit4 #c1 p4 #eag1 #aijb4 ,footnote #agj3 ,mc,clelland1 ,phil4 ,mag4 ,july #aijd4 ,footnote #aga3 ,pas*51 ,phys4 ,zeit4 #e1 ,no4 #ah1 p4 #efc1 #aijd4 ,footnote #agb3 ,a4 ,s4 ,eve1 ,phil4 ,mag4 ,nov4 #aijd4 ,footnote #agc3 ,pas*51 ,annal4 d4 ,physik1 #ad1 p4 #aad1 #aijd2 #ad1 #b1 p4 #chi1 #aijd4 ,phys4 ,zeit4 #e1 ,no4 #ah1 p4 #efc1 #aijd4 ,footnote #agd3 ,pas*51 ,phys4 ,zeit4 #e1 ,no4 #ah1 p4 #efc1 #aijd4 ,footnote #age3 ,ru!r=d & ,b>nes1 ,phil4 ,mag4 ,may #aije4 ,nature1 p4 #aea1 ,dec4 #ae1 #aijd4 ,footnote #agf3 ,b>kla1 ,nature1 ,m>* #ag1 #aijd4 ,footnote #agg3 ,becqu]el1 ,c4,r4 #acb1 pp4 #cga1 #gcd1 #abhf4 #aija4 ,footnote #agh3 ,mme ,curie1 ,?se prs5te la ,facult des ,sci5ces1 ,p>is #aijc1 p4 #he4 ,footnote #agi3 ,a4 ,s4 ,eve1 ,phil4 ,mag4 ,dec4 #aijd4 ,footnote #ahj3 ,9 a rec5t pap] 7,phil4 ,mag4 ,feb4 #aije71 ,mc,clelland has1 9 ! ma91 confirm$ ! exp]im5tal results obta9$ by ,eve4 ,an electromet] 0 us$ in/ead ( an electroscope4 ,he f9ds1 9 addition1 t ! am\nt ( second>y radiation dep5ds on ! angle ( incid5ce ( ! prim>y rays1 & is greate/ = an angle ( #de4 ,9 a lett] to ,nature 7,feb4 #bc1 p4 #cij1 #aije71 he /ates t m rec5t exp]im5ts h %[n t ! am\nt ( second>y radiation f diff]5t sub/ances is a function ( _! atomic weights r ?an ( _! d5sities4 ,9 e case exam9$1 ! am\nt ( second>y radiation increases ) ! atomic weight1 b is n proportional to x4 ,footnote #aha3 ,ru!r=d & ,mc,clung1 ,phil4 ,trans4 ,a4 p4 #be1 #aija4 ,footnote #ahb3 ,mey] & ,s*weidl]1 ,wi5 ,b]4 #aac1 ,july1 #aijd4 ,footnote #ahc3 ,ru!r=d & ,gri]1 ,phil4 ,mag4 ,sept4 #aijb4 ,,*apt] ,v4 ,,prop]ties ,,( ,,! ,,radiations4 #aae4 ,besides _! p[] ( act+ on a photographic plate1 & ( ioniz+ gases1 ! radiations f active bodies are able to produce m>k$ *emical & physical actions 9 v>i\s sub/ances4 ,mo/ ( ^! effects are due ei!r to ! or rays4 ,! rays produce little effect 9 comp>ison4 ,s9ce ! rays are simil> 9 all respects to high velocity ca?ode rays1 x is to be expect$ t !y w produce effects simil> 9 "* to ^? produc$ by ! ca?ode rays 9 a vacuum tube4 ,phosphoresc5t action4 ,becqu]el#ahd has /udi$ ! action ( radium rays 9 produc+ phosphoresc5ce 9 v>i\s bodies4 ,! sub/ance to be te/$ 0 plac$ above ! radium 9 ! =m ( p[d] on a v ?9 mica plate4 ,exam9ation 0 made ( ! sulphides ( calcium & /rontium1 ruby1 diamond1 v>ieties ( sp>1 phosphorus & hexagonal bl5de4 ,sub/ances l ! ruby & sp>1 :i* phosphoresce "u lum9\s rays1 did n phosphoresce "u ! radium rays4 ,on ! o!r h&1 ^? :i* 7 made lum9\s by ultra-violet light 7 also lum9\s "u ! action ( radium rays4 ,! radium rays %[ di/9ct diff]5ces f ,x rays4 ,= example1 a diamond :i* 0 v lum9\s ) radium rays 0 unaffect$ by ,x rays4 ,! d\ble sulphate ( uranium & potassium is m lum9\s ?an hexagonal bl5de "u ,x rays1 b ! rev]se is true = radium rays2 "u ! influ5ce ( ^! rays1 sulphide ( calcium gave a blue lum9osity b 0 h>dly affect$ by ,x rays4 ,! foll[+ table %[s ! relative phosphoresc5ce excit$ 9 v>i\s bodies4 ,sub/ance ,)\t scre54 ,across scre5 ,int5sity ( black pap] ,hexagonal bl5de #accf #jd ,plat9o-cyanide ( #aii #je b>ium ,diamond #aad #ja ,d\ble sulphate ( #ajj #ca ,uranium & ,potassium ,calcium ,fluoride #cj #jb ,9 ! la/ column ! int5sity )\t ! scre5 is 9 ea* case tak5 z unity4 ,! great dim9ution ( int5sity aft] ! rays h pass$ ?r\gh black pap] %[s t mo/ ( ! phosphoresc5ce develop$ )\t ! scre5 is1 9 ! majority ( cases1 due to ! rays4 ,b>y#ahe has made a v complete exam9ation ( ! class ( sub/ances :i* become lum9\s "u radium rays4 ,he f\nd t ! great majority ( sub/ances belong to ! alkali metals & alkal9e e>?s4 ,all ^! sub/ances 7 also phosphoresc5t "u ! action ( ,x rays4 ,cry/all9e z9c sulphide 7,sidot's bl5de7 phosphoresces v brightly "u ! influ5ce ( ! rays f radium & o!r v active sub/ances4 ,?is 0 obs]v$ by ,curie & ,debi]ne 9 _! /udy ( ! radium emanation & ! excit$ activity produc$ by x4 ,x has also be5 l>gely us$ by ,giesel z an optical means ( detect+ ! pres5ce ( emanations f v active sub/ances4 ,x is an especially s5sitive means ( detect+ ! pres5ce ( rays1 :5 x exhibits ! 8sc9tillat+0 prop]ty already discuss$ 9 section #if4 ,9 ord] to %[ ! lum9osity due to ! rays1 ! scre5 %\ld be held close to ! active sub/ance1 z ! rays are absorb$ 9 _! passage ?r\gh a few c5timetres ( air4 ,z9c sulphide is also lum9\s "u ! action ( ! rays1 b ! phosphoresc5ce is f> m p]si/5t ?an :5 produc$ by ! rays4 ,v beautiful lum9\s effects are produc$ by l>ge cry/als ( ! plat9ocyanides expos$ to ! radium rays4 ,^? conta9+ li?ium give a brilliant p9k col\r4 ,! calcium & b>ium salts fluoresce ) a deep gre5 light1 & ! sodium comp\nd ) a lemon yell[4 ,! m9]al willemite 7z9c silicate7 0 rec5tly f\nd by ,kunz to be an ev5 m s5sitive means ( detect+ ! pres5ce ( ! radiations ?an plat9ocyanide ( b>ium4 ,x fluoresces %[+ a beautiful gre5i% col\r1 & a piece ( m9]al expos$ to ! action ( ! rays appe>s q transluc5t4 ,! cry/als ( ! plat9ocyanides ( b>ium & li?ium are especially suit$ = %[+ ! action ( ! rays1 &1 9 ?is respect1 are sup]ior to willemite4 ,a v /rik+ effect is %[n by ! m9]al kunzite--a new v>iety ( spodum5e discov]$ by ,kunz#ahf4 ,?is is a transp>5t gem l cry/al1 (t5 ( v l>ge size1 :i* gl[s ) a beautiful r$di% col\r "u ! action ( ! or rays1 b does n appe> to be s5sitive to ! rays4 ,! lum9osity ext5ds ?r\gh\t ! cry/al1 b is n s m>k$ z 9 ! plat9ocyanides or willemite4 ,! m9]al sp>teite#ahg1 a =m ( calcite conta9+ a few p] c5t4 ( manganese1 has be5 f\nd by ,ambre*t to fluoresce ) a v deep orange light "u ! & rays4 ,! col\r appe>s to dep5d on ! int5sity ( ! rays1 & is deep] close to ! radium ?an at "s di/ance away4 ,if kunzite & sp>teite are expos$ to ! action ( ! ca?ode rays 9 a vacuum tube1 ! col\r is diff]5t f t produc$ by ! radium rays4 ,! =m] appe>s a deep yell[1 in/ead ( ! deep r$ obs]v$ ) ! radium rays4 ,! diff]5t actions ( ! radium rays on ^! fluoresc5t sub/ances c be illu/rat$ v simply & beautifully by ! foll[+ exp]im5t4 ,a small ,u tube is fill$ ) fragm5ts ( ! fluoresc5t sub/ance arrang$ 9 lay]s4 ,! ,u tube is imm]s$ 9 liquid air & ! emanation f ab\t #cj mgrs4 ( radium bromide is cond5s$ 9 ! tube4 ,on clos+ ! tube & remov+ x f ! liquid air1 ! emanation di/ributes itself uni=mly 9 ! tube4 ,! %ades ( col\r produc$ 9 ! diff]5t sub/ances are cle>ly se54 ,x is obs]v$ t all ! cry/als increase 9 lum9osity = sev]al h\rs1 on acc\nt ( ! excit$ activity produc$ by ! emanation4 ,?is effect is especially obs]v$ 9 kunzite1 :i* at fir/ h>dly responds to ! rays1 s9ce ! & rays1 :i* causes x to fluoresce1 are n giv5 out by ! emanation itself b by "o ( its lat] products4 ,! int5sity ( ! & rays is1 9 consequ5ce1 small at fir/ b rises to a maximum aft] sev]al h\rs2 ! lum9osity obs]v$ v>ies 9 a correspond+ mann]4 ,sir ,william ,crookes#ahh has made an exam9ation ( ! effect ( cont9u$ exposure ( a diamond to ! radium rays4 ,an 8(f-col\r0 diamond1 ( a pale yell[ col\r1 0 plac$ inside a tube ) radium bromide4 ,aft] #gh days' exposure1 ! diamond _h d>k5$ & become blui% gre5 9 t9t2 :5 heat$ at #ej 9 a mixture ( potassium *lorate = t5 days1 ! diamond lo/ its dull surface col\r & 0 bright & transp>5t1 & its t9t _h *ang$ to a pale blui% gre54 ,! rays h ?us a d\ble action on ! diamond2 ! less p5etrat+ rays produce a sup]ficial d>k5+ due to ! *ange ( ! surface into graphite1 :ile ! m p5etrat+ rays & ! rays produce a *ange ( col\r ?r\gh\t its mass4 ,! diamond phosphoresc$ brightly dur+ ! :ole c\rse ( its exposure to ! rays4 ,crookes also obs]v$ t ! diamond /ill reta9$ en\gh activity to affect a photographic plate #ce days aft] removal1 al?\gh1 dur+ ! p]iod ( #aj days1 x 0 heat$ 9 a mixture suffici5tly p[]ful to remove ! out] sk9 ( graphite4 ,?is residual activity may possibly be due to a sl[ trans=mation product ( ! emanation :i* is deposit$ on ! surface ( bodies 7see *apt] ,,xi74 ,m>ckwald obs]v$ t ! rays f radio-tellurium produc$ m>k$ phosphoresc5ce on "s k9ds ( diamonds4 ,an acc\nt ( ! v>i\s lum9\s effects produc$ on diff]5t gems by exposure to ! radium & act9ium rays has be5 giv5 by ,kunz & ,bask]ville#ahi4 ,bo? z9c sulphide & plat9ocyanide ( b>ium dim9i% 9 lum9osity aft] exposure = "s "t to ! action ( ! rays4 ,to reg5]ate a scre5 ( ! latt]1 exposure to sol> light is necess>y4 ,a simil> ph5om5on has be5 obs]v$ by ,vill>d = a scre5 expos$ to ,rntg5 rays4 ,giesel made a scre5 ( plat9ocyanide ( radio-active b>ium4 ,! scre51 v lum9\s at fir/1 gradually turn$ br[n 9 col\r1 & at ! same "t ! cry/als became di*roic4 ,9 ?is condition ! lum9osity 0 mu* less1 al?\gh ! active sub/ance _h increas$ 9 activity aft] prep>ation4 ,_m ( ! sub/ances :i* are lum9\s "u ! rays f active sub/ances lose ?is prop]ty to a l>ge ext5t at l[ temp]atures#aij4 #aaf4 ,lum9osity ( radium comp\nds4 ,all radium comp\nds are spontane\sly lum9\s4 ,?is lum9osity is especially brilliant 9 ! dry haloid salts1 & p]si/s = long int]vals ( "t4 ,9 damp air ! salts lose a l>ge am\nt ( _! lum9osity1 b !y recov] x on dry+4 ,) v active radium *loride1 ! ,curies h obs]v$ t ! light *anges 9 col\r & int5sity ) "t4 ,! orig9al lum9osity is recov]$ if ! salt is dissolv$ & dri$4 ,_m inactive prep>ations ( radif]\s b>ium are /rongly lum9\s4 ,! writ] has se5 a prep>ation ( impure radium bromide :i* gave out a light suffici5t to read by 9 a d>k room4 ,! lum9osity ( radium p]si/s ov] a wide range ( temp]ature & is z bright at ! temp]ature ( liquid air z at ord9>y temp]atures4 ,a slight lum9osity is obs]v$ 9 a solution ( radium1 & if cry/als are be+ =m$ 9 ! solution1 !y c be cle>ly di/+ui%$ 9 ! liquid by _! great] lum9osity4 #aag4 ,spectrum ( ! phosphoresc5t light ( radium & act9ium4 ,comp\nds ( radium1 ) a l>ge admixture ( b>ium1 are usually /rongly self-lum9\s4 ,?is lum9osity decreases ) increas+ purity1 & pure radium bromide is only v feebly self-lum9\s4 ,a spectroscopic exam9ation ( ! slight phosphoresc5t light ( pure radium bromide has be5 made by ,sir ,william & ,lady ,hugg9s#aia4 ,on view+ ! light ) a direct vision spectroscope1 !re 7 fa9t indications ( a v>iation ( lum9osity at diff]5t po9ts along ! spectrum4 ,9 ord] to get a photograph ( ! spectrum )9 a reasonable "t1 !y made use ( a qu>tz spectroscope ( special design :i* _h be5 previ\sly employ$ 9 a spectroscopic exam9ation ( fa9t cele/ial objects4 ,aft] ?ree days' exposure ) a slit ( ( an in* 9 wid?1 a negative 0 obta9$ :i* %[$ a numb] ( bright l9es4 ,! magnifi$ spectrum is %[n 9 ,fig4 #df ,a4 ,! l9es ( ?is spectrum 7 f\nd to agree n only 9 position b also 9 relative int5sity ) ! b& spectrum ( nitrog54 ,! b& spectrum ( nitrog5 & also ! sp>k spectrum#aib ( radium are %[n 9 ! same figure4 ,"s "t aft]w>ds ,sir ,william ,crookes & ,pr(4 ,dew> %[$ t ?is spectrum ( nitrog5 0 n obta9$ if ! radium 0 conta9$ 9 a highly exhau/$ tube4 ,?us x appe>s t ! spectrum is due to ! action ( ! radium rays ei!r on occlud$ nitrog5 or ! nitrog5 9 ! atmosph]e surr\nd+ ! radium4 ,x is v rem>kable t a phosphoresc5t light1 l t ( radium bromide1 %\ld %[ a bright l9e spectrum ( nitrog54 ,x %[s t radium at ord9>y temp]atures is able to set up radiations :i* are produc$ only by ! electric dis*>ge "u special conditions4 ,sir ,william & ,lady ,hugg9s 7 l$ to exam9e ! spectrum ( ! natural phosphoresc5t light ( radium ) ! hope t "s indications might be obta9$ !reby ( ! processes occurr+ 9 ! radium atom4 ,s9ce ! ma9 radiation f radium consi/s ( positively *>g$ atoms project$ ) great velocity1 radiations mu/ be set up bo? 9 ! expell$ body & 9 ! sy/em f :i* x escapes4 ,illu/ration3 ,fig4 #df;a4 ,giesel#aic obs]v$ t ! spectrum ( ! phosphoresc5t light ( act9ium consi/s ( ?ree bright l9es4 ,measurem5ts ( ! wave l5g? 7 made by ,h>tmann#aid4 ,! lum9osity 0 v slight & a long exposure 0 requir$4 ,! l9es obs]v$ 7 9 ! r$1 blue & gre54 ,! wave l5g? & velocity are %[n bel[4 ,l9e ,int5sity #a #aj #dhhed #ja ng/rm units #b #f #ecjj #f #c #a #eiji #aj ,! l9e #dhhe 0 v broad2 ! o!r two l9es 7 s feeble t x 0 difficult to det]m9e _! wave l5g? ) accuracy4 ,h>tmann sugge/s t ^! l9es may be f\nd 9 ! spectrum ( ! new />s4 ,! l9es obs]v$ h no connection ) radium or its emanation#aie4 #aah4 ,!rmo-lum9esc5ce4 ,e4 ,wi$emann & ,s*midt#aif h %[n t c]ta9 bodies aft] exposure to ! ca?ode rays or ! electric sp>k become lum9\s :5 !y are heat$ to a temp]ature mu* bel[ t requir$ to cause inc&esc5ce4 ,?is prop]ty ( !rmo-lum9esc5ce is mo/ /rik+ly exhibit$ 9 c]ta9 cases :]e two salts1 "o ( :i* is mu* 9 excess ( ! o!r1 are precipitat$ toge!r4 ,x is to be expect$ t su* bodies w\ld also acquire ! prop]ty :5 expos$ to ! or ca?odic rays ( radium4 ,?is has be5 f\nd to be ! case by ,wi$emann#aig4 ,becqu]el %[$ t fluor-sp>1 expos$ to ! radium rays1 0 lum9\s :5 heat$4 ,! glass tubes 9 :i* radium is kept are rapidly black5$4 ,on heat+ ! tube1 a /rong lum9osity is obs]v$1 & ! coloration to a l>ge ext5t disappe>s4 ,! peculi>ity ( _m ( ^! bodies lies 9 ! fact t ! prop]ty ( becom+ lum9\s :5 heat$ is reta9$ = a long int]val ( "t aft] ! body is remov$ f ! influ5ce ( ! excit+ cause4 ,x appe>s probable t ! rays cause *emical *anges 9 ^! bodies1 :i* are p]man5t until heat is appli$4 ,a portion ( ! *emical en]gy is !n releas$ 9 ! =m ( visible light4 ,physical actions4 #aai4 ,"s electric effects4 ,radium rays h ! same effect z ultra-violet light & ,rntg5 rays 9 increas+ ! facility ) :i* a sp>k passes betwe5 electrodes4 ,el/] & ,geitel#aih %[$ t if two electrodes 7 sep>at$ by a di/ance su* t ! sp>k j refus$ to pass1 on br++ ne> a specim5 ( radium ! sp>k at once passes4 ,?is effect is be/ %[n ) %ort sp>ks f a small induction coil4 ,! ,curies h obs]v$ t radium completely envelop$ by a lead scre5 #a cm4 ?ick produces a simil> action4 ,! effect 9 t case is due to ! rays alone4 ,?is action ( ! rays c be v simply illu/rat$ by connect+ two sp>k-gaps ) ! induction coil 9 p>allel4 ,! sp>k-gap ( "o circuit is adju/$ s t ! dis*>ge j refuses to pass across x1 b passes by ! o!r4 ,:5 "s radium is br\ght ne> ! sil5t sp>k-gap1 ! sp>k at once passes & ceases 9 ! o!r#aii4 ,hempt9ne#bjj f\nd t ! electrodeless dis*>ge 9 a vacuum tube began at a high] pressure :5 a /rong prep>ation ( radium 0 br\ght ne> ! tube4 ,9 "o exp]im5t ! dis*>ge )\t ! rays began at #ea mms4 b ) ! radium rays at #fh mms4 ,! col\r ( ! dis*>ge 0 also alt]$4 ,him/$t#bja f\nd t ! resi/ance ( sel5ium 0 dim9i%$ by ! action ( radium rays 9 ! same way z by ord9>y light4 ,f4 ,h5n+#bjb exam9$ ! electrical resi/ance ( a b>ium *loride solution conta9+ radium ( activity #ajjj1 b c\ld obs]ve no appreciable diff]5ce betwe5 x & a simil> pure solution ( b>ium *loride4 ,?is exp]im5t %[s t ! action ( ! rays f ! radium does n produce any appreciable *ange 9 ! conductivity ( ! b>ium solution4 ,kohlraus* & ,h5n+#bjc h rec5tly made a detail$ exam9ation ( ! conductivity ( pure radium bromide solutions1 & h obta9$ results v simil> to ^? = ! correspond+ b>ium solutions4 ,kohlraus*#bjd f\nd t ! conductivity ( wat] expos$ to ! radiations f radium increas$ m rapidly ?an wat] :i* _h n be5 expos$4 ,?is increase ( conductivity may h be5 due to an increase ( ! conductivity ( ! wat] itself1 or to an increas$ rate ( solution ( ! glass ( ! conta9+ vessel4 ,specim5s ( /rongly active mat]ial h be5 employ$ to obta9 ! pot5tial at any po9t ( ! atmosph]e4 ,! ionization due to ! active sub/ance is s int5se t ! body to :i* x is atta*$ rapidly takes up ! pot5tial ( ! air surr\nd+ ! active sub/ance4 ,9 ?is respect x is m conv5i5t & rapid 9 its action ?an ! ord9>y tap] or wat] dropp]1 b on acc\nt ( ! di/urbance ( ! electric field by ! /rong ionization produc$1 x is probably n s accurate a me?od z t ( ! wat] dropp]4 #abj4 ,effect on liquid & solid dielectrics4 ,p4 ,curie#bje made ! v important obs]vation t liquid dielectrics became p>tial conductors "u ! influ5ce ( radium rays4 ,9 ^! exp]im5ts ! radium1 conta9$ 9 a glass tube1 0 plac$ 9 an inn] ?9 cyl9d] ( copp]4 ,?is 0 surr\nd$ by a conc5tric copp] cyl9d]1 & ! liquid to be exam9$ fill$ ! space betwe54 ,a /rong electric field 0 appli$1 & ! curr5t ?r\gh ! liquid measur$ by means ( an electromet]4 ,! foll[+ numb]s illu/rate ! results obta9$3 ,sub/ance ,conductivity 9 megohms p] #a cm4 ,c>bon bisulphide #bj #aj ,petroleum e!r #ae ,amyl9e #ad ,c>bon *loride #h ,b5z5e #d ,liquid air #ac ,vasel9e oil #af ,liquid air1 vasel9e oil1 petroleum e!r1 amyl9e1 are normally ne>ly p]fect insulators4 ,! conductivity ( amyl9e & petroleum e!r due to ! rays at #ag ,c4 0 only ( its value at #j ,c4 ,!re is ?us a m>k$ action ( temp]ature on ! conductivity4 ,= v active mat]ial ! curr5t 0 proportional to ! voltage4 ,) mat]ial ( only ( ! activity1 x 0 f\nd t ,ohm's law 0 n obey$4 ,! foll[+ numb]s 7 obta9$3 ,volts ,curr5t #ej #aji #ajj #ahe #bjj #bee #djj #cce ,= an increase ( voltage ( #h times1 ! curr5t only increases ab\t #c times4 ,! curr5t 9 ! liquid ?us t5ds to become 8saturat$0 z does ! ord9>y ionization curr5t ?r\gh a gas4 ,^! results h an important be>+ on ! ionization !ory1 & %[ t ! radiation probably produces ions 9 ! liquid z well z 9 ! gas4 ,x 0 also f\nd t ,x rays increas$ ! conductivity to ab\t ! same ext5t z ! radium rays4 ,becqu]el#bjf has rec5tly %[n t solid p>aff9 expos$ to ! & rays ( radium acquires ! prop]ty ( conduct+ electricity to a slight ext5t4 ,aft] removal ( ! radium ! conductivity dim9i%es ) "t accord+ to ! same law z = an ioniz$ gas4 ,^! results %[ t a solid z well z a liquid & gase\s dielectric is ioniz$ "u ! influ5ce ( radium rays4 #aba4 ,effect ( temp]ature on ! radiations4 ,becqu]el#bjg1 by ! electric me?od1 det]m9$ ! activity ( uranium at ! temp]ature ( liquid air1 & f\nd t x did n diff] m ?an #a p] c5t4 f ! activity at ord9>y temp]atures4 ,9 8 exp]im5ts1 ! rays f ! uranium 7 absorb$ be=e rea*+ ! te/+ vessel1 & ! electric curr5t measur$ 0 due to ! rays alone4 ,p4 ,curie#bjh f\nd t ! lum9osity ( radium & its p[] ( excit+ fluoresc5ce 9 bodies 7 reta9$ at ! temp]ature ( liquid air4 ,obs]vations by ! electric me?od %[$ t ! activity ( radium 0 unalt]$ at ! temp]ature ( liquid air4 ,if a radium comp\nd is heat$ 9 an op5 vessel1 x is f\nd t ! activity1 measur$ by ! rays1 falls to ab\t #be p] c5t4 ( its orig9al value4 ,?is is h[ev] n due to a *ange 9 ! radio-activity1 b to ! release ( ! radio-active emanation1 :i* is /or$ 9 ! radium4 ,no alt]ation is obs]v$ if ! radium is heat$ 9 a clos$ vessel f :i* none ( ! radio-active products are able to escape4 #abb4 ,motion ( radium 9 an electric field4 ,joly#bji f\nd t a disc1 "o side ( :i* is coat$ ) a few milligrams ( radium bromide1 exhibits1 :5 an electrifi$ body is br\ght ne> x1 motions v diff]5t to ^? obs]v$ 9 ! case ( an inactive sub/ance4 ,! electrifi$ body1 :e!r positive or negative1 repels ! susp5d$ body if br\ght up to x on ! side coat$ ) radium1 b attracts x if pres5t$ to ! nak$ side4 ,?is effect is v simply %[n by con/ruct+ a small app>atus l a radiomet]4 ,two cov]$ glasses are atta*$ to ! end ( a glass fibre ab\t #f cms4 long1 ! surfaces ly+ 9 ! same plane4 ,! app>atus is free to rotate on a pivot4 ,! two vanes are coat$ on alt]nate faces ) radium bromide1 & ! :ole app>atus conta9$ )9 a glass receiv]4 ,if an electrifi$ rod ( ebonite or seal+ wax is br\ght up close to ! receiv]1 a rotation is communicat$ to ! vane :i* increases z ! pressure ( ! air is l[]$ to #e or #f cms4 ( m]cury4 ,by plac+ ! app>atus betwe5 p>allel plates connect$ ) ! t]m9als ( a ,wim%ur/ ma*9e1 a /eady rotation is communicat$ to ! vanes4 ,! rotation is always 9 su* a direction t ! radium coat$ surface is repell$ f ! electrifi$ body4 ,?is action 0 exam9$ /ill fur!r by atta*+ ! vanes to ! glass beam ( a ,c\lomb's balance4 ,a metal sph]e1 :i* c\ld be *>g$ f )\t1 0 fix$ fac+ ! side coat$ ) radium4 ,a repulsion 0 always obs]v$ except :5 ! *>ge 0 v /rong & ! vane ne> ! sph]e4 ,if1 h[ev]1 ! two vanes 7 connect$ by a light wire & a simil> sph]e plac$ exactly opposite ! o!r1 an attraction 0 obs]v$ if "o sph]e 0 *>g$1 b a repulsion if bo? 7 *>g$4 ,^! effects 7 obs]v$ :e!r ! vanes 7 ( alum9ium or glass4 ,joly f\nd t ! effect c\ld n be expla9$ by any direct action due to ! movem5t ( ! ions 9 an electric field4 ,! recoil1 due to ! expulsion ( p>ticles f "o side ( ! vane1 is f> too small to acc\nt = ! movem5t obs]v$4 ,?is effect c1 ,i ?9k1 be simply acc\nt$ = by tak+ into consid]ation ! diff]5ce 9 conductivity ( ! gas on ! two sides ( ! radium coat$ vane4 ,if a small vane1 coat$ uni=mly ) radium on bo? sides1 & m\nt$ on an insulat+ support1 be br\ght ne> a *>g$ body kept at a con/ant pot5tial1 x acts l a wat] dropp] & rapidly acquires v ne>ly ! av]age pot5tial :i* exi/$ at t po9t be=e ! vane 0 br\ght up4 ,! me*anical =ce act+ on ! vane w1 9 consequ5ce1 be small4 ,if1 h[ev]1 ! vane is only coat$ ) radium on ! side ne> ! *>g$ body1 ! ionization & consequ5tly ! conductivity ( ! gas is mu* great] betwe5 ! vane & ! *>g$ body ?an on ! opposite side4 ,suppose1 = simplicity1 ! body is *>g$ to a positive pot5tial4 ,on acc\nt ( ! great] conductivity ( ! gas on ! side fac+ ! *>g$ body1 x w rapidly acquire a positive *>ge1 & ! pot5tial ( ! vane w rea* a high] value ?an exi/$ at t place be=e ! vane 0 introduc$4 ,?is w result 9 a repulsion ( ! vane4 ,?is also acc\nts = ! attraction obs]v$ 9 ! exp]im5t ) ! ,c\lomb's balance already ref]r$ to4 ,suppose t "o sph]e is positively *>g$ & ! o!r e>!d1 & ! two vanes metallically connect$ toge!r4 ,! vane next to ! *>g$ body w become *>g$ positively1 b ?is *>ge w be dissipat$ rapidly on acc\nt ( ! ionization ( ! gas close to ! opposite vane1 &1 9 mo/ conditions1 ?is loss ( *>ge w be s rapid t ! pot5tial ( ! vane is unable to rea* ! value :i* w\ld exi/ at t place 9 ! field1 if ! vane 7 remov$4 ,!re w1 9 consequ5ce1 be an attract+ =ce act+ on ! vane t[>ds ! sph]e4 ,! repulsion obs]v$ by ,joly is ?us only an indirect result ( ! ionization 9 ! gas produc$ by ! radium1 & %\ld be %[n "u conditions :]e simil> unequal di/ribution ( ionization is produc$ by any o!r s\rces4 ,s9ce radium gives out heat at a fairly rapid rate1 a radiomet] 9 :i* ! vanes 7 coat$ on "o side ) radium in/ead ( lampblack1 %\ld rotate at l[ pressure ( ! gas1 ev5 if no s\rce ( light is br\ght ne> x4 ,?is %\ld evid5tly be ! case1 s9ce ! face coat$ ) radium %\ld rea* a slightly high] temp]ature ?an ! o!r4 ,?is exp]im5t has be5 tri$1 b ! effect seems too small to produce rotation ( ! vanes4 ,*emical actions4 #abc4 ,rays f active radium prep>ations *ange oxyg5 into ozone#baj4 ,its pres5ce c be detect$ by ! smell or by ! action on iodide ( potassium pap]4 ,?is effect is due to ! & rays f ! radium1 & n to ! lum9\s rays f x4 ,s9ce en]gy is requir$ to produce ozone f oxyg51 ?is mu/ be d]iv$ f ! en]gy ( ! radiations4 ,! ,curies f\nd t radium comp\nds rapidly produc$ coloration 9 glass4 ,= mod]ately active mat]ial ! col\r is violet1 = m active mat]ial x is yell[4 ,long cont9u$ action black5s ! glass1 al?\gh ! glass may h no lead 9 its composition4 ,?is coloration gradually ext5ds ?r\gh ! glass1 & is dep5d5t to "s ext5t on ! k9d ( glass us$4 ,giesel#baa f\nd t he c\ld obta9 z mu* coloration 9 rock-salt & fluor-sp> by radium rays1 z by exposure to ! action ( ca?ode rays 9 a vacuum tube4 ,! coloration1 h[ev]1 ext5d$ mu* deep] ?an t produc$ by ! ca?ode rays4 ,?is is to be expect$1 s9ce ! radium rays h a high] velocity1 & consequ5tly great] p5etrat+ p[]1 ?an ! ca?ode rays produc$ 9 an ord9>y vacuum tube4 ,gold/e9 obs]v$ t ! coloration is f> m int5se & rapid :5 ! salts are melt$ or heat$ to a r$ heat4 ,melt$ potassium sulphate1 "u ! action ( a v active prep>ation ( radium1 0 rapidly col\r$ a /rong gre5i% blue :i* gradually *ang$ into a d>k gre54 ,salomons5 & ,drey]#bab f\nd t plates ( qu>tz 7 col\r$ by exposure to radium rays4 ,:5 exam9$ m9utely1 plates cut p]p5dicul> to ! optic axis %[$ ! pres5ce ( l9es & /riae1 p>allel to ! b9>y axes4 ,adjac5t portions ( ! /riat$ sy/em diff]$ consid]ably 9 int5sity ( coloration & cle>ly reveal$ ! het]og5eity ( /ructures ( ! cry/al4 ,! cause ( ^! colorations by ca?ode & radium rays has be5 ! subject ( mu* discussion4 ,el/] & ,geitel#bac obs]v$ t a specim5 ( potassium sulphate1 col\r$ gre5 by radium rays1 %[$ a /rong photo-electric action1 i4e4 x rapidly lo/ a negative *>ge ( electricity :5 expos$ to ! action ( ultra-violet light4 ,all sub/ances col\r$ by ca?ode rays %[ a /rong photo-electric action1 &1 s9ce ! metals sodium & potassium !mselves %[ photo-electric action to a v rem>kable degree1 ,el/] & ,geitel h sugge/$ t ! colorations are caus$ by a solid solution ( ! metal 9 ! salt4 ,al?\gh ! coloration due to radium rays ext5ds deep] ?an t due to ! ca?ode rays1 :5 expos$ to light ! col\r fades away at ab\t ! same rate 9 ! two cases4 ,becqu]el#bad f\nd t :ite phosphorus is *ang$ into ! r$ v>iety by ! action ( radium rays4 ,?is action 0 %[n to be due ma9ly to ! rays4 ,! second>y radiation set up by ! prim>y rays also produc$ a m>k$ effect4 ,radium rays1 l ord9>y light rays1 also caus$ a precipitate ( calomel 9 ! pres5ce ( oxalic acid4 ,h>dy & ,miss ,willcock#bae f\nd t a solution ( iod(orm 9 *lor(orm turn$ purple aft] exposure = #e m9utes to ! rays f #e milligrams ( radium bromide4 ,?is action is due to ! lib]ation ( iod9e4 ,by te/+ ! effect ( scre5s ( diff]5t ?icknesses1 ov] ! radium1 ?is action 0 f\nd to be ma9ly due to ! rays f ! radium4 ,rntg5 rays produce a simil> coloration4 ,h>dy#baf also obs]v$ an action ( ! radium rays on ! coagulation ( globul94 ,two solutions ( globul9 f ox s]um 7 us$1 "o made electro-positive by add+ acetic acid1 & ! o!r electro-negative by add+ ammonia4 ,:5 ! globul9 0 expos$ close to ! radium 9 nak$ drops1 ! opalesc5ce ( ! electro-positive solution rapidly dim9i%$1 %[+ t ! solution became m complete4 ,! electro-negative solution 0 rapidly turn$ to a jelly & became opaque4 ,^! actions 7 f\nd to be due to ! rays ( radium alone4 ,?is is fur!r evid5ce 9 fav\r ( ! view t ! rays consi/ ( project$ positively *>g$ bodies ( atomic dim5sions1 = a simil> coagulation effect is produc$ by ! metallic ions ( liquid electrolytes1 & has be5 %[n by ,w4 ,c4 ,d4 ,:e?am#bag to be due to ! electric *>ges c>ri$ by ! ions4 #abd4 ,gases evolv$ f radium4 ,curie & ,debi]ne#bah obs]v$ t radium prep>ations plac$ 9 a vacuum tube cont9ually l[]$ ! vacuum4 ,! gas evolv$ 0 always accompani$ by ! emanation1 b no new l9es 7 obs]v$ 9 its spectrum4 ,giesel#bai has obs]v$ a simil> evolution ( gas f solutions ( radium bromide4 ,giesel =w>d$ "s active mat]ial to ,runge & ,bdl&]1 9 ord] t !y might te/ ! gas spectroscopically4 ,f #a gram ( a #e p] c5t4 radium prep>ation !y obta9$ #ce c4c4 ( gas 9 #af days4 ,?is gas 0 f\nd1 h[ev]1 to be ma9ly hydrog51 ) #ab p] c5t4 ( oxyg54 ,9 lat] exp]im5ts ,ramsay & ,soddy#bbj f\nd t #ej milligrams ( radium bromide evolv$ gases at ! rate ( ab\t #je c4c4 p] day4 ,?is is a rate ( evolution ab\t twice t obs]v$ by ,runge & ,bdl&]4 ,on analys+ ! gases ab\t #bhi p] c5t4 consi/$ ( oxyg51 & ! re/ hydrog54 ,! slight excess ( hydrog5 ov] t atta9$ 9 ! decomposition ( wat]1 !y consid] to be due to ! action ( oxyg5 on ! grease ( ! /op-cocks4 ,! radio-active emanation f radium has a /rong oxidiz+ action & rapidly produces c>bon dioxide1 if c>bonace\s matt] is pres5t4 ,! production ( gas is probably due to ! action ( ! radiations 9 decompos+ wat]4 ,! am\nt ( en]gy requir$ to produce ! rate ( decomposition obs]v$ by ,ramsay & ,soddy--ab\t #aj c4c4 p] day = #a gram ( radium bromide--corresponds to ab\t #cj gram-calories p] day4 ,?is am\nt ( en]gy is ab\t two p] c5t4 ( ! total en]gy emitt$ 9 ! =m ( heat4 ,ramsay & ,soddy 7loc4 cit47 h also obs]v$ ! pres5ce ( helium 9 ! gases evolv$ by solution ( radium bromide4 ,?is important result is consid]$ 9 detail 9 section #bfg4 ,physiological actions4 #abe4 ,walkh(f fir/ obs]v$ t radium rays produce burns ( mu* ! same "* z ^? caus$ by ,rntg5 rays4 ,exp]im5ts 9 ?is direction h be5 made by ,giesel1 ,curie & ,becqu]el1 & o!rs1 ) v simil> results4 ,!re is at fir/ a pa9ful irritation1 !n inflammation sets 91 :i* la/s f #aj to #bj days4 ,?is effect is produc$ by all prep>ations ( radium1 & appe>s to be due ma9ly to ! & rays4 ,c>e has to be tak5 9 h&l+ radium on acc\nt ( ! pa9ful inflammation set up by ! rays4 ,if a f+] is held = "s m9utes at ! base ( a capsule conta9+ a radium prep>ation1 ! sk9 becomes inflam$ = ab\t #ae days & !n peels (f4 ,! pa9ful feel+ does n disappe> = two mon?s4 ,danysz#bba f\nd t ?is action is ma9ly conf9$ to ! sk91 & does n ext5d to ! und]ly+ tissue4 ,cat]pill>s subject$ to ! action ( ! rays lo/ _! p[] ( motion 9 sev]al days & f9ally di$4 ,radium rays h be5 f\nd b5eficial 9 c]ta9 cases ( canc]4 ,! effect is app>5tly simil> to t produc$ by ,rntg5 rays1 b ! use ( radium possesses ! great advantage t ! radiat+ s\rce c be enclos$ 9 a f9e tube & introduc$ at ! p>ticul> po9t at :i* ! action ( ! rays is requir$4 ,! rays h also be5 f\nd to h9d] or /op ! developm5t ( microbes#bbb4 ,x w\ld be out ( place "h to give an acc\nt ( ! num]\s exp]im5ts t h be5 made by physici/s & physiologi/s on ! action ( ! rays ( radium & ( o!r radio-active sub/ances on diff]5t organisms1 su* z cat]pill>s1 mice & gu9ea-pigs4 ,9 "s cases1 ! exp]im5ts h be5 c>ri$ out by plac+ ! organisms 9 an atmosph]e impregnat$ ) ! radium emanation4 ,! effect ( an exposure "u su* conditions = sev]al days or weeks has be5 f\nd g5]ally h>mful & 9 _m cases fatal4 ,! lit]ature 9 ?is new dep>tm5t ( /udy is already l>ge & is increas+ rapidly4 ,ano!r int]e/+ action ( ! radium rays has be5 obs]v$ by ,giesel4 ,on br++ up a radium prep>ation to ! clos$ eye1 9 a d>k room1 a s5sation ( diffuse light is obs]v$4 ,?is effect has be5 exam9$ by ,him/$t & ,nagel#bbc :o h %[n t x is due to a fluoresc5ce produc$ by ! rays 9 ! eye itself4 ,! bl9d are able to p]ceive ?is lum9osity if ! ret9a is intact1 b n if ! ret9a is diseas$4 ,h>dy & ,&]son#bbd h exam9$ ?is effect 9 "s detail4 ,! s5sation ( light is produc$ bo? by ! & rays4 ,! eyelid practically absorbs all ! rays1 s t ! lum9osity obs]v$ ) a clos$ eye is due to ! rays alone4 ,! l5s & ret9a ( ! eye are /rongly phosphoresc5t "u ! action ( ! & rays4 ,h>dy & ,&]son consid] t ! lum9osity obs]v$ 9 a d>k room ) ! op5 eye 7! phosphoresc5t light ( ! radium itself be+ /opp$ by black pap]7 is to a l>ge ext5t due to ! phosphoresc5ce set up 9 ! eyeball4 ,! rays1 = ! mo/ "p1 produce ! s5sation ( light :5 !y /rike ! ret9a4 ,tommas9a /at$ t ! air exhal$ by man conta9$ a l>g] proportion ( ions ?an ord9>y air1 &1 9 consequ5ce1 caus$ an increas$ rate ( dis*>ge ( an electroscope4 ,! exp]im5t 0 repeat$ by ,el/] & ,geitel b ) negative results4 ,on ! o!r h&1 !y f\nd t ! brea? ( ,dr ,giesel1 ( ,brauns*weig1 :o _h be5 engag$ cont9u\sly 9 ! *emical sep>ation ( ! radio-active bodies1 caus$ a rapid loss ( *>ge ( an electroscope4 ,?is increas$ rate ( dis*>ge 0 probably ma9ly due to ! radium emanation1 ) :i* 8 sy/em _h become impregnat$ by inhal+ ! emanation-lad5 air ( ! laboratory4 ,footnote #ahd3 ,becqu]el1 ,c4 ,r4 #abi1 p4 #iab1 #ahii4 ,footnote #ahe3 ,b>y1 ,c4 ,r4 #acj1 p4 #ggf1 #aijj4 ,footnote #ahf3 ,kunz & ,bask]ville1 ,am]4 ,j\rn4 ,sci5ce ,,xvi4 p4 #cce1 #aijc4 ,footnote #ahg3 ,see ,nature1 p4 #ebc1 ,m>* #ca1 #aijd4 ,footnote #ahh3 ,crookes1 ,proc4 ,roy4 ,soc4 #gd1 p4 #dg1 #aijd4 ,footnote #ahi3 ,kunz & ,bask]ville1 ,sci5ce ,,xviii1 p4 #gfi1 ,dec4 #ah1 #aijc4 ,footnote #aij3 ,beilby 9 a rec5t communication to ! ,royal ,society 7,feb4 #i & #bc1 #aije7 has exam9$ 9 "s detail ! production ( phosphoresc5ce by ! & rays ( radium & has put =w>d a !ory to acc\nt = ! diff]5t actions obs]v$4 ,footnote #aia3 ,hugg9s1 ,proc4 ,roy4 ,soc4 #gb1 pp4 #aif & #dji1 #aijc4 ,footnote #aib3 ,! sp>k spectrum ( ! radium bromide %[$ ! ,h & ,k l9es ( calcium & also fa9tly "s ( ! /rong l9es ( b>ium4 ,! *>act]i/ic l9es ( radium ( wave-l5g?s #chadei1 #cfdig1 #dcdjf & #bgjhf1 z %[n by ,dem>ay & o!rs are cle>ly %[n 9 ! figure4 ,! /rong l9e ( wave-l5g? ab\t #bhad is due to radium4 ,footnote #aic3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 #cg1 p4 #afif1 #aijd4 ,footnote #aid3 ,h>tmann1 ,phys4 ,zeit4 #e1 ,no4 #ah1 p4 #egj1 #aijd4 ,footnote #aie3 ,9 a rec5t pap]1 ,giesel 7,b]4 d4 ,d4 ,*em4 ,ges4 ,no4 #c1 p4 #gge1 #aije7 has %[n t ! bright l9es are due to didymium1 :i* is pres5t z an impurity4 ,exposure ( didymium to ! radium rays also causes ! appe>ance ( ! l9es4 ,footnote #aif3 ,wi$emann & ,s*midt1 ,wi$4 ,annal4 #ei1 p4 #fjd1 #ahie4 ,footnote #aig3 ,wi$emann1 ,phys4 ,zeit4 #b1 p4 #bfi1 #aija4 ,footnote #aih3 ,el/] & ,geitel1 ,annal4 d4 ,phys4 #fi1 p4 #fgc1 #ahii4 ,footnote #aii3 ,will[s & ,peck 7,phil4 ,mag4 ,m>*1 #aije7 f\nd t "u "s conditions1 especially = long sp>ks1 ! rays ( radium h9d]$ ! passage ( ! sp>k4 ,footnote #bjj3 ,hempt9ne1 ,c4 ,r4 #acc1 p4 #icd1 #aija4 ,footnote #bja3 ,him/$t1 ,phys4 ,zeit4 p4 #dgf1 #aijj4 ,footnote #bjb3 ,h5n+1 ,annal4 d4 ,phys4 p4 #efb1 #aijb4 ,footnote #bjc3 ,kohlraus* & ,h5n+1 ,v]h4 ,deuts*4 ,phys4 ,ges4 #f1 p4 #add1 #aijd4 ,footnote #bjd3 ,kohlraus*1 ,v]h4 ,deuts*4 ,phys4 ,ges4 #e1 p4 #bfa1 #aijd4 ,footnote #bje3 ,p4 ,curie1 ,c4 ,r4 #acd1 p4 #dbj1 #aijb4 ,footnote #bjf3 ,becqu]el1 ,c4 ,r4 #acf1 p4 #aagc1 #aijc4 ,footnote #bjg3 ,becqu]el1 ,c4 ,r4 #acc1 p4 #aii1 #aija4 ,footnote #bjh3 ,p4 ,curie1 ,socit de ,physique1 ,m>* #b1 #aijj4 ,footnote #bji3 ,joly1 ,phil4 ,mag4 ,m>*1 #aijd4 ,footnote #baj3 ,s4 & ,p4 ,curie1 ,c4 ,r4 #abi1 p4 #hbc1 #ahii4 ,footnote #baa3 ,giesel1 ,v]h&lg4 d4 ,d4 ,phys4 ,ges4 ,jan4 #e1 #aijj4 ,footnote #bab3 ,salomons5 & ,drey]1 ,c4 ,r4 #aci1 p4 #ecc1 #aijd4 ,footnote #bac3 ,el/] & ,geitel1 ,phys4 ,zeit4 p4 #aac1 ,no4 #c1 #aijb4 ,footnote #bad3 ,becqu]el1 ,c4 ,r4 #acc1 p4 #gji1 #aija4 ,footnote #bae3 ,h>dy & ,miss ,willcock1 ,proc4 ,roy4 ,soc4 #gb1 p4 #bjj1 #aijc4 ,footnote #baf3 ,h>dy1 ,proc4 ,physiolog4 ,soc4 ,may #af1 #aijc4 ,footnote #bag3 ,:e?am1 ,phil4 ,mag4 ,nov4 #ahii2 ,!ory ( ,solution1 ,camb4 #aijb1 p4 #cif4 ,footnote #bah3 ,curie & ,debi]ne1 ,c4 ,r4 #acb1 p4 #gfh1 #aija4 ,footnote #bai3 ,giesel1 ,b]4 ,d4 d4 ,*em4 ,ges4 #ce1 p4 #cfje1 #aijb4 ,footnote #bbj3 ,ramsay & ,soddy1 ,proc4 ,roy4 ,soc4 #gb1 p4 #bjd1 #aijc4 ,footnote #bba3 ,danysz1 ,c4 ,r4 #acf1 p4 #dfa1 #aijc4 ,footnote #bbb3 ,as*k9ass & ,casp>i1 ,ar*4 d4 ,ges4 ,physiologie1 #hf1 p4 #fjc1 #aija4 ,footnote #bbc3 ,him/$t & ,nagel1 ,drude's ,annal4 #d1 p4 #ecg1 #aija4 ,footnote #bbd3 ,h>dy & ,&]son1 ,proc4 ,roy4 ,soc4 #gb1 p4 #cic1 #aijc4 ,,*apt] ,,vi4 ,,cont9u\s ,,production ,,( ,,radio-,,active ,,matt]4 #abf4 ,an acc\nt w n[ be giv5 ( "s exp]im5ts :i* h ?r[n mu* light1 n only on ! nature ( ! processes :i* s]ve to ma9ta9 ! radio-activity ( ! radio-active bodies1 b also on ! s\rce ( ! en]gy cont9u\sly emitt$ by ^? bodies4 ,9 ?is *apt]1 = simplicity1 ! radio-activity ( uranium & ?orium w alone be consid]$1 = x w be se5 lat] t ! *anges tak+ place 9 ^! two sub/ances are typical ( ^? :i* occur 9 all radio-active sub/ances4 ,we h se5 7section #bc7 t !re is "s d\bt :e!r ! radio-activity ( ?orium is due to t elem5t itself1 or to an unkn[n radio-active con/itu5t associat$ ) x4 ,?is unc]ta9ty1 h[ev]1 w pres5t no s]i\s difficulty :5 we are discuss+ ! radio-activity ( ?orium1 = ! g5]al conclusions are1 = ! mo/ "p1 indep5d5t ( :e!r ?orium is ! prim>y radio-active con/itu5t or n4 ,= simplicity1 h[ev]1 x w be assum$ = ! pres5t t ! radio-activity is due to ?orium itself4 ,if future rese>* %\ld def9itely %[ t ! radio-activity1 ord9>ily obs]v$ 9 ?orium1 is due to a new radio-active elem5t mix$ ) x1 ! radio-active processes consid]$ w ref] to ?is new elem5t4 #abg4 ,uranium ,x4 ,! exp]im5ts ( ,mme ,curie %[ t ! radio-activity ( uranium & radium is an atomic ph5om5on4 ,! activity ( any uranium comp\nd dep5ds only on ! am\nt ( t elem5t pres5t1 & is unaffect$ by its *emical comb9ation ) o!r sub/ances1 & is n appreciably affect$ by wide v>iations ( temp]ature4 ,x w\ld ?us seem probable1 s9ce ! activity ( uranium is a specific prop]ty ( ! elem5t1 t ! activity c\ld n be sep>at$ f x by *emical ag5cies4 ,9 #aijj1 h[ev]1 ,sir ,william ,crookes#bbe %[$ t1 by a s+le *emical op]ation1 uranium c\ld be obta9$ photographically inactive :ile ! :ole ( ! activity c\ld be conc5trat$ 9 a small residue free f uranium4 ,?is residue1 to :i* he gave ! "n ( ,ur ,x1 0 _m hundr$ times m active photographically1 weight = weight1 ?an ! uranium f :i* x _h be5 sep>at$4 ,! me?od employ$ = ?is sep>ation 0 to precipitate a solution ( ! uranium ) ammonium c>bonate4 ,on dissolv+ ! precipitate 9 an excess ( ! reag5t1 a light precipitate rema9$ beh9d4 ,?is 0 filt]$1 & con/itut$ ! ,ur ,x4 ,! active sub/ance ,ur ,x 0 probably pres5t 9 v small quantity1 mix$ ) impurities d]iv$ f ! uranium4 ,no new l9es 7 obs]v$ 9 its spectrum4 ,a p>tial sep>ation ( ! activity ( uranium 0 also effect$ by ano!r me?od4 ,cry/alliz$ uranium nitrate 0 dissolv$ 9 e!r1 :5 x 0 f\nd t ! uranium divid$ itself betwe5 ! e!r & wat] pres5t 9 two unequal fractions4 ,! small "p dissolv$ 9 ! wat] lay] 0 f\nd to conta9 practically all ! activity :5 exam9$ by ! photographic me?od1 :ile ! o!r fraction 0 almo/ inactive4 ,^! results1 tak5 by !mselves1 po9t$ v /rongly to ! conclusion t ! activity ( uranium 0 n due to ! elem5t itself1 b to "s o!r sub/ance1 associat$ ) x1 :i* _h di/9ct *emical prop]ties4 ,results ( a simil> "* 7 obs]v$ by ,becqu]el#bbf4 ,x 0 f\nd t b>ium c\ld be made photographically v active by add+ b>ium *loride to ! uranium solution & precipitat+ ! b>ium z sulphate4 ,by a succession ( precipitations ! uranium 0 r5d]$ photographically almo/ inactive1 :ile ! b>ium 0 /rongly active4 ,! inactive uranium & ! active b>ium 7 laid aside2 b1 on exam9+ !m a ye> lat]1 x 0 f\nd t ! uranium _h completely rega9$ its activity1 :ile t ( ! b>ium _h completely disappe>$4 ,! loss ( activity ( uranium 0 ?us only tempor>y 9 "*4 ,9 ! above exp]im5ts1 ! activity ( uranium 0 exam9$ by ! photographic me?od4 ,! photographic action produc$ by uranium is due almo/ entirely to ! rays4 ,! rays1 9 comp>ison1 h little if any effect4 ,n[ ! radiation f ,ur ,x consi/s entirely ( rays1 & is consequ5tly photographically v active4 ,if ! activity ( uranium _h be5 measur$ electrically )\t any scre5 ov] x1 ! curr5t obs]v$ w\ld h be5 due v l>gely to ! rays1 & little *ange w\ld h be5 obs]v$ aft] ! removal ( ,ur ,x1 s9ce only ! con/itu5t responsible = ! rays 0 remov$4 ,?is important po9t is discuss$ 9 m detail 9 section #bje4 #abh4 ,?orium ,x4 ,ru!r=d & ,soddy#bbg1 work+ ) ?orium comp\nds1 f\nd t an int5sely active con/itu5t c\ld be sep>at$ f ?orium by a s+le *emical op]ation4 ,if ammonia is add$ to a ?orium solution1 ! ?orium is precipitat$1 b a l>ge am\nt ( ! activity is left beh9d 9 ! filtrate1 :i* is *emically free f ?orium4 ,?is filtrate 0 evaporat$ to dryness1 & ! ammonium salts driv5 (f by ignition4 ,a small residue 0 obta9$ :i*1 weight = weight1 0 9 "s cases sev]al ?\s& times m active ?an ! ?orium f :i* x 0 obta9$1 :ile ! activity ( ! precipitat$ ?orium 0 r$uc$ to less ?an "o half ( its orig9al value4 ,?is active con/itu5t 0 nam$ ,? ,x f analogy to ,crookes' ,ur ,x4 ,! active residue 0 f\nd to consi/ ma9ly ( impurities f ! ?orium2 ! ,? ,x c\ld n be exam9$ *emically1 & probably 0 pres5t only 9 m9ute quantity4 ,x 0 also f\nd t an active con/itu5t c\ld be p>tly sep>at$ f ?orium oxide by %ak+ x ) wat] = "s "t4 ,on filt]+ ! wat]1 & evaporat+ d[n1 a v active residue 0 obta9$ :i* 0 analog\s 9 all respects to ,? ,x4 ,on exam9+ ! products a mon? lat]1 x 0 f\nd t ! ,? ,x 0 no long] active1 :ile ! ?orium _h completely rega9$ its activity4 ,a long s]ies ( measurem5ts 0 !n und]tak5 to exam9e ! "t-rate ( ^! processes ( decay & recov]y ( activity4 ,illu/ration3 ,fig4 #dg4 ,! results are %[n graphically 9 ,fig4 #dg1 :]e ! f9al activity ( ! ?orium & ! initial activity ( ! ,? ,x are 9 ea* case tak5 z #ajj4 ,! ord9ates repres5t ! activities det]m9$ by means ( ! ionization curr5t1 & ! abscissae repres5t ! "t 9 days4 ,x w be obs]v$ t bo? curves are irregul> = ! fir/ two days4 ,! activity ( ! ,? ,x increas$ at fir/1 :ile ! activity ( ! ?orium dim9i%$4 ,disreg>d+ ^! initial irregul>ities ( ! curves1 :i* w be expla9$ 9 detail 9 section #bjh1 x w be se5 t1 aft] ! fir/ two days1 ! "t tak5 = ! ?orium to recov] half its lo/ activity is ab\t equal to ! "t tak5 by ! ,? ,x to lose half its activity4 ,?is "t 9 ea* case is ab\t f\r days4 ,! p]c5tage proportion ( ! activity rega9$ by ! ?orium1 ov] any giv5 int]val1 is approximately equal to ! p]c5tage proportion ( ! activity lo/ by ! ,? ,x dur+ ! same int]val4 ,illu/ration3 ,fig4 #dh4 ,if ! recov]y curve is produc$ backw>ds to meet ! v]tical axis1 x does s at a m9imum ( #be p] c5t41 & ! above conclusions hold m accurately1 if ! recov]y is assum$ to />t f ?is m9imum4 ,?is is cle>ly %[n by ,fig4 #dh1 :]e ! p]c5tages ( activity recov]$1 reckon$ f ! #be p] c5t4 m9imum1 are plott$ z ord9ates4 ,9 ! same figure ! decay curve1 aft] ! second day1 is %[n on ! same scale4 ,! activity ( ! ,? ,x decays ) ! "t accord+ to an expon5tial law1 fall+ to half value 9 ab\t f\r days4 ,if ,i is ! initial activity & ,it is ! activity aft] a "t t1 !n frac ,i ,it e-t 1 :]e is a con/ant & e ! natural base ( log>i?ms4 ,! exp]im5tal curve ( ! rise ( activity f a m9imum to a maximum value is !re=e express$ by ! equation frac ,it ,i #a e-t 1 :]e ,i is ! am\nt ( activity recov]$ :5 ! /ate ( con/ant activity is rea*$1 ,it ! activity recov]$ aft] a "t t1 & is ! same con/ant z be=e4 #abi4 ,uranium ,x4 ,simil> results 7 obta9$ :5 uranium 0 exam9$4 ,! ,ur ,x 0 sep>at$ by ,becqu]el's me?od ( successive precipitations ) b>ium4 ,! decay ( ! sep>at$ activity & ! recov]y ( ! lo/ activity are %[n graphically 9 ,fig4 #di4 ,a m detail$ discussion ( ?is exp]im5t is giv5 9 section #bje4 ,illu/ration3 ,fig4 #di4 ,! curves ( decay & recov]y exhibit ! same peculi>ities & c be express$ by ! same equations z 9 ! case ( ?orium4 ,! "t-rate ( decay & recov]y is1 h[ev]1 mu* sl[] ?an = ?orium1 ! activity ( ! ,ur ,x fall+ to half its value 9 ab\t #bb days4 ,a l>ge numb] ( results ( a simil> "* h be5 obta9$ f o!r radio-active products1 sep>at$ f ! radio-elem5ts1 b ! cases ( ?orium & uranium w suffice = ! pres5t to =m a basis = ! discussion ( ! processes t are tak+ place 9 radio-active bodies4 #acj4 ,!ory ( ! ph5om5a4 ,^! processes ( decay & recov]y g on at exactly ! same rate if ! sub/ances are remov$ f ! neighb\rhood ( "o ano!r1 or enclos$ 9 lead1 or plac$ 9 a vacuum tube4 ,x is at fir/ sight a rem>kable ph5om5on t ! processes ( decay & recov]y %\ld be s intimately connect$1 al?\gh !re is no possibility ( mutual int]action betwe5 !m4 ,^! results1 h[ev]1 receive a complete explanation on ! foll[+ hypo!ses3 7#a7 ,t !re is a con/ant rate ( production ( fre% radio-active matt] by ! radio-active body2 7#b7 ,t ! activity ( ! matt] s =m$ decreases accord+ to an expon5tial law ) ! "t f ! mom5t ( its =mation4 ,suppose t q p>ticles ( new matt] are produc$ p] second f a giv5 mass ( matt]4 ,! rate ( emission ( en]gy due to ! p>ticles produc$ 9 ! "t dt1 is1 at ! mom5t ( _! =mation1 equal to ,kqdt1 :]e ,k is a con/ant4 ,x is requir$ to f9d ! activity due to ! :ole matt] produc$ aft] ! process has cont9u$ = a "t ,t4 ,! activity d,i1 due to ! matt] produc$ dur+ ! "t dt at ! "t t1 decays accord+ to an expon5tial law dur+ ! "t ,t t t elapses be=e its activity is e/imat$1 & 9 consequ5ce is giv5 by d,i ,kqe- 7,t-t7 dt 1 :]e is ! con/ant ( decay ( activity ( ! active matt]4 ,! activity ,i,t due to ! :ole matt] produc$ 9 ! "t ,t is ?us giv5 by ,it int,t ,kqe- 7,t-t7 dt frac ,kq 7#a e- ,t7 4 ,! activity rea*es a maximum value ,i :5 ,t is v great1 & is !n giv5 by ,kq ,i ----- ?us frac ,i,t ,i #a e- ,t 4 ,?is equation agrees ) ! exp]im5tal results = ! recov]y ( lo/ activity4 ,ano!r me?od = obta9+ ?is equation is giv5 lat] 9 section #acc4 ,a /ate ( equilibrium is rea*$ :5 ! rate ( loss ( activity ( ! matt] already produc$ is balanc$ by ! activity suppli$ by ! production ( new active matt]4 ,accord+ to ?is view1 ! radio-active bodies are und]go+ *ange1 b ! activity rema9s con/ant ow+ to ! action ( two oppos+ processes4 ,n[1 if ?is active matt] c at any "t be sep>at$ f ! sub/ance 9 :i* x is produc$1 ! decay ( its activity1 z a :ole1 %\ld foll[ an expon5tial law ) ! "t1 s9ce ea* portion ( ! matt] decreases 9 activity accord+ to an expon5tial law ) ! "t1 :atev] its age may be4 ,if ,i is ! initial activity ( ! sep>at$ product1 ! activity ,it aft] an int]val t is giv5 by frac ,i,t ,i e-t 4 ,?us1 ! two assumptions--( uni=m production ( active matt] & ( ! decay ( its activity 9 an expon5tial law f ! mom5t ( its =mation--satisfactorily expla9 ! relation betwe5 ! curves ( decay & recov]y ( activity4 #aca4 ,exp]im5tal evid5ce4 ,x n[ rema9s to consid] fur!r exp]im5tal evid5ce 9 support ( ^! hypo!ses4 ,! prim>y conception is t ! radio-active bodies are able to produce f !mselves matt] ( *emical prop]ties diff]5t f ^? ( ! p>5t sub/ance1 & t ?is process goes on at a con/ant rate4 ,?is new matt] initially possesses ! prop]ty ( activity1 & loses x accord+ to a def9ite law4 ,! fact t a proportion ( ! activity ( radium & ?orium c be conc5trat$ 9 small am\nts ( active matt] l ,? ,x or ,ur ,x does n1 ( itself1 prove directly t a mat]ial con/itu5t responsible = ! activity has be5 *emically sep>at$4 ,= example1 9 ! case ( ! sep>ation ( ,? ,x f ?orium1 x might be suppos$ t ! non-?orium "p ( ! solution is r5d]$ tempor>ily active by its association ) ?orium1 & t ?is prop]ty is reta9$ ?r\gh ! processes ( precipitation1 evaporation1 & ignition1 & f9ally manife/s itself 9 ! residue rema9+4 ,accord+ to ?is view x is to be expect$ t any precipitate capable ( remov+ ! ?orium completely f its solution %\ld yield active residues simil> to ^? obta9$ f ammonia4 ,no su* case has1 h[ev]1 be5 obs]v$4 ,= example1 :5 ?orium nitrate is precipitat$ by sodium or ammonium c>bonate1 ! residue f ! filtrate aft] evaporation & ignition is free f activity & ! ?orium c>bonate obta9$ has ! normal am\nt ( activity4 ,9 fact1 ammonia is ! only reag5t yet f\nd capable ( completely sep>at+ ,? ,x f ?orium4 ,a p>tial sep>ation ( ! ,? ,x c be made by %ak+ ?orium oxide ) wat] ow+ to ! great] solubility ( ,? ,x 9 wat]4 ,?orium & uranium behave q diff]5tly ) reg>d to ! action ( ammonia & ammonium c>bonate4 ,ur ,x is completely precipitat$ ) ! uranium 9 an ammonia solution & ! filtrate is inactive4 ,ur ,x is sep>at$ by ammonium c>bonate1 :ile ,? ,x "u ! same conditions is completely precipitat$ ) ! ?orium4 ,! ,ur ,x & ! ,? ,x ?us behave l di/9ct types ( matt] ) well-m>k$ *emical prop]ties q di/9ct f ^? ( ! sub/ances 9 :i* !y are produc$4 ,! removal ( ,ur ,x by ! precipitation ( b>ium is probably n directly connect$ ) ! *emical prop]ties ( ,ur ,x4 ,! sep>ation is probably due to ! dragg+ d[n ( ! ,ur ,x ) ! d5se b>ium precipitate4 ,sir ,william ,crookes f\nd t ! ,ur ,x 0 dragg$ d[n by precipitates :5 no "q ( insolubility 0 involv$1 & su* a result is to be expect$ if ! ,ur ,x exi/s 9 extremely m9ute quantity4 ,x mu/ be borne 9 m9d t ! actual am\nt ( ! active con/itu5ts ,? ,x & ,ur ,x1 sep>at$ f ?orium & uranium1 is probably inf9itesimal1 & t ! great] proportion ( ! residues is due to impurities pres5t 9 ! salt & ! reag5ts1 a v small am\nt ( active matt] be+ mix$ ) !m4 #acb4 ,rate ( production ( ,? ,x4 ,if ! recov]y ( ! activity ( uranium or ?orium is due to ! cont9u\s production ( new active matt]1 x %\ld be possible to obta9 exp]im5tal evid5ce ( ! process4 ,z ! case ( ?orium has be5 mo/ fully inve/igat$1 a brief acc\nt w be giv5 ( "s exp]im5ts made by ,ru!r=d & ,soddy#bbh to %[ t ,? ,x is produc$ cont9u\sly at a con/ant rate4 ,prelim9>y exp]im5ts %[$ t ?ree successive precipitations 7 suffici5t to remove ! ,? ,x almo/ completely f ! ?orium4 ,! g5]al me?od employ$ 0 to precipitate a solution ( #e grams ( ?orium-nitrate ) ammonia4 ,! precipitate 0 !n r$issolv$ 9 nitric acid & ! ?orium aga9 precipitat$ z be=e1 z rapidly z possible1 s t ! ,? ,x produc$ 9 ! "t betwe5 successive precipitations %\ld n appreciably affect ! results4 ,! removal ( ! ,? ,x 0 foll[$ by measurem5ts ( ! activity ( ! residues obta9$ f successive filtrates4 ,9 ?ree successive precipitations ! activities ( ! residues 7 proportional to #ajj1 #h1 #af respectively4 ,?us two precipitations are ne>ly suffici5t to free ! ?orium f ,? ,x4 ,! ?orium fre$ f ,? ,x 0 !n all[$ to /& = a def9ite "t1 & ! am\nt ( ,? ,x =m$ dur+ t "t f\nd by precipitat+ x1 & measur+ its radio-activity4 ,accord+ to ! !ory1 ! activity ,it ( ! ?orium =m$ 9 ! "t t is giv5 by frac ,it ,i #a e-t 1 :]e ,i is ! total activity ( ,? ,x1 :5 !re is radio-active equilibrium4 ,if t is small1 ,it ------ t4 ,i ,s9ce ! activity ( ,? ,x falls to half value 9 #d days1 ! value ( express$ 9 h\rs #jjgb4 ,aft] /&+ a p]iod ( #a h\r ab\t 1 aft] #a day 1 aft] #d days ( ! maximum %\ld be obta9$4 ,! exp]im5tal results obta9$ %[$ an agreem5t1 z good z c\ld be expect$1 ) ! equation express+ ! result t ! ,? ,x 0 be+ produc$ at a con/ant rate4 ,! ?orium-nitrate :i* _h be5 fre$ f ,? ,x 0 all[$ to /& = "o mon?1 & !n x 0 aga9 subject$ to ! same process4 ,! activity ( ! ,? ,x 0 f\nd to be ! same z t obta9$ f an equal am\nt ( ! orig9al ?orium-nitrate4 ,9 "o mon?1 !re=e1 ! ,? ,x _h be5 reg5]at$1 & _h rea*$ a maximum value4 ,by leav+ ! ?orium "t to recov] fully its activity1 ?is process c be repeat$ indef9itely1 & equal am\nts ( ,? ,x are obta9$ at ea* precipitation4 ,ord9>y comm]cial ?orium-nitrate & ! pure/ nitrate obta9able %[$ exactly ! same action1 & equal am\nts ( ,? ,x c\ld be obta9$ f equal weights4 ,^! processes ?us appe> to be indep5d5t ( ! *emical purity ( ! sub/ance#bbi4 ,! process ( ! production ( ,? ,x is cont9u\s1 & no alt]ation has be5 obs]v$ 9 ! am\nt produc$ 9 ! giv5 "t aft] repeat$ sep>ations4 ,aft] #bc precipitations ext5d+ ov] #i days1 ! am\nt produc$ 9 a giv5 int]val 0 ab\t ! same z at ! beg9n+ ( ! process4 ,^! results are all 9 agreem5t ) ! view t ! ,? ,x is be+ cont9u\sly produc$ f ! ?orium comp\nd at a con/ant rate4 ,! am\nt ( active matt] produc$ f #a gram ( ?orium is probably extremely m9ute1 b ! electrical effects due to its activity are s l>ge t ! process ( production c be foll[$ aft] extremely %ort int]vals4 ,) a s5sitive electromet] ! am\nt ( ,? ,x produc$ p] m9ute 9 #aj grams ( ?orium-nitrate gives a rapid movem5t to ! electromet] ne$le4 ,= l>g] int]vals x is necess>y to add additional capacity to ! sy/em to br+ ! effects )9 range ( ! in/rum5t4 #acc4 ,rate ( decay ( activity4 ,x has be5 %[n t ! activity ( ,ur ,x & ,? ,x decays accord+ to an expon5tial law ) ! "t4 ,?is1 we %all see lat]1 is ! g5]al law ( decay ( activity 9 any type ( active matt]1 obta9$ by itself1 & fre$ f any second>y active products :i* x may1 itself1 produce4 ,9 any case1 :5 ?is law is n fulfill$1 x c be %[n t ! activity is due to ! sup]position ( two or m effects1 ea* ( :i* decays 9 an expon5tial law ) ! "t4 ,! physical int]pretation ( ?is law /ill rema9s to be discuss$4 ,x has be5 %[n t 9 uranium & ?orium comp\nds !re is a cont9u\s production ( active matt] :i* keeps ! comp\nd 9 radio-active equilibrium4 ,! *anges by :i* ! active matt] is produc$ mu/ be *emical 9 nature1 s9ce ! products ( ! action are diff]5t 9 *emical prop]ties f ! matt] 9 :i* ! *anges take place4 ,! activity ( ! products has af=d$ ! means ( foll[+ ! *anges occurr+ 9 !m4 ,x n[ rema9s to consid] ! connection betwe5 ! activity at any "t1 & ! am\nt ( *emical *ange tak+ place at t "t4 ,9 ! fir/ place1 x is f\nd exp]im5tally t ! saturation ionization curr5t it1 aft] ! active product has be5 all[$ to decay = a "t t1 is giv5 by frac it i e-t 1 :]e i is ! initial saturation curr5t & ! con/ant ( decay4 ,n[ ! saturation curr5t is a measure ( ! total numb] ( ions produc$ p] second 9 ! te/+ vessel4 ,x has already be5 %[n t ! rays1 :i* produce ! great] proportion ( ionization 9 ! gas1 consi/ ( positively *>g$ p>ticles project$ ) great velocity4 ,suppose = simplicity t ea* atom ( active matt]1 9 ! c\rse ( its *ange1 gives rise to "o project$ p>ticle4 ,ea* p>ticle w produce a c]ta9 av]age numb] ( ions 9 its pa? be=e x /rikes ! b\nd>ies or is absorb$ 9 ! gas4 ,s9ce ! numb] ( project$ p>ticles p] second is equal to ! numb] ( atoms *ang+ p] second1 ! numb] ( atoms nt :i* *ange p] second at ! "t t is giv5 by frac nt n e-t 1 :]e n is ! initial numb] :i* *ange p] second4 ,on ?is view1 !n1 ! law ( decay expresses ! result t ! numb] ( atoms *ang+ 9 unit "t1 dim9i%es accord+ to an expon5tial law ) ! "t4 ,! numb] ( atoms ,nt :i* rema9 un*ang$ aft] an int]val t is giv5 by ,nt inttinfty nt dt frac n e-t 4 ,if ,n is ! numb] ( atoms at ! beg9n+1 ,n frac n 1 ,?us frac ,nt ,n e-t 7#a74 or ! law ( decay expresses ! fact t ! activity ( a product at any "t is proportional to ! numb] ( atoms :i* rema9 un*ang$ at t "t4 ,?is is ! same z ! law ( monomolecul> *ange 9 *emi/ry1 & expresses ! fact t !re is only "o *ang+ sy/em4 ,if ! *ange dep5d$ on ! mutual action ( two sy/ems1 ! law ( decay w\ld be diff]5t1 s9ce ! rate ( decay 9 t case w\ld dep5d on ! relative conc5tration ( ! two react+ sub/ances4 ,?is is n s1 = n a s+le case has yet be5 obs]v$ 9 :i* ! law ( decay 0 affect$ by ! am\nt ( active matt] pres5t4 ,f ! above equation 7#a7 d,nt ------- -,nt1 dt or ! numb] ( sy/ems *ang+ 9 unit "t is proportional to ! numb] un*ang$ at t "t4 ,9 ! case ( recov]y ( activity1 aft] an active product has be5 remov$1 ! numb] ( sy/ems *ang+ 9 unit "t1 :5 radio-active equilibrium is produc$1 is equal to ,n4 ,?is mu/ be equal to ! numb] q ( new sy/ems appli$ 9 unit "t1 or q ,n1 q & ------2 ,n has ?us a di/9ct physical mean+1 & may be def9$ z ! proportion ( ! total numb] ( sy/ems pres5t :i* *ange p] second4 ,x has diff]5t values = diff]5t types ( active matt]1 b is inv>iable = any p>ticul> type ( matt]4 ,= ?is reason1 w be t]m$ ! 8radio-active con/ant0 ( ! product4 ,we are n[ 9 a position to discuss ) m physical def9it5ess ! gradual gr[? ( ,? ,x 9 ?orium1 aft] ! ,? ,x has be5 completely remov$ f x4 ,let q p>ticles ( ,? ,x be produc$ p] second by ! ?orium1 & let ,n be ! numb] ( p>ticles ( ,? ,x pres5t at any "t t aft] ! orig9al ,? ,x 0 remov$4 ,! numb] ( p>ticles ( ,? ,x :i* *ange e second is ,n1 :]e is ! radio-active con/ant ( ,? ,x4 ,n[1 at any "t dur+ ! process ( recov]y1 ! rate ( increase ( ! numb] ( p>ticles ( ,? ,x ! rate ( production ! rate ( *ange2 t is d,n ------ q ,n4 dt ,! solution ( ?is equation is ( ! =m ,n ae-t b 1 :]e a & b are con/ants4 ,n[ :5 t is v great1 ! numb] ( p>ticles ( ,? ,x pres5t rea* a maximum value ,n4 ,?us1 s9ce ,n ,n :5 t inf9ity1 b ,n2 s9ce ,n #j :5 t #j1 a b #j2 h5ce b -a ,n1 & ! equation becomes frac ,n ,n #a e-t 4 ,?is is equival5t to ! equation already obta9$ 9 section #acj1 s9ce ! int5sity ( ! radiation is always proportional to ! numb] ( p>ticles pres5t4 #acd4 ,influ5ce ( conditions on ! rate ( decay4 ,s9ce ! activity ( any product1 at any "t1 may be tak5 z a measure ( ! rate at :i* *emical *ange takes place1 x may be us$ z a means ( det]m9+ ! effect ( conditions on ! *anges occurr+ 9 radio-active matt]4 ,if ! rate ( *ange %\ld be accel]at$ or ret>d$1 x is to be expect$ t ! value ( ! radio-active con/ant w be increas$ or decreas$1 i4e4 t ! decay curve w be diff]5t "u diff]5t conditions4 ,no su* effect1 h[ev]1 has yet be5 obs]v$ 9 any case ( radio-active *ange1 :]e none ( ! active products produc$ are all[$ to escape f ! sy/em4 ,! rate ( decay is unalt]$ by any *emical or physical ag5cy1 & 9 ?is respect ! *anges 9 radio-active matt] are %>ply di/+ui%$ f ord9>y *emical *anges4 ,= example1 ! rate ( decay ( activity f any product takes place at ! same rate :5 ! sub/ance is expos$ to light z :5 x is kept 9 ! d>k1 & at ! same rate 9 a vacuum z 9 air or any o!r gas at atmosph]ic pressure4 ,its rate ( decay is unalt]$ by surr\nd+ ! active matt] by a ?ick lay] ( lead "u conditions :]e no ord9>y radiation f outside c affect x4 ,! activity ( ! matt] is unaffect$ by ignition or *emical treatm5t4 ,! mat]ial giv+ rise to ! activity c be dissolv$ 9 acid & re-obta9$ by evaporation ( ! solution )\t alt]+ ! activity4 ,! rate ( decay is ! same :e!r ! active matt] is reta9$ 9 ! solid /ate or kept 9 solution4 ,:5 a product has lo/ its activity1 resolution or heat does n reg5]ate x1 & z we %all see lat]1 ! rate ( decay ( ! active products1 s f> exam9$1 is ! same at a r$ heat z at ! temp]ature ( liquid air4 ,9 fact1 no v>iation ( physical or *emical conditions has l$ to any obs]vable diff]5ce 9 ! decay ( activity ( any ( ! num]\s types ( active matt] :i* h be5 exam9$4 #ace4 ,effect ( conditions on ! rate ( recov]y ( activity4 ,! recov]y ( ! activity ( a radio-elem5t ) "t1 :5 an active product is sep>at$ f x1 is gov]n$ by ! rate ( production ( fre% active matt] & by ! decay ( activity ( t already produc$4 ,s9ce ! rate ( decay ( ! activity ( ! sep>at$ product is indep5d5t ( conditions1 ! rate ( recov]y ( activity c be modifi$ only by a *ange ( ! rate ( production ( fre% active matt]4 ,z f> z exp]im5ts h gone1 ! rate ( production1 l ! rate ( decay1 is indep5d5t ( *emical or physical conditions4 ,!re are inde$ c]ta9 cases :i* are app>5t exceptions to ?is rule4 ,= example1 ! escape ( ! radio-active emanations f ?orium & radium is readily affect$ by heat1 moi/ure & solution4 ,a m ?or\gh inve/igation1 h[ev]1 %[s t ! exception is only app>5t & n real4 ,^! cases w be discuss$ m 9 detail 9 *apt] ,,vii1 b x may be /at$ "h t ! diff]5ces obs]v$ are due to diff]5ces 9 ! rate ( escape ( ! emanations into ! surr\nd+ gas1 & n to diff]5ces 9 ! rate ( production4 ,= ?is reason x is difficult to te/ ! "q at issue 9 ! case ( ! ?orium comp\nds1 :i* 9 mo/ cases readily all[ ! emanation produc$ by !m to escape into ! air4 ,9 ord] to %[ t ! rate ( production is indep5d5t ( molecul> /ate1 temp]ature1 etc41 x is necess>y 9 su* a case to und]take a long s]ies ( measurem5ts ext5d+ ov] ! :ole "t ( recov]y4 ,x is impossible to make accurate relative comp>isons to see if ! activity is alt]$ by ! conv]sion ( "o comp\nd into ano!r4 ,! relative activity 9 su* a case1 :5 measur$ by spread+ a def9ite weight ( mat]ial uni=mly on a metal plate1 v>ies greatly ) ! physical conditions ( ! precipitate1 al?\gh ! total activity ( two comp\nds may be ! same4 ,! foll[+ me?od#bcj (f]s an accurate & simple means ( /udy+ :e!r ! rate ( production ( active matt] is influ5c$ by molecul> /ate4 ,! sub/ance is *emically conv]t$ into any comp\nd requir$1 c>e be+ tak5 t active products are recov]$ dur+ ! process4 ,! new comp\nd is !n spread on a metal plate & comp>$ ) a /&>d sample ( uranium = sev]al days or weeks z requir$4 ,if ! rate ( production ( active matt] is alt]$ by ! conv]sion1 !re %\ld be an increase or decrease ( activity to a new /eady value1 :]e ! production ( active matt] is aga9 balanc$ by ! rate ( decay4 ,?is me?od has ! great advantage ( be+ indep5d5t ( ! physical condition ( ! precipitate4 ,x c be appli$ satisfactorily to a comp\nd ( ?orium l ! nitrate & ! oxide :i* has be5 heat$ to a :ite heat1 aft] :i* treatm5t only a slight am\nt ( emanation escapes4 ,! nitrate 0 conv]t$ into ! oxide 9 a plat9um crucible by treatm5t ) sulphuric acid & ignition to a :ite heat4 ,! oxide s obta9$ 0 spread on a plate1 b no *ange ( its activity 0 obs]v$ ) "t1 %[+ t 9 ?is case ! rate ( production 0 indep5d5t ( molecul> /ate4 ,?is me?od1 :i* is limit$ 9 ! case ( ?orium1 may be appli$ g5]ally to ! uranium comp\nds :]e ! results are n complicat$ by ! pres5ce ( an emanation4 ,no diff]5ces h yet be5 obs]v$ 9 ! recov]y curves ( diff]5t ?orium comp\nds aft] ! removal ( ,? ,x4 ,= example1 ! rate ( recov]y is ! same :e!r ! precipitat$ hydroxide is conv]t$ into ! oxide or into ! sulphate4 #acf4 ,dis9tegration hypo!sis4 ,9 ! discussion ( ! *anges 9 radio-active bodies1 only ! active products ,ur ,x & ,? ,x h be5 consid]$4 ,x w1 h[ev]1 be %[n lat] t ^! two products are only examples ( _m o!r types ( active matt] :i* are produc$ by ! radio-elem5ts1 & t ea* ( ^! types ( active matt] has def9ite *emical z well z radio-active prop]ties1 :i* di/+ui% x1 n only f ! o!r active products1 b also f ! sub/ance f :i* x is produc$4 ,! full inve/igation ( ^! *anges w be %[n to v]ify 9 e p>ticul> ! hypo!sis t radio-activity is ! accompanim5t ( *emical *anges ( a special k9d occurr+ 9 matt]1 & t ! con/ant activity ( ! radio-elem5ts is due to an equilibrium process1 9 :i* ! rate ( production ( fre% active matt] balances ! rate ( *ange ( t already =m$4 ,! nature ( ! process tak+ place 9 ! radio-elem5ts1 9 ord] to give rise to ! production at a con/ant rate ( new k9ds ( active matt]1 w n[ be consid]$4 ,s9ce 9 ?orium or uranium comp\nds !re is a cont9u\s production ( radio-active matt]1 :i* diff]s 9 *emical prop]ties f ! p>5t sub/ance1 "s k9d ( *ange mu/ be tak+ place 9 ! radio-elem5t4 ,?is *ange1 by :i* new matt] is produc$1 is v diff]5t 9 "* f ! molecul> *anges dealt ) 9 *emi/ry1 = no *emical *ange is kn[n :i* proce$s at ! same rate at ! temp]atures correspond+ to a r$ heat & to liquid air1 & is indep5d5t ( all physical & *emical actions4 ,if1 h[ev]1 ! production ( active matt] is suppos$ to be ! result ( *anges1 n 9 ! molecule1 b 9 ! atom itself1 x is n to be expect$ t ! temp]ature w\ld ex]t mu* influ5ce4 ,! g5]al exp]i5ce ( *emi/ry 9 fail+ to trans=m ! elem5ts by ! action ( temp]ature is itself /rong evid5ce t wide ranges ( temp]ature h n mu* effect 9 alt]+ ! /ability ( ! *emical atom4 ,! view t ! atoms ( ! radio-elem5ts are und]go+ spontane\s dis9tegration 0 put =w>d by ,ru!r=d & ,soddy z a result ( evid5ce ( ?is "*4 ,! discov]y ( ! mat]ial nature ( ! rays add$ /rong confirmation to ! hypo!sis2 = x has be5 po9t$ out 7section #ie7 t ! expulsion ( p>ticles mu/ be ! result ( a dis9tegration ( ! atoms ( ! radio-elem5t4 ,tak+ ! case ( ?orium z an example1 ! processes occurr+ 9 ! atom may be pictur$ 9 ! foll[+ way4 ,x mu/ be suppos$ t ! ?orium atoms are n p]man5tly /able sy/ems1 b1 on an av]age1 a con/ant small proportion ( !m--ab\t "o atom 9 e #aj w suffice--break up p] second4 ,! dis9tegration consi/s 9 ! expulsion f ! atom ( "o or m p>ticles ) great velocity4 ,= simplicity1 x w be suppos$ t ea* atom expels "o p>ticle4 ,x has be5 %[n t ! p>ticle ( radium has a mass ab\t twice t ( ! hydrog5 atom4 ,f ! simil>ity ( ! rays f ?orium & radium1 x is probable t ! p>ticle ( ?orium does n diff] mu* 9 mass f t ( radium1 & may be equal to x4 ,! p>ticles expell$ f ! ?orium atoms z !y break up con/itute :at is kn[n z ! 8non-sep>able activity0 ( ?orium4 ,?is activity1 measur$ by ! rays1 is ab\t #be p] c5t4 ( ! maximum4 ,aft] ! escape ( an p>ticle1 ! "p ( ! atom left beh9d1 :i* has a mass slightly less ?an t ( ! ?orium atom1 t5ds to re>range its compon5ts to =m a tempor>ily /able sy/em4 ,x is to be expect$ t x w diff] 9 *emical prop]ties f ! ?orium atom f :i* x 0 d]iv$4 ,! atom ( ! sub/ance ,? ,x is1 on ?is view1 ! ?orium atom m9us "o p>ticle4 ,! atoms ( ,? ,x are f> m un/able ?an ! atoms ( ?orium1 & "o aft] ! o!r !y break up1 ea* atom expell+ "o p>ticle z be=e4 ,^! project$ p>ticles give rise to ! radiation f ! ,? ,x4 ,s9ce ! activity ( ,? ,x falls to half its orig9al value 9 ab\t f\r days1 on an av]age half ( ! atoms ( ,? ,x break up 9 f\r days1 ! numb] break+ up p] second be+ always proportional to ! numb] pres5t4 ,aft] an atom ( ,? ,x has expell$ an p>ticle1 ! mass ( ! sy/em is aga9 r$uc$1 & its *emical prop]ties are *ang$4 ,x w be %[n 7section #aed7 t ! ,? ,x produces ! ?orium emanation1 :i* exi/s z a radio-active gas1 & t ?is 9 turn is trans=m$ into matt] :i* is deposit$ on solid bodies & gives rise to ! ph5om5a ( excit$ activity4 ,! fir/ few successive *anges occurr+ 9 ?orium are %[n diagrammatically bel[ 7,fig4 #ej74 ,illu/ration3 ,fig4 #ej4 ,?us z a result ( ! dis9tegration ( ! ?orium atom1 a s]ies ( *emical sub/ances is produc$1 ea* ( :i* has di/9ctive *emical prop]ties4 ,ea* ( ^! products is radio-active1 & loses its activity accord+ to a def9ite law4 ,s9ce ?orium has an atomic weight ( #bcg1 & ! weight ( ! p>ticle is ab\t #b1 x is evid5t t1 if only "o p>ticle is expell$ at ea* *ange1 ! process ( dis9tegration c\ld pass ?r\gh a numb] ( successive /ages & yet leave beh9d1 at ! end ( ! process1 a mass comp>able ) t ( ! p>5t atom4 ,x w be %[n lat] t a process ( dis9tegration1 v simil> to t already describ$ = ?orium1 mu/ be suppos$ to take place also 9 uranium1 act9ium & radium4 ,! full discussion ( ?is subject _c be giv5 ) advantage until two ( ! mo/ important products ( ! ?ree sub/ances ?orium1 radium & act9ium1 viz4 ! radio-active emanations & ! matt] :i* causes excit$ activity1 h be5 consid]$ 9 detail4 #acg4 ,magnitude ( ! *anges4 ,x c be calculat$ by sev]al indep5d5t me?ods 7see section #bdf7 t1 9 ord] to acc\nt = ! radio-activity obs]v$ 9 ?orium1 ab\t #c #aj atoms 9 ea* gram ( ?orium suff] dis9tegration p] second4 ,x is well kn[n 7section #ci7 t #a cubic c5timetre ( hydrog5 at atmosph]ic pressure & temp]ature conta9s ab\t #cf #aj molecules4 ,f ?is x foll[s t "o gram ( ?orium conta9s #cf #aj atoms4 ,! fraction :i* breaks up p] second is ?us ab\t #aj4 ,?is is an extremely small ratio1 & x is evid5t t ! process c\ld cont9ue = long int]vals ( "t1 be=e ! am\nt ( matt] *ang$ w\ld be capable ( detection by ! spectroscope or by ! balance4 ,) ! electroscope x is possible to detect ! radiation f #aj gram ( ?orium1 i4e4 ! electroscope is capable ( detect+ ! ionization :i* accompanies ! dis9tegration ( a s+le ?orium atom p] second4 ,! electroscope is ?us an extraord9>ily delicate means = detection ( m9ute *anges 9 matt]1 :i* are accompani$1 z 9 ! case ( ! radio-elem5ts1 by ! expulsion ( *>g$ p>ticles ) great velocity4 ,x is possible to detect by its radiation ! am\nt ( ,? ,x produc$ 9 a second f #a gram ( ?orium1 al?\gh ! process w\ld probably ne$ to cont9ue ?\s&s ( ye>s be=e x c\ld be detect$ by ! balance or ! spectroscope4 ,x is ?us evid5t t ! *anges occurr+ 9 ?orium are ( an ord] ( magnitude q diff]5t f t ( ord9>y *emical *anges1 & x is n surpris+ t !y h nev] be5 obs]v$ by direct *emical me?ods4 ,footnote #bbe3 ,crookes1 ,proc4 ,roy4 ,soc4 #ff1 p4 #dji1 #aijj4 ,footnote #bbf3 ,becqu]el1 ,c4 ,r4 #aca1 p4 #acg1 #aijj2 #acc1 p4 #igg1 #aija4 ,footnote #bbg3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,sept4 & ,nov4 #aijb4 ,trans4 ,*em4 ,soc4 #ha1 pp4 #cba & #hcg1 #aijb4 ,footnote #bbh3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,sept4 #aijb4 ,footnote #bbi3 ,! g5]al me?od ( reg>d+ ! subject w\ld be un*ang$1 ev5 if x 7 prov$ t ! radio-activity ( ?orium is n due to ?orium at all b to a small con/ant am\nt ( a radio-active impurity mix$ ) x4 ,footnote #bcj3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,sept4 #aijb4 ,,*apt] ,,vii4 ,,radio-,,active ,,emanations4 #ach4 ,introduction4 ,a mo/ important & /rik+ prop]ty possess$ by radium1 ?orium1 & act9ium1 b n by uranium or polonium1 is ! p[] ( cont9u\sly emitt+ into ! surr\nd+ space a mat]ial emanation1 :i* has all ! prop]ties ( a radio-active gas4 ,?is emanation is able to diffuse rapidly ?r\gh gases & ?r\gh por\s sub/ances1 & may be sep>at$ f ! gas ) :i* x is mix$ by cond5sation by ! action ( extreme cold4 ,?is emanation =ms a connect+ l9k betwe5 ! activity ( ! radio-elem5ts !mselves & _! p[] ( excit+ activity on surr\nd+ objects1 & has be5 /udi$ m closely ?an ! o!r active products on acc\nt ( its exi/5ce 9 ! gase\s /ate4 ,! emanations f ! ?ree active bodies all possess simil> radio-active prop]ties1 b ! effects are m m>k$ 9 ! case ( ! emanation f radium1 on acc\nt ( ! v great activity ( t elem5t4 ,?orium ,emanation4 #aci4 ,discov]y ( ! emanation4 ,9 ! c\rse ( exam9ation ( ! radiations ( ?orium1 sev]al obs]v]s _h not$ t "s ( ! ?orium comp\nds1 & especially ! oxide1 7 v incon/ant s\rces ( radiation1 :5 exam9$ 9 op5 vessels by ! electrical me?od4 ,ow5s#bca f\nd t ?is incon/ancy 0 due to ! pres5ce ( air curr5ts4 ,:5 a clos$ vessel 0 us$1 ! curr5t1 imm$iately aft] ! introduction ( ! active matt]1 increas$ ) ! "t1 & f9ally rea*$ a con/ant value4 ,by draw+ a /eady /ream ( air ?r\gh ! vessel ! value ( ! curr5t 0 mu* r$uc$4 ,x 0 also obs]v$ t ! radiations c\ld app>5tly pass ?r\gh l>ge ?icknesses ( pap]1 :i* completely absorb$ ! ord9>y radiation4 ,9 an inve/igation ( ^! peculi> prop]ties ( ?orium comp\nds1 ! writ]#bcb f\nd t ! effects 7 due to an emission ( radio-active p>ticles ( "s k9d f ! ?orium comp\nds4 ,?is 8emanation10 z x 0 t]m$ = conv5i5ce1 possesses ! prop]ties ( ioniz+ ! gas & act+ on a photographic plate1 & is able to diffuse rapidly ?r\gh por\s sub/ances l pap] & ?9 metal foil4 ,! emanation1 l a gas1 is completely prev5t$ f escap+ by cov]+ ! active matt] ) a ?9 plate ( mica4 ,! emanation c be c>ri$ away by a curr5t ( air2 x passes ?r\gh a plug ( cotton-wool & c be bubbl$ ?r\gh solutions )\t any loss ( activity4 ,9 ^! respects1 x behaves v diff]5tly f ! ions produc$ 9 ! gas by ! rays f active sub/ances1 = ^! give up _! *>ges completely "u ! same conditions4 ,s9ce ! emanation passes readily ?r\gh l>ge ?icknesses ( c>dbo>d1 & ?r\gh filt]s ( tightly pack$ cotton-wool1 x does n seem likely t ! emanation consi/s ( p>ticles ( du/ giv5 (f by ! active matt]4 ,?is po9t 0 te/$ /ill fur!r by ! me?od us$ by ,aitk5 & ,wilson1 = detect+ ! pres5ce ( du/ p>ticles 9 ! air4 ,! oxide1 enclos$ 9 a pap] cyl9d]1 0 plac$ 9 a glass vessel1 & ! du/ 0 remov$ by repeat$ small expansions ( ! air ov] a wat] surface4 ,! du/ p>ticles act z nuclei = ! =mation ( small drops & are !n remov$ f ! air by ! action ( gravity4 ,aft] repeat$ expansions1 no cl\d 0 =m$1 & ! du/ 0 consid]$ to be remov$4 ,aft] wait+ = "s "t to all[ ! ?orium emanation to collect1 fur!r expansions 7 made b no cl\d result$1 %[+ t = ! small expansions us$1 ! p>ticles 7 too small to become c5tres ( cond5sation4 ,! emanation !n c\ld n be reg>d$ z du/ emitt$ f ?orium4 ,s9ce ! p[] ( diffus+ rapidly ?r\gh por\s sub/ances1 & act+ on a photographic plate1 is also possess$ by a *emical sub/ance l hydrog5 p]oxide1 "s exp]im5ts 7 made to see if ! emanation c\ld be an ag5t ( t "*4 ,x 0 f\nd1 h[ev]1 t hydrog5 p]oxide is n radio-active1 & t its action on ! plate is a purely *emical "o1 :ile x is ! radiation f ! emanation & n ! emanation itself t produces ioniz+ & photographic effects4 #adj4 ,exp]im5tal arrangem5ts4 ,! emanation f ?orium is giv5 (f 9 m9ute quantity4 ,no appreciable l[]+ ( ! vacuum is obs]v$ :5 an emanat+ comp\nd is plac$ 9 a vacuum tube & no new spectrum l9es are obs]v$4 ,= an exam9ation ( ! emanation1 an app>atus simil> 9 pr9ciple to t %[n 9 ,fig4 #ea is conv5i5t4 ,illu/ration3 ,fig4 #ea4 ,! ?orium comp\nd1 ei!r b>e or enclos$ 9 a pap] envelope1 0 plac$ 9 a glass tube ,c4 ,a curr5t ( air f a gasomet]1 aft] pass+ ?r\gh a tube conta9+ cotton-wool to remove du/ p>ticles1 bubbl$ ?r\gh sulphuric acid 9 ! vessel ,a4 ,x !n pass$ ?r\gh a bulb conta9+ tightly pack$ cotton-wool to prev5t any spray be+ c>ri$ ov]4 ,! emanation1 mix$ ) air1 0 c>ri$ f ! vessel ,c ?r\gh a plug ( cotton-wool ,d1 :i* remov$ completely all ! ions c>ri$ ) ! emanation4 ,! latt] !n pass$ into a long brass cyl9d]1 #ge cm4 9 l5g? & #f cm4 9 diamet]4 ,! insulat$ cyl9d] 0 connect$ ) a batt]y 9 ! usual way4 ,?ree insulat$ electrodes1 ,e1 ,f1 ,h1 ( equal l5g?s1 7 plac$ along ! axis ( ! cyl9d]1 support$ by brass rods pass+ ?r\gh ebonite corks 9 ! side ( ! cyl9d]4 ,! curr5t ?r\gh ! gas1 due to ! pres5ce ( ! emanation1 0 measur$ by means ( an electromet]4 ,an insulat+ key 0 arrang$ s t any "o ( ! electrodes ,e1 ,f1 ,h c\ld be rapidly connect$ ) "o pair ( quadrants ( ! electromet]1 ! o!r two be+ always connect$ ) e>?4 ,! curr5t obs]v$ 9 ! te/+ cyl9d] vessel 0 due entirely to ! ions produc$ by ! emanation c>ri$ into ! vessel by ! curr5t ( air4 ,on sub/itut+ a uranium comp\nd = ! ?orium1 n ! slighte/ curr5t 0 obs]v$4 ,aft] a con/ant fl[ has pass$ = ab\t #aj m9utes1 ! curr5t due to ! emanation rea*es a con/ant value4 ,! v>iation ( ! ionization curr5t ) ! voltage is simil> to t obs]v$ = ! gas ioniz$ by ! radiations f ! active bodies4 ,! curr5t at fir/ increases ) ! voltage1 b f9ally rea*es a saturation value4 #ada4 ,duration ( ! activity ( ! emanation4 ,! emanation rapidly loses its activity ) "t4 ,?is is v readily %[n ) ! app>atus ( ,fig4 #ea4 ,! curr5t is f\nd to dim9i% progressively along ! cyl9d]1 & ! v>iation f electrode to electrode dep5ds on ! velocity ( ! fl[ ( air4 ,if ! velocity ( ! air curr5t is kn[n1 ! decay ( activity ( ! emanation ) "t c be d$uc$4 ,if ! fl[ ( air is /opp$1 & ! op5+s ( ! cyl9d] clos$1 ! curr5t /eadily dim9i%es ) "t4 ,! foll[+ numb]s illu/rate ! v>iation ) "t ( ! saturation curr5t1 due to ! emanation 9 a clos$ vessel4 ,! obs]vations 7 tak5 successively1 & z rapidly z possible aft] ! curr5t ( air 0 /opp$4 ,"t 9 seconds ,curr5t #j #ajj #bh #fi #fb #ea #aah #be #aee #ad #baj #fg #bgb #da #cfj #ah ,curve ,a1 ,fig4 #eb1 %[s ! relation exi/+ betwe5 ! curr5t ?r\gh ! gas & ! "t4 ,! curr5t j be=e ! fl[ ( air 0 /opp$ is tak5 z unity4 ,! curr5t ?r\gh ! gas1 :i* is a measure ( ! activity ( ! emanation1 dim9i%es accord+ to an expon5tial law ) ! "t l ! activity ( ! products ,ur ,x & ,? ,x4 ,! rate ( decay is1 h[ev]1 mu* m rapid1 ! activity ( ! emanation decreas+ to half value 9 ab\t "o m9ute4 ,accord+ to ! view develop$ 9 section #acf1 ?is implies t half ( ! emanation p>ticles h und]gone *ange 9 "o m9ute4 ,aft] an int]val ( #aj m9utes ! curr5t due to ! emanation is v small1 %[+ t practically all ! emanation p>ticles pres5t h und]gone *ange4 ,illu/ration3 ,fig4 #eb4 ,! rate ( decay has be5 m accurately det]m9$ by ,rossignol & ,gim+ham#bcc :o f\nd t ! activity fell to half value 9 ab\t #ea seconds4 ,bronson#bcd1 us+ ! /eady deflection me?od describ$ 9 section #fi1 f\nd ! correspond+ "t #ed seconds4 ,! decrease ( ! curr5t ) ! "t is an actual measure ( ! decrease ( ! activity ( ! emanation1 & is n 9 any way influ5c$ by ! "t t ! ions produc$ take to rea* ! electrodes4 ,if ! ions _h be5 produc$ f a uranium comp\nd ! duration ( ! conductivity = a saturation voltage w\ld only h be5 a fraction ( a second4 ,! rate ( decay ( ! activity ( ! emanation is indep5d5t ( ! electromotive =ce act+ on ! gas4 ,?is %[s t ! radio-active p>ticles are n de/roy$ by ! electric field4 ,! curr5t ?r\gh ! gas at any p>ticul> in/ant1 aft] /oppage ( ! fl[ ( air1 0 f\nd to be ! same :e!r ! electromotive =ce _h be5 act+ ! :ole "t or _h be5 j appli$ = ! "t ( ! te/4 ,! emanation itself is unaffect$ by a /rong electric field & s _c be *>g$4 ,by te/+ its activity aft] pass+ x ?r\gh long conc5tric cyl9d]s1 *>g$ to a high pot5tial1 x 0 f\nd t ! emanation c]ta9ly did n move ) a velocity great] ?an #jjjja cm4 p] second1 = a gradi5t ( #a volt p] cm41 & !re 0 no evid5ce to %[ t x mov$ at all4 ,?is conclusion has be5 confirm$ by ! exp]im5ts ( ,mc,clelland#bce4 ,! rate at :i* ! emanation is produc$ is indep5d5t ( ! gas surr\nd+ ! active matt]4 ,if 9 ! app>atus ( ,fig4 #ea air is replac$ by hydrog51 oxyg51 or c>bonic acid1 simil> results are obta9$1 ?\gh ! curr5t obs]v$ 9 ! te/+ vessel v>ies = ! diff]5t gases on acc\nt ( ! unequal absorption by !m ( ! radiation f ! emanation4 ,if a ?orium comp\nd1 enclos$ 9 pap] to absorb ! radiation1 is plac$ 9 a clos$ vessel1 ! saturation curr5t due to ! emanation is f\nd to v>y directly z ! pressure4 ,s9ce ! rate ( ionization is proportional to ! pressure = a con/ant s\rce ( radiation1 ?is exp]im5t %[s t ! rate ( emission ( ! emanation is indep5d5t ( ! pressure ( ! gas4 ,! effect ( pressure on ! rate ( production ( ! emanation is discuss$ 9 m detail lat] 9 section #aeg4 #adb4 ,effect ( ?ickness ( lay]4 ,! am\nt ( emanation emitt$ by a giv5 area ( ?orium comp\nd dep5ds on ! ?ickness ( ! lay]4 ,) a v ?9 lay]1 ! curr5t betwe5 two p>allel plates1 plac$ 9 a clos$ vessel z 9 ,fig4 #ag1 is due v l>gely to ! rays4 ,s9ce ! radiation is v readily absorb$1 ! curr5t due to x practically rea*es a maximum :5 ! surface ( ! plate is completely cov]$ by a ?9 lay] ( ! active mat]ial4 ,on ! o!r h& ! curr5t produc$ by ! emanation increases until ! lay] is sev]al millimetres 9 ?ickness1 & !n is n mu* alt]$ by add+ fre% active matt]4 ,?is fall+ (f ( ! curr5t aft] a c]ta9 ?ickness has be5 rea*$ is to be expect$1 s9ce ! emanation1 :i* takes sev]al m9utes to diffuse ?r\gh ! lay] above x1 has already lo/ a l>ge proportion ( its activity4 ,) a ?ick lay] ( ?orium oxide 9 a clos$ vessel1 ! curr5t betwe5 ! plates is l>gely due to ! radiation f ! emanation ly+ betwe5 ! plates4 ,! foll[+ tables illu/rate ! way 9 :i* ! curr5t v>ies ) ! ?ickness ( pap] = bo? a ?9 & a ?ick lay]4 ,,table ,i4 ,?9 ,lay]4 ,?ickness ( %eets ( pap] #jjbg4 ,no4 ( ,curr5t lay]s ( pap] #j #a #a #cg #b #af #c #jh ,,table ,,ii4 ,?ick ,lay]4 ,?ickness ( pap] #jjh cm4 ,no4 ( ,curr5t lay]s ( pap] #j #a #a #gd #b #gd #e #gb #aj #fg #bj #ee ,! initial curr5t ) ! unscre5$ comp\nd is tak5 z unity4 ,9 ,table ,i1 = a ?9 lay] ( ?orium oxide1 ! curr5t dim9i%$ rapidly ) additional lay]s ( ?9 pap]4 ,9 ?is case ! curr5t is due almo/ entirely to ! rays4 ,9 ,table ,,ii ! curr5t falls to #gd = ! fir/ lay]4 ,9 ?is case ab\t #bf ( ! curr5t is due to ! rays1 :i* are practically absorb$ by ! lay] #jjh cm4 9 ?ickness4 ,! sl[ decrease ) additional lay]s %[s t ! emanation diffuses s rapidly ?r\gh a few lay]s ( pap] t !re is little loss ( activity dur+ ! passage4 ,! "t tak5 to diffuse ?r\gh #bj lay]s is h[ev] appreciable1 & ! curr5t consequ5tly has decreas$4 ,aft] pass+ ?r\gh a lay] ( c>dbo>d #af mms4 9 ?ickness ! curr5t is r$uc$ to ab\t "o-fif? ( its orig9al value4 ,9 clos$ vessels ! proportion ( ! total curr5t1 due to ! emanation1 v>ies ) ! di/ance betwe5 ! plates z well z ) ! ?ickness ( ! lay] ( active mat]ial4 ,x also v>ies greatly ) ! comp\nd exam9$4 ,9 ! nitrate1 :i* gives (f only a small am\nt ( emanation1 ! proportion is v mu* small] ?an 9 ! hydroxide1 :i* gives (f a l>ge am\nt ( emanation4 #adc4 ,increase ( curr5t ) "t4 ,! curr5t due to ! emanation does n rea* its f9al value = "s "t aft] ! active matt] has be5 introduc$ into ! clos$ vessel4 ,! v>iation ) "t is %[n 9 ! foll[+ table4 ,! saturation curr5t due to ?orium oxide1 cov]$ ) pap]1 0 obs]v$ betwe5 conc5tric cyl9d]s ( #ee cms4 & #h cm4 diamet]4 ,imm$iately be=e obs]vations on ! curr5t 7 made1 a rapid /ream ( air 0 bl[n ?r\gh ! app>atus4 ,?is remov$ mo/ ( ! emanation4 ,h[ev]1 ! curr5t due to ! ionization ( ! gas by ! emanation1 z x 0 c>ri$ along by ! curr5t ( air1 0 /ill appreciable4 ,! curr5t consequ5tly does n />t f z]o4 ,"t 9 ,curr5t seconds #j #i #bc #be #ec #di #if #fg #abe #gf #aid #hh #bdd #ih #cjd #ii #dhd #ajj ,! results are %[n graphically 9 ,fig4 #eb1 curve ,b4 ,! decay ( ! activity ( ! emanation ) "t1 & ! rate ( increase ( ! activity due to ! emanation 9 a clos$ space1 are connect$ 9 ! same way z ! decay & recov]y curves ( ,? ,x & ,ur ,x4 ,) ! previ\s notation1 ! decay curve is giv5 by frac ,i,t ,i e-t 4 & ! recov]y curve by frac ,it ,i #a e-t 1 :]e is ! radio-active con/ant ( ! emanation4 ,?is relation is to be expect$1 s9ce ! decay & recov]y curves ( ! emanation are det]m9$ by exactly ! same conditions z ! decay & recov]y curves ( ,ur ,x & ,? ,x4 ,9 bo? cases !re is3 7#a7 ,a supply ( fre% radio-active p>ticles produc$ at a con/ant rate4 7#b7 ,a loss ( activity ( ! p>ticles foll[+ an expon5tial law ) ! "t4 ,9 ! case ( ,ur ,x & ,? ,x1 ! active matt] produc$ manife/s its activity 9 ! position 9 :i* x is =m$2 9 ?is new ph5om5on1 a proportion ( ! active matt] 9 ! =m ( ! emanation escapes into ! surr\nd+ gas4 ,! activity ( ! emanation1 due to a ?orium comp\nd kept 9 a clos$ vessel1 ?us rea*es a maximum :5 ! rate ( supply ( fre% emanation p>ticles f ! comp\nd is balanc$ by ! rate ( *ange ( ^? already pres5t4 ,! "t = recov]y ( half ! f9al activity is ab\t #a m9ute1 ! same z ! "t tak5 = ! emanation1 :5 left to itself1 to lose half its activity4 ,if q is ! numb] ( emanation p>ticles escap+ into ! gas p] second1 & ,n ! f9al numb] :5 radio-active equilibrium is rea*$1 !n 7section #acc71 q ,n4 ,s9ce ! activity ( ! emanation falls to half value 9 #a m9ute 1 & ,n #hgq1 or ! numb] ( emanation p>ticles pres5t :5 a /eady /ate is rea*$ is #hg times ! numb] produc$ p] second4 ,radium ,emanation4 #add4 ,discov]y ( ! emanation4 ,%ortly aft] ! discov]y ( ! ?orium emanation1 ,dorn#bcf repeat$ ! results1 &1 9 addition1 %[$ t radium comp\nds also gave (f radio-active emanations1 & t ! am\nt giv5 (f 0 mu* increas$ by heat+ ! comp\nd4 ,! radium emanation diff]s f ! ?orium emanation 9 ! rate at :i* x loses its activity4 ,x decays f> m sl[ly1 b 9 o!r respects ! emanations ( ?orium & radium h mu* ! same prop]ties4 ,bo? emanations ionize ! gas ) :i* !y are mix$1 & affect a photographic plate4 ,bo? diffuse readily ?r\gh por\s sub/ances b are unable to pass ?r\gh a ?9 plate ( mica2 bo? behave l a tempor>ily radio-active gas1 mix$ 9 m9ute quantity ) ! air or o!r gas 9 :i* !y are convey$4 #ade4 ,decay ( activity ( ! emanation4 ,v little emanation escapes f radium *loride 9 ! solid /ate1 b ! am\nt is l>gely increas$ by heat+1 or by dissolv+ ! comp\nd 9 wat]4 ,by bubbl+ air ?r\gh a radium *loride solution1 or pass+ air ov] a heat$ radium comp\nd1 a l>ge am\nt ( emanation may be obta9$ :i* c be collect$1 mix$ ) air1 9 a suitable vessel4 ,exp]im5ts to det]m9e accurately ! rate ( decay ( activity ( ! emanation h be5 made by ,p4 ,curie#bcg1 & ,ru!r=d & ,soddy#bch4 ,9 ! exp]im5ts ( ! latt]1 ! emanation mix$ ) air 0 /or$ ov] m]cury 9 an ord9>y gas-hold]4 ,f "t to "t1 equal quantities ( air mix$ ) ! emanation 7 measur$ (f by a gas pipette & deliv]$ into a te/+ vessel4 ,! latt] consi/$ ( an air-tight brass cyl9d] c>ry+ a c5tral insulat$ electrode4 ,a saturation voltage 0 appli$ to ! cyl9d]1 & ! inn] electrode 0 connect$ to ! electromet] ) a suitable capacity 9 p>allel4 ,! saturation curr5t 0 obs]v$ imm$iately aft] ! introduction ( ! active gas into ! te/+ vessel1 & 0 tak5 z a measure ( ! activity ( ! emanation pres5t4 ,! curr5t increas$ rapidly ) ! "t ow+ to ! production ( excit$ activity on ! walls ( ! conta9+ vessel4 ,?is effect is describ$ 9 detail 9 *apt] ,,viii4 ,! measurem5ts 7 made at suitable int]vals ov] a p]iod ( #cc days4 ,! foll[+ table expresses ! results1 ! initial activity be+ tak5 z #ajj4 ,"t 9 ,relative h\rs ,activity #j #ajj #bjh #heg #ahgf #bdj #cedi #fi #ebai #ae #ghfi #jai ,! activity falls (f accord+ to an expon5tial law ) ! "t1 & decays to half value 9 #cga days4 ,) ! usual notation frac ,i,t ,i e-t 4 ! mean value ( d$uc$ f ! results is giv5 by #baf #aj 4 ,p4 ,curie det]m9$ ! rate ( decay ( activity ( ! emanation by ano!r me?od4 ,! active matt] 0 plac$ at "o end ( a seal$ tube4 ,aft] suffici5t "t _h elaps$ ! portion ( ! tube conta9+ ! radium comp\nd 0 remov$4 ,! loss ( activity ( ! emanation1 /or$ 9 ! o!r "p1 0 te/$ at regul> int]vals by obs]v+ ! ionization curr5t due to ! rays :i* pass$ ?r\gh ! walls ( ! glass vessel4 ,! te/+ app>atus & ! connections are %[n cle>ly 9 ,fig4 #ec4 ,! ionization curr5t is obs]v$ betwe5 ! vessels ,,bb & ,,cc4 ,! glass tube ,a conta9s ! emanation4 ,illu/ration3 ,fig4 #ec4 ,n[ x w be %[n lat] t ! emanation itself gives (f only rays1 & ^! rays are completely absorb$ by ! glass envelope1 unless x is made extremely ?94 ,! rays produc+ ionization 9 ! te/+ vessel 7 ?us n due to ! rays f ! emanation at all1 b to ! & rays due to ! excit$ activity produc$ on ! walls ( ! glass tube by ! emanation inside x4 ,:at 0 actually measur$ 0 ?us ! decay ( ! excit$ activity d]iv$ f ! emanation1 & n ! decay ( activity ( ! emanation itself4 ,s9ce1 h[ev]1 :5 a /eady /ate is rea*$1 ! am\nt ( excit$ activity is ne>ly proportional at any "t to ! activity ( ! emanation1 ! rate ( decay ( ! excit$ activity on ! walls ( ! vessel indirectly furni%es a measure ( ! rate ( decay ( ! emanation itself4 ,?is is only true if ! emanation is plac$ = f\r or five h\rs 9 ! tube be=e obs]vations beg91 9 ord] to all[ ! excit$ activity "t to rea* a maximum value4 ,us+ ?is me?od ,p4 ,curie obta9$ results simil> to ^? obta9$ by ,ru!r=d & ,soddy by ! direct me?od4 ,! activity decay$ accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 #cii days4 ,! exp]im5ts 7 p]=m$ "u ! mo/ v>i$ conditions b ! rate ( decay 0 f\nd to rema9 unalt]$4 ,! rate ( decay did n dep5d on ! mat]ial ( ! vessel conta9+ ! emanation or on ! nature or pressure ( ! gas ) :i* ! emanation 0 mix$4 ,x 0 unaffect$ by ! am\nt ( emanation pres5t1 or by ! "t ( exposure to ! radium1 provid$ suffici5t "t _h elaps$ to all[ ! excit$ activity to rea* a maximum value be=e ! obs]vations 7 begun4 ,p4 ,curie#bci f\nd t ! rate ( decay ( activity 0 n alt]$ by expos+ ! vessel conta9+ ! emanation to diff]5t temp]atures1 rang+ f #dej to #ahj ,c4 ,9 ?is respect ! emanations ( ?orium & radium are q analog\s4 ,! rate ( decay seems to be unaffect$ by any physical or *emical ag5cy1 & ! emanations behave 9 exactly ! same way z ! radio-active products ,? ,x & ,ur ,x1 already ref]r$ to4 ,! radio-active con/ant is ?us a fix$ & unalt]able quantity = bo? emanations1 al?\gh 9 "o case its value is ab\t #ejjj times great] ?an 9 ! o!r4 ,emanations f ,act9ium4 #adf4 ,debi]ne#bdj f\nd t act9ium gives out an emanation simil> to ! emanation ( ?orium & radium4 ,! loss ( activity ( ! emanation is ev5 m rapid ?an = ! ?orium emanation1 = its activity falls to half value 9 #ci seconds4 ,9 consequ5ce ( ! rapid decay ( activity1 ! emanation is able to diffuse ?r\gh ! air only a %ort di/ance f ! active matt] be=e x loses ! great] proportion ( its activity4 ,giesel e>ly obs]v$ t ! radio-active sub/ance sep>at$ by him1 :i* we h se5 7section #ah7 is id5tical 9 radio-active prop]ties ) act9ium1 gave (f a l>ge am\nt ( emanation4 ,x 0 9 consequ5ce ( ?is prop]ty1 t he gave x ! "n ( ! 8emanat+ sub/ance0 & lat] 8emanium40 ,! impure prep>ations ( ?is sub/ance emit ! emanation v freely & 9 ?is respect diff] f mo/ ( ! ?orium comp\nds4 ,! emanation f act9ium l ^? f ?orium & radium possesses ! prop]ty ( excit+ activity on inactive bodies1 b x has n yet be5 /udi$ s completely z ! bett] kn[n emanations ( ?orium & radium4 ,exp]im5ts ) l>ge am\nts ( ,radium ,emanation4 #adg4 ,) v active specim5s ( radium a l>ge am\nt ( emanation c be obta9$1 & ! electrical1 photographic1 & fluoresc5t effects are correspond+ly int5se4 ,on acc\nt ( ! small activity ( ?orium & ! rapid decay ( its emanation ! effects due to x are weak1 & c be /udi$ only = a few m9utes aft] its production4 ,! emanation f radium1 on ! o!r h&1 9 consequ5ce ( ! sl[ decay ( its activity1 may be /or$ mix$ ) air 9 an ord9>y gas-hold]1 & its photographic & electrical actions may be exam9$ sev]al days or ev5 weeks aft]1 q ap>t f ^? ( ! radium f :i* x 0 obta9$4 ,x is1 9 g5]al1 difficult to /udy ! radiation due to ! emanation alone1 on acc\nt ( ! fact t ! emanation is cont9ually produc+ a second>y type ( activity on ! surface ( ! vessel 9 :i* ! emanation is enclos$4 ,?is excit$ activity rea*es a maximum value sev]al h\rs aft] ! introduction ( ! emanation1 &1 z long z x is kept 9 ! vessel1 ?is excit$ activity on ! walls decays at ! same rate z ! emanation itself1 i4e4 x falls to half its initial value 9 ab\t #d days4 ,if1 h[ev]1 ! emanation is bl[n out1 ! excit$ activity rema9s beh9d on ! surface1 b rapidly loses its activity 9 ! c\rse ( a few h\rs4 ,aft] sev]al h\rs ! int5sity ( ! residual radiation is v small4 ,^! effects & _! connection ) ! emanation are discuss$ m fully 9 *apt] ,,viii4 ,giesel#bda has record$ "s int]e/+ obs]vations ( ! effect ( ! radium emanation on a scre5 ( phosphoresc5t z9c sulphide4 ,:5 a few c5tigrams ( moi/ radium bromide 7 plac$ on a scre5 any slight motion ( ! air caus$ ! lum9osity to move to & fro on ! scre54 ,! direction ( phosphoresc5ce c\ld be alt]$ at w by a sl[ curr5t ( air4 ,! effect 0 /ill fur!r increas$ by plac+ ! active mat]ial 9 a tube & bl[+ ! air ?r\gh x t[>ds ! scre54 ,a scre5 ( b>ium plat9ocyanide or ( ,balma9's pa9t fail$ to give any visible light "u ! same conditions4 ,! lum9osity 0 n alt]$ by a magnetic field1 b x 0 affect$ by an electric field4 ,if ! scre5 7 *>g$ ! lum9osity 0 m m>k$ :5 x 0 negative ?an :5 x 0 positive4 ,giesel /ates t ! lum9osity 0 n equally di/ribut$1 b 0 conc5trat$ 9 a peculi> r+-%ap$ mann] ov] ! surface ( ! scre54 ,! conc5tration ( lum9osity on ! negative1 r ?an on ! positive1 electrode is probably due to ! excit$ activity1 caus$ by ! emanation1 & n to ! emanation itself1 = ?is excit$ activity is conc5trat$ *iefly on ! negative electrode 9 an electric field 7see *apt] ,,viii74 ,an exp]im5t to illu/rate ! phosphoresc5ce produc$ 9 "s sub/ances by ! rays f a l>ge am\nt ( emanation is describ$ 9 section #afe4 #adh4 ,curie & ,debi]ne#bdb h inve/igat$ ! emanation f radium1 & ! excit$ activity produc$ by x4 ,"s exp]im5ts 7 made on ! am\nt ( emanation giv5 (f f radium "u v l[ pressures4 ,! tube conta9+ ! emanation 0 exhau/$ to a good vacuum by a m]cury pump4 ,x 0 obs]v$ t a gas 0 giv5 (f f ! radium :i* produc$ excit$ activity on ! glass walls4 ,?is gas 0 extremely active1 & rapidly affect$ a photographic plate ?r\gh ! glass4 ,x caus$ fluoresc5ce on ! surface ( ! glass & rapidly black5$ x1 & 0 /ill active aft] /&+ t5 days4 ,:5 spectroscopically exam9$1 ?is gas did n %[ any new l9es1 b g5]ally ^? ( ! spectra ( c>bonic acid1 hydrog51 & m]cury4 ,9 ! light ( ! results describ$ 9 section #abd ! gas1 giv5 (f by ! radium1 0 probably ! non-active gases hydrog5 & oxyg51 9 :i* ! active emanation 0 mix$ 9 m9ute quantity4 ,x w be %[n lat] 7section #bdb7 t ! en]gy radiat$ f ! emanation is enorm\s comp>$ ) ! am\nt ( matt] involv$1 & t ! effects obs]v$1 9 mo/ cases1 are produc$ by an almo/ inf9itesimal am\nt ( ! emanation4 ,9 fur!r exp]im5ts1 ,curie & ,debi]ne#bdc f\nd t _m sub/ances 7 phosphoresc5t "u ! action ( ! emanation & ! excit$ activity produc$ by x4 ,9 _! exp]im5ts1 two glass bulbs ,a & ,b 7,fig4 #ed7 7 connect$ ) a glass tube4 ,! active mat]ial 0 plac$ 9 ! bulb ,a & ! sub/ance to be exam9$ 9 ! o!r4 ,illu/ration3 ,fig4 #ed4 ,!y f\nd t1 9 g5]al1 sub/ances t 7 phosphoresc5t 9 ord9>y light became lum9\s4 ,! sulphide ( z9c 0 especially brilliant & became z lum9\s z if expos$ to a /rong light4 ,aft] suffici5t "t _h elaps$ ! lum9osity rea*$ a con/ant value4 ,! phosphoresc5ce is p>tly due to ! excit$ activity produc$ by ! emanation on its surface1 & p>tly to ! direct radiation f ! emanation4 ,phosphoresc5ce 0 also produc$ 9 glass4 ,?ur+ian glass %[$ ! mo/ m>k$ effects4 ,! lum9osity ( ! glass 0 f\nd to be ab\t ! same 9 ! two bulbs1 b 0 m m>k$ 9 ! connect+ tube4 ,! effect 9 ! two bulbs 0 ! same ev5 if connect$ by a v n>r[ tube4 ,"s exp]im5ts 7 also made ) a s]ies ( phosphoresc5t plates plac$ 9 ! vessel at v>y+ di/ances ap>t4 ,) ! plates #a mm4 ap>t ! effect 0 v feeble1 b increas$ directly z ! di/ance & 0 l>ge = a di/ance ( #c cms4 ,^! effects receive a g5]al explanation on ! views already put =w>d4 ,:5 ! radium is plac$ 9 ! clos$ vessel1 ! emanation is giv5 (f at a con/ant rate & gradually diffuses ?r\gh\t ! enclosure4 ,s9ce ! "t tak5 = diffusion ( ! emanation ?r\gh tubes ( ord9>y size is small comp>$ ) ! "t requir$ = ! activity to be appreciably r$uc$1 ! emanation1 & also ! excit$ activity due to x1 w be ne>ly equally di/ribut$ ?r\gh\t ! vessel4 ,! lum9osity due to x %\ld ?us be equal at ea* end ( ! tube4 ,ev5 ) a capill>y tube connect+ ! two bulbs1 ! gas cont9u\sly giv5 (f by ! radium w always c>ry ! emanation ) x & cause a practically uni=m di/ribution4 ,! gradual increase ( ! am\nt ( emanation ?r\gh\t ! tube w be giv5 by ! equation frac ,nt ,n #a e-t 4 :]e ,nt is ! numb] ( emanation p>ticles pres5t at ! "t t1 ,n ! numb] pres5t :5 radio-active equilibrium is rea*$1 & is ! radio-active con/ant ( ! emanation4 ,! phosphoresc5t action1 :i* is due p>tly to ! radiations f ! emanation & p>tly to ! excit$ activity on ! walls1 %\ld ?us rea* half ! maximum value 9 f\r days & %\ld practically rea* its limit aft] ?ree weeks' int]val4 ,! v>iation ( lum9osity ) diff]5t di/ances betwe5 ! scre5s is to be expect$4 ,! am\nt ( excit$ activity deposit$ on ! b\nd>ies is proportional to ! am\nt ( emanation pres5t4 ,s9ce ! emanation is equally di/ribut$1 ! am\nt ( excit$ activity deposit$ on ! scre5s1 due to ! emanation betwe5 !m1 v>ies directly z ! di/ance1 provid$ ! di/ance betwe5 ! scre5s is small comp>$ ) _! dim5sions4 ,su* a result w\ld also foll[ if ! phosphoresc5ce 7 due to ! radiation f ! emanation itself1 provid$ t ! pressure ( ! gas 0 l[ en\gh to prev5t absorption ( ! radiation f ! emanation 9 ! gas itself betwe5 ! scre5s4 ,measurem5ts ( ,emanat+ ,p[]4 #adi4 ,emanat+ p[]4 ,! comp\nds ( ?orium 9 ! solid /ate v>y v widely 9 ! am\nt ( emanation !y emit "u ord9>y conditions4 ,x is conv5i5t to use ! t]m emanat+ p[] to express ! am\nt ( emanation giv5 (f p] second by "o gram ( ! comp\nd4 ,s9ce1 h[ev]1 we h no means ( det]m9+ absolutely ! am\nt ( emanation pres5t1 all measurem5ts ( emanat+ p[] are ( necessity comp>ative4 ,9 mo/ cases1 x is conv5i5t to take a giv5 weight ( a ?orium comp\nd1 kept "u conditions z ne>ly z possible con/ant1 & to comp>e ! am\nt ( emanation ( ! comp\nd to be exam9$ ) ?is /&>d4 ,9 ?is way comp>isons ( ! emanat+ p[] ( ?orium comp\nds h be5 made by ,ru!r=d & ,soddy#bdd1 us+ an app>atus simil> to t %[n 9 ,fig4 #ea on page #bdj4 ,a kn[n weight ( ! sub/ance to be te/$ 0 spread on a %all[ di%1 plac$ 9 ! glass tube ,c4 ,a /ream ( dry du/-free air1 kept con/ant dur+ all ! exp]im5ts1 0 pass$ ov] ! comp\nd & c>ri$ ! emanation into ! te/+ vessel4 ,aft] t5 m9utes int]val1 ! curr5t due to ! emanation 9 ! te/+ vessel rea*$ a con/ant value4 ,! comp\nd 0 !n remov$1 & ! /&>d comp>ison sample ( equal weight sub/itut$2 ! saturation curr5t 0 obs]v$ :5 a /eady /ate 0 aga9 rea*$4 ,! ratio ( ^! two curr5ts gives ! ratio ( ! emanat+ p[] ( ! two samples4 ,x 0 f\nd exp]im5tally t1 = ! velocities ( air curr5t employ$1 ! saturation curr5t 9 ! te/+ vessel 0 directly proportional to ! weight ( ?orium1 = weights up to #bj grams4 ,?is is expla9$ by ! supposition t ! emanation is remov$ by ! curr5t ( air f ! mass ( ! comp\nd1 z fa/ z x is =m$4 ,let i saturation curr5t due to a weight ( ! /&>d1 i ( ! sample to be te/$4 7emanat+ p[] ( specim57 i ,!n ---------------------------- ---- --- 7emanat+ p[] ( /&>d7 i ,by means ( ?is relation ! emanat+ p[] ( comp\nds :i* are n ( equal weight c be comp>$4 ,x 0 f\nd t ?orium comp\nds v>i$ enorm\sly 9 emanat+ p[]1 al?\gh ! p]c5tage proportion ( ?orium pres5t 9 ! comp\nd 0 n v diff]5t4 ,= example1 ! emanat+ p[] ( ?orium hydroxide 0 g5]ally #c to #d times great] ?an t ( ord9>y ?oria1 obta9$ f ! manufactur]4 ,?orium nitrate1 9 ! solid /ate1 _h only ( ! emanat+ p[] ( ord9>y ?oria1 :ile prep>ations ( ! c>bonate 7 f\nd to v>y widely among !mselves 9 emanat+ p[]1 :i* dep5d$ ^u slight v>iations 9 ! me?od ( prep>ation4 #aej4 ,effect ( conditions on emanat+ p[]4 ,! emanat+ p[] ( diff]5t comp\nds ( ?orium & radium is mu* affect$ by ! alt]ation ( *emical & physical conditions4 ,9 ?is respect ! emanat+ p[]1 :i* is a measure ( ! rate ( escape ( ! emanation into ! surr\nd+ gas1 mu/ n be confus$ ) ! rate ( decay ( ! activity ( ! emanations !mselves1 :i* has already be5 %[n to be unaffect$ by ext]nal conditions4 ,dorn 7loc4 cit47 fir/ obs]v$ t ! emanat+ p[] ( ?orium & radium comp\nds 0 mu* affect$ by moi/ure4 ,9 a full] inve/igation ( ?is po9t by ,ru!r=d & ,soddy1 x 0 f\nd t ! emanat+ p[] ( ?oria is f two to ?ree times great] 9 a moi/ ?an 9 a dry gas4 ,cont9u$ desiccation ( ! ?oria 9 a glass tube1 conta9+ phosphorus p5toxide1 did n r$uce ! emanat+ p[] mu* bel[ t obs]v$ 9 ord9>y dry air4 ,9 ! same way radium *loride 9 ! solid /ate gives (f v little emanation :5 9 a dry gas1 b ! am\nt is mu* increas$ 9 a moi/ gas4 ,! rate ( escape ( emanation is mu* increas$ by solution ( ! comp\nd4 ,= example1 ?orium nitrate1 :i* has an emanat+ p[] ( only t ( ?oria 9 ! solid /ate1 has 9 solution an emanat+ p[] ( #c to #d times t ( ?oria4 ,p4 ,curie & ,debi]ne obs]v$ t ! emanat+ p[] ( radium 0 also mu* increas$ by solution4 ,temp]ature has a v m>k$ effect on ! emanat+ p[]4 ,! writ]#bde %[$ t ! emanat+ p[] ( ord9>y ?oria 0 increas$ ?ree to f\r times by heat+ ! sub/ance to a dull r$ heat 9 a plat9um tube4 ,if ! temp]ature 0 kept con/ant ! emanation cont9u$ to escape at ! increas$ rate1 b return$ to its orig9al value on cool+4 ,if1 h[ev]1 ! comp\nd 0 heat$ to a :ite heat1 ! emanat+ p[] 0 greatly r$uc$1 & x return$ on cool+ to ab\t #aj ( ! orig9al value4 ,su* a comp\nd is said to be de-emanat$4 ,! emanat+ p[] ( radium comp\nds v>ies 9 a /ill m /rik+ mann] ) rise ( temp]ature4 ,! rate ( escape ( ! emanation is mom5t>ily increas$ ev5 #aj1jjj times by heat+ to a dull r$ heat4 ,?is effect does n cont9ue1 = ! l>ge escape ( ! emanation by heat+ is 9 reality due to ! release ( ! emanation /or$ up 9 ! radium comp\nd4 ,l ?oria1 :5 ! comp\nd has once be5 heat$ to a v high temp]ature1 x loses its emanat+ p[] & does n rega9 x4 ,x rega9s its p[] ( emanat+1 h[ev]1 aft] solution & re-sep>ation4 ,a fur!r exam9ation ( ! effect ( temp]ature 0 made by ,ru!r=d & ,soddy#bdf4 ,! emanat+ p[] ( ?oria decreases v rapidly ) l[]+ ( temp]ature1 & at ! temp]ature ( solid c>bonic acid x is only ab\t #aj ( its ord9>y value4 ,x rapidly returns to its orig9al value :5 ! cool+ ag5t is remov$4 ,increase ( temp]ature f #hj ,c4 to a dull r$ heat ( plat9um ?us increases ! emanat+ p[] ab\t #dj times1 & ! effects c be repeat$ aga9 & aga91 ) ! same comp\nd1 provid$ ! temp]ature is n rais$ to ! temp]ature at :i* de-emanation beg9s4 ,de-emanation sets 9 above a r$ heat1 & ! emanat+ p[] is !n p]man5tly dim9i%$1 b ev5 long-cont9u$ heat+ at a :ite heat nev] entirely de/roys ! emanat+ p[]4 #aea4 ,reg5]ation ( emanat+ p[]4 ,an int]e/+ "q arises :e!r ! de-emanation ( ?orium & radium is due to a removal or alt]ation ( ! sub/ance :i* produces ! emanation1 or :e!r int5se ignition m]ely *anges ! rate ( escape ( ! emanation f ! solid into ! surr\nd+ atmosph]e4 ,x is evid5t t ! physical prop]ties ( ! ?oria are mu* alt]$ by int5se ignition4 ,! comp\nd *anges 9 col\r f :ite to p9k2 x becomes d5s] & also f> less readily soluble 9 acids4 ,9 ord] to te/ if ! emanat+ p[] c\ld be reg5]at$ by a cyclic *emical process1 ! de-emanat$ ?oria 0 dissolv$1 precipitat$ z hydroxide & aga9 conv]t$ into oxide4 ,at ! same "t a specim5 ( ! ord9>y oxide 0 subject$ to an exactly p>allel process4 ,! emanat+ p[] ( bo? ^! comp\nds 0 ! same1 & 0 f two to ?ree times great] ?an t ( ord9>y ?oria4 ,?us de-emanation does n p]man5tly de/roy ! p[] ( ?orium ( giv+ out an emanation1 b m]ely produces an alt]ation ( ! am\nt ( ! emanation :i* escapes f ! comp\nd4 #aeb4 ,rate ( production ( ! emanation4 ,! emanat+ p[] ( ?orium comp\nds1 !n1 is a v v>iable quantity1 mu* affect$ by moi/ure1 heat1 & solution4 ,speak+ g5]ally1 increas$ temp]atures & solution greatly increase ! emanat+ p[] ( bo? ?orium & radium4 ,! wide diff]5ces betwe5 ! emanat+ p[]s ( ^! sub/ances 9 ! solid /ate & 9 solution po9t$ to ! conclusion t ! diff]5ces 7 probably due to ! rate ( escape ( ! emanation into ! surr\nd+ gas1 & n to a v>iation ( ! rate ( reaction :i* gave rise to ! emanation4 ,x is obvi\s t a v slight ret>dation 9 ! rate ( escape ( ! ?orium emanation f ! comp\nd into ! gas1 w1 on acc\nt ( ! rapid decay ( activity ( ! emanation1 produce great *anges 9 emanat+ p[]4 ,! reg5]ation ( ! emanat+ p[] ( de-emanat$ ?oria & radium by solution & *emical treatm5t made x evid5t t ! orig9al p[] ( ?orium & radium ( produc+ ! emanation /ill p]si/$ 9 an unalt]$ degree4 ,! "q :e!r ! emanation 0 produc$ at ! same rate 9 emanat+ z 9 non-emanat+ comp\nds c be put to a %>p quantitative te/4 ,if ! rate ( production ( emanation goes on at ! same rate 9 ! solid comp\nd :]e v little escapes1 z 9 ! solution :]e probably all escapes1 ! emanation mu/ be occlud$ 9 ! comp\nd1 & consequ5tly !re mu/ be a sudd5 release ( ?is emanation on solution ( ! comp\nd4 ,on acc\nt ( ! v sl[ decay ( ! activity ( ! emanation ( radium1 ! effects %\ld be f> m m>k$ 9 t comp\nd ?an 9 ?orium4 ,f ! po9t ( view develop$ 9 section #acc1 ! expon5tial law ( decay ( ! emanation expresses ! result t ,nt ! numb] ( p>ticles rema9+ un*ang$ at ! "t t is giv5 by frac ,nt ,n e-t 7#a74 :]e ,n is ! initial numb] ( p>ticles pres5t4 ,:5 a /eady /ate is rea*$1 ! rate ( production q ( fre% emanation p>ticles is exactly balanc$ by ! rate ( *ange ( ! p>ticles ,n already pres5t1 i4e4 q ,n1 ,n 9 ?is case repres5ts ! am\nt ( emanation 8occlud$0 9 ! comp\nd4 ,sub/itut+ ! value ( f\nd = ! radium emanation 9 section #ade1 ,n ----- #a_/ #dfc1jjj4 q ,! am\nt ( emanation /or$ 9 a non-emanat+ radium comp\nd %\ld !re=e be ne>ly #ejj1jjj times ! am\nt produc$ p] second by ! comp\nd4 ,?is result 0 te/$ 9 ! foll[+ way#bdg4 ,a weight ( #jc gr4 ( radium *loride ( activity #ajjj times t ( uranium 0 plac$ 9 a ,dre*sel bottle & a suffici5t am\nt ( wat] drawn 9 to dissolve x4 ,! releas$ emanation 0 swept out by a curr5t ( air into a small gas hold] & !n into a te/+ cyl9d]4 ,! initial saturation curr5t 0 proportional to ,n4 ,a rapid curr5t ( air 0 !n pass$ ?r\gh ! radium solution = "s "t 9 ord] to remove any slight am\nt ( emanation :i* _h n be5 remov$ initially4 ,! ,dre*sel bottle 0 clos$ air-tight1 & all[$ to /& undi/urb$ = a def9ite "t t4 ,! accumulat$ emanation 0 !n swept out z be=e into ! te/+ vessel4 ,! new ionization curr5t repres5ts ! value ( ,nt ! am\nt ( emanation =m$ 9 ! comp\nd dur+ ! int]val t4 ,9 ! exp]im5t t #aje m9utes1 & ! obs]v$ value ,nt ----- #jaca4 ,n ,assum+ t !re is no decay dur+ ! int]val1 ,nt #aje #fj q4 ,n ,?us --- #dhj1jjj4 q ,mak+ ! small correction = ! decay ( activity dur+ ! int]val1 ,n ----- #dgg1jjj4 q ,we h previ\sly %[n t f ! !ory ,n #a ----- ---- #dfc1jjj4 q ,! agreem5t betwe5 !ory & exp]im5t is ?us z close z c\ld be expect$ f ! nature ( ! exp]im5ts4 ,?is exp]im5t proves conclusively t ! rate ( production ( emanation 9 ! solid comp\nd is ! same z 9 ! solution4 ,9 ! =m] case x is occlud$1 9 ! latt] x escapes z fa/ z x is produc$4 ,x is rem>kable h[ little emanation1 comp>$ ) ! am\nt /or$ up 9 ! comp\nd1 escapes f solid radium *loride 9 a dry atmosph]e4 ,"o exp]im5t %[$ t ! emanat+ p[] 9 ! dry solid /ate 0 less ?an ( ! emanat+ p[] ( ! solution4 ,s9ce ne>ly #ejj1jjj times z mu* emanation is /or$ up 9 ! solid comp\nd z is produc$ p] second1 ?is result %[$ t ! am\nt ( emanation :i* escap$ p] second 0 less ?an #aj ( t occlud$ 9 ! comp\nd4 ,if a solid radium *loride comp\nd is kept 9 a moi/ atmosph]e1 ! emanat+ p[] becomes comp>able ) ! am\nt produc$ p] second 9 ! solution4 ,9 su* a case1 s9ce ! rate ( escape is cont9u\s1 ! am\nt occlud$ w be mu* less ?an ! am\nt = ! non-emanat+ mat]ial4 ,! ph5om5on ( occlusion ( ! radium emanation is probably n connect$ 9 any way ) its radio-activity1 al?\gh ?is prop]ty has "h s]v$ to measure x4 ,! occlusion ( helium by m9]als pres5ts almo/ a complete analogy to ! occlusion ( ! radium emanation4 ,"p ( ! helium is giv5 (f by f]gusonite1 = example1 :5 x is heat$ & all ( x :5 ! m9]al is dissolv$4 #aec4 ,simil> results hold = ?orium1 b1 on acc\nt ( ! rapid loss ( activity ( ! emanation1 ! am\nt ( emanation occlud$ 9 a non-emanat+ comp\nd is v small comp>$ ) t obs]v$ = radium4 ,if ! production ( ! ?orium emanation proce$s at ! same rate "u all conditions1 ! solution ( a solid non-emanat+ comp\nd %\ld be accompani$ by a ru% ( emanation great] ?an t subsequ5tly produc$4 ,) ! same notation z be=e we h = ! ?orium emanation1 ,n #a ----- ----- #hg4 q ,?is result 0 te/$ z foll[s3 a quantity ( f9ely p[d]$ ?orium nitrate1 ( emanat+ p[] ( ord9>y ?oria1 0 dropp$ into a ,dre*sel bottle conta9+ hot wat] & ! emanation rapidly swept out into ! te/+ vessel by a curr5t ( air4 ,! ionization curr5t rose quickly to a maximum1 b soon fell aga9 to a /eady value2 %[+ t ! am\nt ( emanation releas$ :5 ! nitrate dissolves1 is great] ?an ! subsequ5t am\nt produc$ f ! solution4 ,! rapid loss ( ! activity ( ! ?orium emanation makes a quantitative comp>ison l t = radium v difficult4 ,by slightly alt]+ ! conditions ( ! exp]im5t1 h[ev]1 a def9ite pro( 0 obta9$ t ! rate ( production ( emanation is ! same 9 ! solid comp\nd z 9 ! solution4 ,aft] dropp+ 9 ! nitrate1 a rapid air /ream 0 bl[n ?r\gh ! solution = #be seconds into ! te/+ vessel4 ,! air /ream 0 /opp$ & ! ionization curr5t imm$iately measur$4 ,! solution 0 !n all[$ to /& undi/urb$ = #aj m9utes4 ,9 t "t ! accumulation ( ! emanation aga9 atta9$ a practical maximum & aga9 repres5t$ a /eady /ate4 ,! /ream ( air 0 bl[n ?r\gh1 z be=e1 = #be seconds1 /opp$ & ! curr5t aga9 measur$4 ,9 bo? cases1 ! electromet] record$ a movem5t ( #adf divisions p] second4 ,by bl[+ ! same /ream ( air cont9u\sly ?r\gh ! solution ! f9al curr5t correspond$ to #gi divisions p] second or ab\t "o-half ( t obs]v$ aft] ! fir/ ru%4 ,?us ! rate ( production ( emanation is ! same 9 ! solid nitrate z 9 ! solution1 al?\gh ! emanat+ p[]1 i4e4 ! rate ( escape ( ! emanation1 is ov] #fjj times great] 9 ! solution ?an 9 ! solid4 ,x seems probable t ! rate ( production ( emanation by ?orium1 l ! rate ( production ( ,ur ,x & ,? ,x1 is indep5d5t ( conditions4 ,! *anges ( emanat+ p[] ( ! v>i\s comp\nds by moi/ure1 heat1 & solution mu/ !re=e be ascrib$ solely to an alt]ation 9 ! rate ( escape ( ! emanation into ! surr\nd+ gas & n to an alt]ation 9 ! rate ( its production 9 ! comp\nd4 ,on ?is view1 x is easy to see t slight *anges 9 ! mode ( prep>ation ( a ?orium comp\nd may produce l>ge *anges 9 emanat+ p[]4 ,su* effects h be5 (t5 obs]v$1 & mu/ be ascrib$ to slight physical *anges 9 ! precipitate4 ,! fact t ! rate ( production ( ! emanation is indep5d5t ( ! physical or *emical conditions ( ! ?orium1 9 :i* x is produc$1 is ?us 9 h>mony ) :at _h previ\sly be5 obs]v$ = ! radio-active products ,ur ,x & ,? ,x4 ,s\rce ( ! ,?orium ,emanation4 #aed4 ,"s exp]im5ts ( ,ru!r=d & ,soddy#bdh w n[ be consid]$1 :i* %[ t ! ?orium emanation is produc$1 n directly by ! ?orium itself1 b by ! active product ,? ,x4 ,:5 ! ,? ,x1 by precipitation ) ammonia1 is remov$ f a quantity ( ?orium nitrate1 ! precipitat$ ?orium hydroxide does n at fir/ possess appreciable emanat+ p[]4 ,?is loss ( emanat+ p[] is n due1 z 9 ! case ( ! de-emanat$ oxide1 to a ret>dation 9 ! rate ( escape ( ! emanation produc$2 = ! hydroxide1 :5 dissolv$ 9 acid1 /ill gives (f no emanation4 ,on ! o!r h&1 ! solution1 conta9+ ! ,? ,x1 possesses emanat+ p[] to a m>k$ degree4 ,:5 ! precipitat$ hydroxide & ! ,? ,x is left = "s "t1 x is f\nd t ! ,? ,x decreases 9 emanat+ p[]1 :ile ! hydroxide gradually rega9s its emanat+ p[]4 ,aft] ab\t a mon?'s int]val1 ! emanat+ p[] ( ! hydroxide has ne>ly rea*$ a maximum1 :ile ! emanat+ p[] ( ! ,? ,x has almo/ disappe>$4 ,! curves ( decay & recov]y ( emanat+ p[] ) "t are f\nd to be exactly ! same z ! curves ( decay & recov]y ( activity ( ,? ,x & ! precipitat$ hydroxide respectively1 %[n 9 ,fig4 #dg4 ,! emanat+ p[] ( ,? ,x1 z well z its activity1 falls to half value 9 f\r days1 :ile ! hydroxide rega9s half its f9al emanat+ p[] z well z half its lo/ activity 9 ! same int]val4 ,x foll[s f ^! results t ! emanat+ p[] ( ,? ,x is directly proportional to its activity1 i4e4 t ! rate ( production ( emanat+ p>ticles is always proportional to ! numb] ( p>ticles1 project$ f ! ,? ,x p] second4 ,! radiation f ,? ,x ?us accompanies ! *ange ( ! ,? ,x into ! emanation4 ,s9ce ! emanation has *emical prop]ties di/9ct f ^? ( ! ,? ,x1 & also a di/9ctive rate ( decay1 x _c be reg>d$ z a vap\r ( ,? ,x1 b x is a di/9ct *emical sub/ance1 produc$ by ! *anges occurr+ 9 ,? ,x4 ,on ! view advanc$ 9 section #acf1 ! atom ( ! emanation consi/s ( ! "p ( ! atom ( ,? ,x left beh9d aft] ! expulsion ( "o or m p>ticles4 ,! atoms ( ! emanation are un/able1 & 9 turn expel p>ticles4 ,?is projection ( p>ticles con/itutes ! radiation f ! emanation1 :i* s]ves z a measure ( ! am\nt ( emanation pres5t4 ,s9ce ! activity ( ! emanation falls to half value 9 "o m9ute :ile t ( ,? ,x falls to half value 9 f\r days1 ! emanation consi/s ( atoms :i* dis9tegrate at int]vals ne>ly #fjjj times %ort] ?an ^? ( ! atoms ( ,? ,x4 ,s\rce ( ! ,radium & ,act9ium ,emanation4 #aee4 ,no int]m$iate /age--,radium ,x--betwe5 radium & its emanation1 correspond+ to ! ,? ,x = ?orium1 has s f> be5 obs]v$4 ,! emanation f radium is probably produc$ directly f t elem5t4 ,9 ?is respect1 ! radium emanation holds ! same position 9 reg>d to radium z ,? ,x does to ?orium1 & its production f radium c be expla9$ on exactly simil> l9es4 ,x w be %[n lat] 9 *apt] ,x1 t ! emanation ( act9ium1 l t ( ?orium1 does n arise directly f ! p>5t elem5t b f an int]m$iate product act9ium ,x1 :i* is v analog\s 9 physical & *emical prop]ties to ,? ,x4 ,radiations f ! ,emanations4 #aef4 ,special me?ods are necess>y to exam9e ! nature ( ! radiation f ! emanations1 = ! radiations arise f ! volume ( ! gas 9 :i* ! emanations are di/ribut$4 ,"s exp]im5ts to exam9e ! radiations f ! ?orium emanation 7 made by ! writ] 9 ! foll[+ way4 ,illu/ration3 ,fig4 #ee4 ,a highly emanat+ ?orium comp\nd wrapp$ 9 pap] 0 plac$ inside a lead box ,b ab\t #a cm4 deep1 %[n 9 ,fig4 #ee4 ,an op5+ 0 cut 9 ! top ( ! box1 ov] :i* a v ?9 %eet ( mica 0 wax$4 ,! emanation rapidly diffus$ ?r\gh ! pap] into ! vessel1 & aft] t5 m9utes rea*$ a /ate ( radio-active equilibrium4 ,! p5etrat+ p[] ( ! radiation f ! emanation :i* pass$ ?r\gh ! ?9 mica w9d[ 0 exam9$ by ! electrical me?od 9 ! usual way by add+ scre5s ( ?9 alum9ium foil4 ,! results are express$ 9 ! foll[+ table3 ,?ickness ( mica w9d[ #jjae cm4 ,?ickness ( alum9ium foil #jjjcd cm4 ,lay]s ( ,curr5t foil #j #ajj #a #ei #b #cj #c #aj #d #cb ,! great] proportion ( ! conductivity is ?us due to rays1 z 9 ! case ( ! radio-active elem5ts4 ,! am\nt ( absorption ( ^! rays by alum9ium foil is ab\t ! same z t ( ! rays f ! active bodies4 ,no direct comp>ison c be made1 = ! rays f ! emanation %[ ! *>act]i/ic prop]ty ( increas$ rate ( absorption ) ?ickness ( matt] trav]s$4 ,be=e te/+1 ! rays h be5 l>gely absorb$ by ! mica w9d[1 & ! p5etrat+ p[] has consequ5tly decreas$4 ,no alt]ation 9 ! radiation f ! emanation 0 obs]v$ on plac+ an insulat$ wire inside ! emanation vessel1 & *>g+ x to a high positive or negative pot5tial4 ,:5 a /ream ( air ?r\gh ! vessel c>ri$ away ! emanation z fa/ z x 0 produc$1 ! int5sity ( ! radiation fell to a small fraction ( its =m] value4 ,no evid5ce ( any rays 9 ! radiations 0 f\nd 9 ^! exp]im5ts1 al?\gh a v small effect w\ld h be5 detect$4 ,aft] /&+ "s h\rs1 h[ev]1 rays began to appe>4 ,^! 7 due to ! excit$ activity deposit$ on ! walls ( ! vessel f ! emanation1 & n directly to ! emanation itself4 ,! radium emanation1 l t ( ?orium1 only gives rise to rays4 ,?is 0 te/$ 9 ! foll[+ way#bdi3 ,a l>ge am\nt ( emanation 0 introduc$ into a cyl9d] made ( %eet copp] #jje cm4 ?ick1 :i* absorb$ all ! rays b all[$ ! & rays1 if pres5t1 to pass ?r\gh ) b little loss4 ,! ext]nal radiation f ! cyl9d] 0 det]m9$ at int]vals1 comm5c+ ab\t two m9utes aft] ! introduction ( ! emanation4 ,! am\nt obs]v$ at fir/ 0 extremely small1 b increas$ rapidly & practically rea*$ a maximum 9 ?ree or f\r h\rs4 ,?us ! radium emanation only gives out rays1 ! rays appe>+ z ! excit$ activity is produc$ on ! walls ( ! vessel4 ,on sweep+ out ! emanation by a curr5t ( air1 !re 0 no imm$iately appreciable decrease ( ! radiation4 ,?is is ano!r pro( t ! emanation does n emit any rays4 ,9 a simil> way x c be %[n t ! emanation does n give out rays2 ^! rays always make _! appe>ance at ! same "t z ! rays4 ,! me?od ( exam9ation ( ! radiations f ! emanations has be5 giv5 9 "s detail1 z ! results are ( consid]able importance 9 ! discussion1 :i* w be giv5 lat] 9 *apt]s ,x & ,,xi1 ( ! connection betwe5 ! *anges occurr+ 9 radio-active products & ! radiations !y emit4 ,!re is no d\bt t ! emanations1 ap>t f ! excit$ activity to :i* !y give rise1 only give out rays1 consi/+ mo/ probably ( positively *>g$ bodies project$ ) great velocity4 ,effect ( pressure on ! rate ( production ( ! ,emanation4 #aeg4 ,x has already be5 m5tion$ t ! conductivity due to ! ?orium emanation is proportional to ! pressure ( ! gas1 po9t+ to ! conclusion t ! rate ( production ( ! emanation is indep5d5t ( ! pressure1 z well z ( ! nature ( ! surr\nd+ gas4 ,?is result 0 directly confirm$ ) ! app>atus ( ,fig4 #ee4 ,:5 ! pressure ( ! gas "u ! vessel 0 sl[ly r$uc$1 ! radiation1 te/$ outside ! w9d[1 increas$ to a limit1 & !n rema9$ con/ant ov] a wide range ( pressure4 ,?is increase1 :i* 0 f> m m>k$ 9 air ?an 9 hydrog51 is due to ! fact t ! rays f ! emanation 7 p>tially absorb$ 9 ! gas inside ! vessel :5 at atmosph]ic pressure4 ,at pressures ( ! ord] ( #a millimetre ( m]cury ! ext]nal radiation decreas$1 b exp]im5t %[$ t ?is mu/ be ascrib$ to a removal ( ! emanation by ! pump1 & n to a *ange 9 ! rate ( production4 ,! ?orium comp\nds v readily absorb wat]-vap\r1 :i* is sl[ly giv5 (f at l[ pressures1 & 9 consequ5ce "s ( ! emanation is c>ri$ out ( ! vessel ) ! wat]-vap\r4 ,curie & ,debi]ne#bej f\nd t bo? ! am\nt ( excit$ activity produc$ 9 a clos$ vessel conta9+ active samples ( radium1 & also ! "t tak5 to rea* a maximum value1 7 indep5d5t ( ! pressure & nature ( ! gas4 ,?is 0 true 9 ! case ( a solution d[n to ! pressure ( ! saturat$ vap\r1 & 9 ! case ( solid salts to v l[ pressures4 ,:5 ! pump 0 kept go+ at pressures ( ! ord] ( #jja mm4 ( m]cury1 ! am\nt ( excit$ activity 0 mu* dim9i%$4 ,?is 0 probably n due to any alt]ation ( ! rate ( escape ( ! emanation1 b to ! removal ( ! emanation by ! action ( ! pump z fa/ z x 0 =m$4 ,s9ce ! am\nt ( excit$ activity1 :5 9 a /ate ( radio-active equilibrium1 is a measure ( ! am\nt ( emanation produc+ x1 ^! results %[ t ! am\nt ( emanation pres5t :5 ! rate ( production balances ! rate ( decay is indep5d5t ( ! pressure & nature ( ! gas4 ,x 0 also f\nd t ! "t tak5 to rea* ! po9t ( radio-active equilibrium 0 indep5d5t ( ! size ( ! vessel or ! am\nt ( active matt] pres5t4 ,?is proves t ! /ate ( equilibrium _c 9 any way be ascrib$ to ! possession by ! emanation ( any appreciable vap\r pressure2 = if su* 7 ! case1 ! "t tak5 to rea* ! equilibrium value %\ld dep5d on ! size ( ! vessel & ! am\nt ( active matt] pres5t4 ,! results are1 h[ev]1 9 agreem5t ) ! view t ! emanation is pres5t 9 m9ute quantity 9 ! tube1 & t ! equilibrium is gov]n$ purely by ! radio-active con/ant 1 ! con/ant ( decay ( activity ( ! emanation4 ,?is has be5 se5 to be ! same "u all conditions ( conc5tration1 pressure & temp]ature1 &1 provid$ ! rate ( supply ( ! emanation f ! active comp\nd is n *ang$1 ! "t-rate ( increase ( activity to ! equilibrium value w always be ! same1 :atev] ! size ( ! vessel or ! nature & pressure ( ! surr\nd+ gas4 ,*emical ,nature ( ! ,emanations4 #aeh4 ,we %all n[ consid] "s exp]im5ts on ! physical & *emical prop]ties ( ! emanations !mselves1 )\t ref]5ce to ! mat]ial produc+ !m1 9 ord] to see if !y possess any prop]ties :i* connect !m ) any kn[n k9d ( matt]4 ,x 0 soon obs]v$ t ! ?orium emanation pass$ un*ang$ ?r\gh acid solutions1 & lat] ! same result 0 %[n to hold true 9 ! case ( bo? emanations = e reag5t t 0 tri$4 ,prelim9>y obs]vations#bea %[$ t ! ?orium emanation1 obta9$ 9 ! usual way by pass+ air ov] ?oria1 pass$ un*ang$ 9 am\nt ?r\gh a plat9um tube heat$ electrically to ! highe/ temp]ature obta9able4 ,! tube 0 !n fill$ ) plat9um-black1 & ! emanation pass$ ?r\gh x 9 ! cold1 & ) gradually increas+ temp]atures1 until ! limit 0 rea*$4 ,9 ano!r exp]im5t1 ! emanation 0 pass$ ?r\gh a lay] ( r$-hot lead-*romate 9 a glass tube4 ,! curr5t ( air 0 replac$ by a curr5t ( hydrog51 & ! emanation 0 s5t ?r\gh r$-hot magnesium-p[d] & r$-hot palladium-black1 &1 by us+ a curr5t ( c>bon dioxide1 ?r\gh r$-hot z9c-du/4 ,9 e case ! emanation pass$ ?r\gh )\t s5sible *ange 9 ! am\nt4 ,if any?+1 a slight increase occurr$1 ow+ to ! "t tak5 = ! gas-curr5t to pass ?r\gh ! tubes :5 hot be+ slightly less ?an :5 cold1 ! decay en r\te be+ consequ5tly less4 ,! only kn[n gases capable ( pass+ 9 un*ang$ am\nt ?r\gh all ! reag5ts employ$ are ! rec5tly discov]$ memb]s ( ! argon family4 ,b ano!r possible int]pretation might be put ^u ! results4 ,if ! emanation 7 ! manife/ation ( a type ( excit$ radio-activity on ! surr\nd+ atmosph]e1 !n1 s9ce f ! nature ( ! exp]im5ts x 0 necess>y to employ 9 ea* case z ! atmosph]e1 a gas n act$ on by ! reag5t employ$1 ! result obta9$ might be expect$4 ,r$-hot magnesium w\ld n reta9 an emanation consi/+ ( radio-active hydrog51 nor r$-hot z9c-du/ an emanation consi/+ ( radio-active c>bon dioxide4 ,! incorrectness ( ?is explanation 0 %[n 9 ! foll[+ way4 ,c>bon dioxide 0 pass$ ov] ?oria1 !n ?r\gh a ,t-tube1 :]e a curr5t ( air met & mix$ ) x1 bo? pass+ on to ! te/+-cyl9d]4 ,b betwe5 ?is & ! ,t-tube a l>ge soda-lime tube 0 introduc$1 & ! curr5t ( gas 0 ?us fre$ f its admix$ c>bon dioxide1 be=e be+ te/$ 9 ! cyl9d] = ! emanation4 ,! am\nt ( emanation f\nd 0 q un*ang$1 :e!r c>bon dioxide 0 s5t ov] ?oria 9 ! mann] describ$1 or :e!r1 keep+ ! o!r arrangem5ts z be=e1 an equally rapid curr5t ( air 0 sub/itut$ = x4 ,! !ory t ! emanation is an effect ( ! excit$ activity on ! surr\nd+ m$ium is ?us exclud$4 ,exp]im5ts ( a simil> k9d on ! radium emanation 7 made lat]4 ,a /eady /ream ( gas 0 pass$ ?r\gh a radium *loride solution & !n ?r\gh ! reag5t to be employ$1 into a te/+-vessel ( small volume1 s t any *ange 9 ! am\nt ( emanation pass+ ?r\gh c\ld readily be detect$4 ,! radium emanation1 l t ( ?orium1 pass$ un*ang$ 9 am\nt ?r\gh e reag5t us$4 ,9 lat] exp]im5ts by ,sir ,william ,ramsay & ,mr ,soddy#beb1 ! emanation f radium 0 expos$ to /ill m dra/ic treatm5t4 ,! emanation 9 a glass tube 0 sp>k$ = sev]al h\rs ) oxyg5 ov] alkali4 ,! oxyg5 0 !n remov$ by ignit$ phosphorus & no visible residue 0 left4 ,:51 h[ev]1 ano!r gas 0 introduc$1 mix$ ) ! m9ute am\nt ( emanation 9 ! tube & )drawn1 ! activity ( emanation 0 f\nd to be unalt]$4 ,9 ano!r exp]im5t1 ! emanation 0 introduc$ into a magnesium lime tube1 :i* 0 heat$ = ?ree h\rs at a r$ heat4 ,! emanation 0 !n remov$ & te/$1 b no dim9ution 9 its dis*>g+ p[] 0 obs]v$4 ,! emanations ( ?orium & radium ?us )/& *emical treatm5t 9 a mann] hi!rto unobs]v$ except 9 gases ( ! argon family4 #aei4 ,ramsay & ,soddy 7loc4 cit47 record an int]e/+ exp]im5t to illu/rate ! gase\s nature ( ! emanation4 ,a l>ge am\nt ( ! radium emanation 0 collect$ 9 a small glass tube4 ,?is tube phosphoresc$ brightly "u ! influ5ce ( ! rays f ! emanation4 ,! passage ( ! emanation f po9t to po9t 0 obs]v$ 9 a d>k5$ room by ! lum9osity excit$ 9 ! glass4 ,on op5+ ! /op-cock connect+ ) ! ,tpl] pump1 ! sl[ fl[ ?r\gh ! capill>y tube 0 notic$1 ! rapid passage along ! wid] tubes1 ! delay 9 pass+ ?r\gh a plug ( phosphor\s p5toxide1 & ! rapid expansion into ! res]voir ( ! pump4 ,:5 compress$1 ! lum9osity ( ! emanation increas$1 & became v bright z ! small bubble conta9+ ! emanation 0 expell$ ?r\gh ! f9e capill>y tube4 ,diffusion ( ! ,emanations4 #afj4 ,x has be5 %[n t ! emanations ( ?orium & radium behave l radio-active gases1 di/ribut$ 9 m9ute am\nt 9 ! air or o!r gas 9 :i* !y are te/$4 ,) ! small quantities ( active mat]ial s f> inve/igat$1 ! emanations h n yet be5 collect$ 9 suffici5t am\nt to det]m9e _! d5sity4 ,al?\gh ! molecul> weight ( ! emanations _c yet be obta9$ by direct *emical me?ods1 an indirect e/imate ( x c be made by det]m9+ ! rate ( _! int]-diffusion into air or o!r gases4 ,! coeffici5ts ( int]-diffusion ( v>i\s gases h long be5 kn[n1 & ! results %[ t ! coeffici5t ( diffusion ( "o gas into ano!r is1 = ! simpl] gases1 approximately inv]sely proportional to ! squ>e root ( ! product ( _! molecul> weights4 ,if1 !re=e1 ! coeffici5t ( diffusion ( ! emanation into air is f\nd to h a value1 ly+ betwe5 t ( two kn[n gases ,a & ,b1 x is probable t ! molecul> weight ( ! emanation lies betwe5 t ( ,a & ,b4 ,al?\gh ! volume ( ! emanation giv5 (f f radium is v small1 ! electrical conductivity produc$ by ! emanation 9 ! gas1 ) :i* x is mix$1 is (t5 v l>ge1 & (f]s a ready means ( measur+ ! emanation pres5t4 ,"s exp]im5ts h be5 made by ,miss ,brooks & ! writ]#bec to det]m9e ! rate ( ! diffusion ( ! radium emanation into air1 by a me?od simil> to t employ$ by ,los*midt#bed 9 #ahga1 9 8 inve/igations ( ! coeffici5t ( int]-diffusion ( gases4 ,illu/ration3 ,fig4 #ef4 ,fig4 #ef %[s ! g5]al arrangem5t4 ,a long brass cyl9d] ,,ab1 ( l5g? #gc cms41 & diamet] #f cms41 0 divid$ into two equal p>ts by a movable metal slide ,s4 ,! ends ( ! cyl9d] 7 clos$ ) ebonite /opp]s4 ,two insulat$ brass rods1 a & b1 ea* half ! l5g? ( ! tube1 pass$ ?r\gh ! ebonite /opp]s & 7 support$ c5trally 9 ! tube4 ,! cyl9d] 0 insulat$ & connect$ ) "o pole ( a batt]y ( #cjj volts1 ! o!r pole ( :i* 0 e>!d4 ,! c5tral rods c\ld be connect$ ) a s5sitive quadrant electromet]4 ,! cyl9d] 0 cov]$ ) a ?ick lay] ( felt1 & plac$ inside a metal box fill$ ) cotton wool 9 ord] to keep temp]ature conditions z /eady z possible4 ,9 ord] to convey a suffici5t quantity ( emanation into ! half-cyl9d] ,a1 x 0 necess>y to heat ! radium slightly4 ,! slide ,s 0 clos$ & ! side tubes op5$4 ,a sl[ curr5t ( dry air f a gasomet] 0 pass$ ?r\gh a plat9um tube1 9 :i* a small quantity ( radium comp\nd 0 plac$4 ,! emanation 0 c>ri$ ) ! air into ! cyl9d] ,a4 ,:5 a suffici5t quantity _h be5 introduc$1 ! /ream ( air 0 /opp$4 ,! side tubes 7 clos$ by f9e capill>y tubes4 ,^! prev5t$ any appreciable loss ( gas due to ! diffusion1 b s]v$ to keep ! pressure ( ! gas inside ,a at ! pressure ( ! outside air4 ,! ?ree entrance tubes into ! cyl9d]1 %[n 9 ! figure1 7 = ! purpose ( initially mix+ ! emanation & gas z uni=mly z possible4 ,aft] /&+ sev]al h\rs to make temp]ature conditions /eady1 ! slide 0 op5$1 & ! emanation began to diffuse into ! tube ,b4 ,! curr5t ?r\gh ! tubes ,a & ,b 0 measur$ at regul> int]vals by an electromet]1 ) a suitable capacity 9 p>allel4 ,initially !re is no curr5t 9 ,b1 b aft] ! op5+ ( ! slide1 ! am\nt 9 ,a decreas$ & ! am\nt 9 ,b /eadily increas$4 ,aft] sev]al h\rs ! am\nt 9 ea* half is ne>ly ! same1 %[+ t ! emanation is ne>ly uni=mly diffus$ ?r\gh\t ! cyl9d]4 ,x c readily be %[n#bee t if ,k coeffici5t ( diffusion ( ! emanation into air1 t duration ( diffusion exp]im5ts 9 secs41 a total l5g? ( cyl9d]1 ,s p>tial pressure ( emanation 9 tube ,a at end ( diffusion1 ,s p>tial pressure ( emanation 9 tube ,b at end ( diffusion1 !n frac ,s#a ,s#b ,s#a ,s#b frac #h pi#b 7efrac pi#b ,kt a#b frac #ai;e-frac #i pi#b ,kt a#b 4447 4 ,n[ ! values ( ,s & ,s are proportional to ! saturation ionization curr5ts due to ! emanations 9 ! two halves ( ! cyl9d]4 ,f ?is equation ,k c be det]m9$1 if ! relative values ( ,s & ,s are obs]v$ aft] diffusion has be5 9 progress = a def9ite int]val t4 ,! det]m9ation ( ,s & ,s is complicat$ by ! excit$ activity produc$ on ! walls ( ! vessel4 ,! ionization due to ?is mu/ be subtract$ f ! total ionization obs]v$ 9 ea* half ( ! cyl9d]1 = ! excit$ activity is produc$ f ! mat]ial compos+ ! emanation1 & is remov$ to ! electrodes 9 an electric field4 ,! ratio ( ! curr5t due to excit$ activity to ! curr5t due to ! emanation dep5ds on ! "t ( exposure to ! emanation1 & is only proportional to x = exposures ( sev]al h\rs4 ,! me?od g5]ally adopt$ 9 ! exp]im5ts 0 to op5 ! slide = a def9ite int]val1 rang+ 9 ! exp]im5ts f #ae to #abj m9utes4 ,! slide 0 !n clos$ & ! curr5ts 9 ea* half det]m9$ at once4 ,! c5tral rods1 :i* _h be5 kept negatively *>g$ dur+ ! exp]im5ts1 _h mo/ ( ! excit$ activity conc5trat$ on _! surfaces4 ,^! 7 remov$1 new rods sub/itut$ & ! curr5t imm$iately det]m9$4 ,! ratio ( ! curr5ts 9 ! half cyl9d]s "u ^! conditions 0 proportional to ,s & ,s1 ! am\nts ( emanation pres5t 9 ! two halves ( ! cyl9d]4 ,! values ( ,k1 d$uc$ f diff]5t values ( t1 7 f\nd to be 9 good agreem5t4 ,9 ! e>li] exp]im5ts ! values ( ,k 7 f\nd to v>y betwe5 #jh & #ab4 ,9 "s lat] exp]im5ts1 :]e great c>e 0 tak5 to ensure t temp]ature conditions 7 v con/ant1 ! values ( ,k 7 f\nd to v>y betwe5 #jg & #ji4 ,! l[] value #jg is mo/ likely ne>] ! true value1 z temp]ature di/urbances t5d to give too l>ge a value ( ,k4 ,no c]ta9 diff]5ces 7 obs]v$ 9 ! value ( ,k :e!r ! air 0 dry or damp1 or :e!r an electric field 0 act+ or n4 #afa4 ,"s exp]im5ts on ! rate ( diffusion ( ! radium emanation into air 7 made at a lat] date by ,p4 ,curie & ,danne#bef4 ,if ! emanation is conta9$ 9 a clos$ res]voir1 x has be5 %[n t its activity1 :i* is a measure ( ! am\nt ( emanation pres5t1 decreases accord+ to an expon5tial law ) ! "t4 ,if ! res]voir is put 9 communication ) ! outside air ?r\gh a capill>y tube1 ! emanation sl[ly diffuses out1 & ! am\nt ( emanation 9 ! res]voir is f\nd to decrease accord+ to ! same law z be=e1 b at a fa/] rate4 ,us+ tubes ( diff]5t l5g?s & diamet]s1 ! rate ( diffusion 0 f\nd to obey ! same laws z a gas4 ,! value ( ,k 0 f\nd to be #jajj4 ,?is is a slightly great] value ( ,k ?an ! l[e/ value #jjg f\nd by ,ru!r=d & ,miss ,brooks4 ,no m5tion is made by ,curie & ,danne ( hav+ tak5 any special precautions aga9/ temp]ature di/urbances1 & ?is may acc\nt = ! high] value ( ,k obta9$ by !m4 ,!y also f\nd t ! emanation1 l a gas1 always divid$ itself betwe5 two res]voirs1 put 9 connection ) "o ano!r1 9 ! proportion ( _! volumes4 ,9 "o exp]im5t "o res]voir 0 kept at a temp]ature ( #aj ,c4 & ! o!r at #cej ,c4 ,! emanation divid$ itself betwe5 ! two res]voirs 9 ! same proportion z w\ld a gas "u ! same conditions4 #afb4 ,= ! purpose ( comp>ison1 a few ( ! coeffici5ts ( int]-diffusion ( gases1 compil$ f ,l&olt & ,b]n/e9's tables1 are giv5 bel[4 ,gas or vap\r ,coeffici5t ( ,molecul> diffusion into weight air ,wat] vap\r #jaih #ah ,c>bonic acid #jadb #dd gas ,alcohol vap\r #jaja #df ,e!r vap\r #jjgg #gd ,radium #jjg 8 emanation ,! tables1 al?\gh n v satisfactory = ! purpose ( comp>ison1 %[ t ! coeffici5t ( int]-diffusion foll[s ! inv]se ord] ( ! molecul> weights4 ,! value ( ,k = ! radium emanation is slightly less ?an = e!r vap\r1 ( :i* ! molecul> weight is #gd4 ,we may ?us conclude t ! emanation is ( great] molecul> weight ?an #gd4 ,x seems likely t ! emanation has a molecul> weight some:]e 9 ! neighb\rhood ( #ajj1 & is probably great] ?an ?is1 = ! vap\rs ( e!r & alcohol h high] diffusion coeffici5ts comp>$ ) c>bonic acid ?an ! !ory w\ld lead u to anticipate4 ,comp>+ ! diffusion coeffici5ts ( ! emanation & c>bonic acid into air1 ! value ( ! molecul> weight ( ! emanation %\ld be ab\t #agf if ! result obs]v$ = ! simple gases1 viz4 t ! coeffici5t ( diffusion is inv]sely proportional to ! squ>e root ( ! molecul> weights1 holds true 9 ! pres5t case4 ,bum/ead & ,:eel]#beg comp>$ ! rates ( diffusion ( ! radium emanation & ( c>bon dioxide ?r\gh a por\s plate1 & conclud$ t ! molecul> weight ( ! emanation 0 ab\t #ahj4 ,on ! dis9tegration !ory1 ! atom ( ! emanation is d]iv$ f ! radium atom by ! expulsion ( "o p>ticle4 ,?us1 x is to be expect$ t its molecul> weight w\ld be ov] #bjj4 ,x is ( int]e/ to comp>e ! value ( ,k #jg ) ! value ( ,k det]m9$ by ,t[ns5d 7section #cg7 = ! gase\s ions produc$ 9 air at ord9>y pressure & temp]ature1 by ,rntg5 rays or by ! radiations f active sub/ances4 ,t[ns5d f\nd t ! value ( ,k 9 dry air 0 #jbh = ! positive ions & #jdc = ! negative ions4 ,! radium emanation ?us diffuses m rapidly ?an ! ions produc$ by its radiation 9 ! gas1 & behaves z if its mass 7 small] ?an t ( ! ions produc$ 9 air1 b consid]ably great] ?an t ( ! air molecules ) :i* x is mix$4 ,x is n possible to reg>d ! emanation z a tempor>ily modifi$ condition ( ! gas orig9ally 9 contact ) ! active body4 ,"u su* conditions a mu* l>g] value ( ,k w\ld be expect$4 ,! evid5ce d]iv$ f ! exp]im5ts on diffusion /rongly supports ! view t ! emanation is a gas ( heavy molecul> weight4 ,mak[]#beh has rec5tly attack$ ! "q ( ! molecul> weight ( ! radium emanation by ano!r me?od4 ,! rate ( diffusion ( ! emanation ?r\gh a por\s plug ( pla/]-(-,p>is 0 comp>$ ) t ( ! gases oxyg51 c>bon dioxide1 & sulphur dioxide4 ,x 0 f\nd t ,graham's law1 viz4 t ! coeffici5t ( diffusion ,k is inv]sely proportional to ! squ>e root ( its molecul> weight ,m1 0 n /rictly applicable4 ,! value ( ,k ,m 0 n f\nd to be con/ant = ^! gases1 b decreas$ ) increase ( molecul> weight ( ! gas4 ,if1 h[ev]1 a curve 0 plott$ ) ,k ,m z ord9ate & ,k z abscissa1 ! po9ts correspond+ to ! values ( ,o1 ,,co & ,,s 7 f\nd to lie on a /raight l9e4 ,by l9e> extrapolation1 ! molecul> weight ( ! emanation 0 e/imat$4 ,! value obta9$ f exp]im5ts on ?ree diff]5t por\s plugs 0 #hee1 #ig1 & #ii respectively4 ,?is me?od indicates t ! molecul> weight ( ! radium emanation is ab\t #ajj2 b 9 all ! exp]im5ts on diffusion1 x mu/ be rememb]$ t ! emanation1 ^: rate ( int]-diffusion is be+ exam9$1 exi/s 9 m9ute quantity mix$ ) ! gas1 & is comp>$ ) ! rate ( int]-diffusion ( gases :i* are pres5t 9 l>ge quantity4 ,= ?is reason1 d$uctions ( ! molecul> weight ( ! emanation may be subject to comp>atively l>ge errors1 = :i* x is difficult to make correction4 ,diffusion ( ! ,?orium ,emanation4 #afc4 ,on acc\nt ( ! rapid decay ( ! activity ( ! ?orium emanation1 x is n possible to det]m9e ! value ( ,k its coeffici5t ( diffusion into air by ! me?ods employ$ = ! radium emanation4 ,! value ( ,k has be5 det]m9$ by ! writ] 9 ! foll[+ way4 ,a plate ,c1 ,fig4 #eg1 cov]$ ) ?orium hydroxide1 0 plac$ horizontally ne> ! base ( a long v]tical brass cyl9d] ,p4 ,! emanation releas$ f ! ?orium comp\nd diffuses upw>ds 9 ! cyl9d]4 ,illu/ration3 ,fig4 #eg4 ,let p be ! p>tial pressure ( ! emanation at a di/ance x f ! s\rce ,c4 ,?is w be approximately uni=m ov] ! cross section ( ! cyl9d]4 ,f ! g5]al pr9ciples ( diffusion we get ! equation dp dp ,k ----- ---- 4 dx dt ,! emanation is cont9u\sly break+ up & expell+ p>ticles4 ,! emanation-residue ga9s a positive *>ge1 &1 9 an electric field1 is remov$ at once f ! gas to ! negative electrode4 ,s9ce ! activity ( ! emanation at any "t is always proportional to ! numb] ( p>ticles :i* h n brok5 up1 & s9ce ! activity decays ) ! "t accord+ to an expon5tial law1 p p#a e-t 1 :]e p is ! value ( p :5 t #j & is ! radio-active con/ant ( ! emanation4 ,!n dp ---- -p1 dt & dp ,k ----- p4 dx ,?us p ,ae-sqrt frac ,k x ,besqrt frac ,k x 4 ,s9ce p #j :5 x inf9ity1 ,b #j4 ,if p p :5 x #j1 ,a p4 ,?us p p e-sqrt frac ,k x 4 ,x 0 n f\nd conv5i5t 9 ! exp]im5ts to det]m9e ! activity ( ! emanation along ! cyl9d]1 b an equival5t me?od 0 us$ :i* dep5ds ^u measur+ ! di/ribution ( 8excit$ activity10 produc$ along a c5tral rod ,,ab1 :i* is *>g$ negatively4 ,x w be %[n lat] 7section #agg7 t ! am\nt ( excit$ activity at any po9t is always proportional to ! am\nt ( emanation at t po9t4 ,! di/ribution ( 8excit$ activity0 along ! c5tral rod f ! plate ,c upw>ds ?us gives ! v>iation ( p = ! emanation along ! tube4 ,9 ! exp]im5ts1 ! cyl9d] 0 fill$ ) dry air at atmosph]ic pressure & 0 kept at a con/ant temp]ature4 ,! c5tral rod 0 *>g$ negatively & expos$ f "o to two days 9 ! pres5ce ( ! emanation4 ,! rod 0 !n remov$1 & ! di/ribution ( ! excit$ activity along x det]m9$ by ! electric me?od4 ,x 0 f\nd t ! am\nt ( excit$ activity fell (f ) ! di/ance x accord+ to an expon5tial law1 fall+ to half value 9 ab\t #ai cms4 ,?is is 9 agreem5t ) ! above !ory4 ,s9ce ! activity ( ! emanation falls to half value 9 #a m9ute1 #jaae4 ,! value ,k #ji 0 d$uc$ f ! av]age ( a numb] ( exp]im5ts4 ,?is is a slightly great] value ?an ,k #jg1 obta9$ = ! radium emanation1 b ! results %[ t ! two emanations d n diff] mu* f "o ano!r 9 molecul> weight4 ,mak[] 7loc4 cit47 comp>$ ! rates ( diffusion ( ! ?orium & radium emanation ?r\gh a por\s plate1 & conclud$ t ! two emanations 7 ( ab\t ! same molecul> weight1 ?us confirm+ ! results obta9$ by ! above me?od4 ,diffusion ( ! ,emanation into ,liquids4 #afd4 ,exp]im5ts h be5 made by ,wall/abe#bei on ! coeffici5t ( diffusion ( ! radium emanation into v>i\s liquids4 ,! radium emanation 0 all[$ to diffuse into a clos$ res]voir1 conta9+ a cyl9d] ( ! liquid "u obs]vation4 ,! cyl9d] 0 provid$ ) a tube & a /op-cock ext5d+ beyond ! clos$ vessel1 s t diff]5t lay]s ( ! liquid c\ld be remov$4 ,! liquid 0 !n plac$ 9 a clos$ te/+ vessel1 :]e ! ionization curr5t due to ! escape ( ! emanation f ! liquid 0 obs]v$ to rise to a maximum aft] sev]al h\rs1 & !n to decay4 ,?is maximum value ( ! curr5t 0 tak5 z a measure ( ! am\nt ( emanation absorb$ 9 ! liquid4 ,! coeffici5t ( diffusion ,k ( ! emanation into ! liquid c be obta9$ f ! same equation us$ to det]m9e ! diffusion ( ! ?orium emanation into air1 p p e-sqrt frac ,k x 4 :]e is ! con/ant ( decay ( activity ( ! radium emanation & x ! dep? ( ! lay] ( wat] f ! surface4 ,putt+ a sqrt frac ,k 1 x 0 f\nd t = wat] #af1 = toluol #ge4 ,! value ( express$ 9 t]ms ( a day z ! unit ( "t is ab\t #ag4 ,?us ! value ( ,k = ! diffusion ( ! radium emanation into wat] #jff cm4 _/ day4 ,! value ( ,k f\nd by ,/efan#bfj = ! diffusion ( c>bon dioxide into wat] 0 #acf cm4_/day4 ,^! results are ?us 9 h>mony ) ! conclusion drawn f ! diffusion ( ! radium emanation into air1 & %[ t ! radium emanation behaves z a gas ( high molecul> weight4 ,cond5sation ( ! ,emanations4 #afe4 ,cond5sation ( ! emanations4 ,dur+ an inve/igation ( ! effect ( physical & *emical ag5cies on ! ?orium emanation1 ,ru!r=d & ,soddy#bfa f\nd t ! emanation pass$ un*ang$ 9 am\nt ?r\gh a :ite-hot plat9um tube & ?r\gh a tube cool$ to ! temp]ature ( solid c>bon dioxide4 ,9 lat] exp]im5ts ! effects ( /ill l[] temp]atures 7 exam9$1 & x 0 !n f\nd t at ! temp]ature ( liquid air bo? emanations 7 cond5s$#bfb4 ,if ei!r emanation is convey$ by a sl[ /ream ( hydrog51 oxyg51 or air ?r\gh a metal spiral imm]s$ 9 liquid air1 & plac$ 9 connection ) a te/+ vessel z 9 ,fig4 #ea1 no trace ( emanation escapes 9 ! issu+ gas4 ,:5 ! liquid air is remov$ & ! spiral plung$ into cotton-wool1 sev]al m9utes elapse be=e any deflection ( ! electromet] ne$le is obs]v$1 & !n ! cond5s$ emanation volatilizes rapidly1 & ! movem5t ( ! electromet] ne$le is v sudd51 especially 9 ! case ( radium4 ,) a fairly l>ge am\nt ( radium emanation1 "u ! conditions m5tion$1 a v few seconds elapse aft] ! fir/ sign ( movem5t be=e ! electromet] ne$le indicates a deflection ( sev]al hundr$ divisions p] second4 ,x is n necess>y 9 ei!r case t ! emanat+ comp\nd %\ld be reta9$ 9 ! gas /ream4 ,aft] ! emanation is cond5s$ 9 ! spiral1 ! ?orium or radium comp\nd may be remov$ & ! gas /ream s5t directly into ! spiral4 ,b 9 ! case ( ?orium1 "u ^! conditions1 ! effects obs]v$ are naturally small ow+ to ! rapid loss ( ! activity ( ! emanation ) "t1 :i* proce$s at ! same rate at ! temp]ature ( liquid air z at ord9>y temp]atures4 ,if a l>ge am\nt ( radium emanation is cond5s$ 9 a glass ,u tube1 ! progress ( ! cond5sation c be foll[$ by ! eye1 by means ( ! phosphoresc5ce :i* ! radiations excite 9 ! glass4 ,if ! ends ( ! tube are seal$ & ! temp]ature all[$ to rise1 ! gl[ diffuses uni=mly ?r\gh\t ! tube1 & c be conc5trat$ at any po9t to "s ext5t by local cool+ ( ! tube ) liquid air4 #aff4 ,exp]im5tal arrangem5ts4 ,a simple exp]im5tal arrangem5t to illu/rate ! cond5sation & volatilization ( ! emanation & "s ( its *>act]i/ic prop]ties is %[n 9 ,fig4 #eh4 ,! emanation obta9$ f a few milligrams ( radium bromide by solution or heat+ is cond5s$ 9 ! glass ,u tube ,t imm]s$ 9 liquid air4 ,?is ,u tube is !n put into connection ) a l>g] glass tube ,v1 9 ! upp] "p ( :i* is plac$ a piece ( z9c sulphide scre5 ,z1 & 9 ! l[] "p ( ! tube a piece ( ! m9]al willemite4 ,! /op-cock ,a is clos$ & ! ,u tube & ! vessel ,v are p>tially exhau/$ by a pump ?r\gh ! /op-cock ,b4 ,?is l[]+ ( ! pressure causes a m rapid diffusion ( ! emanation :5 releas$4 ,! emanation does n escape if ! tube ,t is kept imm]s$ 9 liquid air4 ,! /op-cock ,b is !n clos$1 & ! liquid air remov$4 ,no lum9osity ( ! scre5 or ! willemite 9 ! tube ,v is obs]v$ = sev]al m9utes1 until ! temp]ature ( ,t rises above ! po9t ( volatilization ( ! emanation4 ,! emanation is !n rapidly c>ri$ into ! vessel ,v1 p>tly by expansion ( ! gas 9 ! tube ,t ) ris+ temp]ature1 & p>tly by ! process ( diffusion4 ,! scre5 ,z & ! willemite ,w are caus$ to phosphoresce brilliantly "u ! influ5ce ( ! rays f ! emanation surr\nd+ !m4 ,illu/ration3 ,fig4 #eh4 ,if ! end ( ! vessel ,v is !n plung$ into liquid air1 ! emanation is aga9 cond5s$ 9 ! l[] end ( ! tube1 & ! willemite phosphoresces mu* m brightly ?an be=e4 ,?is is n due to an increase ( ! phosphoresc5ce ( willemite at ! temp]ature ( ! liquid air1 b to ! effect ( ! rays f ! emanation cond5s$ ar\nd x4 ,at ! same "t ! lum9osity ( ! z9c sulphide gradually dim9i%es1 & practically disappe>s aft] sev]al h\rs if ! end ( ! tube is kept 9 ! liquid air4 ,if ! tube is remov$ f ! liquid air1 ! emanation aga9 volatilizes & lights up ! scre5 ,z4 ,! lum9osity ( ! willemite returns to its orig9al value aft] ! lapse ( sev]al h\rs4 ,?is sl[ *ange ( ! lum9osity ( ! z9c sulphide scre5 & ( ! willemite is due to ! gradual decay ( ! 8excit$ activity0 produc$ by ! emanation on ! surface ( all bodies expos$ to its action 7*apt] ,,viii74 ,! lum9osity ( ! scre5 is ?us due p>tly to ! radiation f ! emanation & p>tly to ! excit$ radiation caus$ by x4 ,z soon z ! emanation is remov$ f ! upp] to ! l[] "p ( ! tube1 ! 8excit$0 radiation gradually dim9i%es 9 ! upp] & increases 9 ! l[] "p ( ! tube4 ,! lum9osity ( ! scre5 gradually dim9i%es ) ! "t z ! enclos$ emanation loses its activity1 b is /ill appreciable aft] an int]val ( sev]al weeks4 ,an app>atus ( a simil> "* to illu/rate ! cond5sation ( ! radium emanation has be5 describ$ by ,p4 ,curie#bfc4 ,illu/ration3 ,fig4 #ei4 #afg4 ,det]m9ation ( ! temp]ature ( cond5sation4 ,a detail$ inve/igation 0 made by ,ru!r=d & ,soddy 7loc4 cit47 ( ! temp]atures at :i* cond5sation & volatilization comm5c$ = ! two emanations4 ,! exp]im5tal arrangem5t ( ! fir/ me?od is %[n cle>ly 9 ,fig4 #ei4 ,a sl[ con/ant /ream ( gas1 ent]+ at ,a1 0 pass$ ?r\gh a copp] spiral ,s1 ov] #c metres 9 l5g?1 imm]s$ 9 a ba? ( liquid e?yl5e4 ,! copp] spiral 0 made to act z its own !rmomet] by det]m9+ its electrical resi/ance4 ,! resi/ance temp]ature curve 0 obta9$ by obs]vation ( ! resi/ances at #j1 ! boil+ po9t ( liquid e?yl5e #ajce1 ! solidification po9t ( e?yl5e #afi & 9 liquid air4 ,! temp]ature ( ! liquid air 0 d$uc$ f ! tables giv5 by ,baly = ! boil+ po9t ( liquid air = diff]5t p]c5tages ( oxyg54 ,! resi/ance-temp]ature curve1 = ! p>ticul> spiral employ$1 0 f\nd to be ne>ly a /raight l9e betwe5 #j & #aib;,c41 cutt+ ! temp]ature axis if produc$ ne>ly at ! absolute z]o4 ,! resi/ance ( ! spiral1 d$uc$ f read+s on an accurately calibrat$ ,we/on millivoltmet]1 ) a con/ant curr5t ?r\gh ! spiral1 0 ?us v approximately proportional to ! absolute temp]ature4 ,! liquid e?yl5e 0 kept vigor\sly /irr$ by an electric motor1 & 0 cool$ to any desir$ temp]ature by surr\nd+ ! vessel ) liquid air4 ,! g5]al me?od employ$ = ! radium emanation 0 to pass a suitable am\nt ( emanation1 mix$ ) ! gas to be us$1 f ! gas hold] ,b into ! spiral1 cool$ bel[ ! temp]ature ( cond5sation4 ,aft] ! emanation 0 cond5s$ 9 ! spiral1 a curr5t ( electrolytic hydrog5 or oxyg5 0 pass$ ?r\gh ! spiral4 ,! temp]ature 0 all[$ to rise gradually1 & 0 not$ at ! in/ant :5 a deflection ( ! electromet]1 due to ! pres5ce ( emanation 9 ! te/+ vessel ,t1 0 obs]v$4 ,! resi/ance1 subject to a slight correction due to ! "t tak5 = ! emanation to be c>ri$ into ! te/+ vessel1 gave ! temp]ature at :i* "s ( ! emanation comm5c$ to volatilize4 ,! ionization curr5t 9 ! te/+ vessel rose rapidly to a maximum value1 %[+ t1 = a small increase ( temp]ature1 ! :ole ( ! radium emanation 0 volatiliz$4 ,! foll[+ table gives an illu/ration ( ! results obta9$ = a curr5t ( hydrog5 ( #ach cubic c5timetres p] second4 ,temp]ature ,divisions p] second ( ! electromet] #afj #j #aef #j #aedc #a #aech #ba #aebe #bd ,! foll[+ table %[s ! results obta9$ = diff]5t curr5ts ( hydrog5 & oxyg54 ,curr5t ( ,gas ,t ,t ,hydrog5 #be c4c4 p] sec4 #aeac #aej #cb #aecg #aea #ib #aeb #aea #ach #aed #aec #bc #afbe #afb ,oxyg5 #cd #aebe #aeae #eh #aee #aec ,! temp]ature ,t 9 ! above table gives ! temp]ature ( initial volatilization1 ,t ! temp]ature = :i* half ( ! cond5s$ emanation _h be5 releas$4 ,= sl[ curr5ts ( hydrog5 & oxyg51 ! values ( ,t & ,t are 9 good agreem5t4 ,= a /ream ( gas z rapid z #bc cubic c5timetres p] second ! value ( ,t is mu* l[]4 ,su* a result is to be expect$2 =1 9 too rapid a /ream1 ! gas is n cool$ to ! temp]ature ( ! spiral1 &1 9 consequ5ce1 ! inside surface ( ! spiral is above ! mean temp]ature1 & "s ( ! emanation escapes at a temp]ature app>5tly mu* l[]4 ,9 ! case ( oxyg51 ?is effect appe>s = a gas /ream ( #jeh cubic c5timetres p] second4 ,9 ! exp]im5ts on ! ?orium emanation1 on acc\nt ( ! rapid loss ( activity1 a slightly diff]5t me?od 0 necess>y4 ,! /eady /ream ( gas 0 pass$ ov] ! ?orium comp\nd1 & ! temp]ature 0 obs]v$ at ! in/ant :5 an appreciable movem5t ( ! electromet] appe>$4 ,?is gave ! temp]ature at :i* a small fraction ( ! ?orium emanation escap$ cond5sation1 & n ! value ,t obs]v$ = ! radium emanation1 :i* gave ! temp]ature = :i* a small fraction ( ! previ\sly cond5s$ emanation 0 volatiliz$4 ,! foll[+ table illu/rates ! results obta9$4 ,curr5t ( ,gas ,temp]ature ,hydrog5 #ga c4c4 p] #aee ,c4 sec4 #ach #aei ,c4 ,oxyg5 #eh #aee ,c4 ,on comp>+ ^! results ) ! values obta9$ = ! radium emanation1 x w be obs]v$ t ) equal gas /reams ! temp]atures are ne>ly ! same4 ,a clos] exam9ation ( ! ?orium emanation %[$1 h[ev]1 t ?is app>5t agreem5t 0 only accid5tal1 & t !re 01 9 reality1 a v m>k$ diff]5ce 9 ! effect ( temp]ature on ! two emanations4 ,x 0 f\nd exp]im5tally t ! radium emanation 0 cond5s$ v ne> ! temp]ature at :i* volatilization comm5c$1 & t ! po9ts ( cond5sation & volatilization 7 def9$ fairly %>ply4 ,illu/ration3 ,fig4 #fj4 ,on ! o!r h&1 ! ?orium emanation requir$ a range ( ov] #cj ,c4 aft] cond5sation _h />t$ 9 ord] to ensure complete cond5sation4 ,fig4 #fj is an example ( ! results obta9$ ) a /eady gas /ream ( #ach c4c4 p] sec4 ( oxyg54 ,! ord9ates repres5t ! p]c5tage proportion ( ! emanation uncond5s$ at diff]5t temp]atures4 ,x w be obs]v$ t cond5sation comm5ces ab\t #abj1 & t v little ( ! emanation escapes cond5sation at #aee ,c4 ,to inve/igate ?is diff]5ce ( behavi\r 9 ! two emanations1 a /atic me?od 0 employ$1 :i* all[$ an exam9ation ( ! two emanations to be made "u comp>able conditions4 ,! emanation1 mix$ ) a small am\nt ( ! gas to be us$1 0 introduc$ into ! cool spiral1 :i* _h be5 exhau/$ previ\sly by means ( a m]cury pump4 ,! am\nt ( emanation rema9+ uncond5s$ aft] def9ite int]vals 0 rapidly remov$ by means ( ! pump1 & 0 c>ri$ ) a con/ant auxili>y /ream ( gas into ! te/+ vessel4 ,te/$ 9 ?is way1 x 0 f\nd t ! volatilization po9t ( ! radium emanation 0 v ne>ly ! same z t obta9$ by ! bl[+ me?od1 viz4 #aej ,c4 ,) ?orium1 on ! o!r h&1 ! cond5sation />t$ at ab\t #abj ,c41 &1 z 9 ! bl[+ me?od1 cont9u$ ov] a range ( ab\t #cj ,c4 ,! proportion ( ! emanation cond5s$ at any temp]ature 0 f\nd to dep5d on a v>iety ( conditions1 al?\gh ! po9t at :i* cond5sation comm5c$1 viz4 #abj ,c41 0 ab\t ! same 9 ea* case4 ,x dep5d$ on ! pressure & nature ( ! gas1 on ! conc5tration ( ! emanation1 & on ! "t = :i* x 0 left 9 ! spiral4 ,= a giv5 temp]ature a great] proportion ( ! emanation 0 cond5s$1 ! l[] ! pressure & ! long] ! "t x 0 left 9 ! spiral4 ,"u ! same conditions1 ! emanation 0 cond5s$ m rapidly 9 hydrog5 ?an 9 oxyg54 #afh4 ,?us !re is no d\bt t ! ?orium emanation beg9s to cond5se at a temp]ature high] ?an t at :i* ! radium emanation cond5ses4 ,! explanation ( ! peculi> behavi\r ( ! ?orium emanation is cle> :5 ! small numb] ( emanation p>ticles pres5t 9 ! gas are tak5 into consid]ation4 ,x has be5 %[n t bo? emanations give out only rays4 ,x is probable t ! p>ticles f ! two emanations are simil> 9 "* & produce ab\t ! same numb] ( ions 9 _! passage ?r\gh ! gas4 ,! numb] ( ions produc$ by ea* p>ticle be=e its en]gy is dissipat$ is probably ab\t #gj1jjj4 7,see section #beb47 ,n[1 9 ! exp]im5t1 ! electromet] readily measur$ a curr5t ( #aj electro/atic units4 ,tak+ ! *>ge on an ion z #cd #aj electro/atic units1 ?is corresponds to a production 9 ! te/+ vessel ( ab\t #c #aj ions p] sec41 :i* w\ld be produc$ by ab\t #dj expell$ p>ticles p] second4 ,ea* radiat+ p>ticle _c expel less ?an "o p>ticle & may expel m1 b x is likely t ! numb] expell$ by an atom ( ! ?orium emanation is n greatly diff]5t f t expell$ by an atom ( ! radium emanation4 ,9 section #acc x has be5 %[n t1 accord+ to ! law ( decay1 ,n p>ticles *ange p] second :5 ,n are pres5t4 ,?us1 to produce #dj p>ticles1 ,n _c be great] ?an #dj4 ,s9ce = ! ?orium emanation is 1 x foll[s t ,n _c be great] ?an #cejj4 ,! electromet] ?us detect$ ! pres5ce ( #cejj p>ticles ( ! ?orium emanation1 & s9ce 9 ! /atic me?od ! volume ( ! cond5s+ spiral 0 ab\t #ae c4c41 ?is correspond$ to a conc5tration ( ab\t #bcj p>ticles p] c4c4 ,an ord9>y gas at atmosph]ic pressure & temp]ature probably conta9s ab\t #cf #aj molecules p] c4c4 ,?us ! emanation w\ld h be5 detect$ on ! spiral if x _h possess$ a p>tial pressure ( less ?an #aj ( an atmosph]e4 ,x is n surpris+ !n t ! cond5sation po9t ( ! ?orium emanation is n %>ply def9$4 ,x is r a matt] ( rem>k t cond5sation %\ld occur s readily ) s sp>se a di/ribution ( emanation p>ticles 9 ! gas2 =1 9 ord] t cond5sation may take place1 x is probable t ! p>ticles mu/ approa* )9 "o ano!r's sph]e ( influ5ce4 ,n[ 9 ! case ( ! radium emanation1 ! rate ( decay is ab\t #ejjj times sl[] ?an t ( ! ?orium emanation1 & consequ5tly ! actual numb] ( p>ticles t mu/ be pres5t to produce ! same ionization p] second 9 ! two cases mu/ be ab\t #ejjj times great] 9 ! case ( radium ?an 9 ! case ( ?orium4 ,?is conclusion involves only ! assumption t ! same numb] ( rays is produc$ by a p>ticle ( emanation 9 ea* case1 & t ! expell$ p>ticles produce 9 _! passage ?r\gh ! gas ! same numb] ( ions4 ,! numb] ( p>ticles pres5t1 9 ord] to be detect$ by ! electromet]1 9 ?is exp]im5t1 mu/ !re=e h be5 ab\t #ejjj #cejj1 i4e4 ab\t #b #aj4 ,! diff]5ce ( behavi\r 9 ! two cases is well expla9$ by ! view t1 = equal electrical effects1 ! numb] ( radium emanation p>ticles mu/ be f> l>g] ?an ! numb] ( ?orium emanation p>ticles4 ,! probability ( ! p>ticles com+ into ea* o!r's sph]e ( influ5ce w increase v rapidly z ! conc5tration ( ! p>ticles increases1 &1 9 ! case ( ! radium emanation1 once ! temp]ature ( cond5sation is atta9$1 all b a small proportion ( ! total numb] ( p>ticles pres5t w cond5se 9 a v %ort "t4 ,9 ! case ( ! ?orium emanation1 h[ev]1 ! temp]ature might be f> bel[ t ( cond5sation1 & yet a consid]able portion rema9 uncond5s$ = comp>atively long int]vals4 ,on ?is view ! exp]im5tal results obta9$ might reasonably be expect$4 ,a great] proportion ( emanation cond5ses ! long] ! "t all[$ = cond5sation "u ! same conditions4 ,! cond5sation occurs m rapidly 9 hydrog5 ?an 9 oxyg51 z ! diffusion is great] 9 ! =m] gas4 ,= ! same reason ! cond5sation occurs fa/] ! l[] ! pressure ( ! gas pres5t4 ,f9ally1 :5 ! emanation is c>ri$ by a /eady /ream ( gas1 a small] proportion cond5ses ?an 9 ! o!r cases1 because ! conc5tration ( emanation p>ticles p] unit volume ( gas is less "u ^! conditions4 ,x is possible t ! cond5sation ( ! emanations may n occur 9 ! gas itself b at ! surface ( ! conta9+ vessel4 ,accurate obs]vations ( ! temp]ature ( cond5sation h s f> only be5 made 9 a copp] spiral1 b cond5sation c]ta9ly occurs 9 tubes ( lead or glass at ab\t ! same temp]ature z 9 tubes ( copp]4 #afi4 ,9 exp]im5ts t 7 made by ! /atic me?od ) a v l>ge quantity ( radium emanation1 a slight am\nt ( escape ( ! cond5s$ emanation 0 obs]v$ sev]al degrees bel[ ! temp]ature at :i* mo/ ( ! emanation 0 releas$4 ,?is is to be expect$1 s9ce1 "u su* conditions1 ! electromet] is able to detect a v m9ute proportion ( ! :ole quantity ( ! emanation cond5s$4 ,special exp]im5ts1 ) a l>ge quantity ( emanation1 t 7 made ) ! spiral imm]s$ 9 a ba? ( rapidly boil+ nitric oxide1 %[$ ?is effect v cle>ly4 ,= example1 ! cond5s$ emanation began to volatilize at #aee ,c4 ,9 #d m9utes ! temp]ature _h ris5 to #aece1 & ! am\nt volatiliz$ 0 f\r times z great z at #aee4 ,9 ! next #e m9utes ! temp]ature _h increas$ to #aebc & practically ! :ole quantity1 :i* 0 at lea/ fifty times ! am\nt at ! temp]ature ( #aece1 _h volatiliz$4 ,x ?us seems probable t1 if ! temp]ature 7 kept /eady at ! po9t at :i* volatilization 0 fir/ obs]v$1 & ! releas$ emanation remov$ at int]vals1 ! :ole ( ! emanation w\ld 9 c\rse ( "t be lib]at$ at t temp]ature4 ,curie & ,dew> & ,ramsay h obs]v$ t ! emanation cond5s$ 9 a ,u tube1 imm]s$ 9 liquid air1 sl[ly escapes if ! pump is kept /eadily work+4 ,^! results po9t to ! probability t ! cond5s$ emanation possesses a true vap\r pressure1 b great ref9em5ts 9 exp]im5tal me?ods w\ld be necess>y be=e su* a conclusion c\ld be def9itely e/abli%$4 ,! true temp]ature ( cond5sation ( ! ?orium emanation is probably ab\t #abj ,c41 & t ( radium ab\t #aej ,c4 ,?us !re is no d\bt t ! two emanations are q di/9ct f ea* o!r 9 ?is respect1 & also ) reg>d to _! radio-activity1 al?\gh !y bo? possess ! prop]ty ( *emical in]tness4 ,^! results on ! temp]atures ( cond5sation d n all[ u to make any comp>ison ( ! cond5sation po9ts ( ! emanations ) ^? ( kn[n gases1 s9ce ! l[]+ ( ! cond5sation po9ts ( gases ) dim9ution ( pressure has n be5 /udi$ at su* extremely m9ute pressures4 #agj4 ,x has be5 f\nd#bfd t ! activity ( ! ?orium emanation1 :5 cond5s$ 9 ! spiral at ! temp]ature ( liquid air1 decay$ at ! same rate z at ord9>y temp]atures4 ,?is is 9 accord ) results ( a simil> k9d obta9$ by ,p4 ,curie = ! radium emanation 7section #ade71 & %[s t ! value ( ! radio-active con/ant is unaffect$ by wide v>iations ( temp]ature4 ,am\nt ( ,emanation f ,radium & ,?orium4 #aga4 ,x has be5 %[n 9 section #ic f exp]im5tal data t #a gram ( radium bromide at its m9imum activity emits ab\t #cf #aj p>ticles p] second4 ,s9ce ! activity due to ! emanation /or$ up 9 radium1 :5 9 a /ate ( radio-active equilibrium1 is ab\t "o qu>t] ( ! :ole & ab\t equal to ! m9imum activity1 ! numb] ( p>ticles project$ p] second by ! emanation f #a gram ( radium bromide is ab\t #cf #aj4 ,x has be5 %[n 9 section #aeb t #dfc1jjj times ! am\nt ( emanation produc$ p] second is /or$ up 9 ! radium4 ,b1 9 a /ate ( radio-active equilibrium1 ! numb] ( emanation p>ticles break+ up p] second is equal to ! numb] produc$ p] second4 ,assum+ t ea* emanation p>ticle 9 break+ up expels "o p>ticle1 x foll[s t ! numb] ( emanation p>ticles pres5t 9 #a gram ( radium bromide 9 radio-active equilibrium is #dfc1jjj #cf #aj1 i4e4 #ag #aj4 ,tak+ ! numb] ( hydrog5 molecules 9 #a c4c4 ( gas at atmosph]ic pressure & temp]ature z #cf #aj 7section #ci71 ! volume ( ! emanation f #a gram ( radium bromide is #df #aj cubic c5timetres at atmosph]ic pressure & temp]ature4 ,assum+ ! composition ( radium bromide z ,ra,br1 ! am\nt f #a gram ( radium 9 radio-active equilibrium is #jhb cubic millimetres4 ,q indep5d5tly ( any me?od ( calculation x 0 e>ly evid5t t ! volume ( ! emanation 0 v small1 = all ! e>li] attempts made to detect its pres5ce by its volume 7 unsuccessful4 ,x w be se51 h[ev]1 t1 :5 l>g] quantities ( radium 7 available = exp]im5t1 ! emanation has be5 collect$ 9 volume suffici5tly l>ge to measure4 ,9 ! case ( ?orium1 ! maximum quantity ( emanation to be obta9$ f #a gram ( ! solid is v m9ute1 bo? on acc\nt ( ! small activity ( ?orium & ( ! rapid break up ( ! emanation aft] its production4 ,s9ce ! am\nt ( emanation1 /or$ 9 a non-emanat+ ?orium comp\nd1 is only #hg times ! rate ( production1 :ile 9 radium x is #dfc1jjj times1 & ! rate ( production ( ! emanation by radium is ab\t #a million times fa/] ?an by ?orium1 x foll[s t ! am\nt ( emanation to be obta9$ f #a gram ( ?orium is n great] ?an #aj ( ! am\nt f an equal weight ( radium1 i4e4 its volume is n great] ?an #aj c4c4 at ! ord9>y pressure & temp]ature4 ,ev5 ) l>ge quantities ( ?orium1 ! am\nt ( emanation is too small ev] to be detect$ by its volume4 #agb4 ,volume ( ! emanation f radium4 ,! evid5ce already consid]$ po9ts v /rongly to ! conclusion t ! emanation possesses all ! prop]ties ( a *emically in]t gas ( high molecul> weight4 ,s9ce ! emanation cont9u\sly breaks up1 & is trans=m$ into a solid type ( matt]1 :i* is deposit$ on ! surface ( bodies1 ! volume ( ! emanation1 :5 sep>at$ f radium1 %\ld contract at ! same rate z x loses its activity1 i4e4 x %\ld decrease to half value 9 ab\t f\r days4 ,! am\nt ( emanation to be obta9$ f a giv5 quantity ( radium is a maximum :5 ! rate ( production ( new emanation balances its rate ( *ange4 ,?is condition is practically atta9$ :5 ! emanation has be5 all[$ to collect = an int]val ( "o mon?4 ,! probable volume ( ! emanation to be obta9$ f #a gram ( radium 0 e>ly calculat$ on c]ta9 assumptions1 & f data !n available ! writ]#bfe d$uc$ t ! volume ( ! emanation f #a gram ( radium lay betwe5 #jf & #f cubic millimetre at atmosph]ic pressure & temp]ature1 & 0 probably ne>] ! latt] value4 ,! volume to be expect$ on ! late/ data has be5 discuss$ 9 ! prec$+ section & %[n to be ab\t #hb cubic mm4 ,! volume ( ! emanation is ?us v small1 b n too small to be detect$ if sev]al c5tigrams ( radium are available4 ,?is has be5 prov$ to be ! case by ,ramsay & ,soddy#bff :o1 by v c>eful exp]im5t1 f9ally succe$$ 9 isolat+ a small quantity ( ! emanation & 9 det]m9+ its volume4 ,! exp]im5tal me?od employ$ by !m w n[ be briefly describ$4 ,illu/ration3 ,fig4 #fa4 ,! emanation f #fj milligrams ( radium bromide 9 solution 0 all[$ to collect = #h days & !n drawn (f ?r\gh ! inv]t$ siphon ,e 7,fig4 #fa7 into ! explosion burette ,f4 ,?is gas consi/$ = ! mo/ "p ( hydrog5 & oxyg51 produc$ by ! action ( ! radiations on ! wat] ( ! solution4 ,aft] explosion1 ! excess ( hydrog5 mix$ ) emanation 0 left "s "t 9 contact ) cau/ic soda1 plac$ 9 ! upp] "p ( ! burette1 9 ord] to remove all trace ( c>bon dioxide4 ,9 ! meantime ! upp] "p ( ! app>atus _h be5 completely evacuat$4 ,! connection ,c to ! pump 0 clos$1 & ! hydrog5 & emanation 7 all[$ to ent] ! app>atus1 pass+ ov] a phosphor\s p5toxide tube ,d4 ,! emanation 0 cond5s$ 9 ! l[] "p ( ! capill>y tube ,a1 by surr\nd+ x ) ! tube ,b fill$ ) liquid air4 ,! process ( cond5sation 0 r5d]$ manife/ by ! brilliant lum9osity ( ! l[] "p ( ! tube4 ,! m]cury f ! burette 0 !n all[$ to run to ,g1 & ! app>atus aga9 completely evacuat$4 ,! connection ( ! pump 0 aga9 clos$1 ! liquid air 0 remov$ & ! volatiliz$ emanation =c$ into ! f9e capill>y tube ,a4 ,obs]vations 7 !n made1 f day to day1 ( ! volume ( ! emanation4 ,! results are giv5 9 ! table bel[4 ,"t ,volume ,"t ,volume ,/>t #jabd cub4 #g days #jjjej cub4 mm4 mm4 #a day #jjbg #i #jjjda #c #jjaa #aa #jjjbj #d #jjjie #ab #jjjaa #f #jjjfc #bh #jjjjd ,! volume contract$ ) ! "t1 & 0 v small aft] a mon?'s int]val1 b ! m9ute bubble ( ! emanation /ill reta9$ its lum9osity to ! la/4 ,! tube became deep purple 9 col\r1 :i* r5d]$ read+s difficult except ) a /rong light4 ,!re 0 a sudd5 decrease 9 ! fir/ day1 :i* may h be5 due to ! m]cury /ick+ 9 ! capill>y tube4 ,! exp]im5ts 7 repeat$ ) ano!r capill>y tube & ! volume ( gas obs]v$ at normal pressure 0 #jjbed c4 mm4 ,! gas obta9$ 0 f\nd to obey ,boyle's law )9 ! limit ( exp]im5tal error ov] a consid]able range ( pressure4 ,b1 unlike 9 ! fir/ exp]im5t1 ! gas did n contract b exp&$ rapidly dur+ ! fir/ few h\rs1 & !n m sl[ly1 f9ally rea*+ a volume aft] #bc days ( #jbfb c4 mm4 or ab\t #aj times ! initial volume4 ,! measurem5ts 7 complicat$ by ! appe>ance ( bubbles ( gas 9 ! top ( ! m]cury column4 ,! diff]5ces obs]v$ 9 ^! two exp]im5ts are difficult to acc\nt =4 ,we %all see1 lat]1 t ! emanation always produces helium1 &1 9 ! fir/ exp]im5t1 ! decrease ( ! volume to z]o indicates t ! helium 0 buri$ or absorb$ 9 ! walls ( ! tube4 ,9 ! second case1 probably ow+ to "s diff]5ce 9 ! glass ( ! capill>y tube1 ! helium may h be5 releas$4 ,?is sugge/ion is confirm$ by ! obs]vation t ! volume ( gas1 aft] ! exp]im5t end$1 gave a brilliant spectrum ( helium4 ,we %all see lat] t !re is consid]able evid5ce t ! p>ticles expell$ f radio-active sub/ances consi/ ( helium atoms4 ,s9ce ! p>ticles are project$ ) great velocity1 !y w fir/ be buri$ 9 ! walls ( ! tube1 & !n may gradually diffuse out into ! gas aga9 "u conditions probably dep5d+ on ! k9d ( glass employ$4 ,s9ce p>ticles are project$ f ! emanation & also f two ( ! rapidly *ang+ products :i* arise f x1 ! volume ( helium %\ld1 on ?is view1 be ?ree times ! initial volume ( ! emanation4 ,if ! helium produc$ escap$ f ! walls ( ! tube into ! gas1 ! app>5t volume ( ! gas 9 ! capill>y %\ld increase to ?ree times ! initial volume 9 a mon?'s int]val1 = dur+ t "t ! emanation itself has be5 trans=m$ into a solid type ( matt] deposit$ on ! walls ( ! tube4 ,ramsay & ,soddy conclud$ f _! exp]im5ts t ! maximum volume ( emanation to be obta9$ f #a gram ( radium 0 ab\t #a cubic millimetre at /&>d pressure & temp]ature1 & t ! emanation 0 produc$ f #a gram ( radium at ! rate ( #c #aj c4 mm4 p] second4 ,?is am\nt is 9 v good agreem5t ) ! calculat$ value1 & is a /rong indication ( ! g5]al correctness ( ! !ory on :i* ! calculations are bas$4 #agc4 ,spectrum ( ! emanation4 ,aft] ! sep>ation ( ! emanation & ! det]m9ation ( its volume1 ,ramsay & ,soddy made num]\s attempts to obta9 its spectrum4 ,9 "s ( ! e>li] exp]im5ts sev]al bright l9es 7 se5 = a %ort "t1 b ^! l9es 7 soon mask$ by ! appe>ance ( ! hydrog5 l9es4 ,9 lat] exp]im5ts ,ramsay & ,collie#bfg succe$$ 9 obta9+ a spectrum ( ! emanation1 :i* p]si/$ = a %ort "t1 dur+ :i* a rapid det]m9ation ( ! wave-l5g?s 0 made4 ,!y /ate t ! spectrum 0 v brilliant1 consi/+ ( v bright l9es1 ! spaces betwe5 be+ p]fectly d>k4 ,! spectrum bore a /rik+ resemblance 9 g5]al "* to ! spectrum ( ! gases ( ! argon family4 ,! spectrum soon fad$1 & ! spectrum ( hydrog5 began to appe>4 ,! foll[+ table %[s ! wave-l5g? ( ! l9es obs]v$ 9 ! spectrum4 ,! degree ( co9cid5ce ( ! l9es ( kn[n wave-l5g?s %[s t ! error is probably less ?an five ng/rm units4 ,wave-l5g? ,rem>ks #fefg ,hydrog5 ,c2 true wave-l5g?1 #fefc2 obs]v$ ea* "t4 #fcjg ,obs]v$ only at fir/2 evanesc5t4 #eige #eiee #ehje ,obs]v$ ea* "t2 p]si/5t4 #egij ,m]cury2 true wave-l5g?1 #egij4 #egfh #egfi4 #egbe ,obs]v$ only at fir/2 evanesc5t4 #eeie ,obs]v$ ea* "t2 p]si/5t & /rong4 #edfe ,m]cury2 true wave-l5g?1 #edfa4 #eaje ,n obs]v$ at fir/2 appe>$ aft] "s seconds2 p]si/$ & 0 visible dur+ ! second exam9ation4 #dihe ,obs]v$ ea* "t2 p]si/5t & /rong4 #dhfe ,hydrog5 ,f2 true wave-l5g?1 #dhfa4 #dfij ,obs]v$ only at fir/4 #dfej ,n obs]v$ :5 ! emanation 0 exam9$ aga94 #dfcj #dcfj ,m]cury3 true wave-l5g?1 #dcei4 ,! exp]im5ts 7 repeat$ ) a new supply ( emanation1 & "s ( ! /rong] l9es 7 obs]v$ aga91 :ile "s new l9es made _! appe>ance4 ,ramsay & ,collie sugge/ t ! /rong l9e #eeie may be id5tical ) a l9e :i* 0 obs]v$ by ,pick]+#bfh 9 ! spectrum ( lightn+1 & 0 n id5tifi$ ) ! spectrum ( any kn[n gas4 ,until l>ge quantities ( radium are available = ! exp]im5t] x w\ld appe> difficult to make sure h[ _m ( ^! l9es mu/ be ascrib$ to ! spectrum ( ! emanation or to measure ! wave-l5g?s ) accuracy4 ,! results are ( great int]e/1 z %[+ t ! emanation has a def9ite & new spectrum ( ! same g5]al "* z ! argon gr\p ( gases to :i*1 z we h se51 x is *emically alli$4 ,summ>y ( ,results4 #agd4 ,! inve/igations into ! nature ( ! radio-active emanations h ?us l$ to ! foll[+ conclusions3--,! radio-elem5ts ?orium1 radium & act9ium cont9u\sly produce f !mselves radio-active emanations at a rate :i* is con/ant "u all conditions4 ,9 "s cases1 ! emanations cont9u\sly diffuse f ! radio-active comp\nds into ! surr\nd+ gas2 9 o!r cases1 ! emanations are unable to escape f ! mat]ial 9 :i* !y are produc$1 b are occlud$1 & c only be releas$ by solution or by ! action ( heat4 ,! emanations possess all ! prop]ties ( radio-active gases4 ,!y diffuse ?r\gh gases1 liquids1 & por\s sub/ances1 & c be occlud$ 9 "s solids4 ,"u v>y+ conditions ( pressure1 volume1 & temp]ature1 ! emanations di/ribute !mselves 9 ! same way & accord+ to ! same laws z does a gas4 ,! emanations possess ! important prop]ty ( cond5sation "u ! influ5ce ( extreme cold1 & by t means c be sep>at$ f ! gases ) :i* !y are mix$4 ,! radiation f ! emanation is mat]ial 9 nature1 & consi/s ( a /ream ( positively *>g$ p>ticles project$ ) great velocity4 ,! emanations possess ! prop]ty ( *emical in]tness1 & 9 ?is respect resemble ! gases ( ! argon family4 ,! emanations are produc$ 9 m9ute am\nt2 b a suffici5t quantity ( ! radium emanation has be5 obta9$ to det]m9e its volume & its spectrum4 ,) reg>d to _! rates ( diffusion1 ! emanations ( bo? ?orium & radium behave l gases ( high molecul> weight4 ,^! emanations h be5 detect$ & _! prop]ties inve/igat$ by ! prop]ty !y possess ( emitt+ radiations ( a special "*4 ,^! radiations consi/ entirely ( rays1 i4e4 p>ticles1 project$ ) great velocity1 :i* c>ry a positive *>ge & h a mass ab\t twice t ( ! hydrog5 atom4 ,! emanations d n possess ! prop]ty ( p]man5tly radiat+1 b ! int5sity ( ! radiations dim9i%es accord+ to an expon5tial law ) ! "t1 fall+ to half value1 f act9ium 9 #d seconds1 f ?orium 9 "o m9ute1 & f radium 9 ab\t f\r days4 ,! law ( decay ( activity does n seem to be influ5c$ by any physical or *emical ag5cy4 ,! emanation p>ticles gradually break up1 ea* p>ticle z x breaks up expell+ a *>g$ body4 ,! emanation aft] x has radiat$ ceases to exi/ z su*1 b is trans=m$ into a new k9d ( matt]1 :i* is deposit$ on ! surface ( bodies & gives rise to ! ph5om5a ( excit$ activity4 ,?is la/ prop]ty1 & ! connection ( ! emanation ) x1 are discuss$ 9 detail 9 ! next *apt]4 ,footnote #bca3 ,ow5s1 ,phil4 ,mag4 p4 #cfj1 ,oct4 #ahii4 ,footnote #bcb3 ,ru!r=d1 ,phil4 ,mag4 p4 #a1 ,jan4 #aijj4 ,footnote #bcc3 ,rossignol & ,gim+ham1 ,phil4 ,mag4 ,july1 #aijd4 ,footnote #bcd3 ,bronson1 ,am]4 ,j\rn4 ,sci5ce1 ,feb4 #aije4 ,footnote #bce3 ,phil4 ,mag4 ,april1 #aijd4 ,footnote #bcf3 ,dorn1 ,abh4 d]4 ,natur=s*4 ,ges4 fr ,halle-a-,s41 #aijj4 ,footnote #bcg3 ,p4 ,curie1 ,c4 ,r4 #ace1 p4 #heg1 #aijb4 ,footnote #bch3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #bci3 ,p4 ,curie1 ,c4 ,r4 #acf1 p4 #bbc1 #aijc4 ,footnote #bdj3 ,debi]ne1 ,c4 ,r4 #acf1 p4 #adf1 #aijc4 ,footnote #bda3 ,giesel1 ,b]4 ,d4 deuts*4 ,*em4 ,ges4 p4 #cfjh1 #aijb4 ,footnote #bdb3 ,curie & ,debi]ne1 ,c4 ,r4 #acb1 pp4 #edh & #gfh1 #aija4 ,footnote #bdc3 ,curie & ,debi]ne1 ,c4 ,r4 #acc1 p4 #ica1 #aija4 ,footnote #bdd3 ,ru!r=d & ,soddy1 ,trans4 ,*em4 ,soc4 p4 #cba1 #aijb4 ,phil4 ,mag4 ,sept4 #aijb4 ,footnote #bde3 ,ru!r=d1 ,phys4 ,zeit4 #b1 p4 #dbi1 #aija4 ,footnote #bdf3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,nov4 #aijb4 ,footnote #bdg3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #bdh3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,nov4 #aijb4 ,footnote #bdi3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #bej3 ,curie & ,debi]ne1 ,c4 ,r4 #acc1 p4 #ica1 #aija4 ,footnote #bea3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,nov4 #aijb4 ,footnote #beb3 ,ramsay & ,soddy1 ,proc4 ,roy4 ,soc4 #gb1 p4 #bjd1 #aijc4 ,footnote #bec3 ,ru!r=d & ,miss ,brooks1 ,trans4 ,roy4 ,soc4 ,canada #aija1 ,*em4 ,news #aijb4 ,footnote #bed3 ,los*midt1 ,sitzungsb]4 d4 ,wi54 ,akad4 #fa1 ,,ii4 p4 #cfg1 #ahga4 ,footnote #bee3 ,see ,/efan1 ,sitzungsb]4 d4 ,wi54 ,akad4 #fc1 ,,ii4 p4 #hb1 #ahga4 ,footnote #bef3 ,p4 ,curie & ,danne1 ,c4 ,r4 #acf1 p4 #acad1 #aijc4 ,footnote #beg3 ,bum/ead & ,:eel]1 ,am]4 ,j\r4 ,sci5ce1 ,feb4 #aijd4 ,footnote #beh3 ,mak[]1 ,phil4 ,mag4 ,jan4 #aije4 ,footnote #bei3 ,wall/abe1 ,phys4 ,zeit4 #d1 p4 #gba1 #aijc4 ,footnote #bfj3 ,/efan1 ,wi54 ,b]4 #b1 p4 #cga1 #ahgh4 ,footnote #bfa3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,nov4 #aijb4 ,footnote #bfb3 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #bfc3 ,p4 ,curie1 ,socit de ,physique1 #aijc4 ,footnote #bfd3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #bfe3 ,nature1 ,aug4 #bj1 #aijc4 ,footnote #bff3 ,proc4 ,roy4 ,soc4 #gc1 ,no4 #did1 p4 #cdf1 #aijd4 ,footnote #bfg3 ,proc4 ,roy4 ,soc4 #gc1 ,no4 #die1 p4 #dgj1 #aijd4 ,footnote #bfh3 ,pick]+1 ,a/rophys4 ,j\rn4 ,vol4 #ad1 p4 #cfh1 #aija4 ,,*apt] ,,viii4 ,,excit$ ,,radio-,,activity4 #age4 ,excit$ radio-activity4 ,"o ( ! mo/ int]e/+ & rem>kable prop]ties ( ?orium1 radium1 & act9ium1 is _! p[] ( 8excit+0 or 8induc+0 tempor>y activity on all bodies 9 _! neighb\rhood4 ,a sub/ance :i* has be5 expos$ = "s "t 9 ! pres5ce ( radium or ?orium behaves z if its surface 7 cov]$ ) an invisible deposit ( int5sely radio-active mat]ial4 ,! 8excit$0 body emits radiations capable ( affect+ a photographic plate & ( ioniz+ a gas4 ,unlike ! radio-elem5ts !mselves1 h[ev]1 ! activity ( ! body does n rema9 con/ant aft] x has be5 remov$ f ! influ5ce ( ! excit+ active mat]ial1 b decays ) ! "t4 ,! activity la/s = sev]al h\rs :5 due to radium & sev]al days :5 due to ?orium4 ,?is prop]ty 0 fir/ obs]v$ by ,m4 & ,mme4 ,curie#bfi = radium1 & indep5d5tly by ! writ]#bgj = ?orium#bga4 ,if any solid body is plac$ inside a clos$ vessel conta9+ an emanat+ comp\nd ( ?orium or radium1 its surface becomes radio-active4 ,= ?orium comp\nds ! am\nt ( excit$ activity on a body is 9 g5]al great] ! ne>] x is to ! active mat]ial4 ,9 ! case ( radium1 h[ev]1 provid$ ! body has be5 expos$ = sev]al h\rs1 ! am\nt ( excit$ activity is to a l>ge ext5t indep5d5t ( ! position ( ! body 9 ! vessel conta9+ ! active mat]ial4 ,bodies are made active :e!r expos$ directly to ! action ( ! radio-active sub/ance or scre5$ f ! action ( ! direct rays4 ,?is has be5 cle>ly %[n 9 "s exp]im5ts ( ,p4 ,curie4 ,a small op5 vessel a 7,fig4 #fb7 conta9+ a solution ( radium is plac$ inside a l>g] clos$ vessel ,v4 ,illu/ration3 ,fig4 #fb4 ,plates ,a1 ,b1 ,c1 ,d1 ,e are plac$ 9 v>i\s positions 9 ! enclosure4 ,aft] exposure = a day1 ! plates aft] removal are f\nd to be radio-active ev5 9 positions completely %ield$ f ! action ( ! direct rays4 ,= example1 ! plate ,d %ield$ f ! direct radiation by ! lead plate ,p is z active z ! plate ,e1 expos$ to ! direct radiation4 ,! am\nt ( activity produc$ 9 a giv5 "t on a plate ( giv5 area 9 a def9ite position is indep5d5t ( ! mat]ial ( ! plate4 ,plates ( mica1 copp]1 c>dbo>d1 ebonite1 all %[ equal am\nts ( activity4 ,! am\nt ( activity dep5ds on ! area ( ! plate & on ! am\nt ( free space 9 its neighb\rhood4 ,excit$ radio-activity is also produc$ 9 wat] if expos$ to ! action ( an emanat+ comp\nd4 #agf4 ,conc5tration ( excit$ radio-activity on ! negative electrode4 ,:5 ?orium or radium is plac$ 9 a clos$ vessel1 ! :ole int]ior surface becomes /rongly active4 ,9 a /rong electric field1 on ! o!r h&1 ! writ] f\nd t ! activity 0 conf9$ entirely to ! negative electrode4 ,by suitable arrangem5ts1 ! :ole ( ! excit$ activity1 :i* 0 previ\sly di/ribut$ ov] ! surface ( ! vessel1 c be conc5trat$ on a small negative electrode plac$ inside ! vessel4 ,an exp]im5tal arrangem5t = ?is purpose is %[n 9 ,fig4 #fc4 ,illu/ration3 ,fig4 #fc4 ,! metal vessel ,v conta9+ a l>ge am\nt ( ?oria is connect$ ) ! positive pole ( a batt]y ( ab\t #cjj volts4 ,! wire ,,ab to be made active is fa/5$ to a /\t] rod ,,bc1 pass+ ?r\gh an ebonite cork inside a %ort cyl9d] ,d1 fix$ 9 ! side ( ! vessel4 ,?is rod is connect$ ) ! negative pole ( ! batt]y4 ,9 ?is way ! wire ,,ab is ! only conductor expos$ 9 ! field ) a negative *>ge1 & x is f\nd t ! :ole ( ! excit$ activity is conc5trat$ ^u x4 ,9 ?is way x is possible to make a %ort ?9 metal wire ov] #aj1jjj times z active p] unit surface z ! ?oria f :i* ! excit$ activity is d]iv$4 ,9 ! same way1 ! excit$ activity due to radium c be conc5trat$ ma9ly on ! negative electrode4 ,9 ! case ( ?orium1 if ! c5tral wire be *>g$ positively1 x %[s no appreciable activity4 ,) radium1 h[ev]1 a positively *>g$ body becomes slightly active4 ,9 mo/ cases1 ! am\nt ( activity produc$ on ! positive electrode is n m ?an #e ( ! correspond+ am\nt :5 ! body is negatively *>g$4 ,= bo? ?orium & radium1 ! am\nt ( excit$ activity on electrodes ( ! same size is indep5d5t ( _! mat]ial4 ,all metals are made active to equal ext5ts = equal times ( exposure4 ,:5 no electric field is act+1 ! same am\nt ( activity is produc$ on insulators l mica & glass z on conductors ( equal dim5sions4 #agg4 ,connection betwe5 ! emanations & excit$ activity4 ,an exam9ation ( ! conditions "u :i* excit$ activity is produc$ %[s t !re is a v close connection betwe5 ! emanation & ! excit$ activity4 ,if a ?orium comp\nd is cov]$ ) sev]al %eets ( pap]1 :i* cut (f ! rays b all[ ! emanation to pass ?r\gh1 excit$ activity is /ill produc$ 9 ! space above x4 ,if a ?9 %eet ( mica is wax$ d[n ov] ! active mat]ial1 ?us prev5t+ ! escape ( ! emanation1 no excit$ activity is produc$ outside x4 ,uranium & polonium :i* d n give (f an emanation are n able to produce excit$ activity on bodies4 ,n only is ! pres5ce ( ! emanation necess>y to cause excit$ activity1 b ! am\nt ( excit$ activity is always proportional to ! am\nt ( emanation pres5t4 ,= example1 de-emanat$ ?oria produces v little excit$ activity comp>$ ) ord9>y ?oria4 ,9 all cases ! am\nt ( excit$ activity produc$ is proportional to ! emanat+ p[]4 ,:5 pass+ ?r\gh an electric field ! emanation loses its prop]ty ( excit+ activity at ! same rate z ! radiat+ p[] dim9i%es4 ,?is 0 %[n by ! foll[+ exp]im5t4 ,a sl[ con/ant curr5t ( air f a gasomet]1 fre$ f du/ by its passage ?r\gh cotton-wool1 pass$ ?r\gh a rectangul> wood5 tube #gj cms4 long4 ,f\r equal insulat$ metal plates ,a1 ,b1 ,c1 ,d1 7 plac$ at regul> int]vals along ! tube4 ,! positive pole ( a batt]y ( #cjj volts 0 connect$ ) a metal plate plac$ 9 ! bottom ( ! tube1 :ile ! negative pole 0 connect$ ) ! f\r plates4 ,a mass ( ?oria 0 plac$ 9 ! bottom ( ! tube "u ! plate ,a1 & ! curr5t due to ! emanation det]m9$ at ea* ( ! f\r plates4 ,aft] pass+ a curr5t ( air ( #jb cm4 p] second = #g h\rs along ! tube1 ! plates 7 remov$ & ! am\nt ( excit$ activity produc$ on !m 0 te/$ by ! electric me?od4 ,! foll[+ results 7 obta9$4 ,relative ,relative curr5t due excit$ to emanation activity ,plate ,a #a #a ,b #ee #dc ,c #ah #af ,d #jgb #jfa ,)9 ! errors ( measurem5t1 ! am\nt ( excit$ activity is ?us proportional to ! radiation f ! emanation1 i4e4 to ! am\nt ( emanation pres5t4 ,! same consid]ations hold = ! radium emanation4 ,! emanation 9 ?is case1 on acc\nt ( ! sl[ loss ( its activity1 c be /or$ mix$ ) air = long p]iods 9 a gasomet]1 & its effects te/$ q indep5d5tly ( ! active matt] f :i* x is produc$4 ,! ionization curr5t due to ! excit$ activity produc$ by ! emanation is always proportional to ! curr5t due to ! emanation = ! p]iod ( "o mon? or m t its activity is l>ge en\gh to be measur$ conv5i5tly by an electromet]4 ,if1 at any "t dur+ ! int]val1 "s ( ! emanation is remov$ & introduc$ into a new te/+ vessel1 ! ionization curr5t w imm$iately comm5ce to increase1 ris+ 9 ! c\rse ( f\r or five h\rs to ab\t twice its orig9al value4 ,?is increase ( ! curr5t is due to ! excit$ activity produc$ on ! walls ( ! conta9+ vessel4 ,on bl[+ out ! emanation1 ! excit$ activity is left beh9d1 & at once beg9s to decay4 ,:atev] its age1 ! emanation /ill possesses ! prop]ty ( caus+ excit$ activity1 & 9 am\nt always proportional to its activity1 i4e4 to ! am\nt ( emanation pres5t4 ,^! results %[ t ! p[] ( excit+ activity on inactive sub/ances is a prop]ty ( ! radio-active emanations1 & is proportional to ! am\nt ( emanation pres5t4 ,! ph5om5on ( excit$ activity _c be ascrib$ to a type ( phosphoresc5ce produc$ by ! rays f ! emanation on bodies2 = x has be5 %[n t ! activity c be conc5trat$ on ! negative electrode 9 a /rong electric field1 ev5 if ! electrode is %ield$ f ! direct radiation f ! active sub/ance :i* gives (f ! emanation4 ,! am\nt ( excit$ activity does n seem 9 any way connect$ ) ! ionization produc$ by ! emanation 9 ! gas ) :i* x is mix$4 ,= example1 if a clos$ vessel is con/ruct$ ) two l>ge p>allel insulat$ metal plates on ! l[] ( :i* a lay] ( ?oria is spread1 ! am\nt ( ! excit$ activity on ! upp] plate :5 *>g$ negatively1 is indep5d5t ( ! di/ance betwe5 ! plates :5 t di/ance is v>i$ f #a millimetre to #b c5timetres4 ,?is exp]im5t %[s t ! am\nt ( excit$ activity dep5ds only on ! am\nt ( emanation emitt$ f ! ?oria2 = ! ionization produc$ ) a di/ance ( #b c5timetres betwe5 ! plates is ab\t t5 times z great z ) a di/ance ( #a millimetre4 #agh4 ,if a plat9um wire be made active by exposure to ! emanation ( ?oria1 its activity c be remov$ by treat+ ! wire ) c]ta9 acids#bgb4 ,= example1 ! activity is n mu* alt]$ by imm]s+ ! wire 9 hot or cold wat] or nitric acid1 b m ?an #hj ( x is remov$ by dilute or conc5trat$ solutions ( sulphuric or hydro*loric acid4 ,! activity has n be5 de/roy$ by ?is treatm5t b is manife/$ 9 ! solution4 ,if ! solution be evaporat$1 ! activity rema9s beh9d on ! di%4 ,^! results %[ t ! excit$ activity is due to a deposit on ! surface ( bodies ( radio-active matt] :i* has def9ite prop]ties z reg>ds solution 9 acids4 ,?is active matt] is dissolv$ 9 "s acids1 b1 :5 ! solv5t is evaporat$1 ! active matt] is left beh9d4 ,?is active matt] is deposit$ on ! surface ( bodies1 = x c be p>tly remov$ by rubb+ ! body ) a clo?1 & almo/ completely by sc\r+ ! plate ) s& or em]y pap]4 ,if a negatively *>g$ wire is plac$ 9 ! pres5ce ( a l>ge quantity ( radium emanation1 x becomes int5sely active4 ,if ! wire1 aft] removal1 is drawn across a scre5 ( z9c sulphide1 or willemite1 a portion ( ! active matt] is rubb$ (f1 & a lum9\s trail is left beh9d on ! scre54 ,! am\nt ( active matt] deposit$ is extremely small1 = no diff]5ce ( weight has be5 detect$ 9 a plat9um wire :5 made extremely active4 ,on exam9+ ! wire "u a microscope1 no trace ( =eign matt] is obs]v$4 ,x foll[s f ^! results t ! matt] :i* causes excit$ activity is _m ?\s& times m active1 weight = weight1 ?an radium itself4 ,x is conv5i5t to h a def9ite "n = ?is radio-active matt]1 = ! t]m 8excit$ activity0 only ref]s to ! radiation f ! active matt] & n to ! matt] itself4 ,! t]m 8active deposit0 w be g5]ally appli$ to ?is matt]4 ,! active deposit f ! ?ree sub/ances ?orium1 radium1 & act9ium is1 9 ea* case1 d]iv$ f its respective emanation1 & possesses ! same g5]al prop]ty ( conc5tration on ! negative electrode 9 an electric field & ( act+ z a non-volatile type ( matt] :i* is deposit$ f ! gas on to ! surface ( bodies4 ,^! active deposits1 :ile all soluble 9 /rong acids1 are *emically di/9ct f ea* o!r4 ,! t]m 8active deposit0 c1 h[ev]1 only be us$ :5 ! matt] is spok5 ( z a :ole2 = x w be %[n lat] t ! matt]1 "u ord9>y conditions1 is complex & conta9s sev]al con/itu5ts :i* h di/9ctive physical & *emical prop]ties & also a di/9ctive rate ( *ange4 ,accord+ to ! !ory advanc$ 9 section #acf1 we may suppose t ! emanation ( ?orium1 radium1 & act9ium is un/able & breaks up ) ! expulsion ( an p>ticle4 ,! residue ( ! atom ( ! emanation diffuses to ! sides ( ! vessel or is remov$ to ! negative electrode 9 an electric field4 ,?is active deposit is 9 turn un/able & breaks up 9 sev]al successive /ages4 ,! 8excit$ activity0 prop] is ! radiation set up by ! active deposit 9 consequ5ce ( ! *anges occurr+ 9 x4 ,on ?is view1 ! emanation is ! p>5t ( ! active deposit 9 ! same way t ,? ,x is ! p>5t ( ! emanation4 ,! proportionality :i* always exi/s betwe5 ! activity ( ! emanation & ! excit$ activity to :i* x gives rise1 is at once expla9$1 if "o sub/ance be ! p>5t ( ! o!r4 #agi4 ,decay ( ! excit$ activity produc$ by ?orium4 ,! excit$ activity produc$ 9 a body aft] a long exposure to ! emanations ( ?orium1 decays 9 an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #aa h\rs4 ,! foll[+ table %[s ! rate ( decay ( ! excit$ activity produc$ on a brass rod4 ,"t 9 ,curr5t h\rs #j #ajj #gi #fd #aah #dgd #bcd #aif #bib #ach #cbf #ajc #dib #cg #fba #ahf #gad #jhf ,! results are %[n graphically 9 ,fig4 #fd1 ,curve ,a4 ,illu/ration3 ,fig4 #fd4 ,! int5sity ( ! radiation ,i aft] any "t t is giv5 by frac ,i ,i e-t 1 :]e is ! radio-active con/ant4 ,! rate ( decay ( excit$ activity1 l t ( ! activity ( o!r radio-active products1 is n appreciably affect$ by *ange ( conditions4 ,! rate ( decay is indep5d5t ( ! conc5tration ( ! excit$ activity1 & ( ! mat]ial ( ! body on :i* x is produc$4 ,x is indep5d5t also ( ! nature & pressure ( ! gas 9 :i* x decays4 ,! rate ( decay is un*ang$ :e!r ! excit$ activity is produc$ on ! body ) or )\t an electric field4 ,! am\nt ( excit$ activity produc$ on a body increases at fir/ ) ! "t1 b rea*es a maximum aft] an exposure ( sev]al days4 ,an example ( ! results is giv5 9 ! foll[+ table4 ,9 ?is exp]im5t a rod 0 made ! ca?ode 9 a clos$ vessel conta9+ ?oria4 ,x 0 remov$ at int]vals = ! %ort "t necess>y to te/ its activity & !n replac$4 ,"t 9 ,curr5t h\rs #aeh #fc #cbe #aje #ehc #bi #ihc #dj #adjj #ei #bcda #gg #bihc #hc #dgjj #ij #gbej #ie #ifjj #ajj ,^! results are %[n graphically 9 ,curve ,b1 ,fig4 #fd4 ,x is se5 t ! decay & recov]y curves may be repres5t$ approximately by ! foll[+ equations4 ,= ! decay curve ,a1 frac ,i ,i e-t 4 ,= ! recov]y curve ,b1 frac ,i ,i #a e-t 4 ,! two curves are ?us complem5t>y to "o ano!r2 !y are connect$ 9 ! same way z ! decay & recov]y curves ( ,ur ,x1 & are susceptible ( a simil> explanation4 ,! am\nt ( excit$ radio-activity rea*es a maximum value :5 ! rate ( supply ( fre% radio-active p>ticles balances ! rate ( *ange ( ^? already deposit$4 #ahj4 ,excit$ radio-activity produc$ by a %ort exposure4 ,! initial portion ( ! recov]y curve ,b1 ,fig4 #fd1 is n accurately repres5t$ by ! above equation4 ,! activity = ! fir/ few h\rs increases m sl[ly ?an w\ld be expect$ f ! equation4 ,?is result1 h[ev]1 is completely expla9$ 9 ! light ( lat] results4 ,! writ]#bgc f\nd t1 = a %ort exposure ( a body to ! ?orium emanation1 ! excit$ activity ^u x aft] removal1 in/ead ( at once decay+ at ! normal rate1 increas$ = sev]al h\rs4 ,9 "s cases ! activity ( ! body increas$ to ?ree or f\r times its orig9al value 9 ! c\rse ( a few h\rs & !n decay$ ) ! "t at ! normal rate4 ,= an exposure ( #da m9utes to ! emanation ! excit$ activity aft] removal rose to ?ree times its initial value 9 ab\t #c h\rs & !n fell aga9 at ab\t ! normal rate to half value 9 #aa h\rs4 ,) a long] "t ( exposure to ! emanation1 ! ratio ( ! increase aft] removal is mu* less m>k$4 ,= a day's exposure1 ! activity aft] removal beg9s at once to dim9i%4 ,9 ?is case1 ! increase ( activity ( ! matt] deposit$ 9 ! la/ few h\rs does n comp5sate = ! decrease ( activity ( ! active matt] z a :ole1 & consequ5tly ! activity at once comm5ces to decay4 ,?is increase ( activity ) "t expla9s ! initial irregul>ity 9 ! recov]y curve1 = ! active matt] deposit$ dur+ ! fir/ few h\rs takes "s "t to rea* its maximum activity1 & ! initial activity is1 9 consequ5ce1 small] ?an w\ld be expect$ f ! equation4 ,! increase ( activity on a rod expos$ = a %ort int]val 9 ! pres5ce ( ! ?orium emanation has be5 fur!r inve/igat$ by ,miss ,brooks4 ,! curve ,c 9 ,fig4 #fe %[s ! v>iation ) "t ( ! activity ( a brass rod expos$ = #aj m9utes 9 ! emanation vessel fill$ ) du/-free air4 ,! excit$ activity aft] removal increas$ 9 ! c\rse ( #cg h\rs to five times its initial value1 & aft]w>ds decay$ at ! normal rate4 ,! dott$ l9e curve ,d repres5ts ! v>iation ( activity to be expect$ if ! activity decay$ expon5tially ) ! "t4 ,! explanation ( ?is rem>kable action is consid]$ 9 detail 9 section #bjg4 ,illu/ration3 ,fig4 #fe4 #aha4 ,effect ( du/ on ! di/ribution ( excit$ activity4 ,miss ,brooks#bgd1 work+ 9 ! ,cav5di% ,laboratory1 obs]v$ t ! excit$ activity due to ! ?orium emanation appe>$ 9 "s cases on ! anode 9 an electric field1 & t ! di/ribution ( excit$ activity v>i$ 9 an app>5tly caprici\s mann]4 ,?is effect 0 f9ally trac$ to ! pres5ce ( du/ 9 ! air ( ! emanation vessel4 ,= example1 ) an exposure ( #e m9utes ! am\nt ( excit$ activity to be obs]v$ on a rod dep5d$ on ! "t t ! air _h be5 all[$ to rema9 undi/urb$ 9 ! emanation vessel be=eh&4 ,! effect increas$ ) ! "t ( /&+1 & 0 a maximum aft] ab\t #ah h\rs4 ,! am\nt ( excit$ activity obta9$ on ! rod 0 !n ab\t #bj times z great z ! am\nt obs]v$ = air fre%ly introduc$4 ,! activity ( ?is rod did n increase aft] removal1 b ) fre% air1 ! excit$ activity1 = an exposure ( #e m9utes1 increas$ to five or six times its initial value4 ,?is anomal\s behavi\r 0 f\nd to be due to ! pres5ce ( du/ p>ticles 9 ! air ( ! vessel1 9 :i* ! bodies 7 made radio-active4 ,^! p>ticles ( du/1 :5 %ut up 9 ! pres5ce ( ! emanation1 become radio-active4 ,:5 a negatively *>g$ rod is introduc$ into ! vessel1 a "p ( ! radio-active du/ is conc5trat$ on ! rod & its activity is add$ to ! normal activity produc$ on ! wire4 ,aft] ! air 9 ! vessel has be5 left undi/urb$ = an int]val suffici5tly long to all[ ea* ( ! p>ticles ( du/ to rea* a /ate ( radio-active equilibrium1 on ! application ( an electric field1 all ! positively *>g$ du/ p>ticles w at once be c>ri$ to ! negative electrode4 ,! activity ( ! electrode at once comm5ces to decay1 s9ce ! decay ( ! activity ( ! du/ p>ticles on ! wire q masks ! initial rise ( ! normal activity produc$ on ! wire4 ,"p ( ! radio-active du/ is also c>ri$ to ! anode1 & ! proportion increases ) ! l5g? ( "t dur+ :i* ! air has be5 undi/urb$4 ,! greate/ am\nt obta9$ on ! anode 0 ab\t #fj ( t on ! ca?ode4 ,^! anomal\s effects 7 f\nd to disappe> if ! air 0 made du/-free by pass+ ?r\gh a plug ( glass wool1 or by application = "s "t ( a /rong electric field4 #ahb4 ,decay ( excit$ activity f radium4 ,! excit$ activity produc$ on bodies by exposure to ! radium emanation decays mu* m rapidly ?an ! ?orium excit$ activity4 ,= %ort times ( exposure#bge to ! emanation ! decay curve is v irregul>4 ,?is is %[n 9 ,fig4 #ff4 ,x 0 f\nd t ! int5sity ( ! radiation measur$ by ! rays decreas$ rapidly = ! fir/ #aj m9utes aft] removal1 b ab\t #ae m9utes aft] removal rea*$ a value :i* rema9$ ne>ly con/ant = an int]val ( ab\t #bj m9utes4 ,x !n decay$ to z]o1 f9ally foll[+ an expon5tial law1 ! int5sity fall+ to half value 9 ab\t #bh m9utes4 ,) long] times ( exposure1 ! irregul>ities 9 ! curve are n s m>k$4 ,illu/ration3 ,fig4 #ff4 ,miss ,brooks has rec5tly det]m9$ ! decay curves ( ! excit$ activity ( radium = diff]5t times ( exposure1 measur$ by ! rays4 ,! results are %[n 9 ,fig4 #fg1 :]e ! initial ord9ates repres5t ! activity communicat$ to ! body f diff]5t times ( exposure to a con/ant supply ( emanation4 ,x w be obs]v$ t 9 all cases !re is a sudd5 initial drop ( activity1 :i* becomes less m>k$ ) increas+ "t ( exposure4 ,! activity1 sev]al h\rs aft] removal1 decreases expon5tially 9 all cases1 fall+ to half value 9 ab\t #bh m9utes4 ,n only d ! curves ( v>iation ( ! excit$ activity aft] removal dep5d ^u ! "t ( exposure to ! emanation1 b !y also dep5d ^u :e!r ! or & rays are us$ z a means ( measurem5t4 ,! curves obta9$ = ! rays are id5tical ) ^? f ! rays1 %[+ t ^! two types ( rays always occur toge!r & 9 ! same proportion4 ,! curves measur$ by ! rays are v diff]5t1 especially = ! case ( a %ort exposure to ! emanation4 ,?is is cle>ly %[n 9 ,fig4 #fh1 :i* gives ! & ray curves = exposures ( #aj m9utes1 #dj m9utes1 & #a h\r1 & also ! limit+ case ( an exposure ( #bd h\rs4 ,illu/ration3 ,fig4 #fg4 ,illu/ration3 ,fig4 #fh4 ,ab\t #be m9utes aft] removal1 ! activity decays approximately at ! same rate 9 ea* case4 ,= conv5i5ce ( repres5tation1 ! ord9ates ( ! curves 7 adju/$ s t !y all pass$ ?r\gh a common po9t4 ,we %all see lat] 7*apt] ,,xi7 t ! rates ( decay are n id5tically ! same until sev]al h\rs aft] removal2 b1 9 ! above figure1 x is difficult to repres5t ! slight v>iations4 ,x w be obs]v$ t = ! %ort exposure ( #aj m9utes ! activity measur$ by ! rays is small at fir/ b rises to a maximum 9 ab\t #bb m9utes1 & !n dies away ) ! "t4 ,! curve ( decay ( activity1 measur$ by ! rays = a long exposure1 does n %[ ! rapid initial drop :i* occurs 9 all ! ray curves4 ,curie & ,danne#bgf made an inve/igation ( ! curves ( decay ( excit$ activity = diff]5t times ( exposure to ! radium emanation1 b app>5tly did n take into acc\nt ! fact t measurem5ts made by ! & rays give q diff]5t curves ( decay4 ,"s ( ! family ( curves1 giv5 9 _! pap]1 ref] to ! rays & o!rs to ! rays4 ,!y %[$1 h[ev]1 ! important fact t ! curve ( decay obta9$ by !m = a long exposure 7:i* is id5tical ) ! ray curve7 c\ld be empirically express$ by an equation ( ! =m frac ,it ,i ae-#a t 7a #a7 e-#b t 1 :]e ,i is ! initial int5sity & ,it ! int5sity aft] any "t t2 1 4 ,! num]ical con/ant a #dbj4 ,aft] an int]val ( #be h\rs1 ! log>i?mic decay curve is ne>ly a /raight l9e1 t is1 ! activity falls (f accord+ to an expon5tial law ) ! "t1 decreas+ to half value 9 ab\t #bh m9utes4 ,! full explanation ( ?is equation1 & ( ! peculi>ities ( ! v>i\s decay curves ( ! excit$ activity ( radium1 w be discuss$ 9 detail 9 *apt] ,,xi4 ,z 9 ! case ( ! excit$ activity f ?orium1 ! rate ( decay ( ! excit$ activity f radium is = ! mo/ "p indep5d5t ( ! nature ( ! body made active4 ,curie & ,danne 7loc4 cit47 obs]v$ t ! active bodies gave (f an emanation itself capable ( excit+ activity 9 neighb\r+ bodies4 ,?is prop]ty rapidly disappe>$1 & 0 inappreciable #b h\rs aft] removal4 ,9 c]ta9 sub/ances l celluloid & ca\t*\c1 ! decay ( activity is v mu* sl[] ?an = ! metals4 ,?is effect becomes m m>k$ ) increase ( "t ( exposure to ! emanation4 ,a simil> effect is exhibit$ by lead1 b to a less m>k$ degree4 ,dur+ ! "t ! activity la/s1 ^! sub/ances cont9ue to give (f an emanation4 ,x is probable t ^! div]g5cies f ! g5]al law are n due to an actual *ange 9 ! rate ( decay ( ! true excit$ activity b to an occlusion ( ! emanation by ^! sub/ances dur+ ! int]val ( exposure4 ,aft] exposure ! emanation gradually diffuses out1 & ?us ! activity due to ?is occlud$ emanation & ! excit$ activity produc$ by x decays v sl[ly ) ! "t4 #ahc4 ,active deposit ( v sl[ decay4 ,m4 & ,mme ,curie#bgg h obs]v$ t bodies :i* h be5 expos$ = a long int]val 9 ! pres5ce ( ! radium emanation d n lose all _! activity4 ,! excit$ activity at fir/ decays rapidly at ! normal rate1 fall+ to half value 9 ab\t #bh m9utes1 b a residual activity1 :i* !y /ate is ( ! ord] ( #j1jjj ( ! initial activity1 always rema9s4 ,a simil> effect 0 obs]v$ by ,giesel4 ,! writ] has exam9$ ! v>iation ( ?is residual activity1 & has f\nd t x increases = sev]al ye>s4 ,! results are discuss$ 9 detail 9 *apt] ,,xi4 ,x w !re be %[n t ?is active deposit ( sl[ trans=mation conta9s ! radio-active con/itu5ts pres5t 9 polonium1 radio-tellurium & radio-lead4 ,illu/ration3 ,fig4 #fi4 #ahd4 ,! excit$ activity f act9ium4 ,! emanation ( act9ium1 l t ( ?orium & radium1 produces excit$ activity on bodies1 :i* is conc5trat$ on ! negative electrode 9 an electric field4 ,debi]ne#bgh f\nd t ! excit$ activity decays approximately accord+ to an expon5tial law1 fall+ to half value 9 #da m9utes4 ,giesel#bgi exam9$ ! rate ( decay ( ! excit$ activity ( 8emanium0--:i*1 we h se51 probably conta9s ! same radio-active con/itu5ts z act9ium--& f\nd t x decay$ to half value 9 #cd m9utes4 ,miss ,brooks#bhj f\nd t ! curves ( decay ( ! excit$ activity f ,giesel's emanium v>i$ ) ! "t ( exposure to ! emanation4 ,! results are %[n graphically 9 ,fig4 #fi1 = "t exposures ( #a1 #b1 #e1 #aj & #cj m9utes1 & also = a long exposure ( #ba h\rs4 ,aft] #aj m9utes ! curves h approximately ! same rate ( decay4 ,= conv5i5ce1 ! ord9ates ( ! curves are adju/$ to pass ?r\gh a common po9t4 ,= a v %ort exposure1 ! activity is small at fir/1 b rea*es a maximum ab\t #i m9utes lat] & f9ally decays expon5tially to z]o4 ,! curve ( v>iation ( activity = a v %ort exposure has be5 det]m9$ accurately by ,bronson2 x is %[n lat] 9 ,fig4 #hc4 ,he f\nd t ! decay ( activity is f9ally expon5tial1 fall+ to half value 9 #cf m9utes4 ,! explanation ( ^! curves is discuss$ 9 detail 9 *apt] ,x1 section #bab4 #ahe4 ,physical & *emical prop]ties ( ! active deposit4 ,on acc\nt ( ! sl[ decay ( ! activity ( ! active deposit f ! ?orium emanation1 its physical & *emical prop]ties h be5 m closely exam9$ ?an ! correspond+ deposit f radium4 ,x has already be5 m5tion$ t ! active deposit ( ?orium is soluble 9 "s acids4 ,! writ]#bha f\nd t ! active matt] 0 dissolv$ (f ! wire by /rong or dilute solutions ( sulphuric1 hydro*loric & hydr(luoric acids1 b 0 only slightly soluble 9 wat] or nitric acid4 ,! active matt] 0 left beh9d :5 ! solv5t 0 evaporat$4 ,! rate ( decay ( activity 0 unalt]$ by dissolv+ ! active matt] 9 sulphuric acid1 & all[+ x to decay 9 ! solution4 ,9 ! exp]im5t1 ! active matt] 0 dissolv$ (f an active plat9um wire2 !n equal portions ( ! solutions 7 tak5 at def9ite int]vals1 evaporat$ d[n 9 a plat9um di%1 & ! activity ( ! residue te/$ by ! electric me?od4 ,! rate ( decay 0 f\nd to be exactly ! same z if ! active matt] _h be5 left on ! wire4 ,9 ano!r exp]im5t1 an active plat9um wire 0 made ! ca?ode 9 a copp] sulphate solution1 & a ?9 film ( copp] deposit$ on x4 ,! rate ( decay ( ! activity 0 un*ang$ by ! process4 ,a detail$ exam9ation ( ! physical & *emical prop]ties ( ! active deposit ( ?orium has be5 made by ,f4 von ,l]*#bhb & "s important & int]e/+ results h be5 obta9$4 ,a solution ( ! active deposit 0 prep>$ by dissolv+ ! metal :i* _h be5 expos$ = "s "t 9 ! pres5ce ( ! ?orium emanation4 ,9 mo/ cases ! active matt] 0 precipitat$ ) ! metal4 ,= example1 an active copp] wire 0 dissolv$ 9 nitric acid & !n precipitat$ by cau/ic pota%4 ,! precipitate 0 /rongly active4 ,an active magnesium wire1 dissolv$ 9 hydro*loric acid & !n precipitat$ z phosphate1 also gave an active precipitate4 ,! activity ( ! precipitates decay$ at ! normal rate1 i4e4 ! activity fell to half value 9 ab\t #aa h\rs4 ,exp]im5ts 7 also made on ! solubility ( ! active deposit 9 diff]5t sub/ances4 ,a plat9um plate 0 made active & !n plac$ 9 diff]5t solutions1 & ! decrease ( ! activity obs]v$4 ,9 addition to ! acids already m5tion$1 a l>ge numb] ( sub/ances 7 f\nd to dissolve ! active deposit to "s ext5t4 ,! active matt] 0 h[ev] n dissolv$ to an appreciable ext5t 9 e!r or alcohol4 ,_m sub/ances became active if add$ to ! active solution & !n precipitat$4 ,= example1 an active solution ( hydro*loric acid 0 obta9$ by dissolv+ ! deposit on an active plat9um wire4 ,b>ium *loride 0 !n add$ & precipitat$ z sulphate4 ,! precipitate 0 /rongly active1 ?us sugge/+ t ! active matt] 0 c>ri$ d[n by ! b>ium4 #ahf4 ,electrolysis ( solutions4 ,dorn %[$ t1 if solutions ( radif]\s b>ium *loride 7 electrolys$1 bo? electrodes became tempor>ily active1 b ! anode to a great] degree ?an ! ca?ode4 ,f4 von ,l]* has made a detail$ exam9ation ( ! action ( electrolysis on a solution ( ! active deposit ( ?orium4 ,! matt] 0 dissolv$ (f an active plat9um plate by hydro*loric acid1 & !n electrolys$ betwe5 plat9um electrodes4 ,! ca?ode 0 v active1 b !re 0 no trace ( activity on ! anode4 ,! ca?ode lo/ its activity at a rate mu* fa/] ?an ! normal4 ,) an amalgamat$ z9c ca?ode on ! o!r h&1 ! rate ( decay 0 normal4 ,:5 an active solution ( hydro*loric acid 0 electrolys$ ) an electromotive =ce small] ?an t requir$ to decompose wat]1 ! plat9um became active4 ,! activity decay$ to half value 9 #dge h\rs :ile ! normal fall is to half value 9 #aa h\rs4 ,^! results po9t to ! conclusion t ! active matt] is complex & consi/s ( two p>ts :i* h diff]5t rates ( decay ( activity1 & c be sep>at$ by electrolysis4 ,"u special conditions x 0 f\nd possible to make ! anode active4 ,?is 0 ! case if ! anion atta*$ itself to ! anode4 ,= example1 if an active hydro*loric solution 0 electrolys$ ) a silv] anode1 ! *loride ( silv] =m$ 0 /rongly active & its activity decay$ at a normal rate4 ,! am\nt ( activity obta9$ by plac+ diff]5t metals 9 active solutions = equal times v>i$ greatly ) ! metal4 ,= example1 x 0 f\nd t if a z9c plate & an amalgamat$ z9c plate1 :i* %[ equal pot5tial diff]5ces ) reg>d to hydro*loric acid1 7 dipp$ = equal times 9 two solutions ( equal activity1 ! z9c plate 0 sev5 times z active z ! o!r4 ,! activity 0 almo/ remov$ f ! solution 9 a few m9utes by dipp+ a z9c plate into x4 ,"s metals became active :5 dipp$ into an active solution :ile o!rs did n4 ,plat9um1 palladium1 & silv] rema9$ inactive1 :ile copp]1 t91 lead1 nickel1 iron1 z9c1 cadmium1 magnesium1 & alum9ium became active4 ,^! results /rongly confirm ! view t excit$ activity is due to a deposit ( active matt] :i* has di/9ctive *emical behavi\r4 ,g4 ,b4 ,pegram#bhc has made a detail$ /udy ( ! active deposits obta9$ by electrolysis ( pure & comm]cial ?orium salts4 ,! comm]cial ?orium nitrate obta9$ f ,p4 de ,ha5 gave1 :5 electrolys$1 a deposit ( lead p]oxide on ! anode4 ,?is deposit 0 radio-active1 & its activity decay$ at ! normal rate ( ! excit$ activity due to ?orium4 ,f solutions ( pure ?orium nitrate1 no visible deposit 0 obta9$ on ! anode1 b x 01 h[ev]1 f\nd to be radio-active4 ,! activity decay$ rapidly1 fall+ to half value 9 ab\t "o h\r4 ,"s exp]im5ts 7 also made on ! effect ( add+ metallic salts to ?orium solutions & !n electrolys+ !m4 ,anode & ca?ode deposits ( ! oxides or metals obta9$ 9 ?is way 7 f\nd to be radio-active1 b ! activity fell to half value 9 a few m9utes4 ,! gases produc$ by electrolysis 7 radio-active1 b ?is 0 due to ! pres5ce ( ! ?orium emanation4 ,! explanation ( ! results obta9$ by ,pegram & von ,l]* w be consid]$ lat] 9 section #bjg4 ,x w be %[n t ! active deposit ( ?orium conta9s two di/9ct sub/ances :i* h diff]5t rates ( trans=mation4 #ahg4 ,effect ( temp]ature4 ,! activity ( a plat9um wire :i* has be5 expos$ 9 ! pres5ce ( ! ?orium emanation is almo/ completely lo/ by heat+ ! wire to a :ite heat4 ,miss ,f4 ,gates#bhd f\nd t ! activity 0 n de/roy$ by ! int5se heat1 b manife/$ itself on neighb\r+ bodies4 ,:5 ! active wire 0 heat$ electrically 9 a clos$ cyl9d]1 ! activity 0 transf]r$ f ! wire to ! int]ior surface ( ! cyl9d] 9 unalt]$ am\nt4 ,! rate ( decay ( ! activity 0 n alt]$ by ! process4 ,by bl[+ a curr5t ( air ?r\gh ! cyl9d] dur+ ! heat+1 a "p ( ! active matt] 0 remov$ f ! cyl9d]4 ,simil> results 7 f\nd = ! excit$ activity due to radium4 ,f4 von ,l]* 7loc4 cit47 det]m9$ ! am\nt ( activity remov$ at diff]5t temp]atures4 ,! results are %[n 9 ! foll[+ table = a plat9um wire excit$ by ! ?orium emanation#bhe4 ,temp]ature ,p]c5tage ( activity remov$ ,heat$ #b m9utes #hjj ,c4 #j !n m9ute #ajbj ,c4 #af m #abfj ,c4 #eb #adfj ,c4 #ii ,! effect ( heat on ! volatilization ( ! active deposit ( radium has be5 exam9$ 9 detail by ,curie & ,danne4 ,! int]e/+ & important results obta9$ by !m w be discuss$ 9 *apt] ,,xi1 section #bbf4 #ahh4 ,effect ( v>iation ( ,e4,m4,f4 on am\nt ( excit$ activity f ?orium4 ,x has be5 %[n t ! excit$ activity is conf9$ to ! ca?ode 9 a /rong electric field4 ,9 weak] fields ! activity is divid$ betwe5 ! ca?ode & ! walls ( ! vessel4 ,?is 0 te/$ 9 an app>atus#bhf %[n 9 ,fig4 #gj4 ,illu/ration3 ,fig4 #gj4 ,a is a cyl9drical vessel ( #ee cms4 diamet]1 ,b ! negative electrode pass+ ?r\gh insulat+ ends ,c1 ,d4 ,= a pot5tial diff]5ce ( #ej volts1 mo/ ( ! excit$ activity 0 deposit$ on ! electrode ,b4 ,= ab\t #c volts1 half ( ! total excit$ activity 0 produc$ on ! rod ,b1 & half on ! walls ( ! vessel4 ,:atev] ! voltage appli$1 ! sum ( ! activities on ! c5tral rod & ! walls ( ! cyl9d] 0 f\nd to be a con/ant :5 a /eady /ate 0 rea*$4 ,:5 no voltage 0 appli$1 diffusion alone 0 op]ative1 & 9 t case ab\t #ac p] c5t4 ( ! total activity 0 on ! rod ,b4 ,! application ( an electric field has ?us no influ5ce on ! sum total ( excit$ activity1 b m]ely controls ! proportion conc5trat$ on ! negative electrode4 ,a m detail$ exam9ation ( ! v>iation ) /r5g? ( field ( ! am\nt on ! negative electrode 0 made 9 a simil> mann] by ,f4 ,h5n+#bhg4 ,he f\nd t 9 a /rong electric field ! am\nt ( excit$ activity 0 practically indep5d5t ( ! diamet] ( ! rod ,b1 al?\gh ! diamet] v>i$ betwe5 #ei mm4 & #fj mms4 ,) a small voltage1 ! am\nt on ! negative electrode v>i$ ) its diamet]4 ,! curves %[+ ! relation betwe5 ! am\nt ( excit$ activity & voltage are v simil> 9 "* to ^? obta9$ = ! v>iation ( ! curr5t ?r\gh an ioniz$ gas ) ! voltage appli$4 ,! am\nt ( excit$ activity rea*es a maximum :5 all ! active matt] is remov$ f ! gas z rapidly z x is =m$4 ,) weak] fields1 a portion diffuses to ! sides ( ! vessel1 & produces excit$ activity on ! positive electrode4 #ahi4 ,effect ( pressure on di/ribution ( excit$ activity4 ,9 a /rong electric field1 ! am\nt ( excit$ activity produc$ on ! ca?ode is indep5d5t ( ! pressure d[n to a pressure ( ab\t #aj mms4 ( m]cury4 ,9 "s exp]im5ts made by ! writ]#bhh1 ! emanat+ ?orium comp\nd 0 plac$ inside a clos$ cyl9d] ab\t #d cms4 9 diamet]1 ?r\gh :i* pass$ an insulat$ c5tral rod4 ,! c5tral rod 0 connect$ to ! negative pole ( a batt]y ( #ej volts4 ,:5 ! pressure 0 r$uc$ bel[ #aj mms4 ( m]cury1 ! am\nt ( excit$ activity produc$ on ! negative electrode dim9i%$1 & 0 a v small fraction ( its orig9al value at a pressure ( mm4 ,"s excit$ activity 0 9 ?is case f\nd to be di/ribut$ ov] ! int]ior surface ( ! cyl9d]4 ,x may ?us be conclud$ t at l[ pressures ! excit$ activity appe>s on bo? anode & ca?ode1 ev5 9 a /rong electric field4 ,! probable explanation ( ?is effect is giv5 9 ! next section4 ,curie & ,debi]ne#bhi obs]v$ t :5 a vessel conta9+ an emanat+ radium comp\nd 0 kept pump$ d[n to a l[ pressure1 ! am\nt ( excit$ activity produc$ on ! vessel 0 mu* r$uc$4 ,9 ?is case ! emanation giv5 (f by ! radium 0 remov$ by ! pump ) ! o!r gases cont9u\sly evolv$ f ! radium comp\nd4 ,on acc\nt ( ! v sl[ decay ( activity ( ! emanation1 ! am\nt ( excit$ activity produc$ on ! walls ( ! vessel1 9 ! passage ( ! emanation ?r\gh x1 0 only a m9ute fraction ( ! am\nt produc$ :5 none ( ! emanation giv5 (f 0 all[$ to escape4 #aij4 ,transmission ( excit$ activity4 ,! *>act]i/ic prop]ty ( excit$ radio-activity is t x c be conf9$ to ! ca?ode 9 a /rong electric field4 ,s9ce ! activity is due to a deposit ( radio-active matt] on ! electrifi$ surface1 ! matt] mu/ be transport$ by positively *>g$ c>ri]s4 ,! exp]im5ts ( ,fehrle#bij %[$ t ! c>ri]s ( excit$ activity travel along ! l9es ( =ce 9 an electric field4 ,= example1 :5 a small negatively *>g$ metal plate 0 plac$ 9 ! c5tre ( a metal vessel conta9+ an emanat+ ?orium comp\nd1 m excit$ activity 0 produc$ on ! sides & corn]s ( ! plate ?an at ! c5tral "p4 ,a difficulty h[ev] arises 9 connection ) ! positive *>ge ( ! c>ri]4 ,accord+ to ! view develop$ 9 section #acf & lat] 9 *apt]s ,x & ,,xi1 ! active matt] :i* is deposit$ on bodies & gives rise to excit$ activity1 is itself d]iv$ f ! emanation4 ,! emanations ( ?orium & radium emit only rays1 i4e4 positively *>g$ p>ticles4 ,aft] ! expulsion ( an p>ticle1 ! residue1 :i* is suppos$ to con/itute ! prim>y matt] ( ! active deposit1 %\ld reta9 a negative *>ge1 & be c>ri$ to ! anode 9 an electric field4 ,! exact opposite h[ev] is obs]v$ to be ! case4 ,! exp]im5tal evid5ce does n support ! view t ! positively *>g$ p>ticles1 expell$ f ! emanation1 are directly responsible = ! ph5om5a ( excit$ activity2 = no excit$ activity is produc$ 9 a body expos$ to ! rays ( ! emanation1 provid$ ! emanation itself does n come 9 contact ) x4 ,!re has be5 a t5d5cy to atta* undue importance to ?is app>5t discrepancy betwe5 !ory & exp]im5t4 ,! difficulty is n s mu* to (f] a probable explanation ( ! results z to select f a numb] ( possible causes4 ,:ile !re c be little d\bt t ! ma9 factor 9 ! dis9tegration ( ! atom consi/s 9 ! expulsion ( an p>ticle c>ry+ a positive *>ge1 a complicat$ s]ies ( processes probably occurs be=e ! residue ( ! atom is c>ri$ to ! negative electrode4 ,! exp]im5tal evid5ce sugge/s t "o or m negative electrons ( sl[ velocity escape f ! atom at ! same "t z ! p>ticle4 ,?is is borne out by ! rec5t discov]y t ! p>ticle expell$ f radium1 fre$ f ! ord9>y rays1 & also f polonium1 is accompani$ by a numb] ( sl[ly mov+ & consequ5tly easily absorb$ electrons4 ,if two negative electrons escap$ at ! same "t z ! p>ticle1 ! residue w\ld be left ) a positive *>ge & w\ld be c>ri$ to ! negative electrode4 ,!re is also ano!r exp]im5tal po9t :i* is ( importance 9 ?is connection4 ,9 ! abs5ce ( an electric field1 ! c>ri]s rema9 9 ! gas = a consid]able "t & und]go _! trans=mation 9 situ4 ,!re is also "s evid5ce 7section #bbg7 t1 ev5 9 an electric field1 ! c>ri]s ( ! active deposit are n swept to ! electrode imm$iately aft] ! break up ( ! emanation1 b rema9 "s "t 9 ! gas be=e !y ga9 a positive *>ge4 ,x mu/ be rememb]$ t ! atoms ( ! active deposit d n exi/ z a gas & by ! process ( diffusion w\ld t5d to collect toge!r to =m aggregates4 ,^! aggregates w\ld act z small metallic p>ticles1 &1 if !y 7 electro-positive 9 reg>d to ! gas1 w\ld ga9 a positive *>ge f ! gas4 ,!re c be little d\bt t ! processes occurr+ betwe5 ! break up ( ! emanation & ! deposit ( ! residue 9 ! ca?ode 9 an electric field are complicat$1 & fur!r c>eful exp]im5t is requir$ to elucidate ! sequ5ce ( ! ph5om5a4 ,:atev] view is tak5 ( ! process by :i* ^! c>ri]s obta9 a positive *>ge1 !re c be little d\bt t ! expulsion ( an p>ticle ) great velocity f ! atom ( ! emanation mu/ set ! residue 9 motion4 ,on acc\nt ( ! comp>atively l>ge mass ( ?is residue1 ! velocity acquir$ w be small comp>$ ) t ( ! expell$ p>ticle1 & ! mov+ mass w rapidly be br\ght to re/ at atmosph]ic pressure by collision ) ! gas molecules 9 its pa?4 ,at l[ pressures1 h[ev]1 ! collisions w be s few t x w n be br\ght to re/ until x /rikes ! b\nd>ies ( ! vessel4 ,a /rong electric field w\ld h v little effect 9 controll+ ! motion ( su* a heavy mass1 unless x has be5 initially br\ght to re/ by collision ) ! gas molecules4 ,?is w\ld expla9 :y ! active matt] is n deposit$ on ! ca?ode at l[ pressures 9 an electric field4 ,"s direct evid5ce ( a process ( ?is "*1 obta9$ by ,debi]ne on exam9ation ( ! excit$ activity produc$ by act9ium1 is discuss$ 9 section #aib4 #aia4 ,! foll[+ me?od has be5 employ$ by ! writ]#bia to det]m9e ! velocity ( ! positive c>ri]s ( excit$ activity ( radium & ?orium 9 an electric field4 ,suppose ,a & ,b 7,fig4 #ga7 are two p>allel plates expos$ to ! influ5ce ( ! emanation1 :i* is uni=mly di/ribut$ betwe5 !m4 ,if an alt]nat+ ,e4,m4,f4 ,e is appli$ betwe5 ! plates1 ! same am\nt ( excit$ activity is produc$ on ea* electrode4 ,if1 9 s]ies ) ! s\rce ( ! alt]nat+ ,e4,m4,f41 a batt]y ( ,e4,m4,f4 ,e less ?an ,e is plac$1 ! positive c>ri] moves 9 a /rong] electric field 9 "o half alt]nation ?an 9 ! o!r4 ,a c>ri] consequ5tly moves ov] unequal di/ances dur+ ! two half alt]nations1 s9ce ! velocity ( ! c>ri] is proportional to ! /r5g? ( ! electric field 9 :i* x moves4 ,! excit$ activity w 9 consequ5ce be unequally di/ribut$ ov] ! two electrodes4 ,if ! frequ5cy ( alt]nation is suffici5tly great1 only ! positive c>ri]s )9 a c]ta9 small di/ance ( "o plate c be convey$ to x1 & ! re/1 9 ! c\rse ( sev]al succe$+ alt]nations1 are c>ri$ to ! o!r plate4 ,illu/ration3 ,fig4 #ga4 ,:5 ! plate ,b is negatively *>g$1 ! ,e4,m4,f4 betwe5 ! plates is ,e ,e1 :5 ,b is positive ! ,e4,m4,f4 is ,e ,e4 ,let d di/ance betwe5 ! plates1 ,t "t ( a half alt]nation1 ratio ( ! excit$ radio-activity on ! plate ,b to ! sum ( ! radio-activities on ! plates ,a & ,b1 ,k velocity ( ! positive c>ri]s = a pot5tial-gradi5t ( #a volt p] c5timetre4 ,on ! assumption t ! electric field betwe5 ! plates is uni=m1 & t ! velocity ( ! c>ri] is proportional to ! electric field1 ! velocity ( ! positive c>ri] t[>ds ,b is ,e ,e ---------- ,k d &1 9 ! c\rse ( ! next half alt]nation1 ,e ,e ---------- ,k d t[>ds ! plate ,a4 ,if x is less ?an d1 ! greate/ di/ances x1 x pass$ ov] by ! positive c>ri] dur+ two succe$+ half alt]nations is ?us giv5 by ,e ,e x ---------- ,,kt d & ,e ,e x ---------- ,,kt d ,suppose t ! positive c>ri]s are produc$ at a uni=m rate ( q p] second = unit di/ance betwe5 ! plates4 ,! numb] ( positive c>ri]s :i* rea* ,b dur+ a half alt]nation consi/s ( two p>ts3 7#a7 ,"o half ( ^? c>ri]s :i* are produc$ )9 ! di/ance x ( ! plate ,b4 ,?is numb] is equal to #a --- x q,t #b 7#b7 ,all ! c>ri]s :i* are left )9 ! di/ance x f ,b at ! end ( ! previ\s half alt]nation4 ,! numb] ( ^! c readily be %[n to be #a x --- x ---- q,t #b x ,! rema9d] ( ! c>ri]s1 produc$ betwe5 ,a & ,b dur+ a complete alt]nation1 w rea* ! o!r plate ,a 9 ! c\rse ( succe$+ alt]nations1 provid$ no appreciable recomb9ation takes place4 ,?is mu/ obvi\sly be ! case1 s9ce ! positive c>ri]s travel fur!r 9 a half alt]nation t[>ds ,a ?an !y return t[>ds ,b dur+ ! next half alt]nation4 ,! c>ri]s ?us move backw>ds & =w>ds 9 ! *ang+ electric field1 b on ! :ole move t[>ds ! plate ,a4 ,! total numb] ( positive c>ri]s produc$ betwe5 ! plates dur+ a complete alt]nation is #b;dq,t4 ,! ratio ( ! numb] :i* rea* ,b to ! total numb] produc$ is ?us giv5 by rho frac frac #ab x#aq,t frac #ab x#a frac x#ax#b q,t #b;dq,t frac #ad frac x#a;d frac x#a x#b x#b 4 ,sub/itut+ ! values ( x & x1 we f9d t ,k frac #b 7,e ,e#a7 d#b ,e 7,e ,e#a7 ,t rho 4 ,9 ! exp]im5ts1 ! values ( ,e1 ,e1 d1 & ,t 7 v>i$1 & ! results obta9$ 7 9 g5]al agreem5t ) ! above equation4 ,! foll[+ 7 ! results = ?orium3 ,plates #acj cms4 ap>t4 ,e ,e ,alt]nations ,k ,e ,e p] second #aeb #aja #eg #bg #abe #bbe #aej #eg #ch #aag #cjj #bjj #eg #dd #abd ,plates #b cms4 ap>t4 ,e ,e ,alt]nations ,k ,e ,e p] second #bgc #bjg #dd #cg #adg #cjj #bjj #ec #bhf #ade ,! av]age mobility ,k d$uc$ f a l>ge numb] ( exp]im5ts 0 #ac cms4 p] sec4 p] volt p] cm4 = atmosph]ic pressure & temp]ature4 ,?is velocity is ab\t ! same z ! velocity ( ! positive ion produc$ by ,rntg5 rays 9 air1 viz4 #acg cms4 p] sec4 ,! results obta9$ ) ! radium emanation 7 m unc]ta9 ?an ^? = ?orium on acc\nt ( ! di/ribution ( "s excit$ activity on ! positive electrode4 ,! values ( ! velocities ( ! c>ri]s 7 h[ev] f\nd to be r\ghly ! same = radium z = ?orium4 ,^! results %[ t ! c>ri]s ( ! active deposit travel 9 ! gas ) ab\t ! same velocity z ! positive or negative ions produc$ by ! radiations 9 ! gas4 ,?is indicates ei!r t ! active matt] becomes atta*$ to positive ions1 or t ! active matt] itself1 acquir+ 9 "s way a positive *>ge1 collects a clu/] ( neutral molecules :i* travel ) x4 #aib4 ,c>ri]s ( ! excit$ activity f act9ium & 8emanium40 ,giesel#bib obs]v$ t 8emanium0 gave (f a l>ge quantity ( emanation1 & t ?is emanation gave rise to a type ( radiation :i* he t]m$ ! ,e rays4 ,a n>r[ metal cyl9d] conta9+ ! active sub/ance 0 plac$ ) ! op5 end d[nw>ds1 ab\t #e cms4 above ! surface ( a z9c sulphide scre54 ,! scre5 0 *>g$ negatively to a high pot5tial by an electric ma*9e1 & ! cyl9d] connect$ ) e>?4 ,a lum9\s spot ( light 0 obs]v$ on ! scre51 :i* 0 bright] at ! edge ?an at ! c5tre4 ,a conductor1 connect$ ) e>?1 br\ght ne> ! lum9\s spot app>5tly repell$ x4 ,an insulator did n %[ su* a m>k$ effect4 ,on removal ( ! active sub/ance1 ! lum9osity ( ! scre5 p]si/$ = "s "t4 ,?is 0 probably due to ! excit$ activity produc$ on ! scre54 ,! results obta9$ by ,giesel support ! view t ! c>ri]s ( excit$ activity ( 8emanium0 h a positive *>ge4 ,9 a /rong electric field ! c>ri]s travel along ! l9es ( =ce to ! ca?ode1 & !re cause excit$ activity on ! scre54 ,! movem5t ( ! lum9\s zone on ! approa* ( a conductor is due to ! di/urbance ( ! electric field4 ,debi]ne#bic f\nd t act9ium also gave (f a l>ge am\nt ( emanation1 ! activity ( :i* decay$ v rapidly ) ! "t1 fall+ to half value 9 #ci seconds4 ,?is emanation produces excit$ activity on surr\nd+ objects1 & at dim9i%$ pressure ! emanation produces a uni=m di/ribution ( excit$ activity 9 ! enclosure conta9+ ! emanation4 ,! excit$ activity falls to half value 9 #da m9utes4 ,debi]ne obs]v$ t ! di/ribution ( excit$ activity 0 alt]$ by a /rong magnetic field4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #ga;,a4 ,! active matt] 0 plac$ at ,m1 & two plates ,a & ,b 7 plac$ symmetrically ) reg>d to ! s\rce4 ,on ! application ( a /rong magnetic field normal to ! plane ( ! pap]1 ! excit$ activity 0 unequally di/ribut$ betwe5 ! plates ,a & ,b4 ,! results %[$ t ! c>ri]s ( excit$ activity 7 deviat$ by a magnetic field 9 ! opposite s5se to ! ca?ode rays1 i4e4 ! c>ri]s 7 positively *>g$4 ,9 "s cases1 h[ev]1 ! opposite effect 0 obta9$4 ,debi]ne consid]s t ! excit$ activity ( act9ium is due to 8ions activants10 ! motion ( :i* is alt]$ by a magnetic field4 ,o!r exp]im5ts %[$ t ! magnetic field act$ on ! 8ions activants0 & n on ! emanation4 ,illu/ration3 ,fig4 #ga;,a4 ,! results ( ,debi]ne ?us lead to ! conclusion t ! c>ri]s ( excit$ activity are d]iv$ f ! emanation & are project$ ) consid]able velocity4 ,?is result supports ! view1 advanc$ 9 section #aij1 t ! expulsion ( p>ticles f ! emanation mu/ set ! "p ( ! sy/em left beh9d 9 rapid motion4 ,a close exam9ation ( ! mode ( transf]5ce ( ! excit$ activity by act9ium & ! emanation sub/ance is likely to ?r[ fur!r light on ! processes :i* give rise to ! deposit ( active matt] on ! electrodes4 ,footnote #bfi3 ,m4 & ,mme4 ,curie1 ,c4 ,r4 #abi1 p4 #gad1 #ahii4 ,footnote #bgj3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 & ,feb4 #aijj4 ,footnote #bga3 ,z reg>ds date ( publication1 ! priority ( ! discov]y ( 8excit$ activity0 belongs to ,m4 & ,mme4 ,curie4 ,a %ort pap] on ?is subject1 entitl$ 8,sur la radioactivit provoque p> les rayons de ,becqu]el10 0 communicat$ by !m to ! ,comptes ,r5dus1 ,nov4 #f1 #ahii4 ,a %ort note 0 add$ to ! pap] by ,becqu]el 9 :i* ! ph5om5a ( excit$ activity 7 ascrib$ to a type ( phosphoresc5ce4 ,on my "p1 ,i _h simultane\sly discov]$ ! emission ( an emanation f ?orium comp\nds & ! excit$ activity produc$ by x1 9 ,july1 #ahii4 ,i1 h[ev]1 delay$ publication 9 ord] to "w out 9 "s detail ! prop]ties ( ! emanation & ( ! excit$ activity & ! connection betwe5 !m4 ,! results 7 publi%$ 9 two pap]s 9 ! ,philosophical ,magaz9e 7,jan4 & ,feb4 #aijj7 entitl$ 8,a radio-active sub/ance emitt$ f ?orium comp\nds10 & 8,radio-activity produc$ 9 sub/ances by ! action ( ?orium comp\nds40 ,footnote #bgb3 ,ru!r=d1 ,phil4 ,mag4 ,feb4 #aijj4 ,footnote #bgc3 ,ru!r=d1 ,phys4 ,zeit4 #c1 ,no4 #ab1 p4 #bed1 #aijb4 ,phil4 ,mag4 ,jan4 #aijc4 ,footnote #bgd3 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,footnote #bge3 ,ru!r=d & ,miss ,brooks1 ,phil4 ,mag4 ,july1 #aijb4 ,footnote #bgf3 ,curie & ,danne1 ,c4 ,r4 #acf1 p4 #cfd1 #aijc4 ,footnote #bgg3 ,mme ,curie1 ,?se1 ,p>is1 #aijc1 p4 #aaf4 ,footnote #bgh3 ,debi]ne1 ,c4 ,r4 #ach1 p4 #daa1 #aijd4 ,footnote #bgi3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 ,no4 #c1 p4 #gge1 #aije4 ,footnote #bhj3 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,footnote #bha3 ,ru!r=d1 ,phys4 ,zeit4 #c1 ,no4 #ab1 p4 #bed1 #aijb4 ,footnote #bhb3 ,f4 von ,l]*1 ,annal4 d4 ,phys4 #ab1 p4 #gde1 #aijc4 ,footnote #bhc3 ,pegram1 ,phys4 ,review1 p4 #dbd1 ,dec4 #aijc4 ,footnote #bhd3 ,miss ,gates1 ,phys4 ,review1 p4 #cjj1 #aijc4 ,footnote #bhe3 ,a m complete exam9ation ( ! effect ( temp]ature on ! excit$ activity ( ?orium has be5 made by ,miss ,slat] 7section #bjg74 ,footnote #bhf3 ,ru!r=d1 ,phil4 ,mag4 ,feb4 #aijj4 ,footnote #bhg3 ,h5n+1 ,annal4 d4 ,phys4 #g1 p4 #efb1 #aijb4 ,footnote #bhh3 ,ru!r=d1 ,phil4 ,mag4 ,feb4 #aijj4 ,footnote #bhi3 ,curie & ,debi]ne1 ,c4 ,r4 #acb1 p4 #gfh1 #aija4 ,footnote #bij3 ,fehrle1 ,phys4 ,zeit4 #c1 ,no4 #g1 p4 #acj1 #aijb4 ,footnote #bia3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 #aijc4 ,footnote #bib3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 #cf1 p4 #cdb1 #aijc4 ,footnote #bic3 ,debi]ne1 ,c4 ,r4 #acf1 pp4 #ddf & #fga1 #aijc2 #ach1 p4 #daa1 #aijd4 ,,*apt] ,,ix4 ,,!ory ,,( ,,successive ,,*anges4 #aic4 ,introduction4 ,we h se5 9 previ\s *apt]s t ! radio-activity ( ! radio-elem5ts is always accompani$ by ! production ( a s]ies ( new sub/ances ) "s di/9ctive physical & *emical prop]ties4 ,= example1 ?orium produces f itself an int5sely radio-active sub/ance1 ,? ,x1 :i* c be sep>at$ f ! ?orium 9 consequ5ce ( its solubility 9 ammonia4 ,9 addition1 ?orium gives rise to a gase\s product1 ! ?orium emanation1 & also to ano!r sub/ance :i* is deposit$ on ! surface ( bodies 9 ! neighb\rhood ( ! ?orium1 :]e its pres5ce is indicat$ by ! ph5om5on kn[n z 8excit$ activity40 ,a close exam9ation ( ! orig9 ( ^! products %[s t !y are n produc$ simultane\sly1 b arise 9 consequ5ce ( a succession ( *anges orig9at+ 9 ! radio-elem5t4 ,?orium fir/ ( all gives rise to ! product ,? ,x4 ,! ,? ,x produces f itself ! ?orium emanation1 & ?is 9 turn is trans=m$ into a non-volatile sub/ance4 ,a simil> s]ies ( *anges is obs]v$ 9 radium1 ) ! exception t !re is no product 9 radium correspond+ to ! ,? ,x 9 ! case ( ?orium4 ,radium fir/ ( all produces an emanation1 :i*1 l ?orium1 is trans=m$ into a non-volatile sub/ance4 ,9 uranium only "o product1 ,ur ,x1 has be5 obs]v$1 = uranium does n give (f an emanation & 9 consequ5ce does n produce excit$ activity on bodies4 ,z a typical example ( ! evid5ce1 f :i* x is d$uc$ t "o sub/ance is ! p>5t ( ano!r1 we w consid] ! connection ( ! two products ,? ,x & ! ?orium emanation4 ,x has be5 %[n 7section #aed7 t aft] ! sep>ation ( ,? ,x f a ?orium solution1 by precipitation ) ammonia1 ! precipitat$ ?orium hydroxide has lo/ to a l>ge ext5t its p[] ( emanat+4 ,?is _c be ascrib$ to a prev5tion ( escape ( ! emanation produc$ 9 x1 = v little emanation is obs]v$ :5 a curr5t ( air is drawn ?r\gh ! hydroxide 9 a /ate ( solution1 :5 mo/ ( ! emanation pres5t w\ld be c>ri$ (f4 ,on ! o!r h&1 ! solution conta9+ ! ,? ,x gives (f a l>ge quantity ( emanation1 %[+ t ! p[] ( giv+ (f an emanation belongs to ! product ,? ,x4 ,n[ x is f\nd t ! quantity ( emanation giv5 (f by ! sep>at$ ,? ,x decreases accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 f\r days4 ,! rate ( production ( emanation ?us falls (f accord+ to ! same law & at ! same rate z ! activity ( ! ,? ,x measur$ 9 ! ord9>y mann] by ! rays4 ,n[ ?is is exactly ! result to be expect$ if ! ,? ,x is ! p>5t ( ! emanation1 = ! activity ( ,? ,x at any "t is proportional to its rate ( *ange1 i4e41 to ! rate ( production ( ! second>y type ( matt] by ! emanation 9 consequ5ce ( a *ange 9 x4 ,s9ce ! rate ( *ange ( ! emanation 7half trans=m$ 9 #a m9ute7 is v rapid comp>$ ) ! rate ( *ange ( ,? ,x1 ! am\nt ( emanation pres5t w be practically proportional to ! activity ( ! ,? ,x at any in/ant1 i4e41 to ! am\nt ( un*ang$ ,? ,x pres5t4 ,! obs]v$ fact t ! hydroxide rega9s its p[] ( emanat+ 9 ! c\rse ( "t is due to ! production ( fre% ,? ,x by ! ?orium1 :i* 9 turn produces ! emanation4 ,9 a simil> way1 excit$ activity is produc$ on bodies ov] :i* ! emanation is pass$1 & 9 am\nt proportional to ! activity ( ! emanation1 i4e41 to ! am\nt ( ! emanation pres5t4 ,?is %[s t ! active deposit1 :i* gives rise to ! ph5om5on ( excit$ activity1 is itself a product ( ! emanation4 ,! evid5ce ?us seems to be conclusive t ,? ,x is ! p>5t ( ! emanation & t ! emanation is ! p>5t ( ! deposit$ matt]4 #aid4 ,*emical & ,physical prop]ties ( ! active products4 ,ea* ( ^! radio-active products is m>k$ by "s di/9ctive *emical & physical prop]ties :i* diff]5tiate x f ! prec$+ & succe$+ products4 ,= example1 ,? ,x behaves z a solid4 ,x is soluble 9 ammonia1 :ile ?orium is n4 ,! ?orium emanation behaves z a *emically in]t gas & cond5ses at a temp]ature ( #abj ,c4 ,! active deposit f ! emanation behaves z a solid & is readily soluble 9 sulphuric & hydro*loric acids & is only slightly soluble 9 ammonia4 ,! /rik+ dissimil>ity :i* exi/s 9 _m cases betwe5 ! *emical & ! physical prop]ties ( ! p>5t matt] & ! product to :i* x gives rise is v well illu/rat$ by ! case ( radium & ! radium emanation4 ,radium is an elem5t s closely alli$ 9 *emical prop]ties to b>ium t1 ap>t f a slight diff]5ce 9 ! solubility ( ! *lorides & bromides1 x is difficult to di/+ui% *emically betwe5 !m4 ,x has a def9ite spectrum ( bright l9es simil> 9 _m respects to ! spectra ( ! alkal9e e>?s4 ,l b>ium1 x is non-volatile at ord9>y temp]ature4 ,on ! o!r h&1 ! emanation :i* is cont9ually produc$ f radium is a radio-active & *emically in]t gas1 :i* is cond5s$ at a temp]ature ( #aej ,c4 ,bo? 9 its spectrum & 9 ! abs5ce ( def9ite *emical prop]ties1 x resembles ! argon-helium gr\p ( in]t gases1 b diff]s f ^! gases 9 c]ta9 m>k$ features4 ,! emanation mu/ be consid]$ to be an un/able gas :i* breaks d[n into a non-volatile type ( matt]1 ! dis9tegration be+ accompani$ by ! expulsion ( heavy atoms ( matt] 7 p>ticles7 project$ ) great velocity4 ,?is rate ( break+ up is n affect$ by temp]ature ov] ! consid]able range :i* has be5 exam9$4 ,aft] a mon?'s int]val1 ! volume ( ! emanation has %runk to a small portion ( its initial value4 ,b ! mo/ /rik+ prop]ty ( ! emanation1 :i*1 z we %all see lat] 7*apt] ,,xii71 is a direct consequ5ce ( its radio-activity1 is ! enorm\s am\nt ( en]gy emitt$ f x4 ,! emanation 9 break+ up ?r\gh its successive /ages emits ab\t #c million times z mu* en]gy z is giv5 out by ! explosion ( an equal volume ( hydrog5 & oxyg51 mix$ 9 ! prop] proportions to =m wat]2 & yet1 9 ?is latt] *emical reaction m heat is emitt$ ?an 9 any o!r kn[n *emical *ange4 ,we h se5 t ! two emanations & ! products ,ur ,x1 ,? ,x lose _! activity ) ! "t accord+ to a simple expon5tial law1 & at a rate t is indep5d5t--z f> z obs]vation has gone--( ! *emical & physical ag5ts at our disposal4 ,! "t tak5 = ea* ( ^! products to fall to half its value is ?us a def9ite physical con/ant :i* s]ves to di/+ui% x f all o!r products4 ,on ! o!r h&1 ! v>iation ( ! excit$ activity produc$ by ^! emanations does n ev5 approximately obey su* a law4 ,! rate ( decay dep5ds n only on ! "t ( exposure to ! respective emanations1 b also1 9 ! case ( radium1 on ! type ( radiation :i* is us$ z a means ( comp>ative measurem5t4 ,x w be %[n1 9 succe$+ *apt]s1 t ! complexity ( ! decay is due to ! fact t ! matt] 9 ! active deposits und]goes sev]al successive trans=mations1 & t ! peculi>ities ( ! curves ( decay1 obta9$ "u diff]5t conditions1 c be expla9$ completely on ! assumption t two *anges occur 9 ! active deposit f bo? ?orium & act9ium & six 9 ! active deposit f radium4 #aie4 ,nom5clature4 ,! nom5clature to be appli$ to ! num]\s radio-active products is a "q ( great importance & also "o ( consid]able difficulty4 ,s9ce !re are at lea/ sev5 di/9ct sub/ances produc$ f radium1 & probably five f ?orium & act9ium1 x is nei!r advisable nor conv5i5t to give ea* a special "n su* z is appli$ to ! p>5t elem5ts4 ,at ! same "t1 x is becom+ m & m necess>y t ea* product %\ld be labell$ 9 su* a way z to indicate its place 9 ! succession ( *anges4 ,?is difficulty is especially felt 9 discuss+ ! num]\s *anges 9 ! active deposits f ! diff]5t emanations4 ,_m ( ! names atta*$ to ! products 7 giv5 at ! "t ( _! discov]y1 be=e _! position 9 ! s*eme ( *anges 0 und]/ood4 ,9 ?is way ! names ,ur ,x1 ,? ,x 7 appli$ to ! active residues obta9$ by *emical treatm5t ( uranium & ?orium4 ,s9ce1 9 all probability1 ^! sub/ances are ! fir/ products ( ! two elem5ts1 x may be advisable to reta9 ^! names1 :i* c]ta9ly h ! advantage ( brevity4 ,! "n 8emanation0 0 orig9ally giv5 to ! radio-active gas f ?orium1 & has s9ce be5 appli$ to ! simil> gase\s products ( radium & act9ium4 ,f9d+ ! "n 8radium emanation0 some:at long & clumsy1 ,sir ,william ,ramsay#bid has rec5tly sugge/$ 8ex-radio0 z an equival5t4 ,?is "n is c]ta9ly brief & is also sugge/ive ( its orig92 b at lea/ six o!r ex-radios1 ^: p>5tage is z c]ta9 z t ( ! emanation1 rema9 unnam$4 ,a difficulty arises 9 apply+ ! correspond+ names ex-?orio1 ex-act9io to ! o!r gase\s products1 =1 unlike radium1 ! emanations ( ?orium & act9ium are probably ! second1 n ! fir/1 dis9tegration product ( ! radio-elem5ts 9 "q4 ,ano!r "n ?us has to be appli$ to ! fir/ product 9 ^! cases4 ,x may be advisable to give a special "n to ! emanation1 s9ce x has be5 ! product mo/ inve/igat$ & 0 ! fir/ to be isolat$ *emically2 b1 on ! o!r h&1 ! "n 8radium emanation0 is hi/orically int]e/+1 & sugge/s a type ( volatile or gase\s matt]4 ,s9ce ! t]m 8excit$0 or 8induc$0 activity ref]s only to ! radiations f ! active body1 a "n is requir$ = ! radiat+ matt] itself4 ,! writ] 9 ! fir/ edition ( ?is book sugge/$ ! "n 8emanation ,x40#bie ,?is title 0 giv5 f analogy to ! names ,ur ,x & ,? ,x1 to indicate t ! active matt] 0 product ( ! emanation4 ,! "n1 h[ev]1 is n v suitable1 &1 9 addition1 c only be appli$ to ! initial product deposit$1 & n to ! fur!r products ( its decomposition4 ,x is v conv5i5t 9 discuss+ ma!matically ! !ory ( successive *anges to suppose t ! deposit$ matt] call$ ,a is *ang$ into ,b1 ,b into ,c1 ,c into ,d1 & s on4 ,i h !re=e disc>d$ ! "n emanation ,x1 & h us$ ! t]ms radium ,a1 radium ,b1 & s on1 to signify ! successive products ( ! decomposition ( ! emanation ( radium4 ,a simil> nom5clature is appli$ to ?orium & act9ium4 ,?is sy/em ( notation is ela/ic & simple1 & ,i h f\nd x ( great conv5i5ce 9 ! discussion ( successive products4 ,9 speak+ g5]ally ( ! active matt]1 :i* causes excit$ activity1 )\t reg>d to its con/itu5ts1 ,i h us$ ! t]m 8active deposit40 ,! s*eme ( nom5clature employ$ 9 ?is book is cle>ly %[n bel[3-- ,radium ,?orium ,uranium ,act9ium ,radium ,? ,x ,ur ,x ,act9ium ,x emanation ,radium ,a ,?orium ,f9al ,act9ium 7,active7 emanation product emanation ,radium ,b ,?orium ,act9ium 7,active7 ,a ,a 7,active7 7,active7 ,radium ,c ,?orium ,act9ium 7,active7 ,b ,b 7,active7 7,active7 ,radium ,d ,?orium ,act9ium 7,active7 ,c ,c 7f9al7 7f9al7 c4 ,ea* product on ?is s*eme is ! p>5t ( ! product bel[ x4 ,s9ce only two products h be5 obs]v$ 9 ! active deposit ( ?orium & act9ium1 ?orium ,c & act9ium ,c respectively ref] to _! f9al inactive products4 ,x w be %[n 9 ! next *apt] t1 z 9 ! case ( ?orium1 an int]m$iate product exi/s betwe5 act9ium & its emanation4 ,f analogy to ! products ,? ,x & ,ur ,x1 ?is sub/ance is t]m$ 8act9ium ,x40 #aif4 ,!ory ( ,successive ,*anges4 ,be=e consid]+ ! evid5ce f :i* ^! *anges are d$uc$1 ! g5]al !ory ( successive *anges ( radio-active matt] w be consid]$4 ,x is suppos$ t ! matt] ,a *anges into ,b1 ,b into ,c1 ,c into ,d1 & s on4 ,ea* ( ^! *anges is suppos$ to take place accord+ to ! same law z a monomolecul> *ange 9 *emi/ry1 i4e41 ! numb] ,n ( p>ticles un*ang$ aft] a "t t is giv5 by ,m ,n e-t 1 :]e ,n is ! initial numb] & ! con/ant ( ! *ange4 ,s9ce d,n_/dt -,n1 ! rate ( *ange at any "t is always proportional to ! am\nt ( matt] un*ang$4 ,x has previ\sly be5 po9t$ out t ?is law ( decay ( ! activity ( ! radio-active products is an expression ( ! fact t ! *ange is ( ! same type z a monomolecul> *emical *ange4 ,suppose t ,p1 ,q1 ,r repres5t ! numb] ( p>ticles ( ! matt] ,a1 ,b1 & ,c respectively at any "t t4 ,let 1 1 be ! con/ants ( *ange ( ! matt] ,a1 ,b1 & ,c respectively4 ,ea* atom ( ! matt] ,a is suppos$ to give rise to "o atom ( ! matt] ,b1 "o atom ( ,b to "o ( ,c1 & s on4 ,! expell$ 8rays0 or p>ticles are non-radio-active1 & s d n ent] into ! !ory4 ,x is n difficult to d$uce ma!matically ! numb] ( atoms ( ,p1 ,q1 ,r1 444 ( ! matt] ,a1 ,b1 ,c1 444 exi/+ at any "t t aft] ?is matt] is set aside1 if ! initial values ( ,p1 ,q1 ,r1 444are giv54 ,9 practice1 h[ev]1 x is g5]ally only necess>y to employ ?ree special cases ( ! !ory :i* correspond1 = example1 to ! *anges 9 ! active deposit1 produc$ on a wire expos$ to a con/ant am\nt ( radium emanation & !n remov$1 7#a7 :5 ! "t ( exposure is extremely %ort comp>$ ) ! p]iod ( ! *anges1 7#b7 :5 ! "t ( exposure is s long t ! am\nt ( ea* ( ! products has rea*$ a /eady limit+ value1 & 7#c7 = any "t ( exposure4 ,!re is also ano!r case ( importance :i* is practically a conv]se ( ,case #c1 viz4 :5 ! matt] ,a is suppli$ at a con/ant rate f a prim>y s\rce & ! am\nts ( ,a1 ,b1 ,c are requir$ at any subsequ5t "t4 ,! solution ( ?is c1 h[ev]1 be d$uc$ imm$iately f ,case #c )\t analysis4 #aig4 ,,case #a4 ,suppose t ! matt] initially consid]$ is all ( "o k9d ,a4 ,x is requir$ to f9d ! numb] ( p>ticles ,p1 ,q1 ,r ( ! matt] ,a1 ,b1 ,c respectively pres5t aft] any "t t4 ,!n ,p ne-#a t 1 if n is ! numb] ( p>ticles ( ,a initially pres5t4 ,n[ d,q1 ! increase ( ! numb] ( p>ticles ( ! matt] ,b p] unit "t1 is ! numb] suppli$ by ! *ange 9 ! matt] ,a1 less ! numb] due to ! *ange ( ,b into ,c1 ?us d,q_/dt ,p ,q 7#a74 ,simil>ly d,r_/dt ,q ,r 7#b74 ,sub/itut+ 9 7#a7 ! value ( ,p 9 t]ms ( n1 frac d,q dt #a ne-#a t #b ,q 4 ,! solution ( ?is equation is ( ! =m ,q n 7ae-#a t be-#b t7 4444447#c74 ,by sub/itution x is f\nd t a _/7 74 ,s9ce ,q #j :5 t #j1 b -7 74 ,?us ,q frac n#a #a #b 7e-#b t - e-#a t7 4444 7#d74 ,sub/itut+ ?is value ( ,q 9 7#b71 x c readily be %[n t ,r n 7ae-#a t be-#b t ce-#c t7 44444 7#e74 :]e a frac #a #b 7#a #b7 7#a - #c7 1 b frac - #a #b 7#a #b7 7#b #c7 1 c frac #a #b 7#a #c7 7#b - #c7 1 ,illu/ration3 ,fig4 #gb4 ,! v>iation ( ! values ( ,p1 ,q1 ,r ) ! "t t1 aft] removal ( ! s\rce1 is %[n graphically 9 ,fig4 #gb1 curves ,a1 ,b1 & ,c respectively4 ,9 ord] to draw ! curves = ! practical case :i* w be consid]$ lat] correspond+ to ! fir/ ?ree *anges 9 radium ,a1 ! values ( 1 1 7 tak5 z #che #aj1 #ech #aj1 #dac #aj respectively1 i4e41 ! times requir$ = ea* successive type ( matt] to be half trans=m$ are ab\t #c1 #ba1 & #bh m9utes respectively4 ,! ord9ates ( ! curves repres5t ! relative numb] ( atoms ( ! matt] ,a1 ,b1 & ,c exi/+ at any "t1 & ! value ( n1 ! orig9al numb] ( atoms ( ! matt] ,a deposit$1 is tak5 z #ajj4 ,! am\nt ( matt] ,b is initially z]o1 & 9 ?is p>ticul> case1 passes ?r\gh a maximum ab\t #aj m9utes lat]1 & !n dim9i%es ) ! "t4 ,9 a simil> way1 ! am\nt ( ,c passes ?r\gh a maximum ab\t #cg m9utes aft] removal4 ,aft] an int]val ( sev]al h\rs ! am\nt ( bo? ,b & ,c dim9i%es v approximately accord+ to an expon5tial law ) ! "t1 fall+ to half value aft] int]vals ( #ba & #bh m9utes respectively4 #aih4 ,,case #b4 ,a prim>y s\rce supplies ! matt] ,a at a con/ant rate & ! process has cont9u$ s long t ! am\nt ( ! products ,a1 ,b1 ,c1 444 has rea*$ a /eady limit+ value4 ,! prim>y s\rce is !n sudd5ly remov$4 ,x is requir$ to f9d ! am\nts ( ,a1 ,b1 ,c1 444 rema9+ at any subsequ5t "t t4 ,9 ?is case1 ! numb] n ( p>ticles ( ,a1 deposit$ p] second f ! s\rce1 is equal to ! numb] ( p>ticles ( ,a :i* *ange into ,b p] second1 & ( ,b into ,c1 & s on4 ,?is requires ! relation n ,p ,q ,r 7#f71 :]e ,p1 ,q1 ,r are ! maximum numb]s ( p>ticles ( ! matt] ,a1 ,b1 & ,c :5 a /eady /ate is rea*$4 ,! values ( ,p1 ,q1 ,r at any "t t aft] removal ( ! s\rce are giv5 by equations ( ! same =m z 7#c7 & 7#e7 = a %ort exposure4 ,rememb]+ ! condition t initially ,p ,p n_/1 ,q ,q n_/1 ,r ,r n_/1 x c readily be %[n t ,p frac n #a e-#a t 4444 7#g71 ,q frac n #a #b 7frac #a #b e-#b t e-#a t7 4444 7#h71 ,r n 7ae-#a t be-#b t ce-#c t7 4444 7#i71 :]e a frac #b 7#a #b7 7#a - #c7 1 b frac -#a 7#a #b7 7#b - #c7 1 c frac #a #b #c 7#a #c7 7#b #c7 4 ,illu/ration3 ,fig4 #gc4 ,! relative numb]s ( atoms ( ,p1 ,q1 ,r exi/+ at any "t are %[n graphically 9 ,fig4 #gc1 curves ,a1 ,b1 ,c respectively4 ,! numb] ( atoms ,r is tak5 z #ajj = comp>ison1 & ! values ( 1 1 are tak5 correspond+ to ! #c1 #ba1 & #bh-m9ute *anges 9 ! active deposit ( radium4 ,a comp>ison ) ,fig4 #gb = a %ort exposure br+s out v cle>ly ! v>iation 9 ! relative am\nts ( ,p1 ,q1 ,r 9 ! two cases4 ,initially ! am\nt ( ,r decreases v sl[ly4 ,?is is a result ( ! fact t ! supply ( ,c due to ! break+ up ( ,b at fir/1 ne>ly comp5sates = ! break+ up ( ,c4 ,! values ( ,q & ,r aft] sev]al h\rs decrease expon5tially1 fall+ to half value 9 #bh m9utes4 #aii4 ,,case #c4 ,suppose t a prim>y s\rce has suppli$ ! matt] ,a at a con/ant rate = any "t ,t & is !n sudd5ly remov$4 ,requir$ ! am\nts ( ,a1 ,b1 ,c at any subsequ5t "t4 ,suppose t n p>ticles ( ! matt] ,a are deposit$ ea* second4 ,aft] a "t ( exposure ,t1 ! numb] ( p>ticles ,p,t ( ! matt] ,a pres5t is giv5 by ,p,t n int,t e-#a t dt frac n #a 7#a - e-#a ,t7 4 ,at any "t t1 aft] removal ( ! s\rce1 ! numb] ( p>ticles ,p ( ! matt] ,a is giv5 by ,p ,p,t e-#a t frac n #a 7#a e-#a ,t7 e-#a t 4 ,consid] ! numb] ( p>ticles ndt ( ! matt] ,a produc$ dur+ ! int]val dt4 ,at any lat] "t t1 ! numb] ( p>ticles d,q ( ! matt] ,b1 :i* result f ! *ange 9 ,a1 is giv5 7see equation #d7 by d,q frac n #a #a #b 7e-#b t e-#a t7 dt n f7t7 dt 4444 7#aj74 ,aft] a "t ( exposure ,t1 ! numb] ( p>ticles ,q,t ( ! matt] ,b pres5t is readily se5 to be giv5 by ,q,t n 7f7,t7 dt f7,t dt7 dt 444 f7#j7 dt7 n int,t f7t7 dt 4 ,if ! body is remov$ f ! emanation aft] an exposure ,t1 at any lat] "t t ! numb] ( p>ticles ( ,b is 9 ! same way giv5 by ,q n intt,tt f7t7 dt 4 ,x w be not$ t ! me?od ( d$uction ( ,q,t & ,q is indep5d5t ( ! p>ticul> =m ( ! function f7t74 ,sub/itut+ ! p>ticul> value ( f7t7 giv5 9 equation 7#aj7 & integrat+1 x c readily be d$uc$ t frac ,q ,q,t frac ae-#b t be-#a t a - b 4444 7#aa71 :]e a frac 7#a e-#b ,t #b 1 b frac 7#a e-#a ,t #a 1 ,9 a simil> way1 ! numb] ( p>ticles ,r ( ! matt] ,c pres5t at any "t c be d$uc$ by sub/itution ( ! value ( f7t7 9 equation 7#e74 ,^! equations are1 h[ev]1 too complicat$ 9 =m = simple application to exp]im5t1 & w n be consid]$ "h4 #bjj4 ,,case #d4 ,! matt] ,a is suppli$ at a con/ant rate f a prim>y s\rce4 ,requir$ to f9d ! numb] ( p>ticles ( ,a1 ,b1 ,c at any subsequ5t "t t1 :5 initially ,a1 ,b1 ,c are abs5t4 ,! solution c be simply obta9$ 9 ! foll[+ way4 ,suppose t ! conditions ( ,case #b are fulfill$4 ,! products ,a1 ,b1 ,c are 9 radio-active equilibrium & let ,p1 ,q1 ,r be ! numb] ( p>ticles ( ea* pres5t4 ,suppose ! s\rce is remov$4 ,! values ( ,p1 ,q1 ,r at any subsequ5t "t are giv5 by equations 7#g71 7#h7 & 7#i7 respectively4 ,n[ suppose ! s\rce1 :i* has be5 remov$1 /ill cont9ues to supply ,a at ! same con/ant rate & let ,p1 ,q1 ,r be ! numb] ( p>ticles ( ,a1 ,b1 ,c aga9 pres5t ) ! s\rce at any subsequ5t "t4 ,n[ we h se51 t ! rate ( *ange ( any individual product1 consid]$ by itself1 is indep5d5t ( conditions & is ! same :e!r ! matt] is mix$ ) ! p>5t sub/ance or remov$ f x4 ,s9ce ! values ( ,p1 ,q1 ,r repres5t a /eady /ate :]e ! rate ( supply ( ea* k9d ( matt] is equal to its rate ( *ange1 ! sum ( ! numb] ( p>ticles ,a1 ,b1 ,c pres5t at any "t ) ! s\rce1 & 9 ! matt] f :i* x 0 remov$1 mu/ at all times be equal to ,p1 ,q1 ,r1 4441 t is ,p ,p ,p1 ,q ,q ,q1 ,r ,r ,r4 ,?is mu/ obvi\sly be ! case1 = o!rwise !re w\ld be a de/ruction or creation ( matt] by ! m]e process ( sep>ation ( ! s\rce f its products2 b1 by hypo!sis1 nei!r ! rate ( supply f ! s\rce1 nor ! law ( *ange ( ! products1 has be5 9 any way alt]$ by removal4 ,sub/itut+ ! values ( ,p1 ,q1 ,r f equations 7#g71 7#h71 & 7#i71 we obta9 frac ,p#a ,p #a e-#a t 1 frac ,q#a ,q #a frac 7#a e-#b t - #b;e-#a t7 #a #b 1 frac ,r#a ,r #a #c 7ae-#a t be-#b t ce-#c t7 1 :]e a1 b1 & c h ! values giv5 aft] equation 7#i74 ,! curves repres5t+ ! increase ( ,p1 ,q1 ,r1 are ?us1 9 all cases1 complem5t>y to ! curves %[n 9 ,fig4 #gc4 ,! sum ( ! ord9ates ( ! two curves ( rise & decay at any "t is equal to #ajj4 ,we h already se5 examples ( ?is 9 ! case ( ! decay & recov]y curves ( ,ur ,x & ,? ,x4 #bja4 ,activity ( a mixture ( products4 ,9 ! previ\s calculations we h se5 h[ ! numb] ( p>ticles ( ea* ( ! successive products v>ies ) ! "t "u diff]5t conditions4 ,x is n[ necess>y to consid] h[ ?is numb] is connect$ ) ! activity ( ! mixture ( products4 ,if ,n is ! numb] ( p>ticles ( a product1 ! numb] ( p>ticles break+ up p] second is ,n1 :]e is ! con/ant ( *ange4 ,if ea* p>ticle ( ea* product1 9 break+ up1 emits "o p>ticle1 we see t ! numb] ( p>ticles expell$ p] second f ! mixture ( products at any "t is equal to ,p ,q ,r 4441 :]e ,p1 ,q1 ,r1 444 are ! numb]s ( p>ticles ( ! successive products ,a1 ,b1 ,c1 4444 ,sub/itut+ ! values ( ,p1 ,q1 ,r already f\nd f any "o ( ! f\r cases previ\sly consid]$1 ! v>iation ( ! numb] ( p>ticles expell$ p] second ) ! "t c be det]m9$4 ,! ideal me?od ( measur+ ! activity ( any mixture ( radio-active products w\ld be to det]m9e ! numb] ( or p>ticles expell$ f x p] second4 ,9 practice1 h[ev]1 ?is is inconv5i5t & also v difficult exp]im5tally4 ,c]ta9 practical difficulties arise 9 endeav\r+ to comp>e ! activity ( "o product ) ano!r4 ,we %all see lat] t1 9 _m cases1 all ( ! successive products d n emit rays4 ,"s give out & rays alone1 :ile !re are sev]al 8rayless0 products1 t is1 products :i* d n emit ei!r 1 1 or rays4 ,9 ! case ( radium1 = example1 radium ,a gives out only rays1 radium ,b no rays at all1 :ile radium ,c gives out 1 1 & rays4 ,9 practice1 ! relative activity ( any individual product at any "t is usually det]m9$ by relative measurem5ts ( ! saturation ionization curr5t produc$ betwe5 ! electrodes ( a suitable te/+ vessel4 ,let u consid]1 = example1 ! case ( a product :i* gives out only rays4 ,! passage ( ! p>ticles ?r\gh ! gas produces a l>ge numb] ( ions 9 its pa?4 ,s9ce ! p>ticles f any individual product are project$ ) ! same av]age velocity "u all conditions1 ! relative am\nt ( ! ionization produc$ p] second 9 ! te/+ vessel s]ves z an accurate means ( det]m9+ ! v>iation ( its activity4 ,no two products1 h[ev]1 emit p>ticles ) ! same av]age velocity4 ,we h se5 t ! rays f "s products are m readily /opp$ 9 ! gas ?an o!rs4 ,?us ! relative saturation curr5t1 due to two diff]5t products 9 a te/+ vessel1 does n s]ve z an accurate me?od ( comp>+ ! relative numb] ( p>ticles expell$ p] second4 ,! ratio ( ! curr5ts w 9 g5]al dep5d ^u ! di/ance betwe5 ! plates ( ! te/+ vessel1 &1 unless ! relative ionization due to ! av]age p>ticle f ! two products is kn[n f o!r data1 ! comp>ison ( ! curr5ts c1 at be/1 be only an approximate guide to ! relative numb] ( p>ticles escap+ into ! gas4 #bjb4 ,"s examples w n[ be consid]$ to %[ h[ ! factors1 above consid]$1 influ5ce ! "* ( ! curves ( activity obta9$ "u diff]5t exp]im5tal conditions4 ,= ! purpose ( illu/ration1 we %all consid] ! v>iation aft] removal ( ! excit$ activity on a body expos$ = diff]5t times to a con/ant supply ( ! radium emanation4 ,! active deposit on removal consi/s 9 g5]al ( a mixture ( ! products radium ,a1 ,b1 & ,c4 ,! nature ( ! rays f ea* product1 ! "t = ea* product to be trans=m$1 & ! value ( are tabulat$ bel[ = conv5i5ce3-- ,product ,rays ,t4 7sec7 ,radium ,a rays #c m94 #che #aj ,radium ,b no rays #ba m94 #ech #aj ,radium ,c 1 1 #bh m94 #dac rays #aj ,s9ce only ! product ,c gives rise to & rays1 ! activity measur$ by ei!r ( ^! types ( rays w be proportional to ! am\nt ( ,c pres5t at any "t1 i4e4 to ! value ( ,r at any "t4 ,= a long exposure1 ! v>iation ( activity ) "t measur$ by ! & rays w ?us be repres5t$ by ! upp] curve ,,cc ( ,fig4 #gc1 :]e ! ord9ates repres5t activity4 ,?is curve w be se5 to be v simil> 9 %ape to ! exp]im5tal curve = a long exposure :i* is giv5 9 ,fig4 #fh4 ,s9ce radium ,b does n give out rays1 ! numb] ( p>ticles expell$ f ! active deposit p] second is proportional to ,p ,r4 ,! activity measur$ by ! rays1 us+ ! electrical me?od1 is ?us proportional at any "t to ,p ,k,r1 :]e ,k is a con/ant :i* repres5ts ! ratio ( ! numb] ( ions1 produc$ 9 ! te/+ vessel1 by an p>ticle f ,c comp>$ ) t f an p>ticle emitt$ by ,a4 ,x w be se5 lat] t1 = ?is p>ticul> case1 ,k is ne>ly unity4 ,tak+ ,k #a1 ! activity at any "t aft] removal is proportional to ,p ,r4 ,,case #a4 ,we %all fir/ consid] ! activity curve = a %ort exposure to ! radium emanation4 ,! relative values ( ,p1 ,q1 & ,r at any "t correspond+ to ?is case are graphically %[n 9 ,fig4 #gd4 ,! activity measur$ by ! rays at any "t w be ! sum ( ! activities due to ,a & ,c sep>ately4 ,let curve ,,aa 7,fig4 #gd7 repres5t ! activity due to ,a4 ,?is decreases expon5tially1 fall+ to half value 9 #c m9utes4 ,9 ord] to %[ ! small activity due to ,c cle>ly 9 ! ,figure1 ! activity due to ,a is plott$ aft] an int]val ( #f m9utes1 :5 ! activity has be5 r$uc$ to #be p] c5t4 ( its maximum value4 ,! activity due to ,c is proportional to ,r1 & 9 ord] to repres5t ! activity due to ,c to ! same scale z ,a1 x is necess>y to r$uce ! scale ( ! ord9ates ( curve ,,cc 9 ,fig4 #gb 9 ! ratio _/4 ,illu/ration3 ,fig4 #gd4 ,! activity due to ,c is ?us repres5t$ by ! curve ,,ccc1 ,fig4 #gd4 ,! total activity is ?us repres5t$ by a curve ,a ,c ^: ord9ates are ! sum ( ! ord9ates ( ,a & ,c4 ,?is !oretical activity curve is se5 to be v simil> 9 its g5]al features to ! exp]im5tal curve %[n 9 ,fig4 #ff1 :]e ! activity f a v %ort exposure is measur$ by ! rays4 ,,case #b4 ,! activity curve = a long exposure to ! emanation w n[ be consid]$4 ,! activity aft] removal ( ,a & ,c is proportional to ,p ,r1 :]e ! values ( ,p & ,r are graphically %[n 9 ,fig4 #ge by ! curves ,,aa1 ,,cc4 ,initially aft] removal1 ,p ,r1 s9ce ,a & ,c are 9 radio-active equilibrium1 & ! same numb] ( p>ticles ( ea* product break up p] second4 ,! activity due to ,a alone is %[n 9 curve ,,aa1 ,fig4 #ge4 ,! activity decreases expon5tially1 fall+ to half value 9 #c m9utes4 ,! activity due to ,c at any "t is proportional to ,r1 & is initially equal to t ( ,a4 ,! activity curve due to ,c is ?us repres5t$ by ! curve ,,cc1 :i* is ! same curve z ! upp] curve ,,cc ( ,fig4 #gc4 ,! activity ( ,a & ,c toge!r is repres5t$ by ! upp] curve ,a ,c 7,fig4 #ge71 :]e ! ord9ates are equal to ! sum ( ! ord9ates ( ! curves ,a & ,c4 ,?is !oretical curve is se5 to be v simil> 9 %ape to ! exp]im5tal curve 7,fig4 #fg7 %[+ ! decay ( activity ( ! active deposit f a long exposure measur$ by ! rays4 ,illu/ration3 ,fig4 #ge4 #bjc4 ,effect ( a rayless *ange on ! activity curves4 ,c]ta9 important cases occur 9 ! analysis ( radio-active *anges1 :5 "o ( ! products does n give rise to rays & s _c be detect$ directly4 ,! pres5ce ( ?is rayless *ange c1 h[ev]1 be readily obs]v$ by ! v>iations :i* occur 9 ! activity ( ! succe$+ product4 ,let u consid]1 = example1 ! case :]e ! inactive matt] ,a1 initially all ( "o k9d1 *anges into ! matt] ,b :i* gives out rays4 ,! inactive matt] ,a is suppos$ to be trans=m$ accord+ to ! same law z ! radio-active products4 ,let 1 be ! con/ants ( ! *ange ( ,a & ,b respectively4 ,if n is ! numb] ( p>ticles ( ,a1 initially pres5t1 we see f ! equation 7#d71 section #aig1 t ! numb] ( p>ticles ( ! matt] ,b pres5t at any "t is giv5 by ,q frac n#a #a #b 7e-#b t - e#a t7 4 ,diff]5tiat+ & equat+ to z]o1 x is se5 t ! value ( ,q passes ?r\gh a maximum at a "t ,t giv5 by ! equation #b e-#b ,t #a e-#a ,t 4 ,= ! sake ( illu/ration1 we %all consid] ! v>iation ( ! activity ( ! active deposit ( ?orium1 due to a v %ort exposure to ! emanation4 ,?orium ,a gives out no rays1 & ?orium ,b gives out 1 1 & rays1 :ile ?orium ,c is inactive4 ,! matt] ,a is half trans=m$ 9 #aa h\rs1 & ,b is half trans=m$ 9 #ee m9utes4 ,! value ( #age x #aj7sec47 & #bjh x #aj7sec474 ,! activity ( ! mixture ( products ,a ,b is due to ,b alone1 & w1 9 consequ5ce1 be always proportional to ! am\nt ( ,b pres5t1 t is1 to ! value ( ,q4 ,illu/ration3 ,fig4 #gf4 ,! v>iation ( activity ) "t is %[n graphically 9 ,fig4 #gf4 ,! activity rises f z]o to a maximum 9 #bbj m9utes & !n decays1 f9ally decreas+1 accord+ to an expon5tial law1 ) ! "t1 fall+ to half value 9 #aa h\rs4 ,?is !oretical curve is se5 to agree closely 9 %ape ) ! exp]im5tal curve 7,fig4 #fe71 :i* %[s ! v>iation ( ! activity ( ! active deposit ( ?orium1 produc$ by a %ort exposure 9 pres5ce ( ! emanation4 ,!re are sev]al po9ts ( int]e/ 9 connection ) an activity curve ( ?is "*4 ,! activity1 "s h\rs aft] removal1 decays accord+ to an expon5tial law1 n at ! rate ( ! product ,b1 f :i* ! activity rises1 b at ! same rate z ! fir/ rayless trans=mation4 ,?is w also be ! case if ! rayless product has a sl[] rate ( *ange ?an ! succe$+ active product4 ,giv5 an activity curve ( ! "* ( ,fig4 #gf1 we c d$uce f x t ! fir/ *ange is n accompani$ by rays & also ! p]iod ( ! two *anges 9 "q4 ,we are1 h[ev]1 unable to det]m9e f ! curve :i* ( ! p]iods ( *ange ref]s to ! rayless product4 ,x is se5 t ! activity curve is unalt]$ if ! values ( 1 1 t is1 if ! p]iods ( ! products are int]*ang$1 = ! equation is symmetrical 9 1 4 ,= example1 9 ! case ( ! active deposit ( ?orium1 )\t fur!r data x is impossible to decide :e!r ! p]iod ( ! fir/ *ange has a value ( #ee m9utes or #aa h\rs4 ,9 su* cases ! "q c only be settl$ by us+ "s physical or *emical means 9 ord] to sep>ate ! product ,a f ,b1 & !n te/+ ! rate ( decay ( _! activity sep>ately4 ,9 practice1 ?is c (t5 be effect$ by electrolysis or by utiliz+ ! diff]5ce 9 volatility ( ! two products4 ,if n[ a product is sep>at$ f ! mixture ( ,a & ,b :i* loses its activity accord+ to an expon5tial law1 fall+ to half value 9 #ee m9utes 7& su* is exp]im5tally obs]v$71 we c at once conclude t ! active product ,b has ! p]iod ( #ee m9utes4 ,! *>act]i/ic features ( ! activity curve %[n 9 ,fig4 #gf becomes less m>k$ ) increase ( ! "t ( exposure ( a body to ! emanation1 t is1 :5 m & m ( ,b is mix$ ) ,a at ! "t ( removal4 ,= a long "t ( exposure1 :5 ! products ,a & ,b are 9 radio-active equilibrium1 ! activity aft] removal is proportional to ,q1 :]e ,q frac n #a #b 7frac #a #b e-#b t e#a t7 1 7see equation #h1 section #aih74 ,! value ( ,q1 9 ?is case1 does n increase aft] removal1 b at once comm5ces to dim9i%4 ,! activity1 9 consequ5ce1 decreases f ! mom5t ( removal1 b m sl[ly ?an w\ld be giv5 by an expon5tial law4 ,! activity f9ally decays expon5tially1 z 9 ! previ\s case1 fall+ to half value 9 #aa h\rs4 ,9 ! previ\s case we h discuss$ ! activity curve obta9$ :5 bo? ! active & inactive product h comp>atively rapid rates ( trans=mation4 ,9 c]ta9 cases :i* arise 9 ! analysis ( ! *anges 9 act9ium & radium1 ! rayless product has a rate ( *ange extremely sl[ comp>$ ) t ( ! active product4 ,?is corresponds to ! case :]e ! active matt] ,b is suppli$ f ,a at a con/ant rate4 ,! activity curve w ?us be id5tical 9 =m ) ! recov]y curves ( ,? ,x & ,ur ,x1 t is1 ! activity ,i at any "t t w be repres5t$ by ! equation frac ,it ,i #a e-#b t 1 :]e ,i is ! maximum value ( ! activity & ! con/ant ( *ange ( ,b4 #bjd4 ,9 ?is *apt] we h consid]$ ! v>iation ) "t1 "u diff]5t conditions1 ( ! numb] ( atoms ( ! successive products1 :5 ! p]iod & numb] ( ! *anges are giv54 ,x has be5 se5 t ! activity curves to be expect$ "u v>i\s conditions c be readily d$uc$ f ! simple !ory4 ,9 practice1 h[ev]1 ! inve/igator has be5 fac$ ) ! mu* m difficult inv]se problem ( d$uc+ ! p]iod1 numb]1 & "* ( ! products1 by analysis ( ! activity curves obta9$ "u v>i\s conditions4 ,9 ! case ( radium1 :]e at lea/ sev5 di/9ct *anges occur1 ! problem has be5 "o ( consid]able difficulty1 & a solution has only be5 possible by devis+ special physical & *emical me?ods ( isolation ( "s ( ! products4 ,we %all see lat] t two rayless *anges occur 9 radium & act9ium & "o 9 ?orium4 ,x is at fir/ sight a v /rik+ fact t ! pres5ce ( a sub/ance :i* does n emit rays c be detect$1 & its prop]ties inve/igat$4 ,?is is only possible :5 ! rayless product is trans=m$ into ano!r sub/ance :i* emits rays2 = ! v>iation ( ! activity ( ! latt] may be su* z to det]m9e n only ! p]iod b also ! physical & *emical prop]ties ( ! p>5t product4 ,9 ! two foll[+ *apt]s ! application ( ! !ory ( successive *anges w be %[n to acc\nt satisfactorily = ! complicat$ processes occurr+ 9 ! radio-elem5ts4 ,footnote #bid3 ,ramsay1 ,proc4 ,roy4 ,soc4 p4 #dgj1 ,june1 #aijd2 ,c4 ,r4 #ach1 ,june #f1 #aijd4 ,footnote #bie3 ,phil4 ,mag4 ,febru>y1 #aijd4 ,,*apt] ,x4 ,,trans=mation ,,products ,,( ,,uranium1 ,,?orium1 ,,& ,,act9ium4 #bje4 ,9 ! la/ *apt] ! ma!matical !ory ( successive *anges has be5 consid]$4 ,! results !re obta9$ w n[ be appli$ to expla9 ! radio-active ph5om5a obs]v$ ) uranium1 ?orium1 act9ium1 radium1 & _! products4 ,trans=mation products ( ,uranium4 ,x has be5 %[n 9 sections #abg & #abi t a radio-active con/itu5t ,ur ,x c be sep>at$ f uranium by sev]al diff]5t processes4 ,! activity ( ! sep>at$ ,ur ,x decays ) ! "t1 fall+ to half value 9 ab\t #bb days4 ,at ! same "t ! uranium1 f :i* ! ,ur ,x has be5 sep>at$1 gradually rega9s its lo/ activity4 ,! laws ( decay ( ,ur ,x & ( ! recov]y ( ! lo/ activity ( ! uranium are express$ by ! equations frac ,i ,i e-t 1 & frac ,it ,i #a e-t 1 :]e is ! radio-active con/ant ( ,ur ,x4 ,! sub/ance ,ur ,x is produc$ f uranium at a con/ant rate1 & ! con/ant radio-activity obs]v$ 9 uranium repres5ts a /ate ( equilibrium1 :]e ! rate ( production ( new active matt] is balanc$ by ! rate ( *ange ( ! ,ur ,x already produc$4 ,! radio-active processes occurr+ 9 uranium pres5t sev]al po9ts ( diff]5ce f ! processes occurr+ 9 ?orium & radium4 ,9 ! fir/ place1 uranium does n give (f an emanation1 & 9 consequ5ce does n produce any excit$ activity on bodies4 ,s f> only "o active product ,ur ,x has be5 obs]v$ 9 uranium4 ,?is active product ,ur ,x diff]s f ,? ,x & ! emanations1 inasmu* z ! radiation f x consi/s almo/ entirely ( rays4 ,?is peculi>ity ( ! radiations f ,ur ,x initially l$ to "s confusion 9 ! int]pretation ( obs]vations on ,ur ,x & ! uranium f :i* x _h be5 sep>at$4 ,:5 exam9$ by ! photographic me?od1 ! uranium fre$ f ,ur ,x %[$ no activity1 :ile ! ,ur ,x possess$ x to an int5se degree4 ,) ! electric me?od1 on ! o!r h&1 ! results obta9$ 7 exactly ! rev]se4 ,! uranium fre$ f ,ur ,x %[$ v little loss ( activity1 :ile ! activity ( ! ,ur ,x 0 v small4 ,! explanation ( ^! results 0 giv5 by ,soddy#bif & by ,ru!r=d & ,gri]#big4 ,! rays ( uranium are photographically almo/ inactive1 b produce mo/ ( ! ionization 9 ! gas4 ,! rays1 on ! o!r h&1 produce a /rong photographic action1 b v little ionization comp>$ ) ! rays4 ,:5 ! ,ur ,x is sep>at$ f ! uranium1 ! uranium does n at fir/ give out any rays4 ,9 ! c\rse ( "t fre% ,ur ,x is produc$ f ! uranium1 & rays beg9 to appe>1 gradually increas+ 9 int5sity until !y rea* ! orig9al value %[n be=e ! sep>ation ( ! ,ur ,x4 ,9 ord] to det]m9e ! recov]y curves ( uranium aft] ! sep>ation ( ,ur ,x1 x 0 ?us necess>y to measure ! rate ( increase ( ! rays4 ,?is 0 done by cov]+ ! uranium ) a lay] ( alum9ium ( suffici5t ?ickness to absorb all ! rays1 & !n measur+ ! ionization due to ! rays 9 an app>atus simil> to ,fig4 #ag4 ,uranium has n yet be5 obta9$ inactive :5 te/$ by ! electric me?od4 ,becqu]el#bih has /at$ t he 0 able to obta9 inactive uranium1 b 9 8 exp]im5ts ! uranium 0 cov]$ ) a lay] ( black pap]1 :i* w\ld entirely absorb ! rays4 ,!re is no evid5ce t ! radiation ( uranium has be5 alt]$ ei!r 9 "* or am\nt by any *emical treatm5t4 ,! rays appe> to be insep>able f ! uranium1 & x w be %[n lat] t ?orium & radium z well z uranium also possess a non-sep>able activity consi/+ entirely ( rays4 ,! *anges occurr+ 9 uranium mu/ !n be consid]$ to be ( two k9ds1 7#a7 ! *ange :i* gives rise to ! rays & ! product ,ur ,x1 7#b7 ! *ange :i* gives rise to ! rays f ,ur ,x4 ,! possibility ( sep>at+ ! ,ur ,x1 :i* gives rise to ! rays ( uranium1 %[s t ! & rays are produc$ q indep5d5tly ( "o ano!r1 & by matt] ( diff]5t *emical prop]ties4 ,foll[+ ! g5]al consid]ations discuss$ 9 section #acf we may suppose t e second "s ( ! atoms ( uranium--a v m9ute fraction ( ! total numb] pres5t w suffice--become un/able & break up1 expell+ an p>ticle ) great velocity4 ,! uranium atom1 m9us "o p>ticle1 becomes ! atom ( ! new sub/ance1 ,ur ,x4 ,?is 9 turn is un/able & breaks up ) ! expulsion ( ! p>ticle & ! appe>ance ( a ray4 ,! *anges occurr+ 9 uranium are graphically %[n 9 ,fig4 #gg4 ,illu/ration3 ,fig4 #gg4 ,on ?is view ! ray activity ( uranium %\ld be an inh]5t prop]ty ( ! uranium1 & %\ld be non-sep>able f x by physical or *emical means4 ,! & ray activity ( uranium is a prop]ty ( ,ur ,x1 :i* diff]s 9 *emical prop]ties f ! p>5t sub/ance & c at any "t be completely remov$ f x4 ,! f9al product1 aft] ! decay ( ,ur ,x1 is s slightly active t its activity has n yet be5 obs]v$4 ,we %all see lat] 7*apt] ,,xiii47 t !re is "s reason to believe t ! *anges 9 uranium d n end at ?is po9t b cont9ue ?r\gh "o or m /ages1 f9ally giv+ rise to radium1 or 9 o!r words t radium is a product ( ! dis9tegration ( ! uranium atom4 ,mey] & ,s*weidl]#bii1 9 a rec5t pap]1 /ate t ! activity due to uranium prep>ations increases some:at 9 a clos$ vessel4 ,on remov+ ! uranium no residual activity1 h[ev]1 0 obs]v$4 ,!y consid] t ?is effect may be due to a v %ort-liv$ emanation emitt$ by uranium4 #bjf4 ,effect ( cry/allization on ! activity ( uranium4 ,mey] & ,s*weidl]#cjj rec5tly obs]v$ t uranium nitrate1 aft] c]ta9 me?ods ( treatm5t1 %[$ rem>kable v>iations ( its activity1 measur$ by ! rays4 ,! ray activity1 on ! o!r h&1 0 unalt]$4 ,"s uranium nitrate 0 dissolv$ 9 wat] & !n %ak5 up ) e!r1 & ! e!r fraction drawn (f4 ,! e>ly exp]im5ts ( ,crookes %[$ t1 by ?is me?od1 ! uranium 9 ! e!r portion 0 photographically inactive4 ,?is is simply expla9$ by suppos+ t ! uranium ,x is insoluble 9 e!r1 & consequ5tly rema9$ beh9d 9 ! wat] fraction4 ,! e!r fraction gradually rega9$ its ray activity at ! normal rate to be expect$ if ,ur ,x 0 produc$ by ! uranium at a con/ant rate1 = x recov]$ half its f9al activity 9 ab\t #bb days4 ,"s ( ! uranium 9 ! wat] fraction 0 cry/alliz$ & plac$ "u an electroscope4 ,! ray activity fell rapidly at fir/ to half its value 9 ! c\rse ( f\r days4 ,! activity !n rema9$ con/ant1 & no fur!r *ange 0 obs]v$ ov] an int]val ( "o mon?4 ,o!r exp]im5ts 7 made ) cry/als ( uranium nitrate1 :i* _h n be5 treat$ ) e!r4 ,! nitrate 0 dissolv$ 9 wat] & a lay] ( cry/als sep>at$4 ,! ray activity ( ^! cry/als fell rapidly at fir/1 ! rate v>y+ some:at 9 diff]5t exp]im5ts1 b rea*$ a m9imum value aft] ab\t five days4 ,! ray activity !n rose aga9 at a sl[ rate = sev]al mon?s4 ,! rapid drop ( activity ( ! cry/als seem$1 at fir/ sight1 to indicate t cry/allization 0 able 9 "s way to alt] ! activity ( uranium4 ,dr ,godlewski1 work+ 9 ! laboratory ( ! writ]1 repeat$ ! "w ( ,mey] & ,s*weidl]1 & obta9$ results ( a simil> "*1 b ! initial drop ( activity 0 f\nd to v>y bo? 9 rate & am\nt 9 diff]5t exp]im5ts4 ,^! results 7 at fir/ v puzzl+ & difficult to expla91 = ! "m liquor1 left beh9d aft] removal ( ! cry/als1 did n %[ ! correspond+ initial rise1 :i* w\ld be expect$ if ! v>iation ( activity 7 due to ! p>tial sep>ation ( "s new product ( uranium4 ,! cause ( ?is effect 01 h[ev]1 r5d]$ v evid5t by a few well-consid]$ exp]im5ts made by ,godlewski4 ,! uranium nitrate 0 dissolv$ 9 hot wat] 9 a flat di%1 & all[$ to cry/allize "u ! electroscope4 ,up to ! mom5t ( cry/allization ! ray activity rema9$ con/ant1 b z soon z ! cry/als comm5c$ to =m at ! bottom ( ! solution ! ray activity rapidly rose 9 ! c\rse ( a few m9utes to five times ! initial value4 ,aft] rea*+ a maximum1 ! activity v gradually decreas$ aga9 to ! normal value4 ,if1 h[ev]1 ! plate ( cry/als 0 rev]s$1 ! ray activity 0 f\nd at fir/ to be mu* small] ?an ! normal1 b increas$ z fa/ z t ( ! o!r side dim9i%$4 ,! explanation ( ?is effect is simple4 ,ur ,x is v soluble 9 wat] &1 at fir/1 does n cry/allize ) ! uranium1 b rema9s 9 ! solution1 &1 consequ5tly1 :5 ! cry/allization comm5ces at ! bottom ( ! vessel ! upp] lay] ( liquid becomes ri*] 9 uranium ,x4 ,s9ce ! rays arise only f ! product ,ur ,x & n f ! uranium itself1 & ! ,ur ,x is mo/ly conf9$ to ! upp] lay]1 a mu* great] proportion ( ! rays escape ?an if ! ,ur ,x 7 uni=mly di/ribut$ ?r\gh\t ! ?ick lay] ( uranium4 ,:5 ! am\nt ( wat] add$ is j suffici5t to supply ! wat] ( cry/allization1 ! ,ur ,x 9 ! upp] lay] ( cry/als gradually diffuses back ?r\gh ! mass &1 9 consequ5ce1 ! activity ( ! upp] surface dim9i%es & ( ! l[] surface rises4 ,a simil> explanation applies to ! effects obs]v$ by ,mey] & ,s*weidl]4 ,! wat] fraction1 left beh9d aft] treatm5t ) e!r1 conta9$ all ! ,ur ,x4 ,! fir/ lay] ( cry/als =m$ 9 x conta9$ "s ,ur ,x1 & ?is 0 = ! mo/ "p conf9$ to ! top lay] ( cry/als4 ,! am\nt ( rays at fir/ dim9i%$ ow+ to ! gradual diffusion ( ! ,ur ,x f ! surface4 ,9 ! fir/ exp]im5t1 ! am\nt ( ,ur ,x pres5t 0 9 radio-active equilibrium ) ! uranium1 &1 aft] ! initial drop1 ! ray activity rema9$ con/ant4 ,9 ! second exp]im5t1 ! gradual rise is due to ! fact t ! cry/als ( uranium fir/ =m$ conta9$ less ?an ! equilibrium am\nt ( ,ur ,x4 ,aft] fall+ to a m9imum1 ! ray activity1 9 consequ5ce1 sl[ly rose aga9 to ! equilibrium value4 ,^! effects exhibit$ by uranium are ( great int]e/1 & illu/rate 9 a /rik+ mann] ! diff]5ce 9 prop]ties ( ,ur ,x & ! uranium4 ,! gradual diffusion ( ! ,ur ,x ?r\gh\t ! mass ( cry/als is notewor?y4 ,by measurem5ts ( ! v>iation ) "t ( ! ray activity1 x %\ld be possible to d$uce its rate ( diffusion into ! cry/alliz$ mass4 ,trans=mation products ( ,?orium4 #bjg4 ,analysis ( ! active deposit4 ,! radio-active processes occurr+ 9 ?orium are f> m complicat$ ?an ^? 9 uranium4 ,x has already be5 %[n 9 *apt] vi t a radio-active product ,? ,x is cont9u\sly produc$ f ! ?orium4 ,?is ,? ,x breaks up1 giv+ rise to ! radio-active emanation4 ,! emanation produces f itself a type ( active matt] :i* is deposit$ on ! surface ( bodies1 :]e x gives rise to ! ph5om5a ( excit$ or induc$ activity4 ,?is active deposit possesses "s di/9ctive *emical & physical prop]ties :i* di/+ui% x f ! emanation & ! ,? ,x4 ,we h se5 7section #ahj7 t ! rate at :i* ! active deposit loses its activity dep5ds ^u ! "t ( exposure ( ! body made active to ! emanation4 ,! explanation ( ! activity curves = diff]5t "t ( exposure w n[ be consid]$4 ,! curve ( v>iation ( activity = a %ort exposure ( #aj m9utes has already be5 giv5 9 ,fig4 #fe4 ,! activity is small at fir/ b increases rapidly ) ! "t2 x passes ?r\gh a maximum ab\t #d h\rs lat]1 & f9ally decays expon5tially ) ! "t1 fall+ to half value 9 #aa h\rs4 ,?is rem>kable effect c be expla9$ completely#cja if x be suppos$ t ! active deposit consi/s ( two di/9ct sub/ances4 ,! matt] initially deposit$ f ! emanation1 :i* w be call$ ?orium ,a1 is suppos$ to be *ang$ into ?orium ,b4 ,?orium ,a is trans=m$ accord+ to ! ord9>y expon5tial law1 b ! *ange is n accompani$ by any ioniz+ rays4 ,9 o!r words1 ! *ange f ,a to ,b is a 8rayless0 *ange4 ,on ! o!r h&1 ,b breaks up into ,c ) ! accompanim5t ( all ?ree k9ds ( rays4 ,on ?is view ! activity ( ! active deposit at any "t repres5ts ! am\nt ( ! sub/ance ,b pres5t1 s9ce ,c is inactive or active to a v m9ute ext5t4 ,if ! v>iation ( ! activity imp>t$ to a body expos$ = a %ort int]val 9 ! pres5ce ( ! ?orium emanation1 is due to ! fact t !re are two successive *anges 9 ! deposit$ matt] ,a1 ! fir/ ( :i* is a 8rayless0 *ange1 ! activity ,it at any "t t aft] removal %\ld be proportional to ! numb] ,qt ( p>ticles ( ! matt] ,b pres5t at t "t4 ,n[1 f equation 7#d7 section #aig1 x has be5 %[n t ,q frac n#a #a #b 7e-#b t - e-#a t7 4444 7#d74 ,! value ( ,qt passes ?r\gh a maximum ,q,t at ! "t ,t :5 frac #b #a e-7#a-b7 ,t 4 ,! maximum activity ,i,t is proportional to ,q,t & frac ,it ,i,t frac ,qt ,q,t frac e-#b t - e-#a t e-#b ,t e-#a ,t 4 ,x w be %[n lat] t ! v>iation ) "t ( ! activity1 imp>t$ to a body by a %ort exposure1 is express$ by an equation ( ! above =m4 ,x ?us rema9s to fix ! values ( 1 4 ,s9ce ! above equation is symmetrical ) reg>d to 1 1 x is n possible to settle f ! agreem5t ( ! !oretical & exp]im5tal curve :i* value ( ref]s to ! fir/ *ange4 ,! curve ( v>iation ( activity ) "t is unalt]$ if ! values ( & are int]*ang$4 ,x is f\nd exp]im5tally t ! activity #e or #f h\rs aft] removal decays v approximately accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 #aa h\rs4 ,?is is ! normal rate ( decay ( ?orium = all times ( exposure1 provid$ measurem5ts are n begun until sev]al h\rs aft] ! removal ( ! active body f ! emanation4 ,?is fixes ! value ( ! con/ants ( "o ( ! *anges4 ,let u assume = ! mom5t t ?is gives ! value ( 4 ,!n #age #aj 7sec74 ,s9ce ! maximum activity is rea*$ aft] an int]val ,t #bbj m9utes 7see ,fig4 #fe71 sub/itut+ ! values ( & ,t 9 ! equation1 ! value ( comes out to be #bjh #aj 7sec74 ,?is value ( corresponds to a *ange 9 :i* half ! matt] is trans=m$ 9 #ee m9utes4 ,sub/itut+ n[ ! values ( 1 1 ,t1 ! equation r$uces to frac ,it ,i,t #a;cdot#cg 7e-#b t e-#b t7 4 ,! agreem5t betwe5 ! results ( ! !oretical equation & ! obs]v$ values is %[n 9 ! foll[+ table3 ,"t 9 ,!oretical ,obs]v$ value m9utes value ( ( ,it_/,i,t ,it_/,i,t #ae #bb #bc #cj #ch #cg #fj #fd #fc #abj #ij #ia #bbj #ajj #ajj #cje #ig #if ,aft] #e h\rs ! activity decreas$ ne>ly expon5tially ) ! "t1 fall+ to half value 9 #aa h\rs4 ,x is ?us se5 t ! curve ( rise ( activity = a %ort exposure is expla9$ v satisfactorily on ! supposition t two *anges occur 9 ! deposit$ matt]1 ( :i* ! fir/ is a rayless *ange4 ,fur!r data are requir$ 9 ord] to fix :i* ( ! "t con/ants ( ! *anges ref]s to ! fir/ *ange4 ,9 ord] to settle ?is po9t1 x is necess>y to isolate "o ( ! products ( ! *anges & to exam9e ! v>iation ( its activity ) "t4 ,if1 = example1 a product c be sep>at$ ^: activity decays to half value 9 #ee m9utes1 x w\ld %[ t ! second *ange is ! m rapid ( ! two4 ,n[ ,pegram#cjb has exam9$ ! radio-active products obta9$ by electrolysis ( ?orium solutions4 ,! rates ( decay ( ! active products dep5d$ ^u conditions1 b he f\nd t1 9 sev]al cases1 rapidly decay+ products 7 obta9$ ^: activity fell to half value 9 ab\t #a h\r4 ,all[+ = ! probability t ! product exam9$ 0 n completely isolat$ by ! electrolysis1 b conta9$ also a trace ( ! o!r product1 ?is result w\ld indicate t ! la/ *ange :i* gives rise to rays is ! m rapid ( ! two4 ,?is po9t is v cle>ly br\ght out by "s rec5t exp]im5ts ( ,miss ,slat]#cjc1 :o has made a detail$ exam9ation ( ! effect ( temp]ature on ! active deposit ( ?orium4 ,a plat9um wire 0 made active by exposure = a long int]val to ! ?orium emanation1 & !n heat$ = a few m9utes to any desir$ temp]ature by means ( ! electric curr5t4 ,! wire1 :ile be+ heat$1 0 surr\nd$ by a lead cyl9d] 9 ord] t any matt] driv5 (f f x %\ld be collect$ on its surface4 ,! decay ( activity bo? ( ! wire & ( ! lead cyl9d] 0 !n te/$ sep>ately4 ,aft] heat+ to a dull r$ heat1 no s5sible dim9ution ( ! activity 0 obs]v$ at fir/1 b ! rate ( decay ( ! activity on ! wire 0 f\nd to be m rapid ?an ! normal4 ,! activity ( ! lead cyl9d] 0 small at fir/ b increas$ to a maximum aft] ab\t #d h\rs & !n decay$ at ! normal rate ) ! "t4 ,^! results are to be expect$ if "s ?orium ,a is volatiliz$ f ! wire2 = ! rise ( activity on ! lead cyl9d] is v simil> to t obs]v$ on a wire expos$ = a %ort "t 9 ! pres5ce ( ! ?orium emanation1 i4e41 "u ! condition t only ?orium ,a is initially pres5t4 ,on heat+ ! wire above #gjj ,c4 ! activity 0 f\nd to be r$uc$1 %[+ t "s ?orium ,b _h also be5 remov$4 ,by heat+ = a few m9utes at ab\t #ajjj ,c4 ne>ly all ! ?orium ,a 0 driv5 (f4 ,! activity on ! wire !n decay$ expon5tially ) ! "t1 fall+ to half value 9 ab\t #a h\r4 ,aft] heat+ = a m9ute at ab\t #abjj ,c4 all ! activity 0 remov$4 ,^! results %[ t ?orium ,a is m volatile ?an ,b1 & t ! product :i* gives out rays1 viz4 ?orium ,b1 has a p]iod ( ab\t #ee m9utes4 ,ano!r s]ies ( exp]im5ts 0 made1 9 :i* an active alum9ium disc 0 plac$ 9 an exhau/$ tube1 & expos$ to ! ca?ode ray dis*>ge4 ,"u ^! conditions1 a "p ( ! activity ( ! disc 0 remov$4 ,:5 ! disc 0 made ! anode1 ! loss ( activity 0 usually #bj to #fj p] c5t4 = half-an-h\r's exposure4 ,if ! disc 0 made ! ca?ode1 ! loss 0 mu* great]1 am\nt+ to ab\t #ij p] c5t4 9 #aj m9utes4 ,"p ( ! active matt] remov$ f ! disc 0 collect$ on a second disc plac$ ne> x4 ,?is second disc on removal lo/ its activity at a f> m rapid rate ?an ! normal4 ,! rate ( decay on ! fir/ disc 0 also alt]$1 ! activity sometimes ev5 increas+ aft] removal4 ,^! results indicate t1 9 ?is case1 ! app>5t volatility ( ! products is rev]s$4 ,?orium ,b is driv5 (f f ! disc m readily ?an ?orium ,a4 ,! rates ( decay obta9$ "u diff]5t conditions 7 satisfactorily expla9$ by suppos+ t ! surfaces ( ! discs aft] exposure to ! dis*>ge 7 coat$ ) diff]5t proportions ( ?orium ,a & ,b4 ,! escape ( ?orium ,b f ! disc "u ! influ5ce ( ! dis*>ge seems r to be ! result ( an action simil> to ! well-kn[n 8sputt]+0 ( electrodes ?an to a direct influ5ce ( temp]ature4 ,! results obta9$ by von ,l]*#cjd on ! electrolysis ( a solution ( ! active deposit also admit ( a simil> int]pretation4 ,products 7 obta9$ on ! electrodes ( diff]5t rates ( decay1 los+ half _! activity 9 times v>y+ f ab\t #a h\r to #e h\rs4 ,?is v>iation is due to ! admixture ( ! two products 9 diff]5t proportions4 ,! evid5ce1 z a :ole1 ?us /rongly supports ! conclusion t ! active deposit f ?orium und]goes two successive trans=mations z foll[s3 7#a7 ,a 8rayless0 *ange = :i* #age #aj1 i4e41 9 :i* half ! matt] is trans=m$ 9 #aa h\rs2 7#b7 ,a second *ange giv+ rise to 1 & rays1 = :i* #bjh #aj1 i4e41 9 :i* half ! matt] is trans=m$ 9 #ee m9utes#cje4 ,x is1 at fir/ sight1 a some:at unexpect$ result t ! f9al rate ( decay ( ! active deposit f ?orium gives ! rate ( *ange n ( ! la/ product itself1 b ( ! prec$+ product1 :i* does n give rise to rays at all4 ,a simil> peculi>ity is obs]v$ 9 ! decay ( ! excit$ activity ( act9ium1 :i* is discuss$ 9 section #bab4 ,= a long exposure 9 ! pres5ce ( a con/ant supply ( ?orium emanation1 ! equation express+ ! v>iation ( activity ) "t is f\nd f equation 7#h71 section #aih1 frac ,it ,i frac ,q ,q frac #b #b - #a e-#a t frac #a #a #b e-#b t frac #b e-#a t #b - #a 7#a cdot#jhc e#a;cdot#ij #ajd t 7 4 ,ab\t #e h\rs aft] removal ! second t]m 9 ! brackets becomes v small1 & ! activity aft] t "t w decay ne>ly accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 #aa h\rs4 ,= any "t ( exposure ,t1 ! activity at "t t aft] ! removal 7see equation #aa1 section #aii7 is giv5 by frac ,it ,i frac ,q ,q,t frac ae-#b t - be-#a t a b 1 :]e ,i is ! initial value ( ! activity1 imm$iately aft] removal1 & a frac #a e-#b ,t #b 1 b frac #a e-#a ,t #a 1 ,by v>iation ( ,t ! curves ( v>iation ( activity = any "t ( exposure c be accurately d$uc$ f ! equation1 :5 ! values ( ! two con/ants 1 are sub/itut$4 ,miss ,brooks#cjf has exam9$ ! decay curves ( excit$ activity = ?orium = diff]5t times ( exposure & has obs]v$ a sub/antial agreem5t betwe5 exp]im5t & !ory4 ,illu/ration3 ,fig4 #gh4 ,! results are %[n graphically 9 ,fig4 #gh4 ,! maximum value ( ! activity is1 = ea* "t ( exposure1 tak5 z #ajj4 ,! !oretical & obs]v$ values are %[n 9 ! ,figure4 #bjh4 ,analysis ( ! decay & recov]y curves ( ,? ,x4 ,! peculi>ities ( ! initial portions ( ! decay & recov]y curves ( ,? ,x & ?orium respectively 7,curves ,a & ,b1 ,fig4 #dg1 p4 #bba71 w n[ be consid]$4 ,x 0 %[n t :5 ! ,? ,x 0 remov$ f ! ?orium by precipitation ) ammonia1 ! radiation increas$ ab\t #ae p] c5t4 dur+ ! fir/ day1 pass$ ?r\gh a maximum1 & !n fell (f accord+ to an expon5tial law1 decreas+ to half value 9 f\r days4 ,at ! same "t ! activity ( ! sep>at$ hydroxide decreas$ = ! fir/ day1 pass$ ?r\gh a m9imum1 & !n sl[ly increas$ aga91 ris+ to its orig9al value aft] ! lapse ( ab\t "o mon?4 ,:5 a ?orium comp\nd is 9 a /ate ( radio-active equilibrium1 ! s]ies ( *anges 9 :i* ,? ,x1 ! emanation1 & ?orium ,a & ,b are produc$1 g on simultane\sly4 ,s9ce a /ate ( equilibrium has be5 rea*$ = ea* ( ^! products1 ! am\nt ( ea* product *ang+ 9 unit "t is equal to ! am\nt ( t product suppli$ f ! prec$+ *ange 9 unit "t4 ,n[ ! matt] ,? ,x is soluble 9 ammonia1 :ile ?orium ,a & ,b are n4 ,! ,? ,x is ?us remov$ f ! ?orium by precipitation ) ammonia1 b ,a & ,b are left beh9d ) ! ?orium4 ,s9ce ! active deposit is produc$ f ! emanation1 :i* 9 turn arises f ,? ,x1 on ! removal ( ! p>5t matt] ,? ,x1 ! radiation due to ?is active deposit w decay1 s9ce ! rate ( production ( fre% matt] no long] balances its own rate ( *ange4 ,disreg>d+ ! initial irregul>ity 9 ! decay curve ( ! active deposit1 its activity w h decay$ to half value 9 ab\t #aa h\rs1 & to "o qu>t] value at ! end ( #bb h\rs4 ,z soon1 h[ev]1 z ! ,? ,x has be5 sep>at$1 new ,? ,x is produc$ 9 ! ?orium comp\nd4 ,! activity ( ?is new ,? ,x is n1 h[ev]1 suffici5t to comp5sate at fir/ = ! loss ( activity due to ! *ange 9 ! active deposit1 s t1 z a :ole1 ! activity w at fir/ decrease1 !n pass ?r\gh a m9imum1 !n increase aga94 ,! correctness ( ?is po9t ( view has be5 te/$ by ,ru!r=d & ,soddy#cjg z foll[s3 ,if ! precipitat$ ?orium hydroxide aft] ! removal ( ,? ,x is put ?r\gh a s]ies ( precipitations ) ammonia at %ort int]vals1 ! ,? ,x is remov$ almo/ z fa/ z x is =m$1 &1 at ! same "t1 ! activity ( ?orium ,b 9 ! ?orium decays4 ,! foll[+ table indicates ! results obta9$4 ,a portion ( ! precipitat$ hydroxide 0 remov$ aft] ea* s]ies ( precipitations & its activity te/$ 9 ! usual way4 ,activity ( hydroxide p] c5t4 ,aft] #a precipitation #df ,aft] #c precipitations at #ci int]vals ( #bd h\rs ,aft] #c m precipitations at #bb int]vals ( #bd h\rs & #c at int]vals ( #h h\rs ,aft] #c m ea* ( #h h\rs #bd ,aft] #f m ea* ( #d h\rs #be ,illu/ration3 ,fig4 #gi4 ,! diff]5ces 9 ! la/ ?ree numb]s are n significant1 = x is difficult to make accurate comp>isons ( ! activity ( ?orium comp\nds :i* h be5 precipitat$ "u slightly diff]5t conditions4 ,x is ?us se5 t z a result ( successive precipitations1 ! activity is r$uc$ to a m9imum ( ab\t #be p] c5t4 ,! recov]y curve ( ! activity ( ?is #bc times precipitat$ hydroxide is %[n 9 ,fig4 #gi4 ,! initial drop 9 ! curve is q abs5t1 & ! curve1 />t+ f ! m9imum1 is practically id5tical ) ! curve %[n 9 ,fig4 #dh1 :i* gives ! recov]y curve ( ?orium hydroxide aft] ! fir/ two days4 ,?is residual activity--ab\t #be p] c5t4 ( ! maximum--is non-sep>able f ! ?orium by any *emical process t has be5 tri$4 ,! initial rise ( activity ( ,? ,x1 aft] x has be5 sep>at$1 w n[ be consid]$4 ,9 all cases x 0 f\nd t ! activity ( ! sep>at$ ,? ,x _h increas$ ab\t #ae p] c5t4 at ! end ( #bd h\rs1 & !n /eadily decay$1 fall+ to half value 9 ab\t f\r days4 ,?is peculi>ity ( ! ,? ,x curve foll[s1 ( necessity1 f ! consid]ations already advanc$ to expla9 ! drop 9 ! recov]y curve4 ,z soon z ! ,? ,x is sep>at$1 x at once produces f itself ! emanation1 & ?is 9 turn produces ?orium ,a & ,b4 ,! activity due to ,b at fir/ m ?an comp5sates = ! decay ( activity ( ! ,? ,x itself4 ,! total activity ?us increases to a maximum1 & !n sl[ly decays to z]o accord+ to an expon5tial law ) ! "t4 ,! curve express+ ! v>iation ( ! activity ( ! sep>at$ ,? ,x ) "t c be d$uc$ f ! !ory ( successive *anges already consid]$ 9 *apt] ,,ix4 ,9 ! pres5t case !re are f\r successive *anges occurr+ at ! same "t1 viz4 ! *ange ( ,? ,x into ! emanation1 ( ! emanation into ?orium ,a1 ( ,a into ,b1 & ( ,b into an inactive product4 ,s9ce1 h[ev]1 ! *ange ( ! emanation into ?orium ,a 7ab\t half *ang$ 9 "o m9ute7 is f> m rapid ?an ! *anges occurr+ 9 ,? ,x or ?orium ,a & ,b1 = ! purposes ( calculation x may be assum$ )\t s]i\s error t ! ,? ,x *anges at once into ! active deposit4 ,! #ee m9ute *ange w also be disreg>d$ = ! same reason4 ,let & be ! con/ants ( decay ( activity ( ,? ,x & ( ?orium ,a respectively4 ,s9ce ! activity ( ,? ,x & ( ?orium ,a falls to half value 9 #d days & #aa h\rs respectively1 ! value ( #jjgb & ( #jfc1 :]e #a h\r is tak5 z ! unit ( "t4 ,! problem r$uces to ! foll[+3 ,giv5 ! matt] ,a 7?orium ,x7 all ( "o k9d1 :i* *anges into ,b 7?orium ,b71 f9d ! activity ( ,a & ,b toge!r at any subsequ5t "t4 ,?is corresponds to ,case ,i4 7section #aig74 ,! am\nt ,q ( ,b at any "t ,t is giv5 by ,q frac #a n #a #b 7e-#b t - e-#a t7 1 & ! activity ,i at any "t ( ! two toge!r is proportional to ,p ,k,q1 :]e ,k is ! ratio ( ! ionization ( ,b comp>$ ) t ( ,a4 ,!n frac ,it ,i frac #a ,p ,k#b ,q #a n e-#a t 7#a frac ,k#b #b #a 7#a e-7#b #a7 t77 1 :]e ,i is ! initial activity due to n p>ticles ( ,? ,x4 ,by comp>ison ( ?is equation ) ! curve ( v>iation ( ! activity ( ,? ,x ) "t1 %[n 9 ,fig4 #dg1 x is f\nd t ,k is almo/ #dd4 ,x mu/ be rememb]$ t ! activity ( ! emanation & ,? ,x are includ$ toge!r1 s t ! activity ( ?orium ,b is ab\t half ( ! activity ( ! two prec$+ products4 ,! calculat$ values ( ,it_/,i = diff]5t values ( t are %[n 9 ! second column ( ! foll[+ table1 & ! obs]v$ values 9 ! ?ird column4 ,"t ,!oretical ,obs]v$ value value #j #ajj #ajj #be days #aji -- #e #aaf -- #a #aae #aag #ae #aaa -- #b #ajd -- #c #hge #hh #d #ge #gb #f #ec #ec #i #cae #bie #ac #aeg #aeb ,illu/ration3 ,fig4 #hj4 ,! !oretical & obs]v$ values ?us agree )9 ! limit ( error 9 ! measurem5ts4 ,! !oretical curve is %[n 9 ,curve ,a1 ,fig4 #hj 7) ! obs]v$ po9ts m>k$1 = comp>ison74 ,! curve ,b %[s ! !oretical curve ( ! decay ( ! activity ( ,? ,x & ! emanation1 suppos+ !re is no fur!r *ange into ! active deposit4 ,curve ,c %[s ! diff]5ce curve betwe5 ! curves ,a & ,b1 i4e4 ! proportion ( ! activity at diff]5t times due to ! active deposit4 ,! activity due to ! latt] ?us rises to a maximum ab\t two days aft] removal ( ! ,? ,x1 & !n decays ) ! "t at ! same rate z ! ,? ,x itself1 i4e4 ! activity falls to half value e f\r days4 ,:5 t exce$s f\r days1 ! t]m e-7#b #a7 t 9 ! !oretical equation is v small4 ,! equation ( decay aft] ?is "t is !re=e express$ by frac ,it ,i 7#a frac ,k#b #b #a7 e-#a t 1 i4e4 ! activity decays accord+ to an expon5tial law ) ! "t4 #bji4 ,radiations f ,?orium products4 ,x has be5 %[n 9 ! la/ section t ! activity ( ?orium1 by successive precipitations ) ammonia1 is r$uc$ to a limit+ value ( almo/ #be p] c5t4 ( ! initial activity4 ,?is 8non-sep>able activity0 consi/s ( rays1 ! & rays be+ altoge!r abs5t4 ,accord+ to ! dis9tegration !ory1 ?is is an expression ( ! fact t ! initial break-up ( ! ?orium atom is accompani$ only by ! expulsion ( p>ticles4 ,we h se5 9 section #aef t ! ?orium emanation also gives out only rays4 ,9 ! active deposit1 ?orium ,a gives out no rays1 :ile ?orium ,b emits all ?ree types ( rays4 ,"s h\rs aft] sep>ation1 ,? ,x gives out 1 1 & rays1 b ! appe>ance ( & rays is probably due to ! ?orium ,b associat$ ) x4 ,! & ray activity ( ,? ,x is mu* r$uc$ if a curr5t ( air is cont9u\sly aspirat$ ?r\gh a solution ( ,? ,x to remove ! emanation4 ,x seems likely t if ! emanation c\ld be remov$ z fa/ z x 0 =m$1 s z to prev5t ! =mation ( ?orium ,b 9 its mass1 ,? ,x itself w\ld give out only rays3 b1 on acc\nt ( ! rapid rate ( *ange ( ! ?orium emanation1 x is difficult to realize ?is exp]im5tally4 #baj4 ,trans=mation products ( ,?orium4 ,! trans=mation products ( ?orium & ! rays emitt$ by !m are graphically %[n bel[ 7,fig4 #ha74 ,illu/ration3 ,fig4 #ha4 ,a table ( ! trans=mation products ( ?orium is %[n bel[1 ) "s ( _! physical & *emical prop]ties4 ,product ,"t to be 7sec7 ,radiations ,physical & half *emical trans=m$ prop]ties ,?orium rays ,insoluble 9 ammonia ,?4 ,x #d days #bjj rays ,soluble 9 #aj ammonia ,emanation #ed secs4 #abh rays ,in]t gas1 #aj cond5ses #abj ,c4 ,?orium ,a #aa h\rs #age no rays ,soluble 9 #aj /rong acids4 ,volatile at a :ite heat4 ,b c be sep>at$ f ,a by electrolysis & by diff]5ce ( volatility4 ,?orium ,b #ee m9s4 #ba 1 1 rays ,same #aj 8 -- -- -- - #baa4 ,trans=mation products ( ,act9ium4 ,x has previ\sly be5 po9t$ out 7sections #ag & #ah7 t ! act9ium ( ,debi]ne & ! emanium ( ,giesel conta9 ! same radio-active con/itu5t4 ,bo? give out a %ort-liv$ emanation :i* imp>ts activity to ! surface ( bodies4 ,rec5tly1 ?anks to ,dr ,giesel ( ,brauns*weig1 prep>ations ( 8emanium0 h be5 plac$ on ! m>ket1 & mo/ ( ! inve/igations t are describ$ lat] h be5 made ) ?is sub/ance4 ,act9ium ,x4 ,act9ium & ?orium are v closely alli$ 9 radio-active prop]ties4 ,bo? emit an emanation :i* is rapidly trans=m$1 b ! rate ( *ange ( ! act9ium emanation is /ill m rapid ?an t ( ?orium1 ! activity decreas+ to half value 9 #cg seconds4 ,miss ,brooks#cjh has analys$ ! active deposit f ! emanation ( act9ium1 & has %[n t two successive *anges occur 9 x1 v simil> 9 "* to ^? obs]v$ 9 ! active deposit ( ?orium4 ,x ?us seem$ probable1 f analogy1 t an int]m$iate product1 correspond+ to ,? ,x 9 ?orium1 w\ld be f\nd 9 act9ium#cji4 ,rec5t "w has v]ifi$ ?is supposition4 ,giesel#caj & ,godlewski#caa indep5d5tly obs]v$ t a v active sub/ance c\ld be sep>at$ f 8emanium10 v simil> 9 *emical & physical prop]ties to ,? ,x 9 ?orium4 ,?is product w1 f analogy1 be call$ 8act9ium ,x40 ,! same me?od1 :i* 0 us$ by ,ru!r=d & ,soddy to sep>ate ,? ,x f ?orium1 is also effective 9 sep>at+ act9ium ,x f act9ium4 ,aft] precipitation ( ! active solution ) ammonia1 act9ium ,x is left beh9d 9 ! filtrate4 ,aft] evaporation & ignition1 a v active residue rema9s4 ,at ! same "t1 ! precipitat$ act9ium loses a l>ge proportion ( its activity4 ,giesel obs]v$ ! sep>ation ( an active product1 us+ a fluoresc5t scre5 to detect ! radiations4 ,a v complete exam9ation ( ! product act9ium ,x has be5 made by ,godlewski 9 ! laboratory ( ! writ]4 ,aft] sep>ation ( act9ium ,x1 ! activity1 :e!r measur$ by ! or rays1 increases ab\t #ae p] c5t4 dur+ ! fir/ day1 & aft]w>ds decays expon5tially ) ! "t1 fall+ to half value 9 #ajb days4 ,! activity ( ! sep>at$ act9ium 0 small at fir/ b /eadily increas$ ) ! "t1 rea*+ a practical maximum aft] an int]val ( sixty days4 ,aft] ! fir/ day1 ! decay & recov]y curves ( activity are complem5t>y to "o ano!r4 ,! curves ( rise & decay are %[n graphically 9 ,fig4 #hb1 curves ,i & ,,ii respectively4 ,godlewski obs]v$ t a solution ( act9ium1 fre$ f act9ium ,x1 gave out v little emanation1 :ile a solution ( act9ium ,x gave (f ! emanation 9 l>ge quantity4 ,! am\nt ( emanation f ! solution 0 measur$ by obs]v+ ! activity produc$ 9 a te/+ vessel1 simil> to t %[n 9 ,fig4 #ea1 :5 a con/ant curr5t ( air 0 pass$ ?r\gh ! solution4 ,! emanat+ p[] ( act9ium ,x decreas$ expon5tially ) ! "t at ! same rate z t at :i* ! act9ium ,x lo/ its activity4 ,at ! same "t ! act9ium solution increas$ 9 emanat+ p[]1 rea*+ its orig9al value aft] ab\t #fj days4 ,! behavi\r ( act9ium & ?orium is ?us q analog\s1 & ! explanation advanc$ to expla9 ! decay & recov]y curves ( ?orium applies equally well to ! correspond+ curves ( act9ium4 ,illu/ration3 ,fig4 #hb4 ,! act9ium ,x is produc$ at a con/ant rate f ! p>5t matt] act9ium1 & is trans=m$ accord+ to an expon5tial law ) ! "t4 ,! con/ant ( *ange #jfh 7day71 & ?is value is *>act]i/ic ( ! product act9ium ,x4 ,z 9 ! case ( ?orium1 ! above exp]im5ts %[ t ! emanation does n arise f act9ium itself b f act9ium ,x4 ,! emanation 9 turn breaks up & gives rise to an active deposit on ! surface ( bodies4 #bab4 ,analysis ( ! active deposit f ! emanation4 ,debi]ne#cab obs]v$ t ! excit$ activity produc$ by act9ium decay$ to half value 9 ab\t #da m9utes4 ,miss ,brooks#cac %[$ t ! curves ( decay ( ! excit$ activity aft] removal dep5d$ ^u ! duration ( exposure to ! emanation4 ,! curves = diff]5t times ( exposure h already be5 %[n 9 ,fig4 #fi4 ,bronson1 us+ ! direct deflection me?od describ$ 9 section #fi1 accurately det]m9$ ! activity curve correspond+ to a %ort exposure to ! act9ium emanation4 ,! curve obta9$ is %[n 9 ,fig4 #hc4 ,illu/ration3 ,fig4 #hc4 ,?is curve is simil> 9 %ape to ! correspond+ curve obta9$ = ! active deposit f ?orium1 & is expla9$ 9 a simil> way4 ,! activity ,it at any "t t is giv5 by frac ,it ,i,t frac e-#b t e-#a t e-#b ,t e-#a ,t 1 :]e & are two con/ants1 & ,i,t ! maximum activity rea*$ aft] an int]val ,t4 ,aft] #bj m9utes ! activity decreas$ expon5tially ) ! "t1 fall+ to half value 9 #ceg m9utes4 ,?is gives ! value #jaid 7m9474 ,by comp>ison ) ! curve1 ! value ( 0 f\nd to be #cag 7m9474 ,?is corresponds to a *ange 9 :i* half ! matt] is trans=m$ 9 #bae m9utes4 ,exactly z 9 ! analog\s curve = ?orium1 x c be %[n t ! matt] initially deposit$ und]goes two *anges1 ! fir/ ( :i* is a rayless "o4 ,! same difficulty arises 9 fix+ :i* ( ! values ( ref]s to ! fir/ *ange4 ,an exp]im5t made by ,miss ,brooks 7loc4 cit47 %[s t ! rayless product has ! sl[] p]iod ( trans=mation4 ,! active deposit ( act9ium 0 dissolv$ (f a plat9um wire & !n electrolys$4 ,! anode 0 f\nd to be active1 & ! activity fell (f expon5tially ) ! "t1 decreas+ to half value 9 ab\t #ae m9utes4 ,all[+ = ! difficulty ( accurately measur+ su* a rapid rate ( decay1 ?is result indicates t ! product :i* gives out rays has ! rapid p]iod ( #bae m9utes4 ,! analysis ( ! active deposit ( act9ium ?us leads to ! foll[+ conclusions3 7#a7 ,! matt] initially deposit$ f ! emanation1 call$ act9ium ,a1 does n give out rays1 & is half trans=m$ 9 #ceg m9utes4 7#b7 ,a *anges into ,b1 :i* is half trans=m$ 9 #bae m9utes1 & gives out bo? & 7& probably 7 rays4 ,godlewski f\nd t ! active deposit ( act9ium 0 v easily volatiliz$4 ,heat+ = sev]al m9utes at a temp]ature ( #ajj ,c4 0 suffici5t to drive (f mo/ ( ! active matt]4 ,! active deposit is readily soluble 9 ammonia & 9 /rong acids4 #bac4 ,radiations f act9ium & its products4 ,act9ium 9 radio-active equilibrium gives out 1 1 & rays4 ,godlewski f\nd sev]al po9ts ( di/9ction betwe5 ! & rays ( act9ium & ( radium4 ,! rays ( act9ium appe> to be homog5e\s1 = ! activity measur$ by an electroscope 0 f\nd to fall (f accurately accord+ to an expon5tial law ) ! ?ickness ( matt] trav]s$4 ,! rays 7 half absorb$ 9 a ?ickness ( #jba mm4 ( alum9ium4 ,?is indicates t ! p>ticles are all project$ f act9ium ) ! same velocity4 ,9 ?is respect act9ium behaves v diff]5tly f radium1 = ! latt] gives out p>ticles ^: velocities v>y ov] a wide range4 ,aft] ! rays 7 absorb$1 ano!r type ( m p5etrat+ rays 0 obs]v$1 :i* probably corresponds to ! rays f ! o!r radio-elem5ts4 ,! rays ( act9ium 71 h[ev]1 f> less p5etrat+ ?an ^? f radium4 ,! activity due to ^! rays 0 r$uc$ to "o-half aft] pass+ ?r\gh #ai mms4 ( lead1 :ile ! ?ickness ( lead requir$ 9 ord] to absorb half ! rays ( radium is ab\t #i mms4 ,! active deposit gave out & 7& probably 7 rays4 ,x 0 difficult to decide def9itely :e!r act9ium ,x gave out z well z rays4 ,:5 ! act9ium ,x 0 heat$ to a r$ heat1 ! activity 0 tempor>ily r$uc$ to ab\t half its initial value4 ,?is decrease 0 probably due to ! removal ( ! active deposit1 :i*1 we h se51 is readily volatiliz$ by heat4 ,if ! ray activity _c be fur!r r$uc$1 ?is w\ld po9t to ! conclusion t act9ium ,x1 z well z act9ium ,b1 gives out rays1 b ! evid5ce s f> obta9$ is n conclusive4 ,! ease ) :i* ! active deposit is volatiliz$ by heat (f]s a v simple explanation ( ! initial peculi>ities ( ! decay & recov]y curves 7,fig4 #hb7 ( act9ium ,x4 ,! activity ( act9ium ,x rises at fir/1 b !re is no correspond+ decrease 9 ! activity ( ! act9ium left beh9d4 ,x has be5 %[n t ! active deposit is soluble 9 ammonia1 &1 9 consequ5ce1 is remov$ ) ! act9ium ,x4 ,! products act9ium ,a & ,b & act9ium ,x1 imm$iately aft] sep>ation1 are 9 radio-active equilibrium & we %\ld n !re=e expect to f9d any increase ( activity aft] removal1 su* z is obs]v$ 9 ! case ( ?orium1 :]e ?orium ,a & ,b are n remov$ ) ?orium ,x4 ,h[ev]1 9 heat+ ! act9ium ,x to drive (f ! ammonium salts1 "s ( ! active deposit is volatiliz$4 ,aft] cool+1 ! am\nt ( ! active deposit increases to ne>ly its old value & !re is a correspond+ increase ( ! activity4 ,illu/ration3 ,fig4 #hd4 #bad4 ,products ( ,act9ium4 ,!re is "o v int]e/+ po9t ( di/9ction betwe5 ! radio-active behavi\r ( ?orium & act9ium4 ,! latt] aft] removal ( act9ium ,x1 %[s only ab\t #e p] c5t4 ( ! orig9al activity1 :ile ?orium1 aft] removal ( ,? ,x1 always %[s a residual activity ( ab\t #be p] c5t4 ( ! maximum value4 ,?is v small residual activity indicates t act9ium1 if completely fre$ f all its products1 w\ld n give out rays at all1 9 o!r words1 ! fir/ *ange 9 act9ium is a rayless "o4 ,! radio-active products ( act9ium are %[n graphically 9 ,fig4 #hd4 ,"s ( _! *emical & physical prop]ties are tabulat$ bel[4 ,products ,"t to be ,rays ,"s ,physical & half ,*emical prop]ties trans=m$ ,act9ium 8 ,no rays ,insoluble 9 ammonia ,act9ium ,x #ajb days 1 7 & 7 ,soluble 9 ammonia ,emanation #ci secs4 rays ,behaves z a gas ,act9ium ,a #ceg m9s4 ,no rays ,soluble 9 ammonia & /rong acids4 ,act9ium ,b #bae m9s4 1 & ,volatiliz$ at #ajj;,c4 ,b c be sep>at$ f ,a by electrolysis ,footnote #bif3 ,soddy1 ,trans4 ,*em4 ,soc4 #ha1 p4 #dfj1 #aijb4 ,footnote #big3 ,ru!r=d & ,gri]1 ,phil4 ,mag4 ,sept4 #aijb4 ,footnote #bih3 ,becqu]el1 ,c4 ,r4 #aca1 p4 #acg1 #aijj4 ,footnote #bii3 ,mey] & ,s*weidl]1 ,wi5 ,b]4 ,dec4 #a1 #aijd4 ,footnote #cjj3 ,mey] & ,s*weidl]1 ,wi5 ,b]4 #aac1 ,july1 #aijd4 ,footnote #cja3 ,ru!r=d1 ,phil4 ,trans4 ,a4 #bjd1 pp4 #afi-bai1 #aijd4 ,footnote #cjb3 ,pegram1 ,phys4 ,rev4 p4 #dbd1 ,decemb]1 #aijc4 ,footnote #cjc3 ,miss ,slat]1 ,phil4 ,mag4 #aije4 ,footnote #cjd3 von ,l]*1 ,ann4 de d4 ,phys4 ,novemb]1 #aijc4 ,footnote #cje3 ,! #8rayless *ange' c]ta9ly does n give out rays1 & special exp]im5ts %[$ t no appreciable am\nt ( rays 7 pres5t4 ,on ! o!r h&1 ! second *ange gives out all ?ree types ( rays4 ,footnote #cjf3 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,footnote #cjg3 ,ru!r=d & ,soddy1 ,trans4 ,*em4 ,soc4 #ha1 p4 #hcg1 #aijb4 ,phil4 ,mag4 ,nov4 #aijb4 ,footnote #cjh3 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,footnote #cji3 ,ru!r=d1 ,phil4 ,trans4 ,a4 p4 #afi1 #aijd4 ,footnote #caj3 ,giesel1 ,b]4 d4 ,d4 ,*em4 ,ges4 p4 #gge1 #aije4 ,footnote #caa3 ,godlewski1 ,nature1 p4 #bid1 ,jan4 #ai1 #aije4 ,footnote #cab3 ,debi]ne1 ,c4 ,r4 #ach1 p4 #daa1 #aijd4 ,footnote #cac3 ,miss ,brooks1 ,phil4 ,mag4 ,sept4 #aijd4 ,,*apt] ,,xi4 ,,trans=mation ,,products ,,( ,,radium4 #bae4 ,radio-activity ( radium4 ,not)/&+ ! enorm\s diff]5ce 9 _! relative activities1 ! radio-activity ( radium pres5ts _m close analogies to t ( ?orium & act9ium4 ,bo? sub/ances give rise to emanations :i* 9 turn produce 8excit$ activity0 on bodies 9 _! neighb\rhood4 ,radium1 h[ev]1 does n give rise to any int]m$iate product betwe5 ! elem5t itself & ! emanation x produces1 or 9 o!r words !re is no product 9 radium correspond+ to ,? ,x 9 ?orium4 ,giesel fir/ drew att5tion to ! fact t a radium comp\nd gradually increas$ 9 activity aft] prep>ation1 & only rea*$ a con/ant value aft] a mon?'s int]val4 ,if a radium comp\nd is dissolv$ 9 wat] & boil$ = "s "t1 or a curr5t ( air drawn ?r\gh ! solution1 on evaporation x is f\nd t ! activity has be5 dim9i%$4 ,! same result is obs]v$ if a solid radium comp\nd is heat$ 9 ! op5 air4 ,?is loss ( activity is due to ! removal ( ! emanation by ! process ( solution or heat+4 ,consid] ! case ( a radium comp\nd :i* has be5 kept = "s "t 9 solution 9 a %all[ vessel1 expos$ to ! op5 air1 & !n evaporat$ to dryness4 ,! emanation :i*1 9 ! /ate ( solution1 0 remov$ z fa/ z x 0 =m$1 is n[ occlud$1 &1 toge!r ) ! active deposit :i* x produces1 adds its radiations to t ( ! orig9al radium4 ,! activity w increase to a maximum value :5 ! rate ( production ( fre% emanation balances ! rate ( *ange ( t already produc$4 ,if n[ ! comp\nd is aga9 dissolv$ or heat$1 ! emanation escapes4 ,s9ce ! active deposit is n volatile & is insoluble 9 wat]1 x is n remov$ by ! process ( solution or heat+4 ,s9ce1 h[ev]1 ! p>5t matt] is remov$1 ! activity due to ! active deposit w imm$iately beg9 to decay1 & 9 ! c\rse ( a few h\rs w h almo/ disappe>$4 ,! activity ( ! radium measur$ by ! rays is !n f\nd to be ab\t #be p] c5t4 ( its orig9al value4 ,?is residual activity ( radium1 consi/+ entirely ( rays1 is non-sep>able1 & has n be5 fur!r dim9i%$ by *emical or physical means4 ,ru!r=d & ,soddy#cad exam9$ ! effect ( aspiration = long int]vals ?r\gh a radium *loride solution4 ,aft] ! fir/ few h\rs ! activity 0 f\nd to be r$uc$ to #be p] c5t41 & fur!r aspiration = ?ree weeks did n produce any fur!r dim9ution4 ,! radium 0 !n evaporat$ to dryness1 & ! rise ( its activity ) "t det]m9$4 ,! results are %[n 9 ! foll[+ table4 ,! f9al activity 9 ! second column is tak5 z "o hundr$4 ,9 column #c is giv5 ! p]c5tage proportion ( ! activity recov]$4 ,"t 9 ,activity ,p]c5tage days ,activity recov]$ #j #bej #j #jgj #ccg #aag #agg #dbg #bcg #dge #fhe #ehj #ghc #hce #ghj #afj #ifj #iej #baj #ajjj #ajjj ,! results are %[n graphically 9 ,fig4 #he4 ,! decay curve ( ! radium emanation is %[n 9 ! same figure4 ,! curve ( recov]y ( ! lo/ activity ( radium is ?us analog\s to ! curves ( recov]y ( uranium & ?orium :i* h be5 fre$ f ! active products ,ur ,x & ,? ,x respectively4 ,! int5sity ,it ( ! recov]$ activity at any "t is giv5 by frac ,it ,i #a e-t 1 :]e ,i is ! f9al value1 & is ! radio-active con/ant ( ! emanation4 ,! decay & recov]y curves are complem5t>y to "o ano!r4 ,illu/ration3 ,fig4 #he4 ,kn[+ ! rate ( decay ( activity ( ! radium emanation1 ! recov]y curve ( ! activity ( radium c ?us at once be d$uc$1 provid$ all ( ! emanation =m$ is occlud$ 9 ! radium comp\nd4 ,:5 ! emanation is remov$ f a radium comp\nd by solution or heat+1 ! activity measur$ by ! rays falls almo/ to z]o1 b increases 9 ! c\rse ( a mon? to its orig9al value4 ,! curve %[+ ! rise ( & rays ) "t is practically id5tical ) ! curve1 ,fig4 #he1 %[+ ! recov]y ( ! lo/ activity ( radium measur$ by ! rays4 ,! explanation ( ?is result lies 9 ! fact t ! & rays f radium only arise f ! active deposit1 & t ! non-sep>able activity ( radium gives out only rays4 ,on removal ( ! emanation1 ! activity ( ! active deposit decays ne>ly to z]o1 & 9 consequ5ce ! & rays almo/ disappe>4 ,:5 ! radium is all[$ to /&1 ! emanation beg9s to accumulate1 & produces 9 turn ! active deposit1 :i* gives rise to & rays4 ,! am\nt ( & rays 7all[+ = a p]iod ( ret>dation ( a few h\rs7 w !n increase at ! same rate z ! activity ( ! emanation1 :i* is cont9u\sly produc$ f ! radium4 #baf4 ,effect ( escape ( emanation4 ,if ! radium all[s "s ( ! emanation produc$ to escape into ! air1 ! curve ( recov]y w be diff]5t f t %[n 9 ,fig4 #he4 ,= example1 suppose t ! radium comp\nd all[s a con/ant fraction ( ! am\nt ( emanation1 pres5t 9 ! comp\nd at any "t1 to escape p] second4 ,if n is ! numb] ( emanation p>ticles pres5t 9 ! comp\nd at ! "t t1 ! numb] ( emanation p>ticles *ang+ 9 ! "t dt is ndt1 :]e is ! con/ant ( decay ( activity ( ! emanation4 ,if q is ! rate ( production ( emanation p>ticles p] second1 ! increase ( ! numb] dn 9 ! "t dt is giv5 by dn qdt ndt ndt1 or dn ----- q 7 7n4 dt ,! same equation is obta9$ :5 no emanation escapes1 ) ! diff]5ce t ! con/ant is replac$ by 4 ,:5 a /eady /ate is rea*$1 dn_/dt is z]o1 & ! maximum value ( n is equal to q_/7 74 ,if no escape takes place1 ! maximum value ( n is equal to q_/4 ,! escape ( emanation w ?us l[] ! am\nt ( activity recov]$ 9 ! proportion _/7 74 ,if n is ! f9al numb] ( emanation p>ticles /or$ up 9 ! comp\nd1 ! integration ( ! above equation gives frac n n #a e-7 alpha7 t 4 ,! curve ( recov]y ( activity is ?us ( ! same g5]al =m z ! curve :5 no emanation escapes1 b ! con/ant is replac$ by 4 ,= example1 if 1 ! equation ( rise ( activity is giv5 by frac n n #a e#b t 1 &1 9 consequ5ce1 ! increase ( activity to ! maximum w be f> m rapid ?an 9 ! case ( no escape ( emanation4 ,a v slight escape ( emanation w ?us produce l>ge alt]ations bo? 9 ! f9al maximum & 9 ! curve ( recov]y ( activity4 ,a numb] ( exp]im5ts h be5 describ$ by ,mme ,curie 9 h] ,?se prs5te la ,facult des ,sci5ces de ,p>is on ! effect ( solution & ( heat 9 dim9i%+ ! activity ( radium4 ,! results obta9$ are 9 g5]al agreem5t ) ! above view1 t #ge p] c5t4 ( ! activity ( radium is due to ! emanation & ! excit$ activity x produces4 ,if ! emanation is :olly or p>tly remov$ by solution or heat+1 ! activity ( ! radium is correspond+ly dim9i%$1 b ! activity ( ! radium comp\nd is spontane\sly recov]$ ow+ to ! production ( fre% emanation4 ,a /ate ( radio-active equilibrium is rea*$1 :5 ! rate ( production ( fre% emanation balances ! rate ( *ange 9 ! emanation /or$ up 9 ! comp\nd4 ,! diff]5ces obs]v$ 9 ! rate ( recov]y ( radium "u diff]5t conditions 7 probably due to v>iations 9 ! rate ( escape ( ! emanation4 #bag4 ,x has be5 %[n 9 section #aeb t ! emanation is produc$ at ! same rate 9 ! solid z 9 ! solution1 & all ! results obta9$ po9t to ! conclusion t ! emanation is produc$ f radium at a con/ant rate1 :i* is indep5d5t ( physical conditions4 ,radium1 l ?orium1 %[s a non-sep>able activity ( #be p] c5t4 ( ! maximum activity1 & consi/+ entirely ( rays4 ,! & rays arise only f ! active deposit4 ,! emanation itself 7section #aef7 gives out only rays4 ,^! results ?us admit ( ! explanation giv5 9 ! case ( ?orium 7section #acf74 ,! radium atoms break up at a con/ant rate ) ! emission ( p>ticles4 ,! residue ( ! radium atom becomes ! atom ( ! emanation4 ,?is 9 turn is un/able & breaks up ) ! expulsion ( an p>ticle4 ,! emanation is half trans=m$ 9 f\r days4 ,we h se5 t ?is emanation gives rise to an active deposit4 ,! results obta9$ up to ?is /age are %[n diagrammatically bel[4 p>ticle p>ticle _/ _/ _/ _/ ,,radium ,,atom ---- ,,atom ,,( ,,emanation ---- ,,atom ,,( ,,active ,,deposit #bah4 ,analysis ( ! active deposit f radium4 ,we h se5 9 *apt] ,,viii t ! excit$ activity produc$ on bodies1 by ! action ( ! radium emanation1 is due to a ?9 film ( active matt] deposit$ on ! surface ( bodies4 ,?is active deposit is a product ( ! decomposition ( ! radium emanation1 & is n due to any action ( ! radiations on ! surface ( ! matt]4 ,! curves %[+ ! v>iation ( ! excit$ activity ) "t are v complicat$1 dep5d+ n only ^u ! "t ( exposure 9 ! pres5ce ( ! emanation1 b also ^u ! type ( radiation us$ = measurem5t4 ,! great] portion ( ! activity ( ?is deposit dies away 9 ! c\rse ( #bd h\rs1 b a v small fraction /ill rema9s1 :i* !n *anges v sl[ly4 ,x w be %[n 9 ?is *apt] t at lea/ six successive trans=mations occur 9 ! active deposit4 ,! matt] initially produc$ f ! emanation is call$ radium ,a1 & ! succe$+ products ,b1 ,c1 ,d1 ,e1 ,f4 ,! equations express+ ! quantity ( ,a1 ,b1 ,c1444444 pres5t at any "t are v complicat$1 b ! comp>ison ( !ory ) exp]im5t may be mu* simplifi$ by tempor>ily disreg>d+ "s unimportant t]ms3 = example1 ! products ,a1 ,b1 ,c are trans=m$ at a v rapid rate comp>$ ) ,d4 ,! activity due to ,d ,e ,f is1 9 mo/ cases1 negligible comp>$ ) t ( ,a or ,c1 be+ usually less ?an ( ! initial activity obs]v$ = ,a or ,c4 ,! analysis ( ! active deposit ( radium may ?us be conv5i5tly divid$ into two /ages3 7#a7 ,analysis ( ! deposit ( rapid *ange1 :i* is ma9ly compos$ ( radium ,a1 ,b1 & ,c2 7#b7 ,analysis ( ! deposit ( sl[ *ange1 :i* is compos$ ( radium ,d1 ,e1 & ,f4 #bai4 ,analysis ( ! deposit ( rapid *ange4 ,9 ! exp]im5ts describ$ bel[1 a radium solution 0 plac$ 9 a clos$ glass vessel4 ,! emanation !n collect$ 9 ! air space above ! solution4 ,! rod1 to be made active1 0 introduc$ ?r\gh an op5+ 9 ! /opp] & expos$ 9 ! pres5ce ( ! emanation = a def9ite int]val4 ,if ! decay 0 to be measur$ by ! rays1 ! rod 0 made ! c5tral electrode 9 a cyl9drical vessel su* z is %[n 9 ,fig4 #ah4 ,a saturat+ voltage 0 appli$1 & ! curr5t betwe5 ! cyl9d]s measur$ by an electromet]4 ,if a v active rod is to be te/$1 a s5sitive galvanomet] c be employ$1 b1 9 su* a case1 a l>ge voltage is requir$ to produce saturation4 ,a sl[ curr5t ( du/-free air 0 cont9u\sly circulat$ ?r\gh ! cyl9d]1 9 ord] to remove any emanation t may h adh]$ to ! rod4 ,= exp]im5ts on ! & rays1 x 0 f\nd advisable to use an electroscope1 su* z is %[n 9 ,fig4 #ab1 in/ead ( an electromet]4 ,= measurem5ts ) ! rays1 ! active rod 0 plac$ "u ! electroscope1 & be=e ent]+ ! vessel ! rays pass$ ?r\gh a %eet ( metal ( suffici5t ?ickness to absorb all ! rays4 ,= measurem5ts ) ! rays1 ! electroscope 0 plac$ on a lead plate #jf cms4 ?ick1 & ! active rod plac$ "u ! lead plate4 ,! & rays 7 completely /opp$ by ! lead1 & ! dis*>ge 9 ! electroscope 0 !n due to ! rays alone4 ,! electroscope is v advantage\s = measurem5ts ( ?is "*1 & accurate obs]vations c be made simply & readily4 ,! curve ( decay ( activity1 measur$ by ! rays1 = an exposure ( #a m9ute 9 ! pres5ce ( ! radium emanation is %[n 9 ,fig4 #hf1 curve ,,bb4 ,! curve exhibits ?ree /ages3-- 7#a7 ,a rapid decay 9 ! c\rse ( #ae m9utes to less ?an #aj p] c5t4 ( ! value imm$iately aft] removal2 7#b7 ,a p]iod ( #cj m9utes 9 :i* ! activity v>ies v little2 7#c7 ,a gradual decrease almo/ to z]o4 ,! initial drop decays v approximately accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #c m9utes4 ,?ree or f\r h\rs aft] removal ! activity aga9 decays accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #bh m9utes4 ,! family ( curves obta9$ = diff]5t times ( exposure h already be5 %[n 9 ,fig4 #fg4 ,^! results ?us indicate3-- 7#a7 ,an initial *ange 9 :i* half ! matt] is trans=m$ 9 #c m9utes2 7#b7 ,a f9al *ange 9 :i* half ! matt] is trans=m$ 9 #bh m9utes4 ,illu/ration3 ,fig4 #hf4 ,be=e consid]+ ! explanation ( ! int]m$iate portion ( ! curve fur!r exp]im5tal results w be consid]$4 ,! curve ( decay ( ! excit$ activity = a long exposure 7#bd h\rs7 is %[n graphically 9 ,fig4 #hf1 curve ,,aa4 ,!re is at fir/ a rapid decrease = ! fir/ #ae m9utes to ab\t #ej p] c5t4 ( ! initial value1 !n a sl[] decay1 &1 aft] an int]val ( ab\t #d h\rs1 a gradual decay ne>ly to z]o1 accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 #bh m9utes4 ,! curves ( v>iation ) "t ( ! excit$ activity :5 measur$ by ! rays are %[n graphically 9 ,figs4 #hg & #hh4 ,fig4 #hg is = a %ort exposure ( #a m9ute4 ,fig4 #hh %[s ! decay = a long exposure ( ab\t #bd h\rs4 ,illu/ration3 ,fig4 #hg4 ,! curves obta9$ = ! rays are q diff]5t f ^? obta9$ = ! rays4 ,= a %ort exposure1 ! activity measur$ by ! rays is at fir/ small1 !n passes ?r\gh a maximum ab\t #cf m9utes aft] removal4 ,!re is !n a gradual decrease1 & aft] sev]al h\rs ! activity decays accord+ to an expon5tial law1 fall+1 z 9 ! o!r cases1 to half value 9 #bh m9utes4 ,! curve %[n 9 ,fig4 #hh = ! rays is v simil> 9 %ape to ! correspond+ curve1 ,fig4 #hf1 curve ,,aa1 = ! rays1 ) ! exception t ! rapid initial drop obs]v$ = ! -ray curve is q abs5t4 ,! lat] portions ( ! curve are simil> 9 %ape1 &1 disreg>d+ ! fir/ #ae m9utes aft] removal1 ! activity decays at exactly ! same rate 9 bo? cases4 ,! curves obta9$ by means ( ! rays are id5tical ) ^? obta9$ = ! rays4 ,?is %[s t ! & rays always occur toge!r & 9 ! same proportion4 ,= increase ( ! "t ( exposure f #a m9ute to #bd h\rs ! curves obta9$ are int]m$iate 9 %ape betwe5 ! two repres5tative limit+ curves1 ,figs4 #hg & #hh4 ,"s ( ^! curves h already be5 %[n 9 ,fig4 #fh4 ,illu/ration3 ,fig4 #hh4 #bbj4 ,explanation ( ! curves4 ,x has be5 po9t$ out t ! rapid initial drop = curves ,a & ,b1 ,fig4 #hf1 is due to a *ange giv+ rise to rays1 9 :i* half ( ! matt] is trans=m$ 9 ab\t #c m9utes4 ,! abs5ce ( ! drop 9 ! correspond+ curves1 :5 measur$ by ! rays1 %[s t ! fir/ #c-m9ute *ange does n give rise to rays2 = if x gave rise to rays1 ! activity %\ld fall (f at ! same rate z ! correspond+ -ray curve4 ,x has be5 %[n t ! activity sev]al h\rs aft] removal decays 9 all cases accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #bh m9utes4 ,?is is ! case :e!r = a %ort or long exposure1 or :e!r ! activity is measur$ by ! 1 1 or rays4 ,?is indicates t ! f9al #bh-m9ute *ange gives rise to all ?ree types ( rays4 ,x w be %[n t ^! results c be completely expla9$ on ! supposition t ?ree successive *anges occur 9 ! deposit$ matt] ( ! foll[+ "*#cae3-- 7#a7 ,a *ange ( ! matt] ,a initially deposit$ 9 :i* half is trans=m$ 9 ab\t #c m9utes4 ,?is gives rise only to rays4 7#b7 ,a second 8rayless0 *ange 9 :i* half ! matt] ,b is trans=m$ 9 #ba m9utes4 7#c7 ,a ?ird *ange 9 :i* half ! matt] ,c is trans=m$ 9 #bh m9utes4 ,?is gives rise to 1 1 & rays4 #bba4 ,analysis ( ! -ray curves4 ,! analysis ( ! *anges is mu* simplifi$ by tempor>ily disreg>d+ ! fir/ #c-m9ute *ange4 ,9 ! c\rse ( #f m9utes aft] removal1 ?ree qu>t]s ( ! matt] ,a has be5 trans=m$ into ,b & #bj m9utes aft] removal all b #a p] c5t4 has be5 trans=m$4 ,! v>iation ( ! am\nt ( matt] ,b or ,c pres5t at any "t agrees m closely ) ! !ory1 if ! fir/ *ange is disreg>d$ altoge!r4 ,a discussion ( ?is important po9t is giv5 lat] 7section #bbh74 ,! explanation ( ! -ray curves 7see ,figs4 #hg & #hh71 obta9$ = diff]5t times ( exposure1 w be fir/ consid]$4 ,= a v %ort exposure1 ! activity measur$ by ! rays is small at fir/1 passes ?r\gh a maximum ab\t #cf m9utes lat]1 & !n decays /eadily ) ! "t4 ,! curve %[n 9 ,fig4 #hg is v simil> 9 g5]al %ape to ! correspond+ ?orium & act9ium curves4 ,x is ?us necess>y to suppose t ! *ange ( ! matt] ,b into ,c does n give rise to rays1 :ile ! *ange ( ,c into ,d does4 ,9 su* a case ! activity 7measur$ by ! rays7 is proportional to ! am\nt ( ,c pres5t4 ,disreg>d+ ! fir/ rapid *ange1 ! activity ,it at any "t t %\ld be giv5 by an equation ( ! same =m 7section #bjg7 z = ?orium & act9ium1 viz41 frac ,it ,i,t frac e-#c t e-#b t e-#c ,t e-#b ,t 1 :]e ,i,t is ! maximum activity obs]v$1 :i* is rea*$ aft] an int]val ,t4 ,s9ce ! activity f9ally decays accord+ to an expon5tial law 7half value 9 #bh m9utes71 "o ( ! values ( is equal to #dac #aj4 ,z 9 ! case ( ?orium & act9ium1 ! exp]im5tal curves d n all[ u to settle :e!r ?is value ( is to be giv5 to or 4 ,f o!r data 7see section #bbf7 x w be %[n lat] t x mu/ ref] to 4 ,?us #dac #aj 7sec74 ,! exp]im5tal curve agrees v closely ) !ory if #ech #aj 7sec74 ,! agreem5t betwe5 !ory & exp]im5t is %[n by ! table giv5 bel[4 ,! maximum value ,i,t 7:i* is tak5 z #ajj7 is rea*$ at a "t ,t #cf m9utes4 ,9 ord] to obta9 ! -ray curve1 ! foll[+ proc$ure 0 adopt$4 ,a lay] ( ?9 alum9ium 0 plac$ inside a glass tube1 :i* 0 !n exhau/$4 ,a l>ge quantity ( radium emanation 0 !n sudd5ly introduc$ by op5+ a /op-cock communicat+ ) ! emanation vessel1 :i* 0 at atmosph]ic pressure4 ,! emanation 0 left 9 ! tube = #ae m9utes & !n 0 rapidly swept out by a curr5t ( air4 ,! alum9ium 0 !n remov$ & 0 plac$ "u an electroscope1 su* z is %[n 9 ,fig4 #ab4 ,! rays f ! alum9ium 7 cut (f by an int]pos$ scre5 ( alum9ium #a mm4 ?ick4 ,! "t 0 reckon$ f a p]iod ( #de seconds aft] ! introduction ( ! emanation4 ,"t 9 ,!oretical ,obs]v$ m9utes value ( value ( activity activity #j #j #j #aj #eha #ee #bj #hhf #hf #cj #igc #ig #cf #ajj #ajj #dj #iih #iie #ej #icd #ib #fj #hcd #hb #hj #fcg #fae #ajj #ddh #dbe #abj #cjh #bi ,!re is ?us a good agreem5t betwe5 ! calculat$ & obs]v$ values ( ! activity measur$ by ! rays4 ,! results are satisfactorily expla9$ if x is suppos$3-- 7#a7 ,t ! *ange ,b into ,c 7half trans=m$ 9 #ba m9utes7 does n give rise to rays2 7#b7 ,t ! *ange ,c into ,d 7half trans=m$ 9 #bh m9utes7 gives rise to rays4 #bbb4 ,^! conclusions are v /rongly support$ by obs]vations ( ! decay measur$ by ! rays = a long exposure4 ,! curve ( decay is %[n 9 ,fig4 #hh & ,fig4 #hi1 curve ,i4 ,illu/ration3 ,fig4 #hi4 ,p4 ,curie & ,danne made ! important obs]vation t ! curve ( decay ,c1 correspond+ to t %[n 9 ,fig4 #hh1 = a long exposure1 c\ld be accurately express$ by an empirical equation ( ! =m frac ,it ,i ae-#c t 7a #a7 e-#b t 1 :]e #ech #aj 7sec7 & #dac #aj 7sec71 & #dbj is a num]ical con/ant4 ,i h f\nd t )9 ! limit ( exp]im5tal error ?is equation repres5ts ! decay ( excit$ activity ( radium = a long exposure1 measur$ by ! rays4 ,! equation express+ ! decay ( activity1 measur$ by ! rays1 diff]s consid]ably f ?is1 especially 9 ! e>ly "p ( ! curve4 ,sev]al h\rs aft] removal ! activity decays accord+ to an expon5tial law ) ! "t1 decreas+ to half value 9 #bh m9utes4 ,?is fixes ! value ( 4 ,! con/ant & ! value ( are d$uc$ f ! exp]im5tal curve by trial4 ,n[ we h already %[n 7section #bjg7 t 9 ! case ( ! active deposit f ?orium1 :]e !re are two *anges ( con/ants & 1 9 :i* only ! second *ange gives rise to a radiation1 ! int5sity ( ! radiation is giv5 by frac ,it ,i frac #b #b #c e-#c t frac #c #b #c e-#b t = a long "t ( exposure 7see equation #h1 section #aih74 ,?is is an equation ( ! same =m z t f\nd exp]im5tally by ,curie & ,danne4 ,on sub/itut+ ! values 1 f\nd by !m1 frac #b #b #c #d;cdot#c 1 & frac #a #a #c #c;cdot#c 4 ,?us ! !oretical equation agrees 9 =m ) t d$uc$ f obs]vation1 & ! values ( ! num]ical con/ants are also closely concordant4 ,if ! fir/ z well z ! second *ange gave rise to a radiation1 ! equation w\ld be ( ! same g5]al =m1 b ! value ( ! num]ical con/ants w\ld be diff]5t1 ! values dep5d+ ^u ! ratio ( ! ionization 9 ! fir/ & second *anges4 ,if1 = example1 x is suppos$ t bo? *anges give out rays 9 equal am\nts1 x c readily be calculat$ t ! equation ( decay w\ld be frac ,it ,i frac cdot#eb #b #c e-#c t cdot#e 7frac #c #b #c - #a7 e-#b t 4 ,tak+ ! values ( & f\nd by ,curie1 ! num]ical factor e-#b t becomes #bae in/ead ( #dc & #aae in/ead ( #cc4 ,! !oretical curve ( decay 9 ?is case w\ld be readily di/+ui%able f ! obs]v$ curve ( decay4 ,! fact t ! equation ( decay f\nd by ,curie & ,danne involves ! necessity ( an initial rayless *ange c be %[n z foll[s3-- ,curve ,i 7,fig4 #hi7 %[s ! exp]im5tal curve4 ,at ! mom5t ( removal ( ! body f ! emanation 7disreg>d+ ! initial rapid *ange71 ! matt] mu/ consi/ ( bo? ,b & ,c4 ,consid] ! matt] :i* exi/$ 9 ! =m ,c at ! mom5t ( removal4 ,x w be trans=m$ accord+ to an expon5tial law1 ! activity fall+ by "o-half 9 #bh m9utes4 ,?is is %[n 9 curve ,,ii4 ,curve ,,iii repres5ts ! diff]5ce betwe5 ! ord9ates ( curves ,i & ,,ii4 ,x w be se5 t x is id5tical 9 %ape ) ! curve 7,fig4 #hg7 %[+ ! v>iation ( ! activity = a %ort exposure1 measur$ by ! rays4 ,x passes ?r\gh a maximum at ! same "t 7ab\t #cf m9utes74 ,! explanation ( su* a curve is only possible on ! assumption t ! fir/ *ange is a rayless "o4 ,! ord9ates ( curve ,,iii express ! activity add$ 9 consequ5ce ( ! *ange ( ! matt] ,b1 pres5t aft] removal1 into ! matt] ,c4 ,! matt] ,b pres5t gradually *anges into ,c1 & ?is1 9 its *ange to ,d1 gives rise to ! radiation obs]v$4 ,s9ce ! matt] ,b alone is consid]$1 ! v>iation ( activity ) "t due to its fur!r *anges1 %[n by curve ,,iii1 %\ld agree ) ! curve obta9$ = a %ort exposure 7see ,fig4 #hg71 & ?is1 z we h se51 is ! case4 ,! agreem5t betwe5 !ory & exp]im5t is %[n 9 ! foll[+ table4 ,! fir/ column gives ! !oretical curve ( decay = a long exposure d$uc$ f ! equation frac ,it ,i frac #b #b #c e-#c t frac #c #b #c e-#b t tak+ ! value ( #ech #aj & #dac #aj4 ,"t 9 ,calculat$ ,obs]v$ m9utes values values #j #ajj #ajj #aj #ifh #igj #bj #hid #hhe #cj #ghf #gge #dj #fib #fge #ej #eii #egj #fj #dib #dhb #hj #cdb #cce #ajj #bbg #bbe #abj #adi #ade ,! second column gives ! obs]v$ activity 7measur$ by means ( an electroscope7 = a long exposure ( #bd h\rs 9 ! pres5ce ( ! emanation4 ,9 cases :]e a /eady curr5t ( air is drawn ov] ! active body1 ! obs]v$ values are slightly l[] ?an ! !oretical4 ,?is is probably due to a slight volatility ( ! product radium ,b at ord9>y temp]atures4 ,illu/ration3 ,fig4 #ij4 #bbc4 ,analysis ( ! -ray curves4 ,! analysis ( ! decay curves ( ! excit$ activity ( radium1 measur$ by ! rays1 w n[ be discuss$4 ,! foll[+ table %[s ! v>iation ( ! int5sity ( ! radiation aft] a long exposure 9 ! pres5ce ( ! radium emanation4 ,a plat9um plate 0 made active by exposure = sev]al days 9 a glass tube conta9+ a l>ge quantity ( emanation4 ,! active plat9um aft] removal 0 plac$ on ! l[] ( two p>allel insulat$ lead plates1 & a saturat+ electromotive =ce ( #fjj volts 0 appli$4 ,! ionization curr5t 0 suffici5tly l>ge to be measur$ by means ( a s5sitive high-resi/ance galvanomet]1 & read+s 7 tak5 z quickly z possible aft] removal ( ! plat9um f ! emanation vessel4 ,! initial value ( ! curr5t 7tak5 z #ajj7 0 d$uc$ by cont9u+ ! curves backw>ds to meet ! v]tical axis 7see ,fig4 #ij71 & 0 f\nd to be #c #aj amp]e4 ,"t 9 ,curr5t m9utes #j #ajj #b #hj #d #fie #f #fbd #h #egf #aj #ebj #ae #dhd #bj #ded #cj #djd #dj #cef #ej #cjd #fj #bed #hj #agd #ajj #aaf #abj #gf ,^! results are %[n graphically 9 ! upp] curve ( ,fig4 #ij4 ,! initial rapid decrease is due to ! decay ( ! activity ( ! matt] ,a4 ,if ! slope ( ! curve is produc$ backw>ds f a "t #bj m9utes aft] removal1 x cuts ! v]tical axis at ab\t #ej4 ,! diff]5ce betwe5 ! ord9ates ( ! curves ,a ,b ,c & ,,ll at any "t is %[n 9 ! curve ,,aa4 ,! curve ,,aa repres5ts ! activity at any "t suppli$ by ! *ange 9 radium ,a4 ,! curve ,,ll />t+ f ! v]tical axis is id5tical ) ! curve already consid]$1 repres5t+ ! decay ( activity measur$ by ! rays = a long exposure 7see ,fig4 #hh74 ,"t 9 ,calculat$ ,obs]v$ m9utes value ( value ( activity activity #j #ajj #ajj #aj #ifh #igj #bj #hid #hib #cj #ghf #hjh #dj #fib #gab #ej #eii #fjh #fj #dib #eja #hj #cdb #cdh #ajj #bbg #bcb #abj #adi #aeb ,?is is %[n by ! agreem5t ( ! numb]s 9 ! above table4 ,! fir/ column 9 ! table above gives ! !oretical values ( ! activity d$uc$ f ! equation frac ,it ,i frac #b #b #c e-#c t frac #c #b #c e-#b t = ! values ( 1 previ\sly employ$4 ,! second column gives ! obs]v$ values ( ! activity d$uc$ f ! decay curve ,,ll4 ,! close agreem5t ( ! curve ,,ll ) ! !oretical curve d$uc$ on ! assumption t !re are two *anges1 ! fir/ ( :i* does n emit rays1 %[s t ! *ange ( radium ,b into ,c does n emit rays4 ,9 a simil> way1 z 9 ! curve ,i1 ,fig4 #hi1 ! curve ,,ll may be analys$ into its two compon5ts repres5t$ by ! two curves ,,cc & ,,bb4 ,! curve ,,cc repres5ts ! activity suppli$ by ! matt] ,c pres5t at ! mom5t ( removal4 ,! curve ,,bb repres5ts ! activity result+ f ! *ange ( ,b into ,c & is id5tical ) ! correspond+ curve 9 ,fig4 #hi4 ,us+ ! same l9e ( reason+ z be=e1 we may ?us conclude t ! *ange ( ,b into ,c is n accompani$ by rays4 ,x has already be5 %[n t x does n give rise to rays1 & ! id5tity ( ! & -ray curves %[s t x does n give rise to rays4 ,! *ange ( ,b into ,c is ?us a 8rayless0 *ange1 :ile ! *ange ( ,c into ,d gives rise to all ?ree k9ds ( rays4 ,an analysis ( ! decay ( ! excit$ activity ( radium ?us %[s t ?ree di/9ct rapid *anges occur 9 ! matt] deposit$1 viz43-- 7#a7 ,! matt] ,a1 d]iv$ f ! *ange 9 ! emanation1 is half trans=m$ 9 #c m9utes & is accompani$ by rays alone2 7#b7 ,! matt] ,b is half trans=m$ 9 #ba m9utes & gives rise to no ioniz+ rays2 7#c7 ,! matt] ,c is half trans=m$ 9 #bh m9utes & is accompani$ by 1 1 & rays2 7#d7 ,a f\r? v sl[ *ange w be discuss$ lat]4 #bbd4 ,equations repres5t+ ! activity curves4 ,! equations repres5t+ ! v>iation ( activity ) "t are = conv5i5ce collect$ bel[1 :]e #ch #aj1 #ech #aj1 #dac #aj3-- 7#a7 ,%ort exposure3 activity measur$ by rays1 frac ,it ,i,t #aj;cdot#c 7e-#c t e-#b t7 :]e ,i,t is ! maximum value ( ! activity2 7#b7 ,long exposure3 activity measur$ by rays1 frac ,it ,i #d;cdot#c 7e-#c t #c;cdot#c e-#b t7 1 :]e ,i is ! initial value2 7#c7 ,any "t ( exposure ,t3 activity measur$ by ! rays1 frac ,it ,i frac ae-#c t be-#b t a b 1 :]e a frac #a e-#c ,t #c 1 b frac #a e-#b ,t #b 2 7#d7 ,activity measur$ by rays3 long "t ( exposure1 frac ,it ,i frac #ab e-#a t frac #ab 7#d;cdot#c e-#c t #c;cdot#c e-#b t7 4 ,! equations = ! rays = any "t ( exposure c be readily d$uc$1 b ! expressions are some:at complicat$4 ,illu/ration3 ,fig4 #ia4 #bbe4 ,equations ( rise ( excit$ activity4 ,! curves express+ ! gradual increase to a maximum ( ! excit$ activity produc$ on a body expos$ 9 ! pres5ce ( a con/ant am\nt ( emanation are complem5t>y to ! curves ( decay = a long exposure4 ,! sum ( ! ord9ates ( ! rise & decay curves is at any "t a con/ant4 ,?is foll[s necess>ily f ! !ory & c also be d$uc$ simply f priori consid]ations4 7,see section #bjj47 ,! curves ( rise & decay ( ! excit$ activity = bo? ! & rays are %[n graphically 9 ,fig4 #ia4 ,! ?ick l9e curves are = ! rays4 ,! diff]5ce betwe5 ! %apes ( ! decay curves :5 measur$ by ! or rays is cle>ly br\ght out 9 ! figure4 ,! equations repres5t+ ! rise ( activity to a maximum are giv5 bel[4 ,= ! & rays1 frac ,it ,imax #a 7#d;cdot#c e-#c t #c;cdot#c e-#b t7 4 ,= ! rays1 frac ,it ,imax #a frac #ab e-#a t frac #ab 7#d;cdot#c e-#c t #c;cdot#c e-#b t7 4 #bbf4 ,effect ( temp]ature4 ,we h s f> n consid]$ ! evid5ce on :i* ! #bh-m9ute r ?an ! #ba-m9ute *ange is suppos$ to take place 9 ! matt] ,c4 ,?is evid5ce has be5 suppli$ by "s rec5t important exp]im5ts ( ,p4 ,curie & ,danne#caf on ! volatilization ( ! active matt] deposit$ by ! emanation4 ,miss ,gates#cag %[$ t ?is active matt] 0 volatiliz$ f a plat9um wire above a r$ heat & deposit$ on ! surface ( a cold cyl9d] surr\nd+ ! wire4 ,curie & ,danne ext5d$ ^! results by subject+ an active plat9um wire = a %ort "t to ! action ( temp]atures v>y+ betwe5 #ae ,c4 & #acej ,c41 & !n exam9+ at room temp]atures ! decay curves n only = ! active matt] rema9+ on ! wire1 b also = ! volatiliz$ "p4 ,!y f\nd t ! activity ( ! di/ill$ "p always increas$ aft] removal1 pass$ ?r\gh a maximum1 & f9ally decay$ accord+ to an expon5tial law to half value 9 #bh m9utes4 ,at a temp]ature ( ab\t #fcj ,c4 ! active matt] left beh9d on ! wire decay$ at once accord+ to an expon5tial law1 fall+ to half value 9 #bh m9utes4 ,p4 ,curie & ,danne %[$ t ! matt] ,b is mu* m volatile ?an ,c4 ,! =m] is completely volatiliz$ at ab\t #fjj ,c41 :ile ! latt] is n completely volatiliz$ ev5 at a temp]ature ( #acjj ,c4 ,! fact t ! matt] ,c1 left beh9d :5 ,b is completely volatiliz$1 decays at once to half value 9 #bh m9utes %[s t ! matt] ,c itself & n ,b is half trans=m$ 9 #bh m9utes4 ,curie & ,danne also f\nd t ! rate ( decay ( ! active matt] v>i$ ) ! temp]ature to :i* ! plat9um wire _h be5 subject$4 ,at #fcj ,c4 ! rate ( decay 0 normal1 at #aajj ,c4 ! activity fell to half value 9 ab\t #bj m9utes1 :ile at #acjj ,c4 x fell to ab\t half value 9 ab\t #be m9utes4 ,i h repeat$ ! exp]im5ts ( ,curie & ,danne & obta9$ v simil> results4 ,x 0 ?\ght possible t ! measur$ rate ( decay obs]v$ aft] heat+ might be due to a p]man5t increase 9 ! rate ( volatilization ( ,c at ord9>y temp]atures4 ,?is explanation1 h[ev]1 is n t5able1 = x 0 f\nd t ! activity decreas$ at ! same rate :e!r ! activity ( ! wire 0 te/$ 9 a clos$ tube or 9 ! op5 ) a curr5t ( air pass$ ov] x4 ,^! results are ( great importance1 = !y indicate t ! rate ( *ange ( ! product ,c is n a con/ant1 b is affect$ by diff]5ces ( temp]ature4 ,?is is ! fir/ case :]e temp]ature has be5 %[n to ex]t an appreciable influ5ce on ! rate ( *ange ( any radio-active product4 #bbg4 ,volatility ( radium ,b at ord9>y temp]ature4 ,miss ,brooks#cah has obs]v$ t a body1 made active by exposure to ! radium emanation1 possesses ! p[] ( excit+ second>y activity on ! walls ( a vessel 9 :i* x is plac$4 ,?is activity 0 usually ab\t ( ! :ole1 b ! am\nt 0 increas$ to ab\t if ! active wire 0 wa%$ 9 wat] & dri$ ov] a gas flame--! me?od (t5 adopt$ to free ! wire ( any trace ( ! radium emanation4 ,?is effect ( produc+ activity 0 mo/ m>k$ imm$iately aft] removal ( ! wire f ! emanation1 & 0 almo/ inappreciable t5 m9utes aft]w>ds4 ,! effect 0 p>ticul>ly noticeable 9 "s exp]im5ts ) a copp] plate1 :i* 0 made active by leav+ x a %ort "t 9 a solution ( ! active deposit f radium4 ,?is active solution 0 obta9$ by plac+ an active plat9um wire 9 dilute hydro*loric acid4 ,on plac+ ! copp] plate 9 a te/+ vessel = a few m9utes1 & !n remov+ x1 activity 0 obs]v$ on ! walls ( ! vessel am\nt+ to ab\t "o p] c5t4 ( ! activity ( ! copp] plate4 ,x 0 f\nd t ?is effect 0 n due to ! emission ( an emanation f ! active body1 b mu/ be ascrib$ to a slight volatility ( radium ,b at ord9>y temp]atures4 ,?is 0 prov$ by obs]vations on ! v>iation ( ! activity ( ! matt] deposit$ on ! walls ( ! vessel4 ,! activity 0 small at fir/1 b rose to a maximum aft] ab\t #cj m9utes1 & !n decay$ ) ! "t4 ,! curve ( rise 0 v simil> to t %[n 9 ,fig4 #hg1 & %[s t ! inactive matt] radium ,b 0 c>ri$ to ! walls & !re *ang$ into ,c1 :i* gave rise to ! radiation obs]v$4 ,! product ,b only escapes f ! body = a %ort "t aft] removal4 ,?is is a /rong indication t its app>5t volatility is connect$ ) ! pres5ce ( ! rapidly *ang+ product radium ,a4 ,s9ce ,a breaks up ) an expulsion ( an p>ticle1 "s ( ! residual atoms con/itut+ radium ,b may acquire suffici5t velocity to escape into ! gas1 & are !n transf]r$ by diffusion to ! walls ( ! vessel4 ,miss ,brooks obs]v$ t ! activity 0 n conc5trat$ on ! negative electrode 9 an electric field b 0 diffus$ uni=mly ov] ! walls ( ! vessel4 ,?is obs]vation is ( importance 9 consid]+ ! explanation ( ! anomal\s effects exhibit$ by ! active deposit ( radium1 :i* w be discuss$ 9 ! foll[+ section4 #bbh4 ,effect ( ! fir/ rapid *ange4 ,we h se5 t ! law ( decay ( activity1 measur$ by ! or rays1 c be expla9$ v satisfactorily if ! fir/ #c-m9ute *ange is disreg>d$4 ,! full !oretical exam9ation ( ! "q giv5 9 sections #aig & #aih & ! curves ( ,figs4 #gb & #gc %[1 h[ev]1 t ! pres5ce ( ! fir/ *ange %\ld ex]cise an effect ( suffici5t magnitude to be detect$ 9 measurem5ts ( ! activity due to ! succe$+ *anges4 ,! "q is ( great int]e/1 = x involves ! important !oretical po9t :e!r ! sub/ances ,a & ,b are produc$ indep5d5tly ( "o ano!r1 or :e!r ,a is ! p>5t ( ,b4 ,9 ! latt] case1 ! matt] ,a :i* is pres5t *anges into ,b1 &1 9 consequ5ce1 ! am\nt ( ,b pres5t aft] ,a is trans=m$ %\ld be some:at great] ?an if ,b 7 produc$ indep5d5tly4 ,s9ce ! *ange ( ,a is fairly rapid1 ! effect %\ld be mo/ m>k$ 9 ! e>ly "p ( ! curve4 ,9 ord] to exam9e ?is po9t exp]im5tally1 ! curve ( rise ( activity1 measur$ by ! rays1 0 det]m9$ imm$iately aft] ! introduction ( a l>ge quantity ( ! radium emanation into a clos$ vessel4 ,! curve ( decay ( activity on a body = a long exposure aft] removal ( ! emanation1 & ! rise ( activity aft] ! introduction ( ! emanation1 are 9 all cases complem5t>y to "o ano!r4 ,:ile1 h[ev]1 x is difficult to measure ) c]ta9ty :e!r ! activity has fall5 9 a giv5 "t1 = example1 f #ajj to #ii or #ihe1 x is easy to be sure :e!r ! correspond+ rise ( activity 9 ! conv]se exp]im5t is #a or #ae p] c5t4 ( ! f9al am\nt4 ,fig4 #ib1 curve ,i1 %[s ! rise ( activity 7measur$ by ! rays7 obta9$ = an int]val ( #bj m9utes aft] ! introduction ( ! emanation4 ,! ord9ates repres5t ! p]c5tage am\nt ( ! f9al activity rega9$ at any "t4 ,curve ,,iii %[s ! !oretical curve obta9$ on ! assumption t ,a is a p>5t ( ,b4 ,?is curve is calculat$ f equation 7#i7 discuss$ 9 section #aih1 & 1 1 are ! values previ\sly f\nd4 ,curve ,,ii gives ! !oretical activity at any "t on ! assumption t ! sub/ances ,a & ,b arise indep5d5tly4 ,?is is calculat$ f an equation ( ! same =m z 7#h71 section #aih4 ,illu/ration3 ,fig4 #ib4 ,x is se5 t ! exp]im5tal results agree be/ ) ! view t ,a & ,b arise indep5d5tly4 ,su* a conclusion1 h[ev]1 is ( too great importance to be accept$ be=e exam9+ closely :e!r ! !oretical conditions are fulfill$ 9 ! exp]im5ts4 ,9 ! fir/ place1 x is assum$ t ! c>ri]s :i* give rise to excit$ activity are deposit$ on ! surface ( ! body1 to be made active imm$iately aft] _! =mation4 ,!re is "s evid5ce1 h[ev]1 t "s ( ^! c>ri]s exi/ = a consid]able int]val 9 ! gas be=e _! deposit on ! body4 ,= example1 x is f\nd t if a body is introduc$ = a %ort int]val1 ab\t #a m9ute1 into a vessel conta9+ ! radium emanation1 :i* has rema9$ undi/urb$ = sev]al h\rs1 ! activity aft] ! fir/ rapid decay 7see ,fig4 #hf1 curve ,b7 is 9 mu* great] proportion ?an if an electric field _h be5 act+ = "s "t previ\sly4 ,?is result indicates t ! c>ri]s ( ,b & ,c bo? collect 9 ! gas & are swept to ! electrode :5 an electric field is appli$4 ,i h also obs]v$ t if radium emanation1 :i* has /ood undi/urb$ = "s "t1 is swept into a te/+ vessel1 ! rise curve is n complem5t>y to ! decay curve1 b indicates t a l>ge am\nt ( radium ,b & ,c 0 pres5t ) ! emanation4 ,! exp]im5ts ( ,miss ,brooks1 previ\sly ref]r$ to1 indicate t radium ,b does n obta9 a *>ge & s w rema9 9 ! gas4 ,dr ,bronson1 work+ 9 ! laboratory ( ! writ]1 has obta9$ evid5ce t a l>ge am\nt ( radium ,d rema9s 9 ! gas ev5 9 a /rong electric field4 ,if ! matt] ,b exi/s to "s ext5t 9 ! gas1 ! diff]5ce betwe5 ! !oretical curves = ?ree successive *anges w\ld be expla9$2 =1 9 transf]r+ ! emanation to ano!r vessel1 ! matt] ,b mix$ ) x w\ld comm5ce at once to *ange into ,c & give rise to a "p ( ! radiation obs]v$4 ,! equal division ( ! activity betwe5 ! products ,a & ,c 7see ,fig4 #ij7 supports ! view t ,c is a product ( ,a1 = :5 radio-active equilibrium is rea*$1 ! numb] ( p>ticles ( ,a *ang+ p] second is equal to ! numb] ( ,b or ,c *ang+ p] second4 ,if ea* atom ( ,a & ,c expels an p>ticle ( ! same mass & ) ! same av]age velocity1 ! activity due to ! matt] ,a %\ld be equal to t due to ! matt] ,c2 & ?is1 z we h se51 is ! case4 ,:ile x is a matt] ( great difficulty to give a def9ite exp]im5tal pro( t radium ,a & ,b are consecutive products1 ,i ?9k !re is little d\bt ( its correctness4 ,accurate det]m9ations ( ! curves ( rise & decay may ?r[ fur!r light on ! complicat$ processes :i* und\bt$ly occur betwe5 ! break+ up ( ! atoms ( ! emanation & ! appe>ance ( ! active deposit on ! electrodes4 #bbi4 ,relative activity suppli$ by ! -ray products ( radium4 ,!re are f\r products 9 radium :i* give out rays1 viz4 radium itself1 ! emanation1 radium ,a & ,c4 ,if ^! products are 9 radio-active equilibrium1 ! same numb] ( p>ticles ( ea* product are trans=m$ p] second &1 if ea* atom breaks up ) ! emission ( "o p>ticle1 ! numb] ( p>ticles expell$ p] second %\ld be ! same = ea* product4 ,s9ce1 h[ev]1 ! p>ticles f ! diff]5t products are n project$ ) ! same velocity1 ! activity1 measur$ by ! ionization curr5t 9 ! usual mann]1 w n be ! same = all products4 ,! activity1 :5 measur$ by ! saturation curr5t betwe5 p>allel plates at suffici5t di/ance ap>t to absorb all ! rays 9 ! gas1 is proportional to ! en]gy ( ! p>ticles escap+ into ! gas4 ,x has be5 %[n t ! m9imum activity ( radium aft] removal ( ! emanation1 measur$ by ! rays1 is #be p] c5t4 ( ! maximum value4 ,! rema9+ #ge p] c5t4 is due to ! p>ticles f ! o!r products4 ,n[ ! activity suppli$ by radium ,a & ,c is ne>ly ! same 7section #bbh74 ,if ! emanation is introduc$ into a cyl9drical vessel ab\t #e cms4 9 diamet]1 ! activity increases to ab\t twice its initial value ow+ to ! deposit ( radium ,a & ,c on ! surface ( ! vessel4 ,?is %[s t ! activity ( ! emanation is ( ab\t ! same magnitude z t suppli$ by radium ,a or ,c1 b an accurate comp>ison is beset ) difficulty1 = ! emanation is di/ribut$ ?r\gh\t ! gas1 :ile radium ,a & ,c are deposit$ on ! walls ( ! vessel4 ,9 addition1 ! relative absorption ( ! emanation comp>$ ) t ( radium ,a & ,c is n kn[n4 ,! writ] has made "s exp]im5ts on ! decrease ( activity ( radium imm$iately aft] heat+ to a suffici5t temp]ature to drive (f ! emanation4 ,! results obta9$ by ?is me?od are complicat$ by ! alt]ation ( ! radiat+ surface 9 consequ5ce ( ! heat+1 b indicate t ! emanation supplies ab\t #gj p] c5t4 ( ! activity ( radium ,a or ,c4 ,?is po9ts to ! conclusion t ! p>ticles f ! emanation are project$ ) less velocity ?an ^? f radium ,c4 ,! foll[+ table %[s approximately ! activity suppli$ by ! diff]5t products ( radium 9 radio-active equilibrium4 ,product ,p]c5tage proportion ( total activity ,radium #be p] c5t4 ,emanation #ag ,radium ,a #bi ,radium ,b #j ,radium ,c #bi ,! products ( radium & _! radiation are graphically %[n lat] 9 ,fig4 #ie4 #bcj4 ,active deposit ( radium ( sl[ trans=mation4 ,x has be5 po9t$ out 7section #ahc7 t a body1 expos$ 9 ! pres5ce ( ! radium emanation1 does n lose all its activity = a long "t aft] removal2 a small residual activity is always obs]v$4 ,! magnitude ( ?is residual activity is dep5d5t n only ^u ! am\nt ( emanation employ$1 b also ^u ! "t ( exposure ( ! body 9 ! pres5ce ( ! emanation4 ,= an exposure ( sev]al h\rs 9 ! pres5ce ( ! emanation1 ! residual activity is less ?an "o-million? ( ! activity imm$iately aft] removal4 ,an acc\nt w n[ be giv5 ( "s inve/igations made by ! writ]#cai on ! nature ( ?is residual activity & ! *emical prop]ties ( ! active matt] itself4 ,x is fir/ ( all necess>y to %[ t ! residual activity arises 9 consequ5ce ( a deposit ( radio-active matt]1 & is n due to "s action ( ! int5se radiations to :i* ! body made active has be5 subject$4 ,! inside ( a long glass tube 0 cov]$ ) equal areas ( ?9 metal1 includ+ alum9ium1 iron1 copp]1 silv]1 lead1 & plat9um4 ,a l>ge am\nt ( radium emanation 0 introduc$ into ! tube1 & ! tube clos$4 ,aft] sev5 days ! metal plates 7 remov$1 &1 aft] all[+ two days to elapse = ! ord9>y excit$ activity to disappe>1 ! residual activity ( ! plates 0 te/$ by an electromet]4 ,! activity ( ! plates 0 f\nd to be unequal1 be+ greate/ = copp] & silv]1 & lea/ = alum9ium4 ,! activity ( copp] 0 twice z great z t ( alum9ium4 ,aft] /&+ = ano!r week ! activity ( ! plates 0 aga9 te/$4 ,! activity ( ea* _h dim9i%$ 9 ! int]val to "s ext5t1 b ! initial diff]5ces obs]v$ _h to a l>ge ext5t disappe>$4 ,aft] rea*+ a m9imum value ! activity ( ea* plate sl[ly b /eadily increas$ at ! same rate4 ,aft] a mon?'s int]val ! activity ( ea* ( ! plates 0 ne>ly ! same1 & m ?an ?ree times ! m9imum value4 ,! initial irregul>ities 9 ! decay curves ( ! diff]5t metals are1 9 all probability1 due to slight b diff]5t degrees ( absorption ( ! radium emanation by ! metal plates1 ! absorption be+ greate/ = copp] & silv] & lea/ = alum9ium4 ,z ! occlud$ emanation 0 sl[ly releas$ or lo/ its activity1 ! activity ( ! metal fell to a limit+ value4 ,! absorption ( ! radium emanation by lead1 p>aff91 & ca\t*\c has be5 notic$ by ,curie & ,danne 7section #ahb74 ,! residual activity on ! plates compris$ bo? & rays1 ! latt] be+ pres5t1 9 all cases1 9 a v unusual proportion4 ,! equality ( ! activity & ! id5tity ( ! radiation emitt$ f ea* plate %[ t ! residual activity is due to *anges ( "s =m ( matt] deposit$ on ! plates1 & t x _c be ascrib$ to an action ( ! int5se radiations2 = if su* 7 ! case1 x w\ld be expect$ t ! activity produc$ on ! diff]5t plates w\ld v>y n only 9 quantity1 b also 9 quality4 ,?is result is confirm$ by ! obs]vation t ! active matt] c be remov$ f a plat9um plate by solution 9 sulphuric acid1 & has o!r di/9ctive *emical & physical prop]ties4 ,! v>iation ) "t ( ! residual activity measur$ by ! rays w fir/ be consid]$4 ,a plat9um plate 0 expos$ 9 ! pres5ce ( ! radium emanation = sev5 days4 ,! am\nt ( emanation initially pres5t 0 equal to t obta9$ f ab\t #c milligrams ( pure radium bromide4 ,! plate imm$iately aft] removal gave a saturation-curr5t1 measur$ betwe5 p>allel plates by a galvanomet]1 ( #ae #aj amp]e4 ,"s h\rs aft] removal1 ! activity decay$ accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 #bh m9utes4 ,?ree days aft] removal ! active plate gave a saturation-curr5t1 measur$ by an electromet]1 ( #e #aj amp]e2 i4e4 #j1jjj ( ! initial activity4 ,! activity 0 obs]v$ to increase /eadily ) ! "t4 ,! results are %[n 9 ,fig4 #ic1 :]e ! "t is reckon$ f ! middle ( ! "t ( exposure to ! emanation4 ,! curve is initially ne>ly a /raight l9e pass+ ?r\gh ! orig94 ,! activity increases ) ! "t = ! int]val ( eight mon?s ov] :i* ! obs]vations h ext5d$4 ,! latt] portions ( ! curve1 h[ev]1 fall bel[ ! tang5t to ! curve drawn ?r\gh ! orig91 %[+ t ! activity is n increas+ proportionately ) ! "t4 ,! active deposit1 obta9$ 9 a diff]5t mann]1 has be5 exam9$ = a /ill long] p]iod4 ,! emanation f #cj milligrams ( radium bromide 0 cond5s$ 9 a glass tube & !n seal$4 ,aft] a mon?'s int]val1 ! tube 0 op5$ & dilute sulphuric acid introduc$4 ,! acid dissolv$ (f ! active deposit 9 ! tube & on driv+ (f ! acid by heat1 a radio-active residue 0 obta9$4 ,! activity ( ?is residue1 measur$ by ! rays1 /eadily increas$ = a p]iod ( #ah mon?s1 b ! curve ( v>iation ( activity ) "t plott$ z 9 ,fig4 #ic t5ds to become m flatt5$1 & is obvi\sly approa*+ a maximum value4 ,illu/ration3 ,fig4 #ic4 ,! explanation ( ?is curve w be consid]$ lat] 9 section #bcf4 #bca4 ,v>iation ( ! ray activity4 ,! residual activity consi/s ( bo? & rays1 ! latt] be+ pres5t initially 9 an unusually l>ge proportion4 ,! proportion ( to rays f ! plat9um plate1 "o mon? aft] removal1 0 at ! mo/ "o-fiftie? ( t f a ?9 film ( radium bromide 9 radio-active equilibrium4 ,unlike ! ray activity1 ! activity measur$ by ! rays rema9s con/ant aft] ! active deposit is ab\t "o mon? old1 &1 9 consequ5ce1 ! proportion ( to rays /eadily increases ) ! "t4 ,! exp]im5ts %[$ t ! int5sity ( ! rays did n v>y mu*1 if at all1 ov] a fur!r p]iod ( eighte5 mon?s4 ,! want ( proportionality betwe5 ! & rays %[s t ! two types ( rays arise f diff]5t products4 ,?is conclusion is confirm$ by exp]im5ts1 to be describ$ lat]1 :i* %[ t ! products giv+ rise to & rays c be tempor>ily sep>at$ f "o ano!r by physical & *emical means4 ,illu/ration3 ,fig4 #id4 ,if obs]vations ( ! active deposit are begun %ortly aft] its =mation1 x is f\nd t ! activity1 measur$ by ! rays1 is small at fir/1 b increases ) ! "t1 rea*+ a practical maximum ab\t #dj days lat]4 ,exp]im5ts 7 made on a plat9um plate1 :i* 0 expos$ = #cge days 9 a vessel conta9+ ! radium emanation4 ,! obs]vations ( ! ray activity began #bd h\rs aft] removal4 ,! results are %[n 9 ,fig4 #id1 :]e ! "t 0 measur$ f ! middle ( ! "t ( exposure to ! emanation4 ,simil> results 7 obta9$ = a negatively *>g$ wire expos$ to ! emanation4 ,! curve1 if produc$ back to ! orig91 is se5 to be v simil> to ! recov]y curves ( ,ur ,x1 & o!r active products1 & c be express$ by ! equation frac ,it ,i #a e-t 1 :]e ,i is ! maximum activity4 ,! activity rea*es half its f9al value 9 ab\t six days1 & ! value ( is equal to #aae 7day74 ,we h %[n 9 section #bjc t a ris+ curve ( ?is "* indicates t ! ray activity arises f a product :i* is suppli$ at a con/ant rate f a prim>y s\rce4 ,be=e discuss+ 9 detail ! explanation ( ^! curves1 %[+ ! rise ) "t ( ! & ray activity1 fur!r exp]im5tal results w be consid]$4 #bcb4 ,effect ( temp]ature on ! activity4 ,a plat9um plate1 made active 9 ! mann] describ$1 0 expos$ to v>y+ temp]atures 9 an electric furnace1 & ! activity te/$ at atmosph]ic temp]ature aft] exposure4 ,f\r m9utes' exposure 9 ! furnace1 at fir/ at #dcj ,c41 & aft]w>ds at #hjj ,c41 _h little1 if any1 effect on ! activity4 ,aft] f\r m9utes at ab\t #ajjj ,c4 ! activity decreas$ ab\t #bj p] c5t41 & a fur!r exposure ( eight m9utes at a temp]ature ( ab\t #ajej ,c4 almo/ completely remov$ ! ray activity4 ,on ! o!r h&1 ! ray activity1 :5 measur$ imm$iately aft] removal1 0 n alt]$ by ! heat+1 b exposure to a /ill high] temp]ature caus$ x to decrease4 ,^! results %[ t ! active matt] consi/s ( two k9ds4 ,! "p :i* emits rays is n volatile at #ajjj ,c41 b ! o!r "p1 :i* emits rays1 is almo/ completely volatiliz$ at t temp]ature4 ,x 0 f\nd1 h[ev]1 t ! ray activity aft] heat+ to ab\t #ajjj 0 n p]man5t1 b decay$ accord+ to an expon5tial law ) ! "t1 ! activity decreas+ to half value 9 ab\t #de days4 ,f ! recov]y curve ( ! ray activity already consid]$1 x 0 to be expect$ t ! activity w\ld decay to half value 9 six days4 ,?is diff]5ce 9 ! p]iods is possibly due to an effect ( ! high temp]ature 9 alt]+ ! rate ( decay ( radium ,e4 ,! p]iod ( six days is m probably correct4 ,! results obta9$ on ! rise & decay ( ! rays1 tak5 toge!r1 %[3-- 7#a7 ,t ! product giv+ rays is suppli$ at a con/ant rate f "s p>5t matt] ( v sl[ rate ( *ange4 7#b7 ,t ?is p>5t matt] is volatiliz$ at or bel[ #ajjj ,c41 & ! ray product is left beh9d4 ,s9ce ! p>5t matt] is remov$1 ! product imm$iately beg9s to lose its activity at its *>act]i/ic rate1 viz4 ! activity falls to half value 9 ab\t six days4 #bcc4 ,sep>ation ( ! con/itu5ts by means ( a bismu? plate4 ,! active matt] ( sl[ decay 0 obta9$ 9 solution by introduc+ dilute sulphuric acid into a glass tube 9 :i* ! emanation f #cj milligrams ( radium bromide _h be5 /or$ = a mon?4 ,! solution %[$ /rong activity & gave out bo? & rays1 ! latt]1 z 9 o!r cases1 be+ pres5t 9 an unusually l>ge proportion4 ,:5 a poli%$ bismu? disk 0 kept = "s h\rs 9 ! solution1 x became /rongly active4 ,! active matt] deposit$ on ! bismu? gave out rays1 b no trace ( rays4 ,aft] sev]al bismu? disks _h be5 successively left 9 ! solution1 ! active matt]1 :i* emits rays1 0 almo/ completely remov$4 ,?is 0 %[n by evaporat+ d[n ! solution aft] treatm5t4 ,! ray activity rema9$ un*ang$1 b t ( ! rays _h be5 r$uc$ to ab\t #aj p] c5t4 ( its orig9al value4 ,?ree bismu? disks1 made active 9 ?is way1 7 set aside & _! activity measur$ at regul> int]vals4 ,! activity fell (f accord+ to an expon5tial law ) ! "t dur+ ! #bjj days s9ce _! removal1 :ile t ( ea* fell to half value on an av]age 9 ab\t #adc days4 ,at ! same "t x 0 obs]v$ t ! solution1 f :i* ! ray activity 0 remov$1 gradually rega9$ its activity1 %[+ t ! active sub/ance :i* gave out rays 0 cont9u\sly produc$ f ! matt] left beh9d 9 ! solution4 #bcd4 ,explanation ( ! results4 ,we h se5 t a close exam9ation ( ! active deposit ( sl[ *ange has disclos$1 7#a7 ! pres5ce ( a ray product :i* loses half ( its activity 9 ab\t six days2 7#b7 ! pres5ce ( an ray product1 :i* is deposit$ on bismu? & is volatiliz$ at #ajjj ,c4 ,?is product loses half ( its activity 9 #adc days2 7#c7 ! pres5ce ( a p>5t sub/ance1 :i* produces ! ray product at a con/ant rate4 ,?is p>5t product mu/ be trans=m$ v sl[ly s9ce ! ray product1 :i* arises f x1 soon rea*es an equilibrium value1 :i* does n *ange appreciably ov] a p]iod ( m ?an "o ye>4 ,! exp]im5tal evid5ce po9ts to ! conclusion t ! p>5t product does n give rise to rays1 b t ! rays arise entirely f ! next product4 ,?is p>5t product _c give rise to rays1 = we h se5 t ! initial ray activity is at fir/ extremely small1 b increases /eadily ) ! "t = a p]iod ( at lea/ eighte5 mon?s4 ,?us ! p>5t product does n give rise to ei!r or rays1 & mu/ be a 8rayless0 product4 ,! fir/ ?ree transition products ( ! radium emanation1 viz4 radium ,a1 ,b & ,c1 h already be5 analys$1 & %[n to be consecutive4 ,x ?us seems probable t ! active deposit ( sl[ *ange mu/ arise f ! successive trans=mations ( ! la/ product radium ,c4 ,! results already obta9$ c be completely expla9$ if x is suppos$ t ?ree transition products1 viz4 radium ,d1 ,e & ,f1 are pres5t 9 ! active deposit ( sl[ rate ( *ange4 ,! prop]ties ( ^! products are summ>iz$ bel[4 ,radium ,d is a rayless product ( v sl[ rate ( *ange4 ,x w be %[n lat] t x is half trans=m$ 9 ab\t #dj ye>s4 ,x is volatile bel[ #ajjj ,c4 & is soluble 9 /rong acids4 ,radium ,e is produc$ f radium ,d4 ,9 break+ up1 x emits 7& probably 7 rays b no rays4 ,x is half trans=m$ 9 ab\t #f days & is n s volatile z radium ,d & ,f4 ,radium ,f is produc$ f radium ,e4 ,x emits only rays & is half trans=m$ 9 #adc days4 ,?is sub/ance 9 solution atta*es itself to bismu?4 ,x is volatile at ab\t #ajjj ,c4 ,ap>t f _! value & int]e/ 9 %[+ ! /ages ( trans=mation ( ! radium atom1 ! results ( ?is analysis h an important be>+ ^u ! orig9 ( "s ( ! well-kn[n radio-active sub/ances sep>at$ f pit*bl5de2 = x w be %[n lat] t ! product radium ,f is ! radio-active sub/ance pres5t 9 radio-tellurium & probably also 9 polonium4 ,9 addition1 !re is v /rong evid5ce t ! radio-active lead obta9$ by ,h(mann conta9s ! ?ree products radium ,d1 ,e & ,f toge!r4 ,! *anges ( radium z f> z !y are at pres5t kn[n1 are %[n diagrammatically 9 ,fig4 #ie4 ,x is possible t fur!r inve/igation w %[ t ! trans=mation does n end ) radium ,f4 ,illu/ration3 ,fig4 #ie4 ,:ile we h %[n t radium ,d is ! p>5t ( ,e1 we h n giv5 any conclusive evid5ce t ,e is ! p>5t ( ,f4 ,?is evid5ce is1 h[ev]1 suppli$ by ! foll[+ exp]im5t4 ,a plat9um plate1 made active 9 ! mann] already describ$1 0 plac$ 9 an electric furnace & heat$ = f\r m9utes at ab\t #ajjj ,c4 ,mo/ ( ! products ,d & ,f 7 volatiliz$1 b ,e 0 left beh9d4 ,s9ce ! p>5t matt] ,d 0 remov$1 ,e at once comm5c$ to lose its ray activity4 ,at ! same "t x 0 obs]v$ t ! small ray activity1 left beh9d on ! plat9um plate1 increas$ rapidly at fir/ & !n m sl[ly1 z ! activity ( ,e became small] & small]4 ,?is exp]im5t %[s conclusively t ,e 0 ! p>5t ( ,f1 ! ray product4 #bce4 ,rate ( trans=mation ( radium ,d4 ,x has be5 obs]v$ exp]im5tally t ea* ( ! products ( radium1 :i* emit rays1 supplies ab\t an equal proportion ( ! activity ( radium :5 9 radio-active equilibrium4 ,s9ce1 :5 equilibrium is rea*$1 ! same numb] ( p>ticles ( ea* ( ! successive products mu/ break up p] second1 ?is is an expression ( ! fact t e atom ( ea* product breaks up ) ! expulsion ( an equal numb] 7probably "o7 ( p>ticles4 ,n[ radium ,d is directly d]iv$ f radium ,c1 &1 s9ce ! rate ( *ange ( ,d is v sl[ comp>$ ) t ( ,c1 ! numb] ( p>ticles ( ,d initially pres5t mu/ be v ne>ly equal to ! numb] ( p>ticles ( radium ,c :i* break up dur+ ! "t t radium ,d is be+ =m$4 ,n[ ,d does n itself give out rays1 b ! succe$+ product ,e does4 ,! products ,d & ,e are practically 9 radio-active equilibrium "o mon? aft] ,d is set aside1 & ! v>iation ( ! ray activity ( ,e !n s]ves z a measure ( ! v>iation ( ! p>5t product ,d4 ,suppose t a vessel is fill$ ) a l>ge quantity ( radium emanation4 ,aft] sev]al h\rs1 ! product radium ,c1 :i* emits rays1 rea*es a maximum value1 & !n decreases at ! same rate z ! emanation loses its activity1 i4e4 x falls to half value 9 #ch days4 ,if ,n is ! numb] ( p>ticles expell$ f radium ,c at its maximum value1 ! total numb] ,q ( p>ticles expell$ dur+ ! life ( ! emanation is giv5 approximately by ,q#a intinfty ,n#a e-#a t dt frac ,n#a #a 1 :]e is ! con/ant ( *ange ( ! emanation4 ,aft] ! emanation has disappe>$1 & ! f9al products ,d ,e are 9 radio-active equilibrium1 suppose t ! numb] ( p>ticles ,n expell$ p] second by radium ,e is det]m9$4 ,if ,q is ! total numb] ( p>ticles expell$ dur+ ! life ( ,d ,e1 !n ,q z be=e is approximately giv5 by ,q ,n_/ :]e is ! con/ant ( *ange ( radium ,d4 ,n[ we h se5 t if ea* p>ticle ( ,c & ( ,e gives rise to "o p>ticle1 x is to be expect$ t ,q ,q1 or ,n ---- ---- 4 ,n ,! ratio ,n_/,n 0 det]m9$ by measur+ ! activity due to ! rays f ,c & ,e 9 ! same te/+-vessel4 ,!n1 s9ce ,n_/,n is kn[n1 & also ! value ( 1 ! value ( ! con/ant ( *ange1 1 ( radium ,d is obta9$4 ,9 ?is way x 0 calculat$ t ,d is half trans=m$ 9 ab\t #dj ye>s4 ,9 ! above calculations x is assum$1 z a fir/ approximation1 t ! rays f ,c & ,e h ! same av]age velocity4 ,?is is probably n accurately ! case1 b ! above numb] c]ta9ly s]ves to fix ! ord] ( magnitude ( ! p]iod ( ! product ,d4 ,?is calculation is confirm$ by obs]vations to be giv5 lat] on ! am\nt ( ,d & ,e 9 old radium4 ,x may be ( int]e/ to m5tion t ! writ] calculat$ ! p]iod ( radium ,f by a simil> me?od1 be=e its value 0 exp]im5tally det]m9$1 & f\nd t ,f %\ld be half trans=m$ 9 ab\t "o ye>4 ,?is is n v diff]5t f ! exp]im5tal value ( #adc days f\nd lat]4 ,9 addition1 x 0 assum$ 9 ! calculation t ! p>ticles f ,c & ,f 7 project$ ) ! same velocity1 & 9 consequ5ce produc$ ! same am\nt ( ionization4 ,9 practice1 h[ev]1 x is f\nd t ! p>ticle ( ,f is absorb$ 9 ab\t half ! di/ance ( ! p>ticles ( ,c1 & 9 consequ5ce produces only ab\t half ( ! ionization ( ! latt]4 ,if ?is correction 7 made1 ! calculat$ p]iod = half trans=mation w\ld be six mon?s in/ead ( "o ye>4 ,a table ( ! trans=mation products ( radium1 toge!r ) "s ( _! physical & *emical prop]ties1 is giv5 bel[4 ,trans=mation ,"t to be ,rays ,*emical & ,products half ,physical trans=m$ ,prop]ties ,radium #abjj ye>s rays -- ,emanation #ch days rays ,*emically in]t gas2 cond5ses at #aej ,c4 ,radium ,a #c m9s4 rays ,behaves z 7active deposit solid2 ( rapid deposit$ on *ange7 ! surface ( bodies2 conc5trat$ on ca?ode 9 electric field4 ,soluble 9 /rong acids2 volatile at a :ite heat4 ,b is m volatile ?an ,a or ,c4 33 ,b 7same7 #ba m9s4 no rays ,same 33 ,c 7same7 #bh m9s4 1 1 rays ,same 33 ,d 7active ab\t #dj no rays ,soluble 9 deposit ( sl[ ye>s /rong acids *ange7 & volatiz$ bel[ #ajjj ,c4 33 ,e 7same7 #f days 7& 7 ,non-volatile at #ajjj;,c4 33 ,f 7same7 #adc days rays ,volatile at #ajjj ,c2 deposit$ f solution on to bismu? plate4 8 -- -- -- #bcf4 ,v>iation ( ! activity ov] long p]iods ( "t4 ,we are n[ 9 a position to calculate ! v>iation ( ! & ray activity ( ! active deposit ov] long p]iods ( "t4 ,if x is suppos$ t ! matt] initially deposit$ consi/s only ( ,d1 ! am\nts ,p1 ,q & ,r ( radium ,d1 ,e & ,f exi/+ at any lat] "t are giv5 by ! equations #c1 #d1 #e1 section #aig4 ,s9ce1 h[ev]1 ! int]m$iate product ,e has a mu* m rapid rate ( *ange ?an ,d or ,f1 ! equations c be simplifi$1 )\t mu* loss ( accuracy1 by disreg>d+ ! *ange ,e1 & by suppos+ t ,d gives out rays & *anges directly into ! ray product ,f4 ,let 1 be ! con/ants ( *ange ,d & ,f respectively4 ,let n be ! numb] ( p>ticles ( ,d pres5t initially4 ,!n us+ ! notation ( section #aig1 ! am\nt ,p ( radium ,d at any "t t is giv5 by ,p n e-#a t 4 ,! am\nt ,q ( radium ,f is giv5 by ,q frac n #a #a #b 7e-#b t - e-#a t7 4 ,illu/ration3 ,fig4 #if4 ,! numb] ( p>ticles emitt$ by ,d ,e p] second1 "s mon?s aft]w>ds1 is #a n e-#a t 1 & ! numb] ( p>ticles emitt$ by radium ,f is frac #a #b n #a #b 7e-#b t e-#a t 7 4 ,! results are %[n graphically 9 ,fig4 #if1 by ! curves ,,ee & ,,ff1 9 :i* ! ord9ates repres5t ! numb] ( & p>ticles expell$ p] second by ! products ,d & ,f respectively4 ,! complete calculation = ?ree *anges %[s t ! numb] ( p>ticles soon rea*es a practical maximum1 & !n decays ne>ly expon5tially ) ! "t1 fall+ to half value 9 #dj ye>s4 ,! numb] ( p>ticles expell$ p] second increases = sev]al ye>s1 b rea*es a maximum aft] #bf ye>s & !n dim9i%es1 f9ally fall+ (f expon5tially ) ! "t to half value 9 #dj ye>s4 ,! exp]im5tal curve ( ! rise ( ray activity1 %[n 9 ,fig4 #ic1 z f> z x has be5 det]m9$1 lies accurately on ?is curve1 if ! maximum is calculat$ f ! above !ory4 ,! obs]v$ activity aft] a p]iod ( #bej days is m>k$ by ! po9t ,x on ! curve4 #bcg4 ,exp]im5ts ) old radium4 ,s9ce ! sub/ance radium ,d is produc$ f radium at a con/ant rate1 ! am\nt pres5t mix$ ) ! radium w increase ) its age4 ,! writ] _h 9 8 possession a small quantity ( impure radium *loride1 k9dly pres5t$ by ,pr(essors ,el/] & ,geitel f\r ye>s be=e4 ,! am\nt ( radium ,d pres5t 9 x 0 te/$ 9 ! foll[+ way3--,! sub/ance 0 dissolv$ 9 wat] & kept cont9u\sly boil+ = a p]iod ( ab\t six h\rs4 ,"u ^! conditions ! emanation is remov$ z rapidly z x is =m$1 & ! rays f ! radium1 due to ! product radium ,c1 practically disappe>4 ,a newly prep>$ specim5 ( radium bromide "u ^! conditions reta9s only a fraction ( #a p] c5t4 ( its orig9al radiation4 ,! old radium1 h[ev]1 %[$ 7imm$iately aft] ?is treatm5t7 an activity measur$ by ! rays ( ab\t #h p] c5t4 ( its orig9al am\nt4 ,! activity c\ld n be r$uc$ any l[] by fur!r boil+ or aspiration ( air ?r\gh ! solution4 ,?is residual ray activity 0 due to ! product radium ,e /or$ up 9 ! radium4 ,! ray activity due to radium ,e 0 ?us ab\t #i p] c5t4 ( t due to radium ,c4 ,disreg>d+ ! diff]5ces 9 ! absorption ( ! rays1 :5 ! activity ( ! product ,e 9 radium rea*es a maximum value1 ! ray activity due to x %\ld be ! same z t due to ,c4 ,s9ce ! p>5t product ,d is half trans=m$ 9 =ty ye>s1 ! am\nt pres5t 9 ! radium aft] f\r ye>s %\ld be ab\t #g p] c5t4 ( ! maximum am\nt2 i4e4 x %\ld %[ a ray activity ( ab\t #g p] c5t4 ( t due to radium ,c4 ,! obs]v$ & calculat$ values 7#g & #i p] c5t4 respectively7 are ?us ( ! same ord] ( magnitude4 ,! am\nt ( rays f radium ,e pres5t 9 pure radium bromide ab\t "o ye> old 0 ab\t #b p] c5t4 ( ! total4 ,! am\nt ( radium ,f pres5t 9 old radium 0 measur$ by obs]vations ( ! activity imp>t$ to a bismu? disk left = sev]al days 9 ! solution1 & 0 f\nd to be ( ! same ord] z ! !oretical value4 ,radium ,f is n deposit$ to an appreciable ext5t on ! bismu? f a wat] solution ( radium bromide4 ,if1 h[ev]1 a trace ( sulphuric acid is add$ to ! solution1 ! radium ,f is readily deposit$ on ! bismu?4 ,! addition ( sulphuric acid to ! radium solution practically effect$ a sep>ation ( radium ,d1 ,e & ,f f ! radium prop]2 = ! latt] 0 precipitat$ z sulphate & ! products ,d1 ,e & ,f rema9$ 9 solution4 ,aft] filt]+1 ! solution conta9$ ! great] proportion ( ! products ,d1 ,e1 & ,f & v little radium4 #bch4 ,v>iation ( ! activity ( radium ) "t4 ,x has be5 %[n t ! activity ( fre%ly prep>$ radium increases at fir/ ) ! "t & practically rea*es a maximum value aft] an int]val ( ab\t "o mon?4 ,! results already consid]$ %[ t !re is a /ill fur!r sl[ increase ( activity ) ! "t4 ,?is is ! case :e!r ! activity is measur$ by ! or rays4 ,x w be %[n lat] t radium is probably half trans=m$ 9 ab\t #ajjj ye>s4 ,f ?is x c readily be calculat$ t aft] a lapse ( ab\t #bjj ye>s ! am\nt ( ! products radium ,d1 ,e & ,f w h rea*$ a maximum value4 ,! same numb] ( atoms ( ea* ( ! products ,c & ,e w !n break up p] second4 ,if ea* atom ( ^! products 9 dis9tegrat+ ?r[s (f an equal numb] 7probably "o7 ( p>ticles1 ! numb] ( p>ticles ?r[n (f p] second w be twice z great z f radium a few mon?s old4 ,! numb] w increase at fir/ at ! rate ( ab\t #b p] c5t4 a ye>4 ,simil> consid]ations apply to ! ray activity4 ,s9ce1 h[ev]1 !re are f\r o!r products ( radium besides radium itself :i* expel p>ticles1 ! numb] ( p>ticles emitt$ p] second f old radium w n be m ?an #be p] c5t4 great] ?an ! numb] f radium a few mon?s old4 ,! activity measur$ by ! rays w ?us n increase m ?an #be p] c5t41 & probably /ill less1 z ! p>ticles f radium ,f produce less ionization ?an ! p>ticles expell$ f ! o!r radium products4 ,! activity ( radium w consequ5tly rise to a maximum aft] #bjj ye>s & !n sl[ly die away ) ! "t4 #bci4 ,pres5ce ( ^! products 9 pit*bl5de4 ,! products radium ,d1 ,e & ,f mu/ be pres5t 9 pit*bl5de 9 am\nts proportional to ! quantity ( radium pres5t1 & %\ld be capable ( sep>ation f ! m9]al by suitable *emical me?ods4 ,! radio-active prop]ties ( ^! sub/ances1 if obta9$ 9 ! pure /ate1 are summ>iz$ bel[4 ,radium ,d :5 fir/ sep>at$1 %\ld give out v little or radiation4 ,! ray activity w rapidly increase1 rea*+ half its maximum value 9 #f days4 ,! ray activity w at fir/ increase ne>ly proportionately ) ! "t1 & w rea* a maximum value aft] an int]val ( ab\t #c ye>s4 ,! & ray activity1 aft] rea*+ a maximum1 w f9ally decay1 ! activity fall+ to half value 9 ab\t #dj ye>s4 ,s9ce radium ,d is half trans=m$ 9 #dj ye>s1 & radium 9 #abjj ye>s1 ! maximum ray activity ( radium ,d1 weight = weight1 w be ab\t #cjj times t ( radium4 ,! ray activity1 at any "t1 w be remov$ by plac+ a bismu? disk 9 ! solution4 ,radium ,f1 aft] sep>ation1 w give out only rays4 ,its activity1 aft] sep>ation1 w decrease accord+ to an expon5tial law1 fall+ to half value 9 #adc days4 ,s9ce radium 9 radio-active equilibrium conta9s f\r products :i* emit rays1 ! numb] ( p>ticles expell$ p] second f radium ,f w1 weight = weight1 be ab\t #hjj times z num]\s z f new radium 9 radio-active equilibrium4 ,s9ce ! p>ticles f radium ,f produce only ab\t half z mu* ionization z ! p>ticles f ! o!r radium products1 ! activity ( radium ,f1 measur$ by ! electric me?od1 w be ab\t #djj times t ( radium4 #bdj4 ,orig9 ( radio-tellurium & polonium4 ,x is n[ necess>y to consid] :e!r ^! products ( radium h be5 previ\sly sep>at$ f pit*bl5de1 & kn[n by o!r names4 ,we %all fir/ consid] ! ray product1 radium ,f4 ,! radio-tellurium ( ,m>ckwald & ! polonium ( ,mme ,curie bo? resemble radium ,f 9 giv+ out only rays1 & 9 be+ deposit$ on a bismu? disk f a solution4 ,if ! active con/itu5t pres5t 9 radio-tellurium is ! same z radium ,f1 its activity %\ld decay at ! same rate z ! latt]4 ,! writ]#cbj has c>efully comp>$ ! rates ( decay ( ! activity ( radium ,f & ( ! radio-tellurium ( ,m>ckwald & f\nd !m to be ! same )9 ! limits ( exp]im5tal error4 ,bo? lose half ( _! activity 9 ab\t #adc days#cba4 ,a simil> value ( ! rate ( decay ( radio-tellurium has be5 obta9$ by ,mey] & ,s*weidl]#cbb4 ,! exp]im5ts on radio-tellurium 7 made ^u ! active bismu? plates suppli$ by ,dr ,/ham] ( ,hamburg1 :i* 7 prep>$ "u ,m>ckwald's directions4 ,an additional pro(#cbc ( ! id5tity ( ^! two products 0 obta9$ by comp>+ ! absorption ( ! rays by alum9ium foil4 ,! rays f diff]5t products are project$ ) diff]5t velocities1 &1 9 consequ5ce1 are unequally absorb$ by matt]4 ,! absorption ( ! rays f ! two products by alum9ium foil agre$ v closely1 indicat+ ! probable id5tity ( ! sub/ances f :i* !y 7 emitt$4 ,!re c ?us be no d\bt t ! active con/itu5t pres5t 9 ! radio-tellurium ( ,m>ckwald is id5tical ) ! product radium ,f4 ,?is is a v int]e/+ result1 & %[s h[ ! close exam9ation ( ! successive trans=mations ( ! radio-active bodies may ?r[ light on ! orig9 ( ! v>i\s sub/ances f\nd 9 pit*bl5de4 ,we h already se5 7section #ba7 t ,m>ckwald1 by special *emical me?ods1 0 able to obta9 a few milligrams ( v active sub/ance by work+ ov] #b tons ( pit*bl5de4 ,we h already se5 7section #bci7 t ?is sub/ance1 if obta9$ 9 ! pure /ate1 %\ld be ab\t #djj times z active z radium4 ,comp>ative measurem5ts ( ! activity ( ?is sub/ance ) radium w ?us indicate ! am\nt ( impurity t is pres5t ) ! =m]4 ,?is me?od %\ld be ( value 9 purify+ radium ,f = ! purpose ( det]m9+ its spectrum1 :i* has n yet be5 obs]v$4 #bda4 ,polonium4 ,s9ce ! sep>ation ( ! active sub/ance by ,m>ckwald1 call$ by him radio-tellurium1 !re has be5 "s discussion z to :e!r ! active con/itu5t is ! same z t pres5t 9 ! polonium ( ,mme ,curie4 ,bo? ( ^! sub/ances h simil> radio-active & *emical prop]ties1 b ! ma9 objection to ! view t ! active con/itu5ts 7 id5tical has re/$ on an e>ly /atem5t ( ,m>ckwald t ! activity ( "o ( 8 v active prep>ations did n decay appreciably 9 ! c\rse ( six mon?s4 ,?is objection is n[ remov$1 = we h se5 t ! activity ( radio-tellurium does decay fairly rapidly4 ,x 0 e>ly recognis$ t ! activity ( ! polonium1 sep>at$ f pit*bl5de by ! me?ods ( ,mme ,curie1 0 n p]man5t1 b decay$ ) ! "t4 ,obs]vations on ! rate ( decay h n be5 v precise1 b ,mme ,curie /ates t "s ( h] prep>ations lo/ half ( _! activity 9 ab\t six mon?s b 9 o!rs ! rate ( decay 0 some:at small]4 ,x is possible t ! initial diff]5ces obs]v$ 9 ! rates ( decay ( diff]5t specim5s ( polonium may be due to ! pres5ce ( "s radium ,d ) ! polonium4 ,! polonium 9 my possession lo/ its activity fairly rapidly1 & 0 r$uc$ to a small portion ( its value 9 ! c\rse ( ab\t f\r ye>s4 ,r\gh obs]vations ( its activity1 made f "t to "t1 %[$ t its activity dim9i%$ to half value 9 ab\t six mon?s4 ,if x is id5tical ) radio-tellurium1 ! activity %\ld decay to half value 9 #adc days1 & ,i ?9k !re is little d\bt t m accurate measurem5t w prove ?is to be ! case4 ,:ile ! pro( ( ! id5tity ( ! active con/itu5t 9 polonium is n s def9ite z = radio-tellurium1 ,i ?9k !re c be no reasonable d\bt t ^! sub/ances bo? conta9 ! same active sub/ance1 :i* is ! sev5? trans=mation product ( radium4 ,m>ckwald has notic$ "s *emical diff]5ces 9 ! behavi\r ( polonium & radio-tellurium1 b little weight c be atta*$ to su* obs]vations1 = x mu/ be rememb]$ t ! active con/itu5t 9 bo? cases is pres5t 9 m9ute quantity 9 ! mat]ial "u exam9ation1 & t ! app>5t *emical prop]ties ( ! active sub/ance are mu* influ5c$ by ! pres5ce ( impurities4 ,! mo/ important & tru/wor?y te/ re/s ^u ! id5tity ( ! radiations & ! p]iod ( decay4 #bda ,a4 ,orig9 ( radio-active lead4 ,"s exp]im5ts w n[ be discuss$ :i* %[ t ! radio-lead fir/ sep>at$ f pit*bl5de by ,h(mann 7section #bb7 conta9s ! products radium ,d1 ,e & ,f4 ,h(mann has obs]v$ t ! activity ( ?is sub/ance did n appreciably decay 9 ! c\rse ( sev]al ye>s4 ,9 "s rec5t exp]im5ts1 ,h(mann1 ,gond] & ,wlfl#cbd h made a close *emical exam9ation ( ! radio-active lead1 & h %[n ! pres5ce ( two radio-active con/itu5ts1 :i* are probably id5tical ) ! products radium ,e & ,f4 ,! radio-active measurem5ts 7 un=tunately n v precise1 & ! p]iods ( *ange ( ! sep>at$ products h n be5 exam9$ v closely4 ,exp]im5ts 7 made on ! effect ( add+ sub/ances to a solution ( radio-lead1 & !n remov+ !m by precipitation4 ,small quantities ( iridium1 rhodium1 palladium1 & plat9um1 9 ! =m ( *lorides1 7 left 9 ! solution = ?ree weeks1 & !n precipitat$ by =mal9 or hydroxylam9e4 ,all ( ^! sub/ances 7 f\nd to give out bo? & rays1 ! activity be+ greate/ = rhodium & lea/ = plat9um4 ,a l>ge proportion ( ! ray activity disappe>$ 9 ! c\rse ( six weeks1 & ( ! ray activity 9 "o ye>4 ,x is probable t ! two products radium ,e & ,f 7 9 "p remov$ ) ! metals f ! radio-lead4 ,we h se5 t radium ,e gives out rays & loses half ( its activity 9 ab\t six days1 :ile radium ,f gives out only rays & its activity falls to half value 9 #adc days4 ,?is conclusion is fur!r confirm$ by exp]im5ts on ! effect ( heat on ! activity ( ^! sub/ances4 ,by heat+ to a full r$ heat1 ! ray activity 0 lo/ 9 a few seconds4 ,?is is 9 agreem5t ) ! results 7section #bcb7 :]e we h se5 t radium ,f is volatiliz$ at ab\t #ajjj ,c4 & radium ,e is left beh9d4 ,salts ( gold1 silv] & m]cury add$ to ! radio-lead 7 f\nd to %[ only ray activity on removal4 ,?is is 9 accordance ) ! view t radium ,f alone is remov$ ) ^! sub/ances4 ,bismu? salts on ! o!r h& %[$ initially & ray activity1 b ! latt] rapidly di$ away4 ,! pres5ce ( rays 9 fre%ly prep>$ polonium 0 e>ly obs]v$ by ,mme ,curie4 ,! & ray activity ( ! radio-lead is mu* r$uc$ by ! precipitation ( bismu? add$ to ! solution4 ,! & ray activity ( ! radio-lead1 h[ev]1 recov]s itself aga94 ,?is result is exactly :at is to be expect$ if radio-lead conta9s radium ,d1 ,e & ,f4 ,radium ,e & ,f are remov$ ) ! bismu?1 b ! p>5t sub/ance1 radium ,d1 is left beh9d1 &1 9 consequ5ce1 a fre% supply ( radium ,e & ,f is produc$4 ,:ile fur!r exp]im5ts are requir$ to settle def9itely :e!r ! products sep>at$ f radio-lead are id5tical ) radium ,e & ,f1 !re c be little d\bt t su* is ! case4 ,?is conclusion is /r5g!n$ by "s exp]im5ts :i* ,i h made on a specim5 ( radio-lead1 :i* 0 k9dly =w>d$ to me by ,mr ,boltwood ( ,new ,hav54 ,?is active lead gave out & rays1 ! latt] be+ 9 unusually l>ge proportion4 ,! active lead 0 f\r mon?s old :5 fir/ te/$4 ,! ray activity 9 ! foll[+ six mon?s has rema9$ s5sibly con/ant1 b ! ray activity has /eadily increas$4 ,^! results are to be expect$ if ! radio-lead conta9s radium ,d4 ,radium ,e w rea* a practical maximum ab\t #dj days aft] sep>ation ( ! product radium ,d ) ! lead4 ,! ray activity due to radium ,f %\ld increase to a maximum 9 ab\t #bf ye>s 7see section #bcf74 ,fur!r exp]im5ts are requir$ to settle :e!r ! lead imm$iately aft] sep>ation f pit*bl5de conta9s only radium ,d1 or :e!r radium ,e also appe>s ) x4 ,x seems likely1 h[ev]1 t ! bismu?1 :i* is initially pres5t 9 solution at ! "t ( sep>ation ( ! lead1 w reta9 bo? radium ,e & ,f1 & t ! pres5ce ( ^! products 9 radio-lead is due to _! production1 aft] sep>ation1 by ! p>5t sub/ance1 radium ,d4 ,x w\ld be ( sci5tific value to sep>ate radium ,d f pit*bl5de & obta9 x 9 ! pure /ate1 =1 a mon? aft] removal1 ! ray activity f x w\ld be ab\t #cjj times z great z f an equal weight ( radium4 ,by plac+ a bismu? plate 9 a solution ( ?is sub/ance1 radium ,f 7polonium7 %\ld be sep>at$1 &1 provid$ a suffici5t int]val is all[$ to elapse1 a fre% supply ( radium ,f c at any "t be obta9$4 ,! rate ( trans=mation ( radium ,d 7half trans=m$ 9 #dj ye>s7 is suffici5tly sl[ n to int]f]e s]i\sly ) its utility 9 mo/ exp]im5ts4 ,! results ( ! comp>ison ( ! products ( radium ) ^? conta9$ 9 polonium1 radio-tellurium & radio-lead are summ>iz$ bel[4 ,radium ,d product 9 new radio-lead1 no rays4 ,half trans=m$ 9 #dj ye>s4 ,radium ,e gives out rays1 sep>at$ ) bismu?1 iridium & plat9um4 ,half trans=m$ 9 #f days4 ,radium ,f product 9 polonium & radio-tellurium4 ,gives out only rays4 ,half trans=m$ 9 #adc days4 #bdb4 ,tempor>y activity ( inactive matt] sep>at$ f radio-active sub/ances4 ,we h se5 9 ! la/ section t ! plat9um metals & bismu? acquire tempor>y activity by _! admixture ) a solution ( radio-lead1 & t ^! effects are v satisfactorily expla9$ on ! view t "s ( ! products ( *ange ( radio-lead are remov$ ) ! inactive sub/ances4 ,v simil> effects h be5 obs]v$ by ,pegram & von ,l]* 7section #ahf71 :5 inactive sub/ances 7 add$ to solutions ( ?orium & ( ! active deposit ( ?orium4 ,^! results1 too1 are almo/ c]ta9ly due to ! removal ( "o or m ( ! products ( ?orium ) ! inactive matt]4 ,examples ( ?is "* may readily be multipli$1 & "s ( ! m int]e/+ & important ( ^! w be briefly discuss$ lat]4 ,!re h be5 two g5]al po9ts ( view reg>d+ ! "* ( ?is activity :i* is tempor>ily acquir$ by inactive matt]4 ,"s p h suppos$ t ! inactive molecules ( ! sub/ance1 mix$ ) ! solution1 acquire by 8radio-active induction0 tempor>y activity1 ! und]ly+ idea be+ t ! close admixture ( an inactive & an active sub/ance has communicat$ ! prop]ty ( radiat+ to "s ( ! molecules ( ! =m]4 ,accord+ to ! dis9tegration !ory ( radio-activity1 on ! o!r h&1 ! tempor>y activity ( orig9ally inactive matt] is n due to any alt]ation ( ! inactive sub/ance itself1 b to an admixture ) x ( "o or m ( ! num]\s radio-active products4 ,! idea ( 8radio-active induction0 has no def9ite exp]im5tal evid5ce 9 support ( x1 :ile !re is mu* indirect evid5ce aga9/ x4 ,we %all n[ consid] h[ ^! facts are int]pret$ accord+ to ! dis9tegration !ory4 ,9 a specim5 ( old radium1 = example1 !re are pres5t1 besides radium itself1 ! sev5 successive products :i* arise f x4 ,ea* ( ^! diff]s 9 *emical & physical prop]ties f ! o!rs4 ,if n[1 = example1 a bismu? rod is introduc$ into ! solution1 "o or m ( ^! products are deposit$ on ! bismu?4 ,?is action is mo/ probably electrolytic 9 nature1 & w dep5d ^u ! electro-*emical behavi\r ( ! bismu? comp>$ ) t ( ! products 9 solution4 ,an electro-negative sub/ance w t5d to remove ! product or products :i* are /rongly electro-positive4 ,?is po9t ( view s]ves to expla9 :y diff]5t metals are made active to diff]5t degrees1 dep5d+ ^u _! position 9 ! electro-*emical s]ies4 ,x seems probable t ! activity communicat$ to inactive matt] by precipitation f an active solution occurs only dur+ ! precipitation4 ,! correctness ( ?is view c\ld readily be te/$ by obs]v+ :e!r ! "t t ! inactive sub/ance is pres5t 9 solution has any effect on ! magnitude ( ! activity imp>t$ to x4 ,:5 x is rememb]$ t 9 pit*bl5de !re are pres5t ! radio-elem5ts uranium1 ?orium1 radium & act9ium & _! num]\s family ( products1 x is n surpris+ t _m ( ! inactive sub/ances sep>at$ f x may %[ v consid]able activity due to ! mixture ( products :i* may be remov$ ) !m4 ,9 c>ry+ out exp]im5ts on ! sep>ation ( radium f pit*bl5de1 ,m4 & ,mme ,curie obs]v$ t ! sep>ation ( ! active sub/ance is fairly complete if ! /age ( purification is n f> advanc$4 ,copp]1 antimony & ars5ic c be sep>at$ only slightly active1 b o!r sub/ances l lead & iron always %[ activity4 ,:5 ! /age ( precipitation is m advanc$1 e sub/ance sep>at$ f ! active solution %[s activity4 ,"o ( ! e>lie/ obs]vations 9 ?is direction 0 made by ,debi]ne1 :o f\nd t b>ium c\ld be made active by solution ) act9ium4 ,! active b>ium remov$ f ! act9ium /ill pres]v$ its activity aft] *emical treatm5t1 &1 9 ?is way1 b>ium *loride 0 obta9$ ^: activity 0 #fjjj times t ( uranium4 ,al?\gh ! activity ( ! b>ium *loride c\ld be conc5trat$ 9 ! same way z ! activity ( radif]\s b>ium *loride1 x did n %[ any ( ! spectroscopic l9es ( radium1 & c\ld n h be5 due to ! admixture ( t elem5t ) ! b>ium4 ,! activity ( ! b>ium 0 n p]man5t1 & ,debi]ne /ates t ! activity fell to ab\t "o-?ird ( its value 9 ?ree mon?s4 ,x seems probable t ! precipitat$ b>ium c>ri$ d[n ) x ! product act9ium ,x1 & also "s ( ! act9ium itself1 & t ! decay obs]v$ 0 due to ! trans=mation ( act9ium ,x4 ,x is int]e/+ to note t b>ium is capable ( remov+ a l>ge numb] ( products ( ! diff]5t radio-elem5ts4 ,?is effect is probably connect$ ) its position 9 ! electro-*emical s]ies1 = b>ium is highly electro-positive4 ,giesel %[$ 9 #aijj t bismu? c\ld be made active by plac+ x 9 a radium solution1 & consid]$ t polonium 0 9 reality bismu? made active by ! process ( induction4 ,9 lat] exp]im5ts1 he f\nd t ! bismu? plate gave out only rays1 & t ! activity ( ! bismu? c\ld n be ascrib$ to radium1 s9ce no rays 7 pres5t4 ,we h se5 t ?is activity ( ! bismu? is due to ! product radium ,f deposit$ on its surface4 ,mme ,curie also f\nd t bismu? 0 made active by solution ) a radium comp\nd1 & succe$$ 9 fractionat+ ! above bismu? 9 ! same way z polonium4 ,9 ?is way bismu? 0 obta9$ #bjjj times z active z uranium1 b ! activity1 l t ( polonium sep>at$ f pit*bl5de1 decreas$ ) ! "t4 ,9 ! light ( ! exp]im5ts on ! trans=mation products ( radium1 x is se5 t ^! e>ly exp]im5ts ( ,mme ,curie add additional confirmation to ! view t ! product 7radium ,f7 sep>at$ f radium itself is id5tical ) ! polonium obta9$ directly f pit*bl5de4 ,footnote #cad3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #cae3 ,ru!r=d1 ,phil4 ,trans4 ,a4 p4 #afi1 #aijd4 ,curie & ,danne1 ,c4 ,r4 p4 #gdh1 #aijd4 ,footnote #caf3 ,p4 ,curie & ,danne1 ,comptes ,r5dus1 #ach1 p4 #gdh1 #aijd4 ,footnote #cag3 ,miss ,gates1 ,phys4 ,rev4 p4 #cjj1 #aijc4 ,footnote #cah3 ,miss ,brooks1 ,nature1 ,july #ba1 #aijd4 ,footnote #cai3 ,ru!r=d1 ,phil4 ,mag4 ,nov4 #aijd4 ,nature1 p4 #cda1 ,feb4 #i1 #aije4 ,footnote #cbj3 ,ru!r=d1 ,nature1 p4 #cda1 ,feb4 #i1 #aije4 ,footnote #cba3 ,m>ckwald 7,b]4 d4 ,d4 ,*em4 ,ges4 p4 #eia1 #aije7 has rec5tly f\nd t ! activity ( 8 radio-tellurium falls to half value 9 #aci days4 ,footnote #cbb3 ,mey] & ,s*weidl]1 ,wi5 ,b]4 ,dec4 #a1 #aijd4 ,footnote #cbc3 ,ru!r=d1 ,phil4 ,trans4 ,a4 p4 #afi1 #aijd4 ,footnote #cbd3 ,h(mann1 ,gond] & ,wlfl1 ,annal4 d4 ,phys4 #ae1 p4 #fae1 #aijd4 ,,*apt] ,,xii4 ,,rate ,,( ,,emission ,,( ,,en]gy4 #bdc4 ,x 0 e>ly recognis$ t a consid]able am\nt ( en]gy is emitt$ by ! radio-active bodies 9 ! =m ( _! *>act]i/ic radiations4 ,mo/ ( ! e>ly e/imates ( ! am\nt ( ?is en]gy 7 bas$ on ! numb] & en]gy ( ! expell$ p>ticles1 & 7 mu* too small4 ,x has be5 po9t$ out 7section #aad7 t ! great] "p ( ! en]gy emitt$ f ! radio-active bodies 9 ! =m ( ioniz+ radiations is due to ! rays1 & t ! rays 9 comp>ison supply only a v small fraction4 ,ru!r=d & ,mc,clung#cbe made an e/imate ( ! en]gy ( ! rays1 emitt$ by a ?9 lay] ( active matt]1 by det]m9+ ! total numb] ( ions produc$ by ! complete absorption ( ! rays4 ,! en]gy requir$ to produce an ion 0 det]m9$ exp]im5tally by obs]vations ( ! heat+ effect ( ,x rays1 & ( ! total numb] ( ions produc$ :5 ! rays 7 completely absorb$ 9 air4 ,! en]gy requir$ to produce an ion 9 air 0 f\nd to be #aij #aj ergs4 ,?is1 z w be %[n 9 ,app5dix ,a1 is probably an ov]-e/imate1 b 0 ( ! "r ord] ( magnitude4 ,f ?is x 0 calculat$ t "o gram ( uranium oxide spread ov] a plate 9 ! =m ( a ?9 p[d]$ lay] emitt$ en]gy into ! air at ! rate ( #jjcb gram calories p] ye>4 ,?is is a v small emission ( en]gy1 b 9 ! case ( an int5sely radio-active sub/ance l radium1 ^: activity is ab\t two million times t ( uranium1 ! correspond+ emission ( en]gy is #fijjj gram calories p] ye>4 ,?is is obvi\sly an "u-e/imate1 = x includes only ! en]gy radiat$ into ! air4 ,! actual am\nt ( en]gy releas$ 9 ! =m ( rays is evid5tly mu* great] ?an ?is on acc\nt ( ! absorption ( ! rays by ! active matt] itself4 ,x w be %[n lat] t ! heat+ effect ( radium & ( its products is a measure ( ! en]gy ( ! expell$ p>ticles4 #bdd4 ,heat emission ( radium4 ,p4 ,curie & ,laborde#cbf fir/ drew att5tion to ! /rik+ result t a radium comp\nd kept itself cont9u\sly at a temp]ature sev]al degrees high] ?an t ( ! surr\nd+ atmosph]e4 ,?us ! en]gy emitt$ f radium c be demon/rat$ by its direct heat+ effect1 z well z by photographic & electric means4 ,curie & ,laborde det]m9$ ! rate ( ! emission ( heat 9 two diff]5t ways4 ,9 "o me?od ! diff]5ce ( temp]ature 0 obs]v$ by means ( an iron-con/ant9e !rmo-c\ple betwe5 a tube conta9+ "o gram ( radif]\s *loride ( b>ium1 ( activity ab\t ( pure radium1 & an exactly simil> tube conta9+ "o gram ( pure b>ium *loride4 ,! diff]5ce ( temp]ature obs]v$ 0 #ae ,c4 ,9 ord] to measure ! rate ( emission ( heat1 a coil ( wire ( kn[n resi/ance 0 plac$ 9 ! pure b>ium *loride1 & ! /r5g? ( ! electric curr5t requir$ to raise ! b>ium to ! same temp]ature z ! radif]\s b>ium 0 obs]v$4 ,9 ! o!r me?od1 ! active b>ium1 enclos$ 9 a glass tube1 0 plac$ inside a ,buns5 calorimet]4 ,be=e ! radium 0 introduc$1 x 0 obs]v$ t ! level ( ! m]cury 9 ! /em rema9$ /eady4 ,z soon z ! radium1 :i* _h previ\sly be5 cool$ 9 melt+ ice1 0 plac$ 9 ! calorimet]1 ! m]cury column began to move at a regul> rate4 ,if ! radium tube 0 remov$1 ! movem5t ( ! m]cury ceas$4 ,x 0 f\nd f ^! exp]im5ts t ! heat emission f ! #a gram ( radif]\s b>ium1 conta9+ ab\t ( its weight ( pure radium *loride1 0 #ad gram-calories p] h\r4 ,measurem5ts 7 also made ) #jjh gram ( pure radium *loride4 ,curie & ,laborde d$uc$ f ^! results t #a gram ( pure radium emits a quantity ( heat equal to ab\t #ajj gram-calories p] h\r4 ,?is result 0 confirm$ by ! exp]im5ts ( ,runge & ,pre*t#cbg & o!rs4 ,z f> z obs]vation has gone at pres5t1 ?is rate ( emission ( heat is cont9u\s & un*ang$ ) lapse ( "t4 ,!re=e1 #a gram ( radium emits 9 ! c\rse ( a day #bdjj1 & 9 ! c\rse ( a ye> #hgf1jjj gram-calories4 ,! am\nt ( heat evolv$ 9 ! union ( hydrog5 & oxyg5 to =m #a gram ( wat] is #cijj gram-calories4 ,x is ?us se5 t #a gram ( radium emits p] day ne>ly z mu* en]gy z is requir$ to dissociate #a gram ( wat]4 ,9 "s lat] exp]im5ts us+ #jg gram ( pure radium bromide1 ,p4 ,curie#cbh f\nd t ! temp]ature ( ! radium indicat$ by a m]cury !rmomet] 0 #c ,c4 above t ( ! surr\nd+ air4 ,?is result 0 confirm$ by ,giesel1 :o obta9$ a diff]5ce ( temp]ature ( #e ,c4 ) #a gram ( radium bromide4 ,! actual rise ( temp]ature obs]v$ w obvi\sly dep5d ^u ! size & nature ( ! vessel conta9+ ! radium4 ,dur+ _! visit to ,engl& 9 #aijc to lecture at ! ,royal ,in/itution1 ,m4 & ,mme ,curie p]=m$ "s exp]im5ts ) ,pr(essor ,dew>1 to te/ by ano!r me?od ! rate ( emission ( heat f radium at v l[ temp]atures4 ,?is me?od dep5d$ on ! measurem5t ( ! am\nt ( gas volatiliz$ :5 a radium prep>ation 0 plac$ inside a tube imm]s$ 9 a liquefi$ gas at its boil+ po9t4 ,! arrangem5t ( ! calorimet] is %[n 9 ,fig4 #ig4 ,illu/ration3 ,fig4 #ig4 ,! small clos$ ,dew> flask ,a conta9s ! radium 9 a glass tube ,r1 imm]s$ 9 ! liquid to be employ$4 ,! flask ,a is surr\nd$ by ano!r ,dew> bulb ,b1 conta9+ ! same liquid1 s t no heat is communicat$ to ,a f ! outside4 ,! gas lib]at$ 9 ! tube ,a is collect$ 9 ! usual way ov] wat] or m]cury1 & its volume det]m9$4 ,by ?is me?od1 ! rate ( heat emission ( ! radium 0 f\nd to be ab\t ! same 9 boil+ c>bon dioxide & oxyg51 & also 9 liquid hydrog54 ,especial int]e/ atta*es to ! result obta9$ ) liquid hydrog51 = at su* a l[ temp]ature ord9>y *emical activity is susp5d$4 ,! fact t ! heat emission ( radium is unalt]$ ov] su* a wide range ( temp]ature indirectly %[s t ! rate ( expulsion ( p>ticles f radium is indep5d5t ( temp]ature1 = x w be %[n lat] t ! heat+ effect obs]v$ is due to ! bomb>dm5t ( ! radium by ! p>ticles4 ,! use ( liquid hydrog5 is v conv5i5t = demon/rat+ ! rate ( heat emission f a small am\nt ( radium4 ,f #jg gram ( radium bromide 7:i* _h be5 prep>$ only #aj days previ\sly7 #gc c4c4 ( gas 7 giv5 (f p] m9ute4 ,9 lat] exp]im5ts ,p4 ,curie 7loc4 cit47 f\nd t ! rate ( emission ( heat f a giv5 quantity ( radium dep5d$ ^u ! "t :i* _h elaps$ s9ce its prep>ation4 ,! emission ( heat 0 at fir/ small1 b aft] a mon?'s int]val practically atta9$ a maximum4 ,if a radium comp\nd is dissolv$ & plac$ 9 a seal$ tube1 ! rate ( heat emission rises to ! same maximum z t ( an equal quantity ( radium 9 ! solid /ate4 #bde4 ,connection ( ! heat emission ) ! radiations4 ,! obs]vation ( ,curie t ! rate ( heat emission dep5d$ ^u ! age ( ! radium prep>ation po9t$ to ! conclusion t ! ph5om5on ( heat emission ( radium 0 connect$ ) ! radio-activity ( t elem5t4 ,x _h long be5 kn[n t radium comp\nds increas$ 9 activity = ab\t a mon? aft] _! prep>ation1 :5 !y rea*$ a /eady /ate4 ,x has be5 %[n 7section #bae71 t ?is increase ( activity is due to ! cont9u\s production by ! radium ( ! radio-active emanation1 :i* is occlud$ 9 ! radium comp\nd & adds its radiation to t ( ! radium prop]4 ,x ?us seem$ probable t ! heat+ effect 0 9 "s way connect$ ) ! pres5ce ( ! emanation4 ,"s exp]im5ts ^u ?is po9t 7 made by ,ru!r=d & ,b>nes#cbi4 ,9 ord] to measure ! small am\nts ( heat emitt$1 a =m ( diff]5tial air calorimet] %[n 9 ,fig4 #ih 0 employ$4 ,two equal glass flasks ( ab\t #ejj c4c4 7 fill$ ) dry air at atmosph]ic pressure4 ,^! flasks 7 connect$ ?r\gh a glass ,u-tube fill$ ) xyl5e1 :i* s]v$ z a manomet] to det]m9e any v>iation ( pressure ( ! air 9 ! flasks4 ,a small glass tube1 clos$ at ! l[] end1 0 introduc$ into ! middle ( ea* ( ! flasks4 ,:5 a cont9u\s s\rce ( heat 0 introduc$ into ! glass tube1 ! air surr\nd+ x 0 heat$ & ! pressure 0 increas$4 ,! diff]5ce ( pressure1 :5 a /eady /ate 0 rea*$1 0 obs]v$ on ! manomet] by means ( a microscope ) a micromet] scale 9 ! eye-piece4 ,on plac+ ! s\rce ( heat 9 ! simil> tube 9 ! o!r flask1 ! diff]5ce 9 pressure 0 rev]s$4 ,9 ord] to keep ! app>atus at a con/ant temp]ature1 ! two flasks 7 imm]s$ 9 a wat]-ba?1 :i* 0 kept well /irr$4 ,illu/ration3 ,fig4 #ih4 ,obs]vations 7 fir/ made on ! heat emission f #cj milligrams ( radium bromide4 ,! diff]5ce 9 pressure obs]v$ on ! manomet] 0 /&>diz$ by plac+ a small coil ( wire ( kn[n resi/ance 9 ! place ( ! radium4 ,! /r5g? ( ! curr5t ?r\gh ! wire 0 adju/$ to give ! same diff]5ce ( pressure on ! manomet]4 ,9 ?is way x 0 f\nd t ! heat emission p] gram ( radium bromide correspond$ to #fe gram-calories p] h\r4 ,tak+ ! atomic weight ( radium z #bbe1 ?is is equival5t to a rate ( emission ( heat f "o gram ( metallic radium ( #aaj gram-calories p] h\r4 ,! emanation f ! #cj milligrams ( radium bromide 0 !n remov$ by heat+ ! radium 7section #bae74 ,by pass+ ! emanation ?r\gh a small glass tube imm]s$ 9 liquid air1 ! emanation 0 cond5s$4 ,! tube 0 seal$ (f :ile ! emanation 0 /ill cond5s$ 9 ! tube4 ,9 ?is way ! emanation 0 conc5trat$ 9 a small glass tube ab\t #d cms4 long4 ,! heat+ effects ( ! 8de-emanat$0 radium & ( ! emanation tube 7 !n det]m9$ at int]vals4 ,x 0 f\nd t1 aft] removal ( ! emanation1 ! heat+ effect ( ! radium decay$ 9 ! c\rse ( a few h\rs to a m9imum1 correspond+ to ab\t #be p] c5t4 ( ! orig9al heat emission1 & !n gradually increas$ aga91 rea*+ its orig9al value aft] ab\t a mon?'s int]val4 ,! heat+ effect ( ! emanation tube 0 f\nd to increase = ! fir/ few h\rs aft] sep>ation to a maximum1 & !n to decay regul>ly ) ! "t accord+ to an expon5tial law1 fall+ to half its maximum value 9 ab\t f\r days4 ,! actual heat emission ( ! emanation tube 0 det]m9$ by s5d+ a curr5t ?r\gh a coil ( wire occupy+ ! same l5g? & position z ! emanation tube4 ,! v>iation ) "t ( ! heat+ effect f #cj milligrams ( radium & ! emanation f x is %[n 9 ,fig4 #ii4 ,illu/ration3 ,fig4 #ii4 ,curve ,a %[s ! v>iation ) "t ( ! heat emission ( ! radium & curve ,b ( ! emanation4 ,! sum total ( ! rate ( heat emission ( ! radium & ! emanation toge!r1 0 at any "t f\nd to be equal to t ( ! orig9al radium4 ,! maximum heat+ effect ( ! tube conta9+ ! emanation f #cj milligrams ( radium bromide 0 #abf gram-calories p] h\r4 ,! emanation toge!r ) ! second>y products :i* arise f x1 obta9$ f "o gram ( radium1 w\ld ?us give out #db gram-calories p] h\r4 ,! emanation /or$ up 9 ! radium is ?us responsible = m ?an two-?irds ( ! total heat emission f radium4 ,x w be se5 lat] t ! decrease to a m9imum ( ! heat+ effect ( radium1 aft] removal ( ! emanation1 is connect$ ) ! decay ( ! excit$ activity4 ,9 a simil> way1 ! increase ( ! heat+ effect ( ! emanation to a maximum "s h\rs aft] removal is also a result ( ! excit$ activity produc$ by ! emanation on ! walls ( ! conta9+ vessel4 ,disreg>d+ = ! mom5t ^! rapid initial *anges 9 heat emission1 x is se5 t ! heat+ effect ( ! emanation & its fur!r products1 aft] rea*+ a maximum1 decreases at ! same rate z t at :i* ! emanation loses its activity1 t is1 x falls to half value 9 f\r days4 ,if ,qmax4 is ! maximum heat+ effect & ,qt ! heat+ effect at any "t t lat]1 !n frac ,qt ,qmax e-t :]e is ! con/ant ( *ange ( ! emanation4 ,! curve ( recov]y ( ! heat+ effect ( radium f its m9imum value is id5tical ) ! curve ( recov]y ( its activity measur$ by ! rays4 ,s9ce ! m9imum heat+ effect is #be p] c5t4 ( ! total1 ! heat emission ,qt at any "t t aft] rea*+ a m9imum is giv5 by frac ,qt ,qmax cdot#be cdot#ge 7#a e-t7 1 :]e ,qmax4 is ! maximum rate ( heat emission & 1 z be=e1 is ! con/ant ( *ange ( ! emanation4 ,! id5tity ( ! curves ( recov]y & fall ( ! heat+ effect ( radium & its emanation respectively ) ! correspond+ curves = ! rise & fall ( radio-activity %[s t ! heat emission ( radium & its products is directly connect$ ) _! radio-activity4 ,! v>iation 9 ! heat emission ( bo? radium & its emanation is approximately proportional to _! activity measur$ by ! rays4 ,x is n proportional to ! activity measur$ by ! or rays1 = ! int5sity ( ^! rays falls ne>ly to z]o "s h\rs aft] removal ( ! emanation1 :ile ! ray activity1 l ! heat+ effect1 is #be p] c5t4 ( ! maximum value4 ,^! results are ?us 9 accordance ) ! view t ! heat emission ( radium accompanies ! expulsion ( p>ticles1 & is approximately proportional to ! numb] expell$4 ,be=e su* a conclusion c be consid]$ e/abli%$1 x is necess>y to %[ t ! heat+ effect ( ! active deposit f ! emanation v>ies 9 ! same way z its ray activity4 ,exp]im5ts made to te/ ?is po9t w n[ be consid]$4 #bdf4 ,heat emission ( ! active deposit f ! emanation4 ,new radium 9 radio-active equilibrium conta9s f\r successive products :i* break up ) ! emission ( p>ticles1 viz4 radium itself1 ! emanation1 radium ,a & ,c4 ,radium ,b does n emit rays at all4 ,! effect ( ! lat] products radium ,d1 ,e & ,f may be neglect$1 if ! radium has n be5 prep>$ = m ?an a ye>4 ,x is n easy to settle def9itely ! relative activity suppli$ by ea* ( ^! products :5 9 radio-active equilibrium1 b x has be5 %[n 9 section #bbi t ! activity is n v diff]5t = ! f\r ray products4 ,! p>ticles f radium ,a & ,c are m p5etrat+ ?an ^? f radium itself & ! emanation4 ,! evid5ce at pres5t obta9$ po9ts to ! conclusion t ! activity suppli$ by ! emanation is less ?an t suppli$ by ! o!r products4 ,?is indicates t ! p>ticles f ! emanation are project$ ) less velocity ?an 9 ! o!r cases4 ,:5 ! emanation is sudd5ly releas$ f radium by heat or solution1 ! products radium ,a1 ,b & ,c are left beh9d4 ,s9ce ! p>5t matt] is remov$1 ! am\nt ( ! products ,a1 ,b1 ,c at once comm5ces to dim9i%1 & at ! end ( ab\t ?ree h\rs rea*es a v small value4 ,if ! heat+ effect dep5ds ^u ! ray activity1 x is ?us to be expect$ t ! heat emission ( ! radium %\ld rapidly dim9i% to a m9imum aft] ! removal ( ! emanation4 ,:5 ! emanation is introduc$ into a vessel1 ! products radium ,a1 ,b & ,c at once appe> & increase 9 quantity1 rea*+ a practical maximum ab\t #c h\rs lat]4 ,! heat+ effect ( ! emanation tube %\ld ?us increase = sev]al h\rs aft] ! introduction ( ! emanation4 ,9 ord] to foll[ ! rapid *anges 9 ! heat+ effect ( radium1 aft] removal ( ! emanation1 ,ru!r=d & ,b>nes 7loc4 cit47 us$ a pair ( diff]5tial plat9um !rmomet]s4 ,ea* !rmomet] consi/$ ( #ce cms4 ( f9e plat9um wire1 w\nd c>efully on ! inside ( a ?9 glass tube #e mms4 9 diamet]1 =m+ a coil #c cms4 long4 ,! glass tube conta9+ ! radium & also ! tube conta9+ ! emanation 7 select$ to slide easily into ! int]ior ( ! coils1 ! wire ?us be+ 9 direct contact ) ! glass envelope conta9+ ! s\rce ( heat4 ,! *ange 9 resi/ance ( ! plat9um !rmomet]s1 :5 ! radium or emanation tube 0 transf]r$ f "o coil to ! o!r1 0 readily measur$4 ,illu/ration3 ,fig4 #ajj4 ,! heat+ effect ( ! radium 9 radio-active equilibrium 0 fir/ accurately det]m9$4 ,! radium tube 0 heat$ to drive (f ! emanation1 :i* 0 rapidly cond5s$ 9 a small glass tube #c cms4 long & #c mms4 int]nal diamet]4 ,aft] all[+ a %ort "t = temp]ature conditions to become /eady1 ! heat+ effect ( ! radium tube 0 measur$4 ,! results are %[n 9 ,fig4 #ajj4 ,an obs]vation c\ld n be tak5 until ab\t #ab m9utes aft] ! removal ( ! emanation1 & ! heat+ effect 0 !n f\nd to h fall5 to ab\t #ee p] c5t4 ( ! maximum value4 ,x /eadily dim9i%$ ) ! "t1 f9ally rea*+ a m9imum value ( #be p] c5t4 sev]al h\rs lat]4 ,x is n possible 9 exp]im5ts ( ?is "* to sep>ate ! heat+ effect ( ! emanation f t suppli$ by radium ,a4 ,s9ce ,a is half trans=m$ 9 ?ree m9utes1 its heat+ effect w h l>gely disappe>$ aft] #aj m9utes1 & ! decrease is !n ma9ly due to *anges 9 radium ,b & ,c4 ,! v>iation ) "t ( ! heat+ effect ( ! active deposit is /ill m cle>ly br\ght out by an exam9ation ( ! rise ( ! heat+ effect :5 ! emanation is introduc$ into a small tube1 & ( ! decrease ( ! heat+ effect aft] ! emanation is remov$4 ,! curve ( rise is %[n 9 ! upp] curve ( ,fig4 #aja4 #dj m9utes aft] ! introduction ( ! emanation1 ! heat+ effect _h ris5 to #ge p] c5t4 ( ! maximum value :i* 0 rea*$ aft] an int]val ( ab\t #c h\rs4 ,illu/ration3 ,fig4 #aja4 ,aft] ! heat+ effect ( ! emanation tube _h atta9$ a maximum1 ! emanation 0 remov$1 & ! decay ) "t obs]v$ z soon z possible aft]w>ds4 ,! results are %[n 9 ! l[] curve ( ,fig4 #aja4 ,x is se5 t ! two curves ( rise & decay are complem5t>y to "o ano!r4 ,! fir/ obs]vation 0 made #aj m9utes aft] removal1 & ! heat+ effect _h !n dropp$ to #dg p] c5t4 ( ! orig9al value4 ,?is sudd5 drop is due p>tly to ! removal ( ! emanation1 & p>tly to ! rapid trans=mation ( radium ,a4 ,! l[] curve is almo/ id5tical 9 %ape ) ! correspond+ ray curve = ! decay ( ! excit$ activity aft] a long exposure 7see ,fig4 #hf7 & cle>ly %[s t ! heat+ effect is directly proportional to ! activity measur$ by ! rays ov] ! :ole range exam9$4 ,! heat+ effect decreases accord+ to ! same law & at ! same rate z ! activity measur$ by ! rays4 ,tw5ty m9utes aft] ! removal ( ! emanation1 radium ,a has be5 almo/ completely trans=m$1 & ! activity is !n proportional to ! am\nt ( radium ,c pres5t1 s9ce ! int]m$iate product ,b does n give out rays4 ,! close agreem5t ( ! activity & heat emission curves %[s t ! heat+ effect is proportional also to ! am\nt ( radium ,c4 ,we may ?us conclude t ! rayless product ,b supplies little if any ( ! heat emission obs]v$4 ,if radium ,b suppli$ ! same am\nt z radium ,c1 ! curve ( decrease ( heat+ effect ) "t w\ld diff] consid]ably f ! activity curve4 ,! conclusion t ! trans=mation ( radium ,b is n accompani$ by ! release ( z mu* heat z ! o!r *anges is to be expect$ if ! heat+ effect is ma9ly due to ! en]gy ( motion ( ! expell$ p>ticles4 ,! relative heat+ effect due to ! radium products is %[n 9 ! foll[+ table4 ,! initial heat+ effect ( ,c is d$uc$ by comp>ison ) ! correspond+ activity curve4 ,products ,radiation ,initial rate ( heat emission ,radium rays #be p] c5t4 ( total ,emanation ,radium ,a #dd ,radium ,b no rays #j ,radium ,c 1 1 #ca rays ,s9ce radium ,a & ,c supply almo/ an equal proportion ( activity1 x is probable t !y h equal initial heat+ effects4 ,if ?is is ! case1 ! heat+ effect ( ! emanation alone is #ac p] c5t4 ( ! total4 #bdg4 ,heat+ effects ( ! & rays4 ,x has be5 %[n 9 section #aad t ! k9etic en]gy ( ! p>ticles emitt$ f radium is probably n great] ?an "o p] c5t4 ( t due to ! p>ticles4 ,if ! heat emission is a result ( bomb>dm5t by ! p>ticles expell$ f its mass1 x is to be expect$ t ! heat+ effect ( ! rays w be v small comp>$ ) t due to ! rays4 ,?is anticipation is borne out by exp]im5t4 ,curie measur$ ! heat+ effect ( radium 7#a7 :5 enclos$ 9 a ?9 envelope1 & 7#b7 :5 surr\nd$ by "o millimetre ( lead4 ,9 ! =m] case a l>ge proportion ( ! rays escap$1 &1 9 ! latt]1 ne>ly all 7 absorb$4 ,! increase ( heat+ effect 9 case 7#b7 0 n m ?an five p] c5t41 & ?is is probably an ov]-e/imate4 ,9 a simil> way1 s9ce ! total ionization due to ! rays is ab\t equal to t produc$ by ! rays1 we %\ld expect t ! heat+ effect ( ! rays w be v small comp>$ ) t aris+ f ! rays4 ,pas*5 made "s exp]im5ts on ! heat+ effect ( radium 9 a ,buns5 ice calorimet] :]e ! radium 0 surr\nd$ by a ?ickness ( #aib cms4 ( lead--a dep? suffici5t to absorb a l>ge proportion ( ! rays4 ,9 8 fir/ publication#ccj1 results 7 giv5 :i* indicat$ t ! heat+ effect ( ! rays 0 ev5 great] ?an t ( ! rays4 ,?is 0 n confirm$ by lat] obs]vations by ! same me?od4 ,he conclud$ t ! ice calorimet] c\ld n be reli$ on to measure su* v small quantities ( heat4 ,aft] ! publication ( ,pas*5's fir/ pap] ,ru!r=d & ,b>nes#cca exam9$ ! "q by a diff]5t me?od4 ,an air calorimet] ( ! =m %[n 9 ,fig4 #ih 0 employ$ :i* 0 f\nd to give v satisfactory results4 ,! heat emission ( radium 0 measur$ 7#a7 :5 ! radium 0 surr\nd$ by a cyl9d] ( alum9ium & 7#b7 :5 surr\nd$ by a cyl9d] ( lead ( ! same dim5sions4 ,! alum9ium absorb$ only a small fraction ( ! rays :ile ! lead /opp$ m ?an half4 ,no c]ta9 diff]5ce betwe5 ! heat+ effect 9 ! two cases 0 obs]v$1 al?\gh f ! e>li] exp]im5ts ( ,pas*5 a diff]5ce ( at lea/ #ej p] c5t4 0 to be expect$4 ,we mu/ !re=e conclude t ! & rays toge!r d n supply m ?an a small p]c5tage ( ! total heat emission ( radium--a result :i* is 9 accordance ) ! calculations bas$ on ! total ionization produc$ by ! diff]5t types ( rays4 #bdh4 ,s\rce ( ! en]gy4 ,x has be5 %[n t ! heat+ effect ( radium is closely proportional to ! activity measur$ by ! rays4 ,s9ce ! activity is g5]ally measur$ betwe5 p>allel plates su* a di/ance ap>t t mo/ ( ! p>ticles are absorb$ 9 ! gas1 ?is result %[s t ! heat+ effect is proportional to ! en]gy ( ! emitt$ p>ticles4 ,! rapid heat emission ( radium foll[s naturally f ! dis9tegration !ory ( radio-activity4 ,! heat is suppos$ to be d]iv$ n f ext]nal s\rces1 b f ! int]nal en]gy ( ! radium atom4 ,! atom is suppos$ to be a complex sy/em consi/+ ( *>g$ p>ts 9 v rapid motion1 & 9 consequ5ce conta9s a l>ge /ore ( lat5t en]gy1 :i* c only be manife/$ :5 ! atom breaks up4 ,= "s reason1 ! atomic sy/em becomes un/able1 & an p>ticle1 ( mass ab\t twice t ( ! hydrog5 atom1 escapes1 c>ry+ ) x its en]gy ( motion4 ,s9ce ! p>ticles w\ld be practically absorb$ 9 a ?ickness ( radium ( less ?an #jja cm41 ! great] proportion ( ! p>ticles1 expell$ f a mass ( radium1 w\ld be /opp$ 9 ! radium itself & _! en]gy ( motion w\ld be manife/$ 9 ! =m ( heat4 ,! radium w\ld ?us be heat$ by its own bomb>dm5t above ! temp]ature ( ! surr\nd+ air4 ,! en]gy ( ! expell$ p>ticles probably does n acc\nt = ! :ole emission ( heat by radium4 ,x is evid5t t ! viol5t expulsion ( a "p ( ! atom mu/ result 9 int5se electrical di/urbances 9 ! atom4 ,at ! same "t1 ! residual p>ts ( ! dis9tegrat$ atom re>range !mselves to =m a p]man5tly or tempor>ily /able sy/em4 ,dur+ ?is process also "s en]gy is probably emitt$1 :i* is manife/$ 9 ! =m ( heat 9 ! radium itself4 ,! view t ! heat emission ( radium is due v l>gely to ! k9etic en]gy possess$ by ! expell$ p>ticles is /rongly confirm$ by calculations ( ! magnitude ( ! heat+ effect to be expect$ on su* an hypo!sis4 ,x has be5 %[n 9 section #ic t "o gram ( radium bromide emits ab\t #add #aj p>ticles p] second4 ,! correspond+ numb] = #a gram ( radium 7,ra #bbe7 is #be #aj4 ,n[ x has be5 calculat$ f exp]im5tal data 9 section #id1 t ! av]age k9etic en]gy ( ! p>ticles expell$ f radium is #ei #aj ergs4 ,s9ce all ( ! p>ticles are absorb$ ei!r 9 ! radium itself or ! envelope surr\nd+ x1 ! total en]gy ( ! p>ticles emitt$ p] second is #ae #aj ergs4 ,?is corresponds to an emission ( en]gy ( ab\t #acj gram calories p] h\r4 ,n[ ! obs]v$ heat+ effect ( radium is ab\t #ajj gram calories p] h\r4 ,consid]+ ! nature ( ! calculation1 ! agreem5t betwe5 ! obs]v$ & exp]im5tal values is z close z w\ld be expect$1 & directly supports ! view t ! heat emission ( radium is due v l>gely to ! bomb>dm5t ( ! radium & conta9+ vessel by ! p>ticles expell$ f its mass4 #bdi4 ,heat+ effect ( ! radium emanation4 ,! enorm\s am\nt ( heat lib]at$ 9 radio-active trans=mations :i* are accompani$ by ! expulsion ( p>ticles is v well illu/rat$ by ! case ( ! radium emanation4 ,! heat emission ( ! emanation releas$ f #a gram ( radium is #ge gram calories p] h\r at its maximum value4 ,?is heat emission is n due to ! emanation alone1 b also to its fur!r products :i* are includ$ ) x4 ,s9ce ! rate ( heat emission decays expon5tially ) ! "t to ab\t half value 9 f\r days1 ! total am\nt ( heat lib]at$ dur+ ! life ( ! emanation f #a gram ( radium is equal to intinfty #ge e-t dt frac #ge #aj1jjj gram calories approximately1 s9ce #jjgb7;h\r74 ,n[ ! volume ( ! emanation f #a gram ( radium is ab\t #a cubic millimetre at /&>d pressure & temp]ature 7section #agb74 ,?us #a cubic c5timetre ( ! emanation w\ld dur+ its trans=mation emit #aj gram calories4 ,! heat emitt$ dur+ ! comb9ation ( #a c4c4 ( hydrog5 & oxyg5 to =m wat] is ab\t #b gram calories4 ,! emanation ?us gives out dur+ its *anges #e #aj times z mu* en]gy z ! comb9ation ( an equal volume ( hydrog5 & oxyg5 to =m wat]1 al?\gh ?is latt] reaction is accompani$ by a l>g] release ( en]gy ?an any o!r kn[n to *emi/ry4 ,! production ( heat f #a c4c4 ( ! radium emanation is ab\t #ba gram calories p] second4 ,?is g5]ation ( heat w\ld be suffici5t to heat to r$ness1 if n to melt d[n1 ! walls ( ! glass tube conta9+ ! emanation4 ,! probable rate ( heat emission f #a gram weight ( ! emanation c readily be d$uc$1 assum+ t ! emanation has ab\t #ajj times ! molecul> weight ( hydrog54 ,s9ce #ajj c4c4 ( ! emanation w\ld weigh ab\t #a gram1 ! total heat emission f #a gram ( ! emanation is ab\t #aj gram calories4 ,x c readily be calculat$ t "o p\nd weight ( ! emanation w\ld1 at its maximum1 radiate en]gy at ! rate ( ab\t #aj1jjj horse-p[]4 ,?is radiation ( en]gy w\ld fall (f ) ! "t1 b ! total emission ( en]gy dur+ ! life ( ! emanation w\ld correspond to #fj1jjj horse-p[] days4 #bej4 ,heat+ effects ( uranium1 ?orium1 & act9ium4 ,s9ce ! heat emission ( radium is a direct consequ5ce ( its bomb>dm5t by ! p>ticles expell$ f its mass1 x is to be expect$ t all ! radio-elem5ts :i* emit rays %\ld also emit heat at a rate proportional to _! ray activity4 ,s9ce ! activity ( pure radium is probably ab\t two million times t ( uranium or ?orium1 ! heat emission f #a gram ( ?orium or uranium %\ld be ab\t #e #aj gram calories p] h\r1 or ab\t #jdd gram calories p] ye>4 ,?is is a v small rate ( g5]ation ( heat1 b x %\ld be detectable if a l>ge quantity ( uranium or ?orium is employ$4 ,exp]im5ts to det]m9e ! heat+ effect ( ?orium h be5 made by ,pegram#ccb4 ,?ree kilograms ( ?orium oxide1 enclos$ 9 a ,dew> bulb1 7 kept 9 an ice-ba?1 & ! diff]5ce ( temp]ature betwe5 ! ?orium & ice-ba? det]m9$ by a set ( iron-con/antan !rmo-electric c\ples4 ,! maximum diff]5ce ( temp]ature obs]v$ 0 #jjd ,c41 &1 f ! rate ( *ange ( temp]ature1 x 0 calculat$ t "o gram ( ?orium oxide lib]at$ #h #aj gram calories p] h\r4 ,a m accurate det]m9ation ( ! heat emission is 9 progress1 b ! results obta9$ are ( ! ord] ( magnitude to be expect$4 #bea4 ,en]gy emitt$ by a radio-active product4 ,an important consequ5ce foll[s f ! fact t ! heat emission is a measure ( ! en]gy ( ! expell$ p>ticles4 ,if ea* atom ( ea* product emits p>ticles1 ! total emission ( en]gy f #a gram ( ! product c at once be det]m9$4 ,! p>ticles f ! diff]5t products are project$ ) ab\t ! same velocity1 & consequ5tly c>ry (f ab\t ! same am\nt ( en]gy4 ,n[ x has be5 %[n t ! en]gy ( ea* p>ticle expell$ f radium is ab\t #ei #aj ergs4 ,mo/ ( ! products probably h an atomic weight 9 ! neighb\rhood ( #bjj4 ,s9ce !re are #cf #aj molecules 9 "o cubic c5timetre ( hydrog51 x c easily be calculat$ t !re are ab\t #cf #aj atoms 9 "o gram ( ! product4 ,if ea* atom ( ! product expels "o p>ticle1 ! total en]gy emitt$ f #a gram ( ! matt] is ab\t #b #aj ergs or #h #aj gram calories4 ,! total emission ( en]gy f a product :i* emits only rays is probably ab\t "o-hundr$? ( ! above am\nt4 ,9 ?is case we h only consid]$ ! en]gy emitt$ f a s+le product indep5d5tly ( ! successive products :i* may arise f x4 ,radium1 = example1 may be consid]$ a radio-active product :i* sl[ly breaks up & gives rise to f\r subsequ5t ray products4 ,! total heat emission f "o gram ( radium & products is ?us ab\t five times ! above am\nt1 or #d #aj gram calories4 ,! total emission ( en]gy f radium is discuss$ lat] 9 section #bff f a slightly diff]5t po9t ( view4 #beb4 ,numb] ( ions produc$ by an p>ticle4 ,9 ! fir/ edition ( ?is book x 0 calculat$ by sev]al indep5d5t me?ods t #a gram ( radium emitt$ ab\t #aj p>ticles p] second4 ,s9ce ! actual numb] has lat] be5 det]m9$ by measur+ ! *>ge c>ri$ by ! rays 7section #ic7 we c1 conv]sely1 use ?is numb] to det]m9e ) m c]ta9ty "s ( ! con/ants ^: values 7 assum$ 9 ! orig9al calculation4 ,= example1 ! total numb] ( ions produc$ by an p>ticle 9 ! gas c readily be det]m9$4 ,! me?od employ$ is z foll[s4 #jdhd mgr4 ( radium bromide 0 dissolv$ 9 wat] & !n spread uni=mly ov] an alum9ium plate4 ,aft] evaporation1 ! saturation ionization curr5t1 due to ! radium at its m9imum activity1 0 f\nd to be #hd #aj amp]e4 ,! plates ( ! te/+ vessel 7 suffici5tly f> ap>t to absorb all ! rays 9 ! gas4 ,! numb] ( p>ticles expell$ p] second into ! gas 0 f\nd exp]im5tally to be #hg #aj4 ,tak+ ! *>ge on an ion z #aac #aj c\lombs 7section #cf71 ! total numb] ( ions produc$ p] second 9 ! gas 0 #ge #aj4 ,?us ea* p>ticle on an av]age produc$ #hf1jjj ions 9 ! gas be=e x 0 absorb$4 ,n[ ,bragg 7section #ajd7 has %[n t ! p>ticles f radium at its m9imum activity are /opp$ 9 ab\t #c cms4 ( air4 ,! results obta9$ by him indicate t ! ionization ( ! p>ticles p] cm4 ( pa? is less ne> ! radium ?an "s di/ance away4 ,assum+1 h[ev]1 z a fir/ approximation t ! ionization is uni=m along ! pa?1 ! numb] ( ions produc$ p] cm4 ( pa? by ! p>ticle is #bi1jjj4 ,s9ce ! ionization v>ies directly z ! pressure1 at a pressure ( #a mm4 ( m]cury ! numb] ( ions p] unit pa? w\ld be ab\t #ch4 ,n[ ,t[ns5d 7section #ajc7 f\nd t ! maximum numb] ( ions produc$ p] unit pa? ( air at #a mm4 pressure by an electron 9 motion 0 #bj1 & 9 ?is case a fre% pair ( ions 0 produc$ at ea* enc\nt] ( ! electron ) ! molecules 9 its pa?4 ,9 ! pres5t case ! p>ticle1 :i* has a v l>ge mass comp>$ ) ! electron1 appe>s to h a l>g] sph]e ( influ5ce ?an ! electron & to ionize twice z _m molecules4 ,9 addition1 ! p>ticle produces _m m ions p] unit pa? ?an an electron mov+ ) ! same velocity1 = x has be5 %[n 7section #ajc7 t ! electron becomes a less effici5t ioniz] aft] a c]ta9 velocity is rea*$4 ,z ,bragg 7loc4 cit47 has po9t$ out1 ?is is to be expect$1 s9ce ! p>ticle consi/s ( a l>ge numb] ( electrons & consequ5tly w\ld be a f> m effici5t ioniz] ?an an isolat$ electron4 ,a calculation ( ! en]gy requir$ to produce an ion by an p>ticle is giv5 9 ,app5dix ,a4 #bec4 ,numb] ( p>ticles expell$ f "o gram ( radium4 ,x is ( importance to comp>e ! total numb] ( p>ticles expell$ f "o gram ( radium 9 radio-active equilibrium1 z1 !oretically1 ?is numb] %\ld be> a def9ite relation to ! total numb] ( p>ticles emitt$4 ,we h se5 t new radium 9 radio-active equilibrium conta9s f\r products :i* emit rays1 viz4 radium itself1 ! emanation1 radium ,a & radium ,c4 ,on ! o!r h&1 rays are expell$ f only "o product1 radium ,c4 ,! same numb] ( atoms ( ea* ( ^! successive products 9 equilibrium break up p] second4 ,if ! dis9tegration ( ea* atom is accompani$ by ! expulsion ( "o p>ticle &1 9 ! case ( radium ,c1 also ( "o p>ticle1 ! numb] ( p>ticles emitt$ f radium 9 radio-active equilibrium w be f\r times ! numb] ( p>ticles4 ,! me?od employ$ by ,wi5 to det]m9e ! numb] ( p>ticles emitt$ f a kn[n quantity ( radium has already be5 discuss$ 9 section #hj4 ,on acc\nt ( ! absorption ( "s ( ! p>ticles 9 ! radium envelope & 9 ! radium itself1 ! numb] f\nd by him is f> too small4 ,x has be5 %[n 9 section #he t a numb] ( easily absorb$ rays are project$ f radium1 _m ( :i* w\ld be /opp$ 9 ! radium itself or 9 ! envelope conta9+ x4 ,9 ord] to elim9ate z f> z possible ! error due to ?is absorption1 9 "s exp]im5ts made by ! writ]1 ! active deposit obta9$ f ! radium emanation r ?an radium itself 0 us$ z a s\rce ( rays4 ,a lead rod1 #d cms4 long & #d mms4 9 diamet]1 0 expos$ z ! negative electrode 9 a l>ge quantity ( ! radium emanation = ?ree h\rs4 ,! rod 0 !n remov$ & ! ray effect f x imm$iately measur$ by an electroscope & comp>$ ) ! correspond+ ray effect f a kn[n weight ( radium bromide 9 radio-active equilibrium4 ,s9ce ! active deposit conta9s ! product radium ,c :i* alone emits rays1 &1 s9ce ! int5sities ( ! & rays are always proportional to ea* o!r1 ! numb] ( p>ticles expell$ f ! lead rod p] second is equal to ! correspond+ numb] f ! weight ( radium bromide :i* gives ! same ray effect z ! lead rod4 ,! rod 0 !n envelop$ 9 a ?ickness ( alum9ium foil ( #jjec cms4--a ?ickness j suffici5t to absorb ! rays--& made ! insulat$ electrode 9 a cyl9drical metal vessel :i* 0 rapidly exhau/$ to a l[ pressure4 ,! curr5t 9 ! two directions 0 measur$ at int]vals by an electromet]1 &1 z we h se5 9 section #ic1 ! algebraic sum ( ^! curr5ts is proportional to ne1 :]e n is ! numb] ( p>ticles expell$ p] second f ! lead rod1 & e ! *>ge on ea* p>ticle4 ,! activity ( ! radium ,c decay$ ) ! "t1 b1 f ! kn[n curve ( decay1 ! results c\ld be correct$ 9 t]ms ( ! initial value imm$iately aft] ! rod 0 remov$ f ! emanation4 ,tak+ into acc\nt t half ( ! p>ticles emitt$ by ! active deposit 7 absorb$ 9 ! radium itself1 & reckon+ ! *>ge on ! p>ticle z #aac #aj c\lombs1 two sep>ate exp]im5ts gave #gf #aj & #gj #aj z ! total numb] ( p>ticles expell$ p] second f "o gram ( radium4 ,tak+ ! mean value1 we may conclude t ! total numb] ( p>ticles expell$ p] second f "o gram ( radium 9 radio-active equilibrium is ab\t #gc #aj4 ,! total numb] ( p>ticles expell$ f "o gram ( radium at its m9imum activity has be5 %[n to be #fb #aj 7section #ic74 ,! approximate agreem5t betwe5 ^! numb]s is a /rong indication ( ! correctness ( ! !oretical views previ\sly discuss$4 ,x is to be expect$ t ! numb] ( p>ticles1 d$uc$ 9 ?is way1 w be some:at great] ?an ! true value1 s9ce ! p>ticles give rise to a second>y radiation consi/+ also ( negatively *>g$ p>ticles mov+ at a high spe$4 ,^! second>y p>ticles1 aris+ f ! impact ( ! p>ticles on ! lead1 w pass ?r\gh ! alum9ium scre5 & add _! effect to ! prim>y rays4 ,! results1 h[ev]1 indicate t f\r p>ticles are expell$ f radium 9 radio-active equilibrium = ea* p>ticle & ?us confirm ! !ory ( successive *anges4 ,footnote #cbe3 ,phil4 ,trans4 ,a4 p4 #be1 #aija4 ,footnote #cbf3 ,p4 ,curie & ,laborde1 ,c4 ,r4 #acf1 p4 #fgc1 #aijc4 ,footnote #cbg3 ,runge & ,pre*t1 ,sitz4 ,ak4 ,wiss4 ,b]l91 ,no4 #ch1 #aijc4 ,footnote #cbh3 ,p4 ,curie1 ,socit de ,physique1 #aijc4 ,footnote #cbi3 ,ru!r=d & ,b>nes1 ,nature1 ,oct4 #bi1 #aijc4 ,phil4 ,mag4 ,feb4 #aijd4 ,footnote #ccj3 ,pas*51 ,phys4 ,zeit4 ,sept4 #ae1 #aijd4 ,footnote #cca3 ,ru!r=d & ,b>nes1 ,nature1 ,dec4 #ah1 #aijd2 ,phil4 ,mag4 ,may1 #aije4 ,footnote #ccb3 ,pegram1 ,sci5ce1 ,may #bg1 #aijd4 ,,*apt] ,,xiii4 ,,radio-,,active ,,processes4 #bed4 ,!ories ( radio-activity4 ,9 previ\s *apt]s1 a detail$ acc\nt has be5 giv5 ( ! nature & prop]ties ( ! radiations1 & ( ! complex processes tak+ place 9 ! radio-active sub/ances4 ,! num]\s products aris+ f ! radio-elem5ts h be5 closely exam9$1 & h be5 %[n to result f a trans=mation ( ! p>5t elem5t ?r\gh a numb] ( well-m>k$ /ages4 ,9 ?is *apt]1 ! application ( ! dis9tegration !ory to ! explanation ( radio-active ph5om5a w be consid]$ /ill fur!r1 & ! logical d$uctions to be drawn f ! !ory w be discuss$ briefly4 ,a review w fir/ be giv5 ( ! work+ hypo!ses :i* h s]v$ z a guide to ! inve/igators 9 ! field ( radio-activity4 ,^! work+ !ories h 9 _m cases be5 modifi$ or ext5d$ ) ! gr[? ( exp]im5tal k4 ,! e>ly exp]im5ts ( ,mme ,curie _h indicat$ t radio-activity 0 an atomic & n a molecul> ph5om5on4 ,?is 0 /ill fur!r sub/antiat$ by lat] "w1 & ! detection & isolation ( radium f pit*bl5de 0 a brilliant v]ification ( ! tru? ( ?is hypo!sis4 ,! discov]y t ! rays ( ! radio-elem5ts 7 simil> to ! ca?ode rays produc$ 9 a vacuum tube 0 an important advance1 & has =m$ ! basis ( sev]al subsequ5t !ories4 ,j4 ,p]r9#ccc1 9 #aija1 foll[+ ! views ( ,j4 ,j4 ,?omson & o!rs1 sugge/$ t ! atoms ( bodies consi/$ ( p>ts & might be lik5$ to a m9iature planet>y sy/em4 ,9 ! atoms ( ! radio-elem5ts1 ! p>ts compos+ ! atoms m di/ant f ! c5tre might be able to escape f ! c5tral attraction & ?us give rise to ! radiation ( en]gy obs]v$4 ,9 ,decemb] #aija1 ,becqu]el#ccd put =w>d ! foll[+ hypo!sis1 :i*1 he /at$1 _h s]v$ him z a guide 9 8 inve/igations4 ,accord+ to ! view ( ,j4 ,j4 ,?omson1 radio-active matt] consi/s ( negatively & positively *>g$ p>ticles4 ,! =m] h a mass ab\t ( ! mass ( ! hydrog5 atom1 :ile ! latt] h a mass ab\t "o ?\s& times great] ?an t ( ! negative p>ticle4 ,! negatively *>g$ p>ticles 7! rays7 w\ld be project$ ) great velocity1 b ! l>g] positive p>ticles ) a mu* l[] velocity =m+ a sort ( gas 7! emanation7 :i* deposits itself on ! surface ( bodies4 ,?is 9 turn w\ld subdivide1 giv+ rise to rays 7excit$ activity74 ,9 a pap] communicat$ to ! ,royal ,society 9 ,june #aijj1 ,ru!r=d & ,mc,clung#cce e/imat$ t ! en]gy1 radiat$ 9 ! =m ( ioniz+ rays into ! gas1 0 #cjjj gram-calories p] ye> = radium ( activity #ajj1jjj times t ( uranium4 ,tak+ ! late/ e/imate ( ! activity ( a pure radium comp\nd z #b1jjj1jjj1 ?is w\ld correspond to an emission ( en]gy into ! gas 9 ! =m ( rays ( ab\t #ff1jjj gram-calories p] gram p] ye>4 ,! sugge/ion 0 made t ?is en]gy might be d]iv$ f a re-gr\p+ ( ! con/itu5ts ( ! atom ( ! radio-elem5ts1 & x 0 po9t$ out t ! possible en]gy to be d]iv$ f a great] conc5tration ( ! compon5ts ( ! atom 0 l>ge comp>$ ) t giv5 out 9 molecul> reactions4 ,9 ! orig9al pap]s#ccf giv+ an acc\nt ( ! discov]y ( ! emanation ( ?orium & ! excit$ radio-activity produc$ by x1 ! view 0 tak5 t bo? ( ^! manife/ations 7 due to radio-active mat]ial4 ,! emanation behav$ l a gas1 :ile ! matt] :i* caus$ excit$ activity atta*$ itself to solids & c\ld be dissolv$ 9 "s acids b n 9 o!rs4 ,ru!r=d & ,miss ,brooks %[$ t ! radium emanation diffus$ ?r\gh air l a gas ( heavy molecul> weight4 ,at a lat] date ,ru!r=d & ,soddy %[$ t ! radium & ?orium emanations behav$ l *emically in]t gases1 s9ce !y 7 unaffect$ by ! mo/ dra/ic physical & *emical treatm5t4 ,on ! o!r h&1 ,p4 ,curie1 :o1 9 conjunction ) ,debi]ne1 _h made a s]ies ( rese>*es on ! radium emanation1 express$ diss5t f ?is view4 ,p4 ,curie#ccg did n consid] t !re 0 suffici5t evid5ce t ! emanation 0 mat]ial 9 nature1 & po9t$ out t no spectroscopic evid5ce ( its pres5ce _h yet be5 obta9$1 & also t ! emanation disappe>$ :5 conta9$ 9 a seal$ vessel4 ,x 0 po9t$ out by ! writ]#cch t ! failure to detect spectroscopic l9es 0 probably a consequ5ce ( ! m9ute quantity ( ! emanation pres5t1 "u ord9>y conditions1 al?\gh ! electrical & phosphoresc5t actions produc$ by ?is small quantity are v m>k$4 ,?is cont5tion is borne out by lat] "w4 ,p4 ,curie at fir/ took ! view t ! emanation 0 n mat]ial1 b consi/$ ( c5tres ( cond5sation ( en]gy atta*$ to ! gas molecules & mov+ ) !m4 ,m4 & ,mme ,curie h ?r\gh\t tak5 a v g5]al view ( ! ph5om5a ( radio-activity1 & h n put =w>d any def9ite !ory4 ,9 ,jan4 #aijb1 !y gave an acc\nt ( ! g5]al work+ !ory#cci :i* _h guid$ !m 9 _! rese>*es4 ,radio-activity is an atomic prop]ty1 & ! recognition ( ?is fact _h creat$ _! me?ods ( rese>*4 ,ea* atom acts z a con/ant s\rce ( emission ( en]gy4 ,?is en]gy may ei!r be d]iv$ f ! pot5tial en]gy ( ! atom itself1 or ea* atom may act z a me*anism :i* in/antly rega9s ! en]gy :i* is lo/4 ,!y sugge/$ t ?is en]gy may be borr[$ f ! surr\nd+ air 9 "s way n acc\nt$ = by ! pr9ciple ( ,c>not4 ,9 ! c\rse ( a detail$ /udy ( ! radio-activity ( ?orium1 ,ru!r=d & ,soddy#cdj f\nd t x 0 necess>y to suppose t ?orium 0 cont9u\sly produc+ f itself new k9ds ( active matt]1 :i* possess tempor>y activity & diff] 9 *emical prop]ties f ! ?orium itself4 ,! con/ant radio-activity ( ?orium 0 %[n to be ! result ( equilibrium betwe5 ! processes ( production ( active matt] & ! *ange ( t already produc$4 ,at ! same "t1 ! !ory 0 advanc$ t ! production ( active matt] 0 a consequ5ce ( ! dis9tegration ( ! atom4 ,! "w ( ! foll[+ ye> 0 devot$ to an exam9ation ( ! radio-activity ( uranium & radium on simil> l9es1 & x 0 f\nd t ! conclusions already advanc$ = ?orium held equally = uranium & radium#cda4 ,! discov]y ( a cond5sation ( ! radio-active emanations#cdb gave additional support to ! view t ! emanations 7 gase\s 9 "*4 ,9 ! meantime1 ! writ]#cdc _h f\nd t ! rays consi/$ ( positively *>g$ bodies atomic 9 size1 project$ ) great velocity4 ,! discov]y ( ! mat]ial nature ( ^! rays s]v$ to /r5g!n ! !ory ( atomic dis9tegration1 & at ! same "t to (f] an explanation ( ! connection betwe5 ! rays & ! *anges occurr+ 9 ! radio-elem5ts4 ,9 a pap] entitl$ 8,radio-active ,*ange10 ,ru!r=d & ,soddy#cdd put =w>d 9 "s detail ! !ory ( atomic dis9tegration z an explanation ( ! ph5om5a ( radio-activity1 & at ! same "t "s ( ! m important consequ5ces :i* foll[ f ! !ory 7 discuss$4 ,9 a pap] ann\nc+ ! discov]y ( ! heat emission ( radium1 ,p4 ,curie & ,laborde#cde /ate t ! heat en]gy may be equally well suppos$ to be d]iv$ f a break+ up ( ! radium atom or f en]gy absorb$ by ! radium f "s ext]nal s\rce4 ,j4 ,j4 ,?omson 9 an article on 8,radium10 communicat$ to ,nature#cdf1 put =w>d ! view t ! emission ( en]gy f radium is probably due to "s *ange )9 ! atom1 & po9t$ out t a l>ge /ore ( en]gy w\ld be releas$ by a contraction ( ! atom4 ,sir ,william ,crookes#cdg1 9 #ahii1 propos$ ! !ory t ! radio-active elem5ts possess ! prop]ty ( ab/ract+ en]gy f ! gas4 ,if ! mov+ molecules1 imp++ m swiftly on ! sub/ance1 7 releas$ f ! active sub/ance at a mu* l[] velocity1 ! en]gy releas$ f ! radio-elem5ts might be d]iv$ f ! atmosph]e4 ,?is !ory 0 advanc$ aga9 lat] on to acc\nt = ! l>ge heat emission ( radium1 discov]$ by ,p4 ,curie & ,laborde4 ,f4 ,re#cdh rec5tly advanc$ a v g5]al !ory ( matt] ) a special application to radio-active bodies4 ,he supposes t ! p>ts ( ! atom 7 orig9ally free1 con/itut+ a nebula ( extreme t5uity4 ,^! p>ts h gradually become unit$ r\nd c5tres ( cond5sation1 & h ?us =m$ ! atoms ( ! elem5ts4 ,on ?is view an atom may be lik5$ to an ext9ct sun4 ,! radio-active atoms occupy a transitional /age betwe5 ! orig9al nebula & ! m /able *emical atoms1 & 9 ! c\rse ( _! contraction give rise to ! heat emission obs]v$4 ,"l ,kelv9 9 a pap] to ! ,briti% ,association meet+1 #aijc1 has sugge/$ t radium may obta9 its en]gy f ext]nal s\rces4 ,if a piece ( :ite pap] is put into "o vessel & a piece ( black pap] into an exactly simil> vessel1 on exposure ( bo? vessels to ! light ! vessel conta9+ ! black pap] is f\nd to be at a high] temp]ature4 ,he sugge/s t radium 9 a simil> mann] may keep its temp]ature above ! surr\nd+ air by its p[] ( absorption ( unkn[n radiations4 ,ri*>z & ,s*5ck#cdi h sugge/$ t radio-activity may be due to ! production & break+ up ( ozone :i* is kn[n to be produc$ by radium salts4 #bee4 ,discussion ( ,!ories4 ,f ! survey ( ! g5]al hypo!ses advanc$ z possible explanations ( radio-activity1 x is se5 t !y may be divid$ broadly into two classes1 "o ( :i* assumes t ! en]gy emitt$ f ! radio-elem5ts is obta9$ at ! exp5se ( ! int]nal en]gy ( ! atom1 & ! o!r t ! en]gy is d]iv$ f ext]nal s\rces1 b t ! radio-elem5ts act z me*anisms capable ( trans=m+ ?is borr[$ en]gy into ! special =ms manife/$ 9 ! ph5om5a ( radio-activity4 ,( ^! two sets ( hypo!ses ! fir/ appe>s to be ! m probable1 & to be be/ support$ by ! exp]im5tal evid5ce4 ,up to ! pres5t n ! slighte/ exp]im5tal evid5ce has be5 adduc$ to %[ t ! en]gy ( radium is d]iv$ f ext]nal s\rces4 ,j4 ,j4 ,?omson 7loc4 cit47 has discuss$ ! "q 9 ! foll[+ way3-- 8,x has be5 sugge/$ t ! radium d]ives its en]gy f ! air surr\nd+ x1 t ! atoms ( radium possess ! faculty ( ab/ract+ ! k9etic en]gy f ! m rapidly mov+ air molecules :ile !y are able to reta9 _! own en]gy :5 9 collision ) ! sl[ly mov+ molecules ( air4 ,i _c see1 h[ev]1 t ev5 ! possession ( ?is prop]ty w\ld expla9 ! behavi\r ( radium2 = imag9e a portion ( radium plac$ 9 a cavity 9 a block ( ice2 ! ice ar\nd ! radium gets melt$2 :]e does ! en]gy = ?is come f8 ,by ! hypo!sis !re is no *ange 9 ! air-radium sy/em 9 ! cavity1 = ! en]gy ga9$ by ! radium is lo/ by ! air1 :ile heat _c fl[ into ! cavity f ! outside1 = ! melt$ ice r\nd ! cavity is hott] ?an ! ice surr\nd+ x40 ,! writ] has rec5tly f\nd t ! activity ( radium is n alt]$ by surr\nd+ x ) a l>ge mass ( lead4 ,a cyl9d] ( lead 0 ca/ #aj cms4 9 diamet] & #aj cms4 high4 ,a hole 0 bor$ 9 "o end ( ! cyl9d] to ! c5tre1 & ! radium1 enclos$ 9 a small glass tube1 0 plac$ 9 ! cavity4 ,! op5+ 0 !n h]metically clos$4 ,! activity 0 measur$ by ! rate ( dis*>ge ( an electroscope by ! rays transmitt$ ?r\gh ! lead1 b no appreciable *ange 0 obs]v$ dur+ a p]iod ( "o mon?4 ,m4 & ,mme ,curie e>ly made ! sugge/ion t ! radiation ( en]gy f ! radio-active bodies might be acc\nt$ = by suppos+ t space is trav]s$ by a type ( ,rntg5 rays1 & t ! radio-elem5ts possess ! prop]ty ( absorb+ !m4 ,rec5t exp]im5ts 7section #bgi7 h %[n t !re is pres5t at ! surface ( ! e>? a v p5etrat+ type ( rays1 simil> to ! rays ( radium4 ,ev5 if x 7 suppos$ t ! radio-elem5ts possess$ ! p[] ( absorb+ ?is radiation1 ! en]gy ( ! rays is f> too m9ute to acc\nt ev5 = ! en]gy radiat$ f an elem5t ( small activity l uranium4 ,9 addition1 all ! evid5ce s f> obta9$ po9ts to ! conclusion t ! radio-active bodies d n absorb ! type ( rays !y emit to any great] ext5t ?an w\ld be expect$ f _! d5sity4 ,x has be5 %[n 7section #hf7 t ?is is true 9 ! case ( uranium4 ,ev5 if x 7 suppos$ t ! radio-elem5ts possess ! prop]ty ( absorb+ ! en]gy ( "s unkn[n type ( radiation1 :i* is able to pass ?r\gh ord9>y matt] ) little absorption1 !re /ill rema9s ! fundam5tal difficulty ( acc\nt+ = ! peculi> radiations f ! radio-elem5ts1 & ! s]ies ( *anges t occur 9 !m4 ,x is n suffici5t = u to acc\nt = ! heat emission only1 = x has be5 %[n 7*apt] ,,xii7 t ! emission ( heat is directly connect$ ) ! radio-activity4 ,9 addition1 ! di/ribution ( ! heat emission ( radium among/ ! radio-active products :i* arise f x is extremely difficult to expla9 on ! hypo!sis t ! en]gy emitt$ is borr[$ f ext]nal s\rces4 ,x has be5 %[n t m ?an two-?irds ( ! heat emitt$ by radium is due to ! emanation toge!r ) ! active deposit :i* is produc$ by ! emanation4 ,:5 ! emanation is sep>at$ f ! radium1 its p[] ( emitt+ heat1 aft] rea*+ a maximum1 decreases ) ! "t accord+ to an expon5tial law4 ,x w\ld ?us be necess>y on ! absorption hypo!sis to po/ulate t mo/ ( ! heat emission ( radium1 obs]v$ "u ord9>y conditions1 is n due to ! radium itself b to some?+ produc$ by ! radium1 ^: p[] ( absorb+ en]gy f ext]nal s\rces dim9i%es ) "t4 ,a simil> argum5t also applies to ! v>iation ) "t ( ! heat+ effect ( ! active deposit produc$ f ! emanation4 ,x has be5 %[n 9 ! la/ *apt] t mo/ ( ! heat+ effect obs]v$ 9 radium & its products mu/ be ascrib$ to ! bomb>dm5t ( ! p>ticles expell$ f ^! sub/ances4 ,x has already be5 po9t$ out 7section #acf7 t x is difficult to imag9e any me*anism1 ei!r int]nal or ext]nal1 :]eby su* enorm\s velocity c sudd5ly be impress$ ^u ! p>ticles4 ,we are =c$ to ! conclusion t ! p>ticle did n sudd5ly acquire ?is en]gy ( motion1 b 0 initially 9 rapid motion 9 ! atom1 & = "s reason1 0 sudd5ly releas$ ) ! velocity :i* x previ\sly possess$ 9 its orbit4 ,! /ronge/ evid5ce aga9/ ! hypo!sis ( absorption ( ext]nal en]gy is t su* a !ory ignores ! fact1 t1 :5ev] radio-activity is obs]v$1 x is always accompani$ by "s *ange :i* c be detect$ by ! appe>ance ( new products hav+ *emical prop]ties di/9ct f ^? ( ! orig9al sub/ances4 ,?is leads to "s =m ( 8*emical0 !ory1 & o!r results %[ t ! *ange is atomic & n molecul>4 #bef4 ,!ory ( radio-active *ange4 ,! processes occurr+ 9 ! radio-elem5ts are ( a "* q di/9ct f any previ\sly obs]v$ 9 *emi/ry4 ,al?\gh x has be5 %[n t ! radio-activity is due to ! spontane\s & cont9u\s production ( new types ( active matt]1 ! laws :i* control ?is production are diff]5t f ! laws ( ord9>y *emical reactions4 ,x has n be5 f\nd possible 9 any way to alt] ei!r ! rate at :i* ! matt] is produc$ or its rate ( *ange :5 produc$4 ,temp]ature1 :i* is su* an important factor 9 alt]+ ! rate ( *emical reactions1 is1 9 ^! cases1 almo/ entirely )\t influ5ce4 ,9 addition1 no ord9>y *emical *ange is kn[n :i* is accompani$ by ! expulsion ( *>g$ atoms ) great velocity4 ,x has be5 sugge/$ by ,arm/rong & ,l[ry#cej t radio-activity may be an exagg]at$ =m ( fluoresc5ce or phosphoresc5ce ) a v sl[ rate ( decay4 ,b no =m ( phosphoresc5ce has yet be5 %[n to be accompani$ by radiations ( ! "* ( ^? emitt$ by ! radio-elem5ts4 ,:atev] hypo!sis is put =w>d to expla9 radio-activity mu/ acc\nt n only = ! production ( a s]ies ( active products1 :i* diff] 9 *emical & physical prop]ties f ea* o!r & f ! p>5t elem5t1 b also = ! emission ( rays ( a special "*4 ,besides ?is1 x is necess>y to acc\nt = ! l>ge am\nt ( en]gy cont9u\sly radiat$ f ! radio-elem5ts4 ,! radio-elem5ts1 besides _! high atomic weights1 d n possess 9 common any special *emical *>act]i/ics :i* diff]5tiate !m f ! o!r elem5ts1 :i* d n possess ! prop]ty ( radio-activity to an appreciable degree4 ,( all ! kn[n elem5ts1 uranium1 ?orium1 & radium possess ! greate/ atomic weights1 viz43 radium #bbe1 ?orium #bcbe1 & uranium #bdj4 ,if a high atomic weight is tak5 z evid5ce ( a complicat$ /ructure ( ! atom1 x might be expect$ t dis9tegration w\ld occur m readily 9 heavy ?an 9 light atoms4 ,at ! same "t1 !re is no reason to suppose t ! elem5ts ( ! highe/ atomic weight mu/ be ! mo/ radio-active2 9 fact1 radium is f> m active ?an uranium1 al?\gh its atomic weight is less4 ,?is is se5 to be ! case also 9 ! radio-active products2 = example1 ! radium emanation is enorm\sly m active weight = weight ?an ! radium itself1 & !re is e reason to believe t ! emanation has an atom light] ?an t ( radium4 ,9 ord] to expla9 ! ph5om5a ( radio-activity1 ,ru!r=d & ,soddy h advanc$ ! !ory t ! atoms ( ! radio-elem5ts suff] spontane\s dis9tegration1 & t ea* dis9tegrat$ atom passes ?r\gh a succession ( well-m>k$ *anges1 accompani$ 9 mo/ cases by ! emission ( rays4 ,a prelim9>y acc\nt ( ?is hypo!sis has already be5 giv5 9 section #acf1 :ile ! ma!matical !ory ( successive *anges1 :i* is bas$ ^u x1 has be5 discuss$ 9 *apt] ,,ix4 ,! g5]al !ory has be5 utiliz$ 9 *apt]s ,x & ,,xi to acc\nt = ! num]\s active sub/ances f\nd 9 uranium1 ?orium1 act9ium & radium4 ,! !ory supposes t1 on an av]age1 a def9ite small proportion ( ! atoms ( ea* radio-active sub/ance becomes un/able at a giv5 "t4 ,z a result ( ?is in/ability1 ! atoms break up4 ,9 mo/ cases1 ! dis9tegration is explosive 9 viol5ce & is accompani$ by ! ejection ( an p>ticle ) great velocity2 9 a few cases1 & p>ticles are expell$ toge!r1 :ile 9 o!rs a p>ticle alone escapes4 ,9 a few cases1 ! *ange 9 ! atom appe>s to be less viol5t 9 "*1 & is n accompani$ by ! expulsion ( ei!r an or p>ticle4 ,! explanation ( ^! rayless *anges is consid]$ 9 section #bei4 ,! expulsion ( an p>ticle1 ( mass ab\t twice t ( ! hydrog5 atom1 leaves beh9d x a new sy/em light] ?an ! orig9al "o1 & possess+ *emical & physical prop]ties q diff]5t f ^? ( ! orig9al elem5t4 ,?is new sy/em aga9 becomes un/able1 & expels ano!r p>ticle4 ,! process ( dis9tegration1 once />t$1 proce$s f /age to /age at a def9ite measurable rate 9 ea* case4 ,at any "t aft] ! dis9tegration has comm5c$1 !re exi/s a proportion ( ! orig9al matt]1 :i* is un*ang$1 mix$ ) ! "p :i* has und]gone *ange4 ,?is is 9 accordance ) ! obs]v$ fact t ! spectrum ( radium1 = example1 does n *ange progressively ) "t4 ,! radium breaks up s sl[ly t only a small fraction has be5 trans=m$ 9 ! c\rse ( a few ye>s4 ,! un*ang$ "p /ill %[s its *>act]i/ic spectrum1 & w cont9ue to d s z long z any radium exi/s4 ,at ! same "t x is to be expect$ t1 9 old radium1 ! spectrum ( ^? products :i* exi/ 9 any quantity %\ld also appe>4 ,! t]m metabolon has be5 sugge/$ z a conv5i5t expression = ea* ( ^! *ang+ atoms1 d]iv$ f ! successive dis9tegration ( ! atoms ( ! radio-elem5ts4 ,ea* metabolon1 on an av]age1 exi/s only = a limit$ "t4 ,9 a collection ( metabolons ( ! same k9d ! numb] ,n1 :i* are un*ang$ at a "t t aft] production1 is giv5 by ,n ,n e-t 1 :]e ,n is ! orig9al numb]4 ,n[ d,n_/dt -,n1 or ! fraction ( ! metabolons pres5t1 :i* *ange 9 unit "t1 is equal to 4 ,! value #a_/ may be tak5 z ! av]age life ( ea* metabolon4 ,?is may be simply %[n z foll[s3--,at any "t t aft] ,n metabolons h be5 set aside1 ! numb] :i* *ange 9 ! "t dt is equal to ,ndt or ,n e-t dt 4 ,ea* metabolon has a life t1 s t ! av]age life ( ! :ole numb] is giv5 by intinfty te-t dt frac #a ,! v>i\s metabolons f ! radio-elem5ts are di/+ui%$ f ord9>y matt] by _! great in/ability & consequ5t rapid rate ( *ange4 ,s9ce a body :i* is radio-active mu/ ipso facto be und]go+ *ange1 x foll[s t none ( ! active products1 = example1 ! emanations & ,? ,x1 c consi/ ( any kn[n k9d ( matt]2 = !re is no evid5ce to %[ t inactive matt] c be made radio-active1 or t two =ms ( ! same elem5t c exi/1 "o radio-active & ! o!r n4 ,= example1 half ( ! matt] con/itut+ ! radium emanation has und]gone *ange aft] an int]val ( f\r days4 ,aft] ! lapse ( ab\t "o mon? ! emanation z su* has ne>ly disappe>$1 hav+ be5 trans=m$ ?r\gh sev]al /ages into o!r & m /able types ( matt]1 :i* are 9 consequ5ce difficult to detect by _! radio-activity4 ,! /rik+ diff]5ce 9 *emical & physical prop]ties :i* exi/s 9 _m cases betwe5 ! v>i\s products !mselves1 & also betwe5 ! prim>y active sub/ance & its products1 has already be5 drawn att5tion to 9 *apt] ,,ix4 ,"s ( ! products %[ di/9ctive electro-*emical behavi\r & c be remov$ f a solution by electrolysis4 ,o!rs %[ diff]5ces 9 volatility :i* h be5 utiliz$ to effect a p>tial sep>ation4 ,!re c be no d\bt t ea* ( ^! products is a def9ite new *emical sub/ance1 & if x c\ld be collect$ 9 suffici5t quantity to be exam9$ by ord9>y *emical means1 w\ld be f\nd to behave l a di/9ct *emical elem5t4 ,x w\ld diff]1 h[ev]1 f ! ord9>y *emical elem5t 9 ! %ortness ( its life1 & ! fact t x is cont9u\sly *ang+ into ano!r sub/ance4 ,we %all see lat] 7section #bfa7 t !re is e reason to believe t radium itself is a metabolon 9 ! true s5se ( ! t]m1 s9ce x is cont9u\sly *ang+1 & is itself produc$ f ano!r sub/ance4 ,! ma9 po9t ( diff]5ce betwe5 x & ! o!r products lies 9 ! comp>ative sl[ness ( its rate ( *ange4 ,x is = ?is reason t radium exi/s 9 pit*bl5de 9 great] quantity ?an ! o!r m rapidly *ang+ products4 ,by work+ up a l>ge am\nt ( ! m9]al1 we h se5 t a suffici5t quantity ( ! pure product has be5 obta9$ = *emical exam9ation4 ,on acc\nt ( ! %ort life ( ! emanation1 x exi/s 9 pit*bl5de 9 mu* less quantity ?an radium1 b x1 too1 has be5 isolat$ *emically & its volume measur$4 ,! extraord9>y prop]ties ( ?is emanation1 or gas1 h already be5 discuss$1 & !re c be no d\bt t1 :ile x exi/s1 x mu/ be consid]$ a new elem5t alli$ 9 *emical prop]ties to ! argon-helium gr\p ( gases4 ,!re c be no d\bt t 9 ! radio-elem5ts we are witness+ ! spontane\s trans=mation ( matt]1 & t ! diff]5t products :i* arise m>k ! /ages or halt+-places 9 ! process ( trans=mation1 :]e ! atoms are able to exi/ = a %ort "t be=e aga9 break+ up into new sy/ems4 #beg4 ,radio-active products4 ,! foll[+ table gives ! li/ ( ! active products or metabolons kn[n to result f ! dis9tegration ( ! ?ree radio-elem5ts4 ,9 ! second column is giv5 ! value ( ! radio-active con/ant = ea* active product1 i4e4 ! proportion ( ! active matt] und]go+ *ange p] second2 9 ! ?ird column ! "t ,t requir$ = ! activity to fall to "o-half1 i4e4 ! "t tak5 = half ! active product to und]go *ange2 9 ! f\r? column1 ! nature ( ! rays f ea* active product1 n includ+ ! rays f ! products :i* result f x2 9 ! fif? column1 a few ( ! m m>k$ physical & *emical prop]ties ( ea* metabolon4 ,products 7sec7 ,t ,nature ( ,*emical & ! rays ,physical prop]ties ( ! product ,uranium -- -- ,soluble 9 excess ( ammonium c>bonate1 soluble 9 e!r4 ,uranium ,x #cf #aj #bb days & ,insoluble 9 excess ( ammonium c>bonate1 soluble 9 e!r & wat]4 ,?orium -- -- ,insoluble 9 ammonia4 ,?orium ,x #bj #aj #d days ,soluble 9 ammonia & wat]4 ,emanation #ac #aj #ec secs4 ,*emically in]t gas ( heavy molecul> weight4 ,cond5ses at #abj ,c4 ,?orium ,a #agd #aj #aa h\rs no rays ,deposit$ on bodies2 conc5trat$ on ! ca?ode 9 an electric field4 ,soluble 9 "s acids2 ,? ,a m volatile ?an ,? ,b2 %[s def9ite electro-*emical behavi\r4 ,?orium ,b #bb #aj #ee m9s4 1 1 ,same 8 -- -- -- ,act9ium -- -- no rays ,insoluble 9 ammonia4 ,act9ium ,x #gh #aj #ajb days 7& 87 ,soluble 9 ammonia4 ,emanation #ag #ci secs4 ,behaves l a gas4 ,act9ium ,a #cb #aj #cf m9s4 no rays ,deposit$ on bodies2 conc5trat$ on ! ca?ode 9 an electric field1 soluble 9 ammonia & /rong acids2 volatiliz$ at a temp]ature ( #ajj ,c41 ,a & ,b c be sep>at$ by electrolysis4 ,act9ium ,b #ed #aj #bae m9s4 1 1 ,same 8 -- -- -- ,radium -- #acjj ye>s ,alli$ *emically to b>ium4 ,emanation #ba #aj #ch days ,*emically in]t gas ( heavy molecul> weight2 cond5ses at #aej ,c4 ,radium ,a #che #aj #c m9s4 ,deposit$ on 7active surface ( deposit ( bodies2 rapid conc5trat$ on *ange7 ca?ode 9 electric field2 soluble 9 /rong acids2 ,b volatiz$ at ab\t #gjj ,c41 ,a & ,c at ab\t #ajjj ,c4 ,radium ,b #ech #aj #ba m9s4 no rays ,same 7same7 ,radium ,c #dac #aj #bh m9s4 1 1 ,same 7same7 ,radium ,d -- ab\t #dj no rays ,soluble 9 7active acids2 volatile deposit ( bel[ #ajjj ,c4 sl[ *ange7 ,radium ,e #ac #aj #f days & ,non-volatile at 7same7 #ajjj ,c4 ,radium ,f #ef #aj #adc days ,deposit$ on 7same7 bismu? f solution2 volatile at ab\t #ajjj ,c41 same prop]ties z radio-tellurium & polonium4 ,! products & _! radiations are indicat$ graphically 9 ,fig4 #ajb on page #dej4 ,illu/ration3 ,fig4 #ajb4 ,"o product has be5 obs]v$ 9 uranium1 f\r 9 ?orium1 f\r 9 act9ium & sev5 9 radium4 ,x is n improbable t a clos] exam9ation ( ! radio-elem5ts may reveal /ill fur!r *anges4 ,if any v rapid trans=mations exi/1 !y w\ld be v difficult to detect4 ,! *ange ( ?orium ,x into ! emanation1 = example1 w\ld probably n h be5 discov]$ if ! product ( ! *ange _h n be5 gase\s 9 "*4 ,! electrolysis ( solutions is1 9 _m cases1 a v p[]ful me?od ( sep>at+ active products f "o ano!r1 & its possibilities h n yet be5 exhau/$4 ,! ma9 family ( *anges ( ! radio-elem5ts1 z f> z !y are kn[n1 h be5 inve/igat$ closely1 & x is n likely t any product ( comp>atively sl[ rate ( *ange has be5 ov]look$4 ,!re is a possibility1 h[ev]1 t two radio-active products may 9 "s cases arise f ! dis9tegration ( a s+le sub/ance4 ,?is po9t is discuss$ fur!r 9 section #bfj4 ,! rem>kable way 9 :i* ! dis9tegration !ory c be appli$ to unravel ! intricacies ( ! succession ( radio-active *anges is v well illu/rat$ 9 ! case ( radium4 ,)\t its aid1 x w\ld n h be5 possible to dis5tangle ! complicat$ processes :i* occur4 ,we h already se5 t ?is analysis has be5 in/rum5tal 9 %[+ t ! sub/ances polonium1 radio-tellurium & radio-lead are 9 reality products ( radium4 ,aft] ! radio-active sub/ances h und]gone ! succession ( *anges trac$ above1 a f9al /age is rea*$ :]e ! atoms are ei!r p]man5tly /able1 or *ange s sl[ly t x is difficult to detect _! pres5ce by means ( _! radio-activity4 ,x is probable1 h[ev]1 t ! process ( trans=mation /ill cont9ues ?r\gh fur!r sl[ /ages4 ,!re is n[ consid]able evid5ce t ! elem5ts uranium1 radium & act9ium are intimately connect$ toge!r4 ,! two latt] probably result f ! break+ up ( uranium4 ,! evid5ce 9 support ( ?is idea is giv5 9 section #bfb1 b !re /ill rema9s mu* "w to be done to bridge ov] ! gaps :i* at pres5t appe> to sep>ate ^! elem5ts f "o ano!r4 ,aft] ! s]ies ( trans=mations h come to an end1 !re w probably rema9 a product or products :i* w be inactive1 or active only to a m9ute ext5t4 ,9 addition1 s9ce ! p>ticles1 expell$ dur+ ! trans=mation1 are mat]ial 9 nature1 & are non-radio-active1 !y mu/ collect 9 "s quantity 9 radio-active matt]4 ,! probability t ! p>ticles consi/ ( helium is consid]$ lat] 9 section #bfh4 ,! value ( ,t1 ! "t = a product to be half-trans=m$1 may be tak5 z a comp>ative measure ( ! /ability ( ! diff]5t metabolons4 ,! /ability ( ! products v>ies ov] a v wide range4 ,= example1 ! value ( ,t = radium ,d is #dj ye>s1 & = ! act9ium emanation #ci secs4 ,?is corresponds to a range ( /ability measur$ by #ch #aj4 ,! range ( /ability is /ill fur!r ext5d$1 :5 x is rememb]$ t ! atoms ( ! radio-elem5ts !mselves are v sl[ly *ang+4 ,! only two metabolons ( ab\t ! same /ability are ?orium ,x & ! radium emanation4 ,9 ea* case1 ! trans=mation is half complet$ 9 ab\t f\r days4 ,i consid] t ! approximate agreem5t ( ! numb]s is a m]e co9cid5ce1 & t ! two types ( matt] are q di/9ct f "o ano!r2 =1 if ! metabolons 7 id5tical1 x w\ld be expect$ t ! *anges :i* foll[ w\ld take place 9 ! same way & at ! same rate1 b su* is n ! case4 ,moreov]1 ,? ,x & ! radium emanation h *emical & physical prop]ties q di/9ct f "o ano!r4 ,x is v rem>kable t ! ?ree radio-active sub/ances1 radium1 ?orium & act9ium1 %\ld exhibit su* a close simil>ity 9 ! succession ( *anges :i* occur 9 !m4 ,ea* ( !m at "o /age ( its dis9tegration emits a radio-active gas1 & 9 ea* case ?is gas is trans=m$ into a solid :i* is deposit$ ^u ! surface ( bodies4 ,x w\ld appe> t1 aft] dis9tegration ( an atom ( any ( ^! has once begun1 !re is a simil> succession ( *anges1 9 :i* ! result+ sy/ems h alli$ *emical & physical prop]ties4 ,su* a connection is ( int]e/ z indicat+ a possible orig9 ( ! recurr5ce ( prop]ties 9 ! atoms ( ! elem5ts1 z exemplifi$ by ! p]iodic law4 ,! connection betwe5 ?orium & act9ium is especially close bo? z reg>ds ! numb] & nature ( ! products4 ,! p]iod ( trans=mation ( ! successive products1 ?\gh diff]+ 9 magnitude1 rises & falls 9 a v analog\s mann]4 ,?is indicates t ! atoms ( ^! two elem5ts are v simil>ly con/itut$4 #beh4 ,am\nt ( ! products4 ,by application ( ! !ory ( successive *anges1 ! probable am\nt ( ea* ( ! products pres5t 9 radium & ! o!r radio-elem5ts c readily be e/imat$4 ,s9ce ea* radio-atom expels "o p>ticle ( atomic weight ab\t t ( hydrog5 or helium1 ! atoms ( ! int]m$iate products w n diff] mu* 9 weight f ! p>5t atom4 ,! approximate weight ( ea* product pres5t 9 a gram ( radium c be readily d$uc$4 ,let ,n,a1 ,n,b1 ,n,c be ! numb] ( atoms ( ! products ,a1 ,b1 ,c pres5t p] gram 9 radio-active equilibrium4 ,let ,a1 ,b1 ,c be ! correspond+ con/ants ( *ange4 ,!n if q is ! numb] ( ! p>5t atoms break+ up p] second1 p] gram1 q ,a,n,a ,b,n,b ,c,n,c4 ,consid] ! case ( ! radium products1 :]e ! value ( q is #fb #aj 7section #ic74 ,kn[+ ! value ( & q1 ! value ( ,n c at once be calculat$4 ,! correspond+ weight c be d$uc$1 s9ce 9 "o gram ( matt] ( atomic weight ab\t #bjj1 !re are ab\t #d #aj atoms 7section #ci74 ,! results are %[n 9 ! foll[+ table3-- ,product ,value ( ,numb] ( ,weight ( 7sec7 atoms1 ,n1 product gram pres5t p] ( radium gram ,radium #bj #aj #cb #aj #h #aj emanation ,radium ,a #ch #aj #ag #aj #d #aj ,radium ,b #ed #aj #ac #aj #c #aj ,radium ,c #da #aj #af #aj #d #aj ,) ! small quantities ( radium available1 ! am\nts ( ! products radium ,a1 ,b & ,c are too small to weigh4 ,x may be possible1 h[ev]1 to detect _! pres5ce by means ( ! spectroscope4 ,9 ! case ( ?orium1 ! weight ( ! product ,? ,x1 :i* is pres5t 9 greate/ quantity1 is f> too small to be detect$4 ,s9ce ! value ( = ,? ,x is ab\t ! same z = ! radium emanation1 ! maximum weight pres5t p] gram is ab\t #d #aj ( a gram1 rememb]+ t q = radium is ab\t #b #aj times ! value = ?orium4 ,ev5 ) a kilogram ( ?orium1 ! am\nt ( ,? ,x is f> too small to be detect$ by its weight4 ,?is me?od c be us$ g5]ally to calculate ! relative am\nts ( any successive products 9 radio-active equilibrium1 provid$ ! value ( = ea* product is kn[n4 ,= example1 x w be %[n lat] t uranium is ! p>5t ( radium & is half trans=m$ 9 ab\t #f #aj ye>s1 :ile radium & radium ,d are half trans=m$ 9 #acjj & #dj ye>s respectively4 ,! weight ( radium pres5t 9 "o gram ( uranium1 :5 equilibrium is e/abli%$1 is ?us #b #aj grams1 & ! weight ( radium ,d is #g #aj grams4 ,9 a m9]al conta9+ a ton ( uranium !re %\ld be ab\t #ah grams ( radium & #jfc grams ( radium ,d4 ,"s rec5t exp]im5ts describ$ 9 section #bfb %[ t ^! !oretical e/imates are ab\t twice too great4 #bei4 ,rayless ,*anges4 ,! exi/5ce ( well-m>k$ *anges 9 radium1 ?orium1 & act9ium1 :i* are n accompani$ by ! expulsion ( or p>ticles1 is ( great int]e/ & importance4 ,s9ce ! rayless *anges are n accompani$ by any appreciable ionization ( ! gas1 _! pres5ce _c be detect$ by direct means4 ,! rate ( *ange ( ! sub/ance c1 h[ev]1 be det]m9$ indirectly1 z we h se51 by measurem5t ( ! v>iation ) "t ( ! activity ( ! succe$+ product4 ,! law ( *ange has be5 f\nd to be ! same z = ! *anges :i* give rise to rays4 ,! rayless *anges are ?us analog\s1 9 "s respects1 to ! monomolecul> *anges obs]v$ 9 *emi/ry1 ) ! diff]5ce t ! *anges are 9 ! atom itself1 & are n due to ! decomposition ( a molecule into simpl] molecules or into its con/itu5t atoms4 ,x mu/ be suppos$ t a rayless *ange is n ( s viol5t a "* z "o :i* gives rise to ! expulsion ( or p>ticles4 ,! *ange may be acc\nt$ = ei!r by suppos+ t !re is a re>rangem5t ( ! compon5ts ( ! atom1 or t ! atom breaks up )\t ! expulsion ( its p>ts ) suffici5t velocity to produce ionization by collision ) ! gas4 ,! latt] po9t ( view1 if correct1 at once indicates ! possibility t undetect$ *anges ( a simil> "* may be tak+ place sl[ly 9 ! non-radio-active elem5ts2 or1 9 o!r words1 t all matt] may be und]go+ a sl[ process ( *ange4 ,! *anges tak+ place 9 ! radio-elem5ts h be5 obs]v$ only 9 consequ5ce ( ! expulsion ) great velocity ( ! p>ts ( ! dis9tegrat$ atom4 ,"s rec5t exp]im5ts describ$ 9 ,app5dix ,a %[ t ! p>ticle f radium ceases to ionize ! gas :5 its velocity falls bel[ ab\t #aj cms4 p] second4 ,x is ?us se5 t p>ticles may be project$ ) a great velocity1 & yet fail to produce ionization 9 ! gas4 ,9 su* a case1 x w\ld be difficult to foll[ ! *anges by ! electrical me?od1 z ! electrical effects w\ld be v small 9 comp>ison ) ^? produc$ by ! kn[n radio-active bodies4 #bfj4 ,radiations f ! products4 ,we h se5 t ! great majority ( ! radio-active products break up ) ! expulsion ( p>ticles1 & t ! p>ticle ) its accompanim5t ( ! ray appe>s 9 mo/ cases only 9 ! la/ rapid *ange4 ,9 ! case ( radium1 = example1 :i* has be5 mo/ closely inve/igat$ on acc\nt ( its great activity1 radium itself1 ! emanation & radium ,a emit only p>ticles2 radium ,b emits no rays at all2 :ile radium ,c emits all ?ree k9ds ( rays4 ,x is difficult to settle ) c]ta9ty :e!r ! products ?orium ,x & act9ium ,x emit p>ticles or n1 b ! & rays c]ta9ly appe> 9 ea* case 9 ! la/ rapid *ange 9 ! active deposit1 &1 9 ?is respect1 behave 9 a simil> mann] to radium4 ,! v sl[ mov+ electrons :i* accompany ! p>ticles emitt$ f radium 7section #ic7 are n tak5 into acc\nt1 = !y appe> to be lib]at$ z a result ( ! impact ( p>ticles on matt]1 & are expell$ ) a spe$ insignificant comp>$ ) t ( ! p>ticles emitt$ f radium ,c4 ,! appe>ance ( & rays only 9 ! la/ rapid *anges ( ! radio-elem5ts is v rem>kable1 & _c be reg>d$ z a m]e co9cid5ce4 ,! f9al expulsion ( a p>ticle results 9 ! appe>ance ( a product ( great /ability1 or1 9 ! case ( radium1 ( a product 7radium ,d7 :i* has f> m /ability ?an ! prec$+ "o4 ,x w\ld appe> t ! initial *anges are accompani$ by ! expulsion ( an p>ticle1 & t once ! p>ticle is expell$1 ! compon5ts ( ! residual atom fall into an arrangem5t ( fairly /able equilibrium1 :]e ! rate ( trans=mation is v sl[4 ,x ?us appe>s probable t ! p>ticle1 :i* is f9ally expell$1 may be reg>d$ z ! active ag5t 9 promot+ ! dis9tegration ( ! radio-atom ?r\gh ! successive /ages4 ,a discussion ( ?is "q w be giv5 ) m advantage lat] 7section #bgj71 :5 ! g5]al "q ( ! /ability ( ! atom is "u consid]ation4 ,x is significant t ! *ange 9 :i* ! ?ree types ( rays appe> is f> m viol5t 9 "* ?an ! prec$+ *anges4 ,n only are ! p>ticles expell$ ) great] velocity ?an 9 any o!r *ange1 b ! p>ticles are project$ ) a velocity v closely approa*+ t ( light4 ,!re is always a possibility t1 9 su* a viol5t explosion 9 ! atom1 n only may ! & p>ticles be expell$1 b ! atom itself may be disrupt$ into sev]al fragm5ts4 ,if ! great] proportion ( ! matt] result+ f ! dis9tegration is ( "o k9d1 x w\ld be difficult to detect ! pres5ce ( a small quantity ( rapidly *ang+ matt] f obs]vations ( ! rate ( decay2 b1 if ! products h di/9ctive electro-*emical behavi\r1 a p>tial sep>ation %\ld1 9 "s cases1 be effect$ by electrolysis4 ,x has already be5 po9t$ out t ! results ( ,pegram & von ,l]* 7section #bjg7 on ! electrolysis ( ?orium solutions may be expla9$ on ! supposition t ?orium ,a & ,b h di/9ctive electro-*emical behavi\r4 ,pegram1 h[ev]1 9 addition obs]v$ ! pres5ce ( a product :i* decay$ to half value 9 six m9utes4 ,?is active product 0 obta9$ by electrolys+ a solution ( pure ?orium salt1 to :i* a small quantity ( copp] nitrate _h be5 add$4 ,! copp] deposit 0 slightly active & lo/ half ( its activity 9 ab\t six m9utes4 ,! pres5ce ( su* radio-active products1 :i* d n come "u ! ma9 s*eme ( *anges1 indicates t1 at "s /age ( ! dis9tegration1 m ?an "o sub/ance results4 ,9 ! viol5t dis9tegration :i* occurs 9 radium ,c & ?orium ,b1 su* a result is to be expect$1 = x is n improbable t !re are sev]al arrangem5ts :]eby ! con/itu5ts ( ! atom =m a sy/em ( "s slight /ability4 ,! two products result+ f ! dis9tegration w\ld probably be pres5t 9 unequal proportion1 &1 unless !y gave out diff]5t k9ds ( rays1 w\ld be difficult to sep>ate f ea* o!r4 #bfa4 ,life ( radium4 ,s9ce ! atoms ( ! radio-elem5ts are cont9u\sly break+ up1 !y mu/ also be consid]$ to be metabolons1 ! only diff]5ce betwe5 !m & metabolons su* z ! emanations ,? ,x & o!rs be+ _! comp>atively great /ability & consequ5t v sl[ rate ( *ange4 ,!re is no evid5ce t ! process ( *ange1 trac$ above1 is rev]sible "u pres5t conditions1 & 9 ! c\rse ( "t a quantity ( radium1 uranium1 or ?orium left to itself mu/ gradually be trans=m$ into o!r types ( matt]4 ,!re seems to be no escape f ?is conclusion4 ,let u consid]1 = example1 ! case ( radium4 ,! radium is cont9u\sly produc+ f itself ! radium emanation1 ! rate ( production be+ always proportional to ! am\nt ( radium pres5t4 ,all ! radium mu/ ultimately be *ang$ into emanation1 :i* 9 turn is trans=m$ ?r\gh a succession ( /ages into o!r k9ds ( matt]4 ,!re is no d\bt t ! emanation is *emically q diff]5t f radium itself4 ,! quantity ( radium mu/ dim9i%1 to comp5sate = ! emanation :i* is =m$2 o!rwise x is necess>y to assume t matt] 9 ! =m ( emanation is creat$ f "s unkn[n s\rce4 ,an approximate e/imate ( ! rate ( *ange ( radium c easily be made by two diff]5t me?ods dep5d+ ^u 7#a7 ! numb] ( atoms ( radium break+ up p] second1 & 7#b7 ! am\nt ( emanation produc$ p] second4 ,x has be5 %[n exp]im5tally 7section #ic7 t #a gram ( radium at its m9imum activity expels #fb #aj p>ticles p] second4 ,! heat+ effect ( radium & also its volume agree closely ) calculation1 if x is suppos$ t ea* atom ( ea* product 9 break+ up emits "o p>ticle4 ,on ?is supposition x is se5 t #fb #aj atoms ( radium break up p] second4 ,n[ x has be5 %[n exp]im5tally 7section #ci7 t "o cubic c5timetre ( hydrog5 at /&>d pressure & temp]ature conta9s #cf #aj molecules4 ,tak+ ! atomic weight ( radium z #bbe1 ! numb] ( atoms 9 #a gram ( radium is equal to #cf #aj4 ,! fraction ( radium :i* breaks up is ?us #aie #aj p] second1 or #ed #aj p] ye>4 ,x foll[s t 9 ea* gram ( radium ab\t half a milligram breaks up p] ye>4 ,! av]age life ( radium is ab\t #ahjj ye>s1 & half ( ! radium is trans=m$ 9 ab\t #acjj ye>s4 ,we %all n[ consid] ! calculation1 bas$ on ! obs]v$ result ( ,ramsay & ,soddy1 t ! volume ( emanation to be obta9$ f "o gram ( radium is ab\t #a cubic millimetre4 ,! exp]im5tal evid5ce bas$ on diffusion results indicates t ! molecul> weight ( ! emanation is ab\t #ajj4 ,if ! dis9tegration !ory is correct1 ! emanation is an atom ( radium m9us "o p>ticle1 & !re=e mu/ h a molecul> weight ( at lea/ #bjj4 ,?is high value is m likely to be correct ?an ! exp]im5tal numb]1 :i* is bas$ on evid5ce t mu/ necess>ily be some:at unc]ta94 ,n[ ! rate ( production ( emanation p] second is equal to ,n1 :]e ,n is ! equilibrium am\nt4 ,tak+ ! molecul> weight z #bjj1 ! weight ( emanation produc$ p] second f #a gram ( radium #hif #aj #ai #aj gram4 ,n[ ! weight ( emanation produc$ p] second is v ne>ly equal to ! weight ( radium break+ up p] second4 ,?us ! fraction ( radium break+ up p] second is ab\t #ai #aj1 :i* is 9 agreem5t ) ! numb] previ\sly calculat$ by ! fir/ me?od4 ,we may ?us conclude t radium is half trans=m$ 9 ab\t #acjj ye>s4 ,tak+ ! activity ( pure radium z ab\t two million times t ( uranium1 & rememb]+ t only "o *ange1 :i* gives rise to rays1 occurs 9 uranium & f\r 9 radium1 x c readily be calculat$ t ! fraction ( uranium *ang+ p] ye> is ab\t #aj4 ,f ?is x foll[s t uranium %\ld be half trans=m$ 9 ab\t #f #aj ye>s4 ,if ?orium is a true radio-active elem5t1 ! "t = half trans=mation is ab\t #bd #aj ye>s1 s9ce ?orium has ab\t ! same activity z uranium b conta9s f\r products :i* emit rays4 ,if ! activity ( ?orium is due to "s radio-active impurity1 no e/imate ( ! l5g? ( its life c be made until ! prim>y active sub/ance has be5 isolat$ & its activity measur$4 #bfb4 ,orig9 ( radium4 ,! *anges 9 radium are ?us fairly rapid1 & a mass ( radium if left to itself %\ld 9 ! c\rse ( a few ?\s& ye>s h lo/ a l>ge proportion ( its radio-activity4 ,tak+ ! above e/imate ( ! life ( radium1 ! value ( is #ed #aj1 ) a ye> z ! unit ( "t4 ,a mass ( radium left to itself %\ld be half trans=m$ 9 #acjj ye>s & only "o-million? "p w\ld rema9 aft] #bf1jjj ye>s4 ,?us suppos+1 = illu/ration1 t ! e>? 0 orig9ally compos$ ( pure radium1 its activity p] gram #bf1jjj ye>s lat] w\ld n be great] ?an ! activity obs]v$ to-day 9 a good specim5 ( pit*bl5de4 ,ev5 suppos+ ?is e/imate ( ! life ( radium is too small1 ! "t requir$ = ! radium practically to disappe> is %ort comp>$ ) ! probable age ( ! e>?4 ,we are ?us =c$ to ! conclusion t radium is be+ cont9u\sly produc$ 9 ! e>?1 unless ! v improbable assumption is made1 t radium 0 9 "s way sudd5ly =m$ at a date rec5t 9 comp>ison ) ! age ( ! e>?4 ,x 0 e>ly sugge/$ by ,ru!r=d & ,soddy#cea t radium might be a dis9tegration product ( "o ( ! radio-elem5ts f\nd 9 pit*bl5de4 ,bo? uranium & ?orium fulfil ! conditions requir$ 9 a possible s\rce ( production ( radium4 ,bo? are pres5t 9 pit*bl5de1 h atomic weights great] ?an t ( radium1 & h rates ( *ange :i* are sl[ comp>$ ) t ( radium4 ,9 "s respects1 uranium fulfils ! conditions requir$ bett] ?an ?orium2 = x has n be5 obs]v$ t m9]als ri* 9 ?orium conta9 mu* radium1 :ile on ! o!r h&1 ! pit*bl5des conta9+ ! mo/ radium conta9 a l>ge proportion ( uranium4 ,if radium is n produc$ f uranium1 x is c]ta9ly a rem>kable co9cid5ce t ! greate/ activity ( pit*bl5de yet obs]v$ is ab\t five or six times t ( uranium4 ,s9ce radium has a life %ort comp>$ ) t ( uranium1 ! am\nt ( radium produc$ %\ld rea* a maximum value aft] a few ?\s& ye>s1 :5 ! rate ( production ( fre% radium--:i* is also a measure ( ! rate ( *ange ( uranium--balances ! rate ( *ange ( t product4 ,9 ?is respect ! process w\ld be exactly analog\s to ! production ( ! emanation by radium1 ) ! diff]5ce t ! radium *anges mu* m sl[ly ?an ! emanation4 ,b s9ce radium itself 9 its dis9tegration gives rise to at lea/ five *anges ) ! correspond+ production ( rays1 ! activity due to ! radium 7measur$ by ! rays71 :5 9 a /ate ( radio-active equilibrium ) uranium1 %\ld be ab\t five times t ( ! uranium t produces x2 = x has be5 %[n t only "o *ange has s f> be5 obs]v$ 9 uranium 9 :i* rays are expell$4 ,tak+ into acc\nt ! pres5ce ( act9ium 9 pit*bl5de1 ! activity obs]v$ 9 ! be/ pit*bl5de is ab\t ! same z w\ld be expect$ if ! radium 7 a dis9tegration product ( uranium4 ,if ?is hypo!sis is correct1 ! am\nt ( radium 9 any pit*bl5de %\ld be proportional to ! am\nt ( uranium pres5t1 provid$ ! radium is n remov$ f ! m9]al by p]colat+ wat]4 ,?is "q has be5 exp]im5tally attack$ by ,boltwood#ceb1 ,mc,coy#cec & ,/rutt#ced4 ,mc,coy measur$ ! relative activities ( diff]5t m9]als 9 ! =m ( p[d] by means ( an electroscope1 & det]m9$ ! am\nt ( uranium pres5t by *emical analysis4 ,8 results indicat$ t ! activity obs]v$ 9 ! m9]als 0 v approximately proportional to _! cont5t ( uranium4 ,s9ce act9ium is pres5t z well z uranium & its products1 ?is w\ld indicate t ! am\nt ( radium & act9ium tak5 toge!r is proportional to ! am\nt ( uranium4 ,?is problem has be5 attack$ m directly by ,boltwood & ,/rutt by measur+ ! relative am\nt ( ! radium emanation evolv$ by diff]5t m9]als4 ,by dissolv+ ! m9]al & !n sett+ x aside 9 a clos$ vessel1 ! am\nt ( emanation pres5t rea*es a maximum value aft] ab\t a mon?'s int]val4 ,! emanation is !n introduc$ into a clos$ vessel conta9+ a gold-leaf electroscope simil> to t %[n 9 ,fig4 #ab4 ,! rate ( movem5t ( ! gold-leaf is proportional to ! am\nt ( emanation f ! solution1 & ?is 9 turn is proportional to ! am\nt ( radium4 ,boltwood has made 9 ?is way a v complete & accurate comp>ison ( ! radium cont5t ( diff]5t v>ieties ( pit*bl5de & o!r ores conta9+ radium4 ,x 0 f\nd t _m ( ! m9]als 9 ! solid /ate all[$ a consid]able fraction ( ! emanation to escape into ! air4 ,! p]c5tage fraction ( ! total am\nt ( emanation lo/ 9 ?is way is %[n 9 ,column ,,ii ( ! foll[+ table4 ,column ,i gives ! maximum am\nt ( emanation pres5t 9 #a gram ( ! m9]al 9 arbitr>y units :5 none ( ! emanation escapes2 ,column ,,iii ! weight 9 grams ( uranium conta9$ 9 #a gram2 & ,column ,,iv ! ratio obta9$ by divid+ ! quantity ( emanation by ! quantity ( uranium4 ,! numb]s 9 ,column ,,iv %\ld be con/ant1 if ! am\nt ( radium is proportional to ! am\nt ( uranium4 ,locality ,i ,,ii ,,iii ,,iv ,sub/ance ,uran9ite ,nor? #agjj #aac #jgdfe #bbh ,c>ol9a ,uran9ite ,colorado #aeea #eb #jfifa #bbc ,gummite ,nor? #adgj #acg #jfech #bbe ,c>ol9a ,uran9ite ,joa*im/hal #acif #ef #jfagd #bbf ,uranophane ,nor? #aagg #hb #jeafh #bbh ,c>ol9a ,uran9ite ,saxony #aaef #bg #jejfd #bbh ,uranophane ,nor? #aace #bbh #jdihd #bbh ,c>ol9a ,?orogummite ,nor? #gbi #afb #jccag #bbj ,c>ol9a ,c>notite ,colorado #dig #afc #jbbfa #bbj ,urano?orite ,norway #beb #ac #jaach #bba ,sam>skite ,nor? #bcd #jg #jajdd #bbd ,c>ol9a ,orangite ,norway #bca #aa #jajcd #bbc ,eux5ite ,norway #aii #je #jjhga #bbh ,?orite ,norway #aff #fb #jjged #bbj ,f]gusonite ,norway #abj #je #jjeeg #bae ,aes*ynite ,norway #ajj #jb #jjdeb #bba ,x5ot9e ,norway #aed #bfj #jjjgj #bbj ,monazite ,nor? #jhh #jjjdc #bje 7s&7 ,c>ol9a ,monazite ,norway #jhd #ab #jjjda #bjg 7crys47 ,monazite ,brazil #jgf #jjjca #bde 7s&7 ,monazite ,conn4 #jfc #jjjcj #baj 7massive7 ,) ! exception ( "s ( ! monazites1 ! numb]s %[ a surpris+ly good agreem5t1 &1 tak+ into consid]ation ! great v>iation ( ! cont5t ( uranium 9 ! diff]5t m9]als1 & ! wide range ( locality f :i* !y 7 obta9$1 ! results af=d a direct & satisfactory pro( t ! am\nt ( radium 9 ! m9]als is directly proportional to ! am\nt ( uranium4 ,9 ?is connection1 x is ( int]e/ to note t ,boltwood f\nd t a consid]able quantity ( radium exi/$ 9 v>i\s v>ieties ( monazite1 al?\gh mo/ ( ! previ\s analyses agre$ 9 /at+ t no uranium 0 pres5t4 ,a c>eful exam9ation 0 9 consequ5ce made to te/ ?is po9t1 & x 0 f\nd by special me?ods t uranium 0 pres5t1 & 9 ab\t ! am\nt to be expect$ f ! !ory4 ,! ord9>y me?ods ( analysis fail$ to give correct results on acc\nt ( ! pres5ce ( phosphates4 ,results ( a simil> "* h rec5tly be5 giv5 by ,/rutt#cee4 ,! weight ( radium 9 a m9]al p] gram ( uranium is ?us a def9ite con/ant ( consid]able practical importance4 ,its value 0 rec5tly det]m9$ by ,boltwood by comp>ison ( ! emanation1 lib]at$ f a kn[n weight ( uran9ite1 ) t lib]at$ f a kn[n quantity ( pure radium bromide1 suppli$ = ! purpose by ! writ]4 ,a measur$ weight ( radium bromide 0 tak5 f a /ock :i* gave out heat at a rate ( slightly ov] #ajj gram calories p] h\r p] gram1 & 0 ?us probably pure4 ,?is 0 dissolv$ 9 wat]1 &1 by successive dilutions1 a /&>d solution 0 made up conta9+ #aj gram ( radium bromide p] c4c4 ,tak+ ! con/itution ( radium bromide z ,ra,br1 x 0 d$uc$ t ! weight ( radium p] gram ( uranium 9 any m9]al 0 #hj #aj gram4 ,! am\nt ( radium 9 a m9]al p] ton ( uranium is ?us #jgb gram4 ,/rutt 7loc4 cit47 obta9$ a value ne>ly twice z great1 b he _h no means ( asc]ta9+ ! purity ( 8 radium bromide4 ,?is am\nt ( radium p] gram ( uranium is ( ! "r ord] ( magnitude to be expect$ on ! dis9tegration !ory1 if uranium is ! p>5t ( radium4 ,! activity ( pure radium1 comp>$ ) uranium1 is n kn[n ) suffici5t accuracy to det]m9e ) accuracy ! !oretical proportion ( radium to uranium4 ,! production ( radium f uranium1 :ile v /rongly support$ by ^! exp]im5ts1 _c be consid]$ def9itely e/abli%$ until direct exp]im5tal evid5ce is obta9$ ( ! gr[? ( radium 9 uranium4 ,! rate ( production ( radium to be expect$ on ! dis9tegration !ory c readily be e/imat$4 ,! fraction ( uranium break+ up p] ye> has be5 calculat$ 7section #bfa7 & %[n to be ab\t #aj p] ye>4 ,?is numb] repres5ts ! weight ( radium produc$ p] ye> f #a gram ( uranium4 ,! emanation1 releas$ f ! am\nt ( radium produc$ 9 "o ye> f #a gram ( uranium1 w\ld cause an ord9>y gold-leaf electroscope to be dis*>g$ 9 ab\t half-an-h\r4 ,if a kilogram ( uranium is us$1 ! am\nt ( radium produc$ 9 a s+le day %\ld be easily detectable4 ,exp]im5ts to detect ! gr[? ( radium 9 uranium h be5 made by sev]al obs]v]s4 ,soddy#cef exam9$ ! am\nt ( emanation giv5 (f at diff]5t times f "o kilogram ( uranium nitrate 9 solution1 :i* 0 orig9ally fre$ f ! small trace ( radium pres5t by a suitable *emical process4 ,! solution 0 kept /or$ 9 a clos$ vessel1 & ! am\nt ( emanation :i* collect$ 9 ! solution 0 measur$ at regul> int]vals4 ,prelim9>y exp]im5ts %[$ t ! actual rate ( production ( radium 0 f> less ?an ! am\nt to be expect$ !oretically1 & at fir/ v little indication 0 obta9$ t radium 0 produc$ at all4 ,aft] all[+ ! uranium to /& = eighte5 mon?s1 ,soddy /ates t ! am\nt ( emanation 0 di/9ctly great] ?an at fir/4 ,! solution aft] ?is int]val conta9$ ab\t #ae #aj gram ( radium4 ,?is gives ! value ( ab\t #b #aj = ! fraction ( uranium *ang+ p] ye>1 :ile ! !oretical value is ab\t #aj4 ,:e?am#ceg also f\nd t a quantity ( uranium nitrate :i* _h be5 set aside = a ye> %[$ an appreciable increase 9 ! cont5t ( radium1 & consid]s t ! rate ( production is fa/] ?an t f\nd by ,soddy4 ,9 8 case1 ! uranium 0 n orig9ally completely fre$ f radium4 ,obs]vations ext5d+ ov] ye>s w be requir$ be=e ! "q c be consid]$ settl$1 = ! accurate e/imation ( small quantities ( radium by ! am\nt ( emanation is beset ) difficulties4 ,?is is especially ! case :]e obs]vations are made ov] wide int]vals ( "t4 ,! writ] has made an exam9ation to see if radium is produc$ f act9ium or ?orium4 ,x 0 ?\ght possible t act9ium might prove to be an int]m$iate product betwe5 uranium & radium4 ,! solutions1 fre$ f radium1 h be5 set aside = a ye>1 b no c]ta9 increase 9 ! cont5t ( radium has be5 obs]v$4 ,!re is little d\bt t ! production ( radium by uranium fir/ proce$s at only a small fraction ( ! rate to be expect$ f !ory4 ,?is is n surpris+ :5 we consid] t probably sev]al *anges int]v5e betwe5 ! product ,ur ,x & ! radium4 ,9 ! case ( radium1 = example1 x has be5 %[n t a numb] ( sl[ *anges foll[ ! rapid *anges ord9>ily obs]v$4 ,on acc\nt ( ! feeble activity ( uranium1 x w\ld n be easy to detect directly ! occurr5ce ( su* *anges4 ,if1 = example1 "o or m rayless products occurr$ betwe5 ,ur ,x & radium1 :i* 7 remov$ f ! uranium by ! same *emical process us$ to free x f radium1 ! rate ( production ( radium w\ld be v small at fir/1 b w\ld be expect$ to increase ) "t z m ( ! int]m$i>y products 7 /or$ up 9 ! uranium4 ,! fact t ! cont5ts ( uranium & radium 9 radio-active m9]als are always proportional to ea* o!r1 c\pl$ ) def9ite exp]im5tal evid5ce t radium is produc$ f uranium1 af=ds an almo/ conclusive pro( t uranium is 9 "s way ! p>5t ( radium4 ,! g5]al evid5ce :i* has be5 advanc$ to %[ t radium mu/ be cont9u\sly produc$ f "s o!r sub/ance applies also to act9ium1 :i* has an activity ( ! same ord] ( magnitude z t ( radium4 ,! pres5ce ( act9ium ) radium 9 pit*bl5de w\ld indicate t ?is sub/ance also is 9 "s way d]iv$ f uranium4 ,x is possible t act9ium may prove to be produc$ ei!r f radium or to be ! int]m$i>y sub/ance betwe5 uranium & radium4 ,if x c\ld be %[n t ! am\nt ( act9ium 9 radio-active m9]als is1 l radium1 proportional to ! am\nt ( uranium1 ?is w\ld af=d indirect pro( ( su* a connection4 ,x is n s simple to settle ?is po9t = act9ium z = radium1 s9ce act9ium gives out a v %ort-liv$ emanation1 & ! me?ods adopt$ to det]m9e ! cont5t ( radium 9 m9]als _c be appli$ )\t consid]able modifications to det]m9e ! am\nt ( act9ium pres5t4 ,! exp]im5tal data1 s f> obta9$1 d n ?r[ mu* light ^u ! orig9 ( ! prim>y active matt] 9 ?orium4 ,h(mann & o!rs 7section #bc7 h %[n t ?orium sep>at$ f m9]als conta9+ uranium is always m active ! great] ! quantity ( uranium pres5t4 ,?is w\ld indicate t ! active sub/ance 9 ?orium also may be d]iv$ f uranium4 ,:ile mu* "w /ill rema9s to be done1 a promis+ beg9n+ has already be5 made 9 det]m9+ ! orig9 & relation ( ! radio-elem5ts4 ,we h se5 t ! connection betwe5 polonium1 radio-tellurium1 & radio-lead ) radium has already be5 e/abli%$4 ,radium itself is n[ add$ to ! li/1 & x is probable t act9ium w soon foll[4 ,:ile ! exp]im5ts und\bt$ly %[ t !re is a def9ite relation betwe5 ! am\nt ( uranium & radium pres5t 9 ! ord9>y radio-active m9]als1 ,danne#ceh has rec5tly call$ att5tion to a v int]e/+ app>5t exception4 ,consid]able quantities ( radium 7 f\nd 9 c]ta9 deposits 9 ! neighb\rhood ( ,issy-l',evque 9 ! ,sane-,loire di/rict1 al?\gh no trace ( uranium 0 pres5t4 ,! active matt] is f\nd 9 pyromorphite 7phosphate ( lead71 9 clays conta9+ lead1 & 9 pegmatite1 b ! radium is usually pres5t 9 great] quantities 9 ! =m]4 ,! pyromorphite is f\nd 9 ve9s ( ! qu>tz & feldsp> rocks4 ,! ve9s are always wet ow+ to ! pres5ce ( a numb] ( spr+s 9 ! neighb\rhood4 ,! cont5t ( uranium 9 ! pyromorphite v>ies consid]ably1 b ,danne consid]s t ab\t a c5tigram ( radium is pres5t p] ton4 ,x seems probable t ! radium f\nd 9 ?is locality has be5 deposit$ f wat] fl[+ ?r\gh x1 possibly 9 pa/ times4 ,! pres5ce ( radium is n surpris+1 s9ce cry/als ( autunite h be5 f\nd ab\t #dj miles di/ant1 & probably !re are deposits conta9+ uranium 9 t region4 ,?is result is ( int]e/1 z sugge/+ t radium may be remov$ ) wat] & deposit$ by physical or *emical action "s di/ance away4 ,x w be %[n 9 ! next *apt] t radium has be5 f\nd v widely di/ribut$ ov] ! surface ( ! e>?1 b g5]ally 9 v small quantities4 #bfc4 ,does ! radio-activity ( radium dep5d ^u its conc5tration8 ,we h se5 t ! radio-active con/ant ( any product is indep5d5t ( ! conc5tration ( ! product4 ,?is result has be5 e/abli%$ ov] a v wide range = "s sub/ances1 & especially = ! radium emanation4 ,no c]ta9 diff]5ce 9 ! rate ( decay ( ! emanation has be5 obs]v$1 al?\gh ! am\nt pres5t 9 unit volume ( ! air has be5 v>i$ a millionfold4 ,x has be5 sugge/$ by ,j4 ,j4 ,?omson#cei t ! rate ( dis9tegration ( radium may be influ5c$ by its own radiations4 ,?is1 at fir/ sight1 appe>s v probable1 = a small mass ( a pure radium comp\nd is subject$ to an int5se bomb>dm5t by ! radiations aris+ f x1 & ! radiations are ( su* a "* t !y might be expect$ to produce a break+ up ( ! atoms ( matt] :i* !y trav]se4 ,if ?is be ! case1 ! radio-activity ( a giv5 quantity ( radium %\ld be a function ( its conc5tration1 & %\ld be great] 9 ! solid /ate ?an :5 dissem9at$ ?r\gh a l>ge mass ( matt]4 ,! writ] has made an exp]im5t to exam9e ?is "q4 ,two glass tubes 7 tak51 9 "o ( :i* 0 plac$ a few milligrams ( pure radium bromide 9 a /ate ( radio-active equilibrium1 & 9 ! o!r a solution ( b>ium *loride4 ,! two tubes 7 connect$ ne> ! top by a %ort cross tube1 & ! op5 ends seal$ (f4 ,! activity ( ! radium 9 ! solid /ate 0 te/$ imm$iately aft] its introduction by plac+ x 9 a def9ite position ne> an electroscope made ( ?9 metal ( ! type %[n 9 ,fig4 #ab4 ,! increas$ rate ( dis*>ge ( ! electroscope due to ! & rays f ! radium 0 obs]v$4 ,:5 a lead plate #f mms4 9 ?ickness 0 plac$ betwe5 ! radium & ! electroscope1 ! rate ( dis*>ge obs]v$ 0 due to ! rays alone4 ,by slightly tilt+ ! app>atus1 ! b>ium solution fl[$ into ! radium tube & dissolv$ ! radium4 ,! tube 0 well %ak51 s z to di/ribute ! radium uni=mly ?r\gh\t ! solution4 ,no appreciable *ange ( ! activity measur$ by ! rays 0 obs]v$ ov] ! p]iod ( "o mon?4 ,! activity measur$ by ! & rays 0 some:at r$uc$1 b ?is 0 n due to a decrease ( ! radio-activity1 b to an increas$ absorption ( ! rays 9 _! passage ?r\gh ! solution4 ,! volume ( ! solution 0 at lea/ #ajjj times great] ?an t ( ! solid radium bromide1 &1 9 consequ5ce1 ! radium 0 subject$ to ! action ( a mu* weak] radiation4 ,i ?9k we may conclude f ?is exp]im5t t ! radiations emitt$ by radium h little if any influ5ce 9 caus+ ! dis9tegration ( ! radium atoms4 ,voll]#cfj rec5tly publi%$ "s exp]im5ts :i* appe>$ to %[ t ! life ( radium v>i$ enorm\sly ) its conc5tration4 ,9 8 exp]im5ts1 solutions ( radium bromide ( kn[n /r5g?s 7 evaporat$ d[n 9 a plat9um vessel #ab sq4 cms4 9 area1 & _! activity te/$ f "t to "t4 ,! activity ( ! radium1 s deposit$1 at fir/ %[$ ! normal rise to be expect$ on acc\nt ( ! production ( ! emanation1 b aft] rea*+ a maximum1 x rapidly decay$4 ,= a weight ( #aj mgrs4 ( radium bromide1 ! activity = example1 practically disappe>$ 9 #bf days aft] rea*+ its maximum4 ,! "t tak5 = ! activity to disappe> increas$ rapidly ) ! am\nt ( radium pres5t4 ,9 ano!r set ( exp]im5ts1 he /ates t ! activity obs]v$ on ! vessel 0 n proportional to ! am\nt ( radium pres5t4 ,= example1 ! activity only increas$ #bd times = a millionfold increase ( ! radium pres5t1 f #aj mgrs4 to #aj mgrs4 ,^! results1 h[ev]1 h n be5 confirm$ by lat] exp]im5ts made by ,eve4 ,he f\nd t1 ov] ! range exam9$1 ! activity 0 directly proportional to ! am\nt ( radium pres5t1 )9 ! limits ( exp]im5tal error4 ,! foll[+ table illu/rates ! results obta9$4 ,! radium 0 evaporat$ d[n 9 plat9um vessels #di sq4 cms4 9 area4 ,weight ( ,activity 9 radium 9 arbitr>y units milligrams #aj #ajjj #aj #ajf #aj #aah #aj #abe ,= an increase ( "o-?\s&fold ( ! quantity ( radium1 ! activity increas$ #hjj times1 :ile ,voll] /ates t ! activity1 9 8 exp]im5ts1 only increas$ #c to #d times4 ,9 ! exp]im5ts ( ,eve1 ! activity 0 measur$ by obs]v+ ! increas$ rate ( dis*>ge ( a gold-leaf electroscope :5 ! plat9um vessel conta9+ ! active deposit 0 plac$ inside ! electroscope4 ,! activity ( #aj mgrs4 0 too small to be measur$ ) accuracy 9 ! electroscope employ$1 :ile #aj mgrs4 gave too rapid a rate ( dis*>ge4 ,on ! o!r h&1 ! me?od ( measurem5t employ$ by ,voll] 0 unsuitable = ! measurem5t ( v weak radio-activity4 ,eve also f\nd t a small quantity ( radium kept 9 a clos$ vessel did n lose its activity ) "t4 ,a silv]$ glass vessel conta9$ a gold-leaf sy/em1 su* z is %[n 9 ,fig4 #ab4 ,a solution conta9+ #aj mgrs4 ( radium bromide 0 evaporat$ ov] ! bottom ( ! vessel ( area #gf sq4 cms4 ,! activity1 aft] rea*+ a maximum1 has rema9$ con/ant ov] ! #ajj days dur+ :i* obs]vations h s f> be5 made4 ,^! exp]im5ts ( ,eve1 z f> z !y g1 %[ t ! activity ( radium is proportional to ! am\nt ( radium pres5t1 & t radium1 kept 9 a clos$ vessel1 %[s no signs ( decreas+ 9 activity4 ,on ! o!r h&1 ,i ?9k !re is no d\bt t a v small quantity ( radium deposit$ on a plate & left 9 ! op5 air does lose its activity fairly rapidly4 ,?is loss ( activity has no?+ :atev] to d ) ! %ortness ( life ( ! radium itself1 b is due to ! escape ( ! radium f ! plate into ! surr\nd+ gas4 ,suppose1 = example1 t a solution conta9+ #aj mgrs4 ( radium bromide is evaporat$ 9 a vessel ( "o sq4 cm4 9 area4 ,?is am\nt ( radium is f> too small to =m ev5 a lay] ( molecul> ?ickness4 ,x seems likely t1 dur+ ! process ( evaporation1 ! radium w\ld t5d to collect 9 small masses & be deposit$ on ! surface ( ! vessel4 ,^! w\ld v readily be remov$ by sl[ curr5ts ( air & s escape f ! plate4 ,! disappe>ance ( su* m9ute am\nts ( radium is to be expect$1 & w\ld probably occur ) all k9ds ( matt] pres5t 9 su* m9ute am\nt4 ,su* an effect has no?+ to d ) an alt]ation ( ! life ( radium & mu/ n be confus$ ) x4 ,! result t ! total radiation f a giv5 quantity ( radium dep5ds only on ! quantity ( radium & n on ! degree ( its conc5tration is ( great importance1 = x all[s u to det]m9e ) accuracy ! cont5t ( radium 9 m9]als & 9 soils 9 :i* ! radium exi/s 9 a v diffus$ /ate4 #bfd4 ,con/ancy ( ! radiations4 ,! e>ly obs]vations on uranium & ?orium _h %[n t _! radio-activity rema9$ con/ant ov] ! p]iod ( sev]al ye>s dur+ :i* !y 7 exam9$4 ,! possibility ( sep>at+ f uranium & ?orium ! active products ,ur ,x & ,? ,x respectively1 ! activity ( :i* decay$ ) ! "t1 seem$ at fir/ sight to contradict ?is4 ,fur!r obs]vation1 h[ev]1 %[$ t ! total radio-activity ( ^! bodies 0 n alt]$ by ! *emical processes1 = x 0 f\nd t ! uranium & ?orium f :i* ! active products 7 remov$1 spontane\sly rega9$ _! radio-activity4 ,at any "t aft] removal ( ! active product1 ! sum total ( ! radio-activity ( ! sep>at$ product toge!r ) t ( ! sub/ance f :i* x has be5 sep>at$ is always equal to t ( ! orig9al comp\nd be=e sep>ation4 ,9 cases :]e active products1 l ,ur ,x & ! radium emanation1 decay ) "t accord+ to an expon5tial law1 ?is foll[s at once f ! exp]im5tal results4 ,if ,i is ! activity ( ! product at any "t t aft] sep>ation1 & ,i ! initial value1 we "k t frac ,i#a ,i e-t 4 ,at ! same "t ! activity ,i recov]$ dur+ ! same int]val t is giv5 by frac ,i#b ,i #a e-t 1 :]e is ! same con/ant z be=e4 ,x ?us foll[s t ,i ,i ,i1 :i* is an expression ( ! above result4 ,! same is also true :atev] ! law ( decay ( activity ( ! sep>at$ product 7see section #bjj74 ,= example1 ! activity ( ,? ,x aft] sep>ation f ?orium at fir/ increases ) ! "t4 ,at ! same "t1 ! activity ( ! residual ?orium comp\nd at fir/ decreases1 & at su* a rate t ! sum ( ! activities ( ! ?orium & its sep>at$ product is always equal to t ( ! orig9al ?orium4 ,?is app>5t con/ancy ( ! total radiation foll[s f ! g5]al result t ! radio-active processes _c 9 any way be *ang$ by ! action ( kn[n =ces4 ,x may be recall$ t ! con/ant ( decay ( ! activity ( a radio-active product has a def9ite fix$ value "u all conditions4 ,x is indep5d5t ( ! conc5tration ( ! active matt]1 ( ! pressure1 & ( ! nature ( ! gas 9 :i* ! sub/ance is plac$1 & x is n affect$ by wide ranges ( temp]ature4 ,! only obs]v$ exception is ! product radium ,c4 ,its value ( increases ) temp]ature to "s ext5t at ab\t #ajjj ,c41 b at #abjj ,c4 returns ne>ly to ! normal value4 ,9 ! same way1 x has n be5 f\nd possible to alt] ! rate ( production ( active matt] f ! radio-elem5ts4 ,9 addition1 !re is n a s+le well-au!nticat$ case :]e radio-activity has be5 alt]$ or de/roy$ 9 any active body or creat$ 9 an inactive elem5t4 ,c]ta9 cases h be5 obs]v$1 :i* at fir/ sight seem to indicate a de/ruction ( radio-activity4 ,= example1 ! excit$ radio-activity is remov$ f a plat9um wire :5 heat$ above a r$ heat4 ,x has be5 %[n1 h[ev]1 by ,miss ,gates 7section #ahg7 t ! radio-activity is n de/roy$1 b is deposit$ 9 unalt]$ am\nt on ! cold] bodies surr\nd+ x4 ,?orium oxide has be5 %[n to lose to a l>ge ext5t its p[] ( emanat+ by ignition to a :ite heat4 ,b a close exam9ation %[s t ! emanation is /ill be+ produc$ at ! same rate1 b is occlud$ 9 ! comp\nd4 ,! total radio-activity ( a giv5 mass ( a radio-elem5t1 measur$ by ! peculi> radiations emitt$1 is a quantity :i* c nei!r be increas$ nor dim9i%$1 al?\gh x may be manife/$ 9 a s]ies ( products :i* are capable ( sep>ation f ! radio-elem5t4 ,! t]m 8cons]vation ( radio-activity0 is ?us a conv5i5t expression ( ! facts kn[n at ! pres5t "t4 ,x is q possible1 h[ev]1 t fur!r exp]im5ts at v high or v l[ temp]atures may %[ t ! radio-activity does v>y4 ,al?\gh no diff]5ce has be5 obs]v$ 9 ! radio-activity ( uranium ov] an int]val ( five ye>s1 x has be5 %[n 7section #bfa7 t on !oretical gr\nds ! radio-activity ( a giv5 quantity ( a radio-elem5t %\ld decrease ) ! "t4 ,! *ange w1 h[ev]1 be s sl[ 9 uranium1 t probably millions ( ye>s mu/ elapse be=e a measurable *ange c take place1 :ile ! total radio-activity ( a giv5 quantity ( matt] left to itself %\ld ?us decrease1 b x ought to be con/ant = a con/ant mass ( ! radio-elem5t4 ,x has already be5 po9t$ out 7section #bch7 t ! activity ( radium1 measur$ by ! & rays1 w probably increase = sev]al hundr$ ye>s aft] its sep>ation4 ,?is is due to ! appe>ance ( fre% products 9 ! radium4 ,ultimately1 h[ev]1 ! activity mu/ decrease accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #acjj ye>s4 ,! cons]vation ( radio-activity applies n only to ! radiations tak5 z a :ole1 b also to ea* specific type ( radiation4 ,if ! emanation is remov$ f a radium comp\nd1 ! am\nt ( radiation ( ! radium at once comm5ces to decrease1 b ?is is comp5sat$ by ! appe>ance ( rays 9 ! radiations f ! vessel 9 :i* ! sep>at$ emanation is /or$4 ,at any "t ! sum total ( ! radiations f ! radium & ! emanation vessel is always ! same z t f ! radium comp\nd be=e ! emanation 0 remov$4 ,simil> results h also be5 f\nd to hold = ! rays4 ,?is 0 te/$ by ! writ] 9 ! foll[+ way4 ,! emanation f "s solid radium bromide 0 releas$ by heat1 & cond5s$ 9 a small glass tube :i* 0 !n seal$ (f4 ,! radium s treat$1 & ! emanation tube1 7 plac$ toge!r "u an electroscope1 ) a scre5 ( lead #a cm4 ?ick int]pos$ 9 ord] to let ?r\gh only ! rays4 ,! exp]im5ts 7 cont9u$ ov] ?ree weeks1 b ! sum total ( ! rays f ! radium & ! emanation tube 01 ov] ! :ole int]val1 equal to t ( ! orig9al radium4 ,dur+ ?is p]iod ! am\nt ( rays f ! radium at fir/ decreas$ to only a few p] c5t4 ( ! orig9al value1 & !n sl[ly increas$ aga91 until at ! end ( ! ?ree weeks x _h ne>ly rega9$ its orig9al value1 be=e ! emanation 0 remov$4 ,at ! same "t ! am\nt ( rays f ! emanation tube rose f z]o to a maximum & !n sl[ly decreas$ aga9 at ! same rate z ! decay ( ! activity ( ! emanation 9 ! tube4 ,?is result %[s t ! am\nt ( rays f radium 0 a con/ant quantity ov] ! int]val ( obs]vation1 al?\gh ! am\nt ( rays f ! radium & emanation tube _h pass$ ?r\gh a cycle ( *anges4 ,!re is "o int]e/+ possibility 9 ?is connection t %\ld be borne 9 m9d4 ,! rays f ! active sub/ances c>ry (f en]gy 9 a v conc5trat$ =m1 & ?is en]gy is dissipat$ by ! absorption ( ! rays 9 matt]4 ,! rays might be expect$ to cause a dis9tegration ( ! atoms ( inactive matt] on :i* !y fall & ?us give rise to a k9d ( radio-activity4 ,?is effect has be5 look$ = by sev]al obs]v]s4 ,ramsay & ,w4 ,t4 ,cooke#cfa /ate t !y h notic$ su* an action1 us+ ab\t a decigram ( radium z a s\rce ( radiation4 ,! radium1 seal$ 9 a glass vessel1 0 surr\nd$ by an ext]nal glass tube & expos$ to ! action ( ! & rays ( radium = sev]al weeks4 ,! inside & outside ( ! glass tube 7 f\nd to be active1 & ! active matt] 0 remov$ by solution 9 wat]4 ,! radio-activity obs]v$ 0 v m9ute1 correspond+ to only ab\t #a milligram ( uranium4 ,! writ] has1 at v>i\s times1 tri$ exp]im5ts ( ?is "* b ) negative results4 ,! greate/ c>e is necess>y 9 su* exp]im5ts to ensure t ! radio-activity is n due to o!r causes besides ! rays f ! radium4 ,?is c>e is especially necess>y 9 laboratories :]e consid]able quantities ( ! radium emanation h be5 all[$ to escape into ! air4 ,! surface ( e sub/ance becomes coat$ ) ! sl[ trans=mation products ( radium1 viz4 radium ,d1 ,e1 & ,f4 ,! activity communicat$ 9 ?is way to orig9ally inactive matt] is (t5 consid]able4 ,?is infection by ! radium emanation ext5ds ?r\gh\t ! :ole laboratory1 on acc\nt ( ! di/ribution ( ! emanation by convection & diffusion4 ,= example1 ,eve#cfb f\nd t e sub/ance :i* he exam9$ 9 ! laboratory ( ! writ] %[$ mu* great] activity ?an ! normal4 ,9 ?is case ! radium _h be5 9 use 9 ! build+ = ab\t two ye>s4 #bfe4 ,loss ( weight ( ! radio-elem5ts4 ,s9ce ! radio-elem5ts are cont9ually ?r[+ (f p>ticles atomic 9 size1 an active sub/ance1 enclos$ 9 a vessel suffici5tly ?9 to all[ ! p>ticles to escape1 mu/ gradually lose 9 weight4 ,?is loss ( weight w be small "u ord9>y conditions1 s9ce ! great] proportion ( ! rays produc$ are absorb$ 9 ! mass ( ! sub/ance4 ,if a v ?9 lay] ( a radium comp\nd 7 spread on a v ?9 %eet ( sub/ance1 :i* did n appreciably absorb ! p>ticles1 a loss ( weight due to ! expulsion ( p>ticles might be detectable4 ,s9ce e_/m #f #aj = ! p>ticle & e #aa #aj electromagnetic units & #be #aj p>ticles are expell$ p] second p] gram ( radium1 ! proportion ( ! mass expell$ is #dh #aj p] second & #aj p] ye>4 ,!re is "o condition1 h[ev]1 "u :i* ! radium %\ld lose 9 weight fairly rapidly4 ,if a curr5t ( air is sl[ly pass$ ov] a radium solution1 ! emanation produc$ w\ld be remov$ z fa/ z x 0 =m$4 ,s9ce ! atom ( ! emanation has a mass probably n mu* small] ?an ! radium atom1 ! fraction ( ! mass remov$ p] ye> %\ld be ne>ly equal to ! fraction ( ! radium :i* *anges p] ye>1 i4e4 "o gram ( radium %\ld dim9i% 9 weight ab\t half a milligram 7section #bfa7 p] ye>4 ,if x is suppos$ t ! p>ticles h weight1 ! loss ( weight due to _! expulsion is v small comp>$ ) t due to ! emission ( p>ticles4 ,! writ] has %[n 7section #bec7 t ab\t #g #aj p>ticles are project$ p] second f #a gram ( radium4 ,! consequ5t loss ( weight w\ld only be ab\t #aj grams p] ye>4 ,except "u v special exp]im5tal conditions1 x w\ld ?us be difficult to detect ! loss ( weight ( radium due to ! expulsion ( p>ticles f its mass4 ,!re is1 h[ev]1 a possibility t radium might *ange 9 weight ev5 ?\gh none ( ! radio-active products 7 all[$ to escape4 ,= example1 if ! view is tak5 t gravitation is ! result ( =ces hav+ _! orig9 9 ! atom1 x is possible t1 if ! atom 7 dis9tegrat$1 ! weight ( ! p>ts might n be equal to t ( ! orig9al atom4 ,a l>ge numb] ( exp]im5ts h be5 made to see if radium prep>ations1 kept 9 a seal$ tube1 alt] 9 weight4 ,) ! small quantities ( radium available to ! exp]im5t]1 no diff]5ce ( weight ( radium prep>ations ) "t has yet be5 e/abli%$ ) c]ta9ty4 ,heydweill] /at$ t he _h obs]v$ a loss ( weight ( radium & ,dorn also obta9$ a slight indication ( *ange 9 weight4 ,^! results h n1 h[ev]1 be5 confirm$4 ,=*1 lat]1 0 unable to obs]ve any appreciable *ange4 ,j4 ,j4 ,?omson#cfc has made exp]im5ts to see if ! ratio ( weight to mass = radium is ! same z = inactive matt]4 ,we h se5 9 section #dh t a *>ge 9 motion possesses an app>5t mass :i* is con/ant = sl[ spe$s b increases z ! spe$ ( light is approa*$4 ,n[ radium emits "s electrons at a velocity comp>able ) ! velocity ( light1 & presumably ^! electrons 7 9 rapid motion 9 ! atom be=e _! expulsion4 ,x might ?us be possible t ! ratio = radium w\ld diff] f t = ord9>y matt]4 ,! p5dulum me?od 0 us$1 & ! radium 0 enclos$ 9 a small light tube susp5d$ by a silk fibre4 ,)9 ! limit ( exp]im5tal error ! ratio ( weight to mass 0 f\nd to be ! same z = ord9>y matt]1 s t we may conclude t ! numb] ( electrons mov+ ) a velocity approa*+ t ( light is small comp>$ ) ! total numb] pres5t4 #bff4 ,total emission ( en]gy f ! radio-elem5t4 ,x has be5 %[n t #a gram ( radium emits en]gy at ! rate ( #ajj gram-calories p] h\r or #hgf1jjj gram-calories p] ye>4 ,if #a gram ( radium 9 radio-active equilibrium be set ap>t1 its radio-activity & consequ5t heat emission is giv5 at a "t t by qe-t 1 :]e is ! con/ant ( decay ( activity ( radium & ( ! initial heat+ effect2 ! total heat emission f #a gram ( radium is giv5 by intinfty qe-t dt frac q 4 ,n[ on ! e/imate ( ! life ( radium giv5 9 section #bfa ! value ( is :5 #a ye> is tak5 z ! unit ( "t4 ,! total heat emission f #a gram ( radium dur+ its life is ?us #af #aj gram-calories4 ,! heat emitt$ 9 ! union ( hydrog5 & oxyg5 to =m #a gram ( wat] is ab\t #d #aj gram-calories1 & 9 ?is reaction m heat is giv5 out = equal weights ?an 9 any o!r *emical reaction kn[n4 ,x is ?us se5 t ! total en]gy emitt$ f #a gram ( radium dur+ its *anges is ab\t "o million times great] ?an 9 any kn[n molecul> *ange4 ,t matt] is able1 "u special conditions1 to emit an enorm\s am\nt ( en]gy1 is well exemplifi$ by ! case ( ! radium emanation4 ,calculations ( ! am\nt ( ?is en]gy h already be5 giv5 9 section #bdi4 ,s9ce ! o!r radio-elem5ts only diff] f radium 9 ! sl[ness ( _! *ange1 ! total heat emission f uranium & ?orium mu/ be ( a simil> high ord] ( magnitude4 ,!re is ?us reason to believe t !re is an enorm\s /ore ( lat5t en]gy resid5t 9 ! atoms ( ! radio-elem5ts4 ,?is /ore ( en]gy c\ld n h be5 recogniz$ if ! atoms _h n be5 und]go+ a sl[ process ( dis9tegration4 ,! en]gy emitt$ 9 radio-active *anges is d]iv$ f ! int]nal en]gy ( ! atoms4 ,! emission ( ?is en]gy does n disobey ! law ( ! cons]vation ( en]gy1 = x is only necess>y to suppose t1 :5 ! radio-active *anges h ceas$1 ! en]gy /or$ up 9 ! atoms ( ! f9al products is less ?an t ( ! orig9al atoms ( ! radio-elem5ts4 ,! diff]5ce betwe5 ! en]gy orig9ally possess$ by ! matt] :i* has und]gone ! *ange1 & ! f9al inactive products :i* arise1 is a measure ( ! total am\nt ( en]gy releas$4 ,!re seems to be e reason to suppose t ! atomic en]gy ( all ! elem5ts is ( a simil> high ord] ( magnitude4 ,) ! exception ( _! high atomic weights1 ! radio-elem5ts d n possess any special *emical *>act]i/ics :i* diff]5tiate !m f ! inactive elem5ts4 ,! exi/5ce ( a lat5t /ore ( en]gy 9 ! atoms is a necess>y consequ5ce ( ! mod]n view develop$ by ,j4 ,j4 ,?omson1 ,l>mor1 & ,lor5tz1 ( reg>d+ ! atom z a complicat$ /ructure consi/+ ( *>g$ p>ts 9 rapid oscillatory or orbital motion 9 reg>d to "o ano!r4 ,! en]gy may be p>tly k9etic & p>tly pot5tial1 b ! m]e conc5tration ( ! *>g$ p>ticles1 :i* probably con/itute ! atom1 9 itself implies a l>ge /ore ( en]gy 9 ! atom1 9 comp>ison ) :i* ! en]gy emitt$ dur+ ! *anges ( radium is insignificant4 ,! exi/5ce ( ?is /ore ( lat5t en]gy does n ord9>ily manife/ itself1 s9ce ! atoms _c be brok5 up into simpl] =ms by ! physical or *emical ag5cies at our disposal4 ,its exi/5ce at once expla9s ! failure ( *emi/ry to trans=m ! atoms1 & also acc\nts = ! rate ( *ange ( ! radio-active processes be+ indep5d5t ( all ext]nal ag5cies4 ,x has n s f> be5 f\nd possible to alt] 9 any way ! rate ( emission ( en]gy f ! radio-elem5ts4 ,if x %\ld ev] be f\nd possible to control at w ! rate ( dis9tegration ( ! radio-elem5ts1 an enorm\s am\nt ( en]gy c\ld be obta9$ f a small quantity ( matt]4 #bfg4 ,production ( helium f radium & ! radium emanation4 ,s9ce ! f9al products1 result+ f a dis9tegration ( ! radio-elem5ts1 are n radio-active1 !y %\ld 9 ! c\rse ( geologic ages collect 9 "s quantity1 & %\ld always be f\nd associat$ ) ! radio-elem5ts4 ,n[ ! inactive products result+ f ! radio-active *anges are ! p>ticles expell$ at ea* /age1 & ! f9al inactive product or products :i* rema91 :5 ! process ( dis9tegration c no long] be trac$ by ! prop]ty ( radio-activity4 ,pit*bl5de1 9 :i* ! radio-elem5ts are mo/ly f\nd1 conta9s 9 small quantity a l>ge proportion ( all ! kn[n elem5ts4 ,9 se>*+ = a possible dis9tegration product common to all ! radio-elem5ts1 ! pres5ce ( helium 9 ! radio-active m9]als is notewor?y2 = helium is only f\nd 9 ! radio-active m9]als1 & is an inv>iable companion ( ! radio-elem5ts4 ,moreov]1 ! pres5ce 9 m9]als ( a light1 in]t gas l helium _h always be5 a matt] ( surprise4 ,! production by radium & ?orium ( ! radio-active emanations1 :i* behave l *emically in]t gases ( ! helium-argon family1 sugge/$ ! possibility t "o ( ! f9al inactive products ( ! dis9tegration ( ! radio-elem5ts might prove to be a *emically in]t gas4 ,! lat] discov]y ( ! mat]ial nature ( ! rays add$ weight to ! sugge/ion2 = ! measurem5t ( ! ratio e_/m ( ! p>ticle indicat$ t if ! p>ticle consi/$ ( any kn[n k9d ( matt]1 x mu/ ei!r be hydrog5 or helium4 ,= ^! reasons1 x 0 sugge/$ 9 #aijb by ,ru!r=d & ,soddy#cfd t helium might be a product ( ! dis9tegration ( ! radio-elem5ts4 ,sir ,william ,ramsay & ,mr ,soddy 9 #aijc und]took an inve/igation ( ! radium emanation1 ) ! purpose ( see+ if x 7 possible to obta9 any spectroscopic evid5ce ( ! pres5ce ( a new sub/ance4 ,fir/ ( all1 !y expos$ ! emanation to v dra/ic treatm5t 7section #aeh71 & confirm$ & ext5d$ ! results previ\sly not$ by ,ru!r=d & ,soddy t ! emanation behav$ l a *emically in]t gas1 & 9 ?is respect possess$ prop]ties analog\s to ! gases ( ! helium-argon gr\p4 ,on obta9+ #cj milligrams ( pure radium bromide 7prep>$ ab\t ?ree mon?s previ\sly7 ,ramsay & ,soddy#cfe exam9$ ! gases1 lib]at$ by solution ( ! radium bromide 9 wat]1 = ! pres5ce ( helium4 ,a consid]able quantity ( hydrog5 & oxyg5 0 releas$ by ! solution 7see section #abd74 ,! hydrog5 & oxyg5 7 remov$ by pass+ ! lib]at$ gases ov] a r$-hot spiral ( p>tially oxidiz$ copp]-wire & ! result+ wat] vap\r 0 absorb$ 9 a phosphorus p5toxide tube4 ,! gas 0 !n pass$ into a small vacuum tube :i* 0 9 connection ) a small ,u tube4 ,by plac+ ! ,u tube 9 liquid air1 mo/ ( ! emanation pres5t 0 cond5s$1 & also mo/ ( ! ,,co pres5t 9 ! gas4 ,on exam9+ ! spectrum ( ! gas 9 ! vacuum tube1 ! *>act]i/ic l9e ,d ( helium 0 obs]v$4 ,?is exp]im5t 0 repeat$ ) #cj milligrams ( radium bromide ab\t f\r mon?s old1 l5t = ! purpose by ! writ]4 ,! emanation & ,,co 7 remov$ by pass+ !m ?r\gh a ,u tube imm]s$ 9 liquid air4 ,a practically complete spectrum ( helium 0 obs]v$1 includ+ ! l9es ( wave-l5g?s #ffgg1 #ehgf1 #ejaf1 #digb1 #dgac & #ddgb4 ,!re 7 also pres5t ?ree o!r l9es ( wave-l5g?s ab\t #fahj1 #efie1 #edee :i* h n yet be5 id5tifi$4 ,9 lat] exp]im5ts1 ! emanation f #ej milligrams ( ! radium bromide 0 convey$ ) oxyg5 into a small ,u tube1 cool$ 9 liquid air1 9 :i* ! emanation 0 cond5s$4 ,fre% oxyg5 0 add$1 & ! ,u tube aga9 pump$ out4 ,! small vacuum tube1 connect$ ) ! ,u tube1 %[$ at fir/ no helium l9es :5 ! liquid air 0 remov$4 ,! spectrum obta9$ 0 a new "o1 & ,ramsay & ,soddy consid]$ x to be probably t ( ! emanation itself4 ,aft] all[+ ! emanation tube to /& = f\r days1 ! helium spectrum appe>$ ) all ! *>act]i/ic l9es1 & 9 addition1 ?ree new l9es pres5t 9 ! helium obta9$ by solution ( ! radium4 ,^! results h s9ce be5 confirm$4 ,! exp]im5ts1 :i* h l$ to su* /rik+ & important results1 7 by no means easy ( p]=mance1 = ! quantity ( helium & ( emanation releas$ f #ej mgrs4 ( radium bromide is extremely small4 ,x 0 necess>y1 9 all cases1 to remove almo/ completely ! o!r gases1 :i* 7 pres5t 9 suffici5t quantity to mask ! spectrum ( ! sub/ance "u exam9ation4 ,! success ( ! exp]im5ts has be5 l>gely due to ! application1 to ?is inve/igation1 ( ! ref9$ me?ods ( gas analysis1 previ\sly employ$ by ,sir ,william ,ramsay ) s mu* skill 9 ! sep>ation ( ! r>e gases x5on & krypton1 :i* exi/ 9 m9ute proportions 9 ! atmosph]e4 ,! fact t ! helium spectrum 0 n pres5t at fir/1 b appe>$ aft] ! emanation _h rema9$ 9 ! tube = "s days1 %[s t ! helium mu/ h be5 produc$ f ! emanation4 ,! emanation _c be helium itself1 =1 9 ! fir/ place1 helium is n radio-active1 & 9 ! second place1 ! helium spectrum 0 n pres5t at fir/1 :5 ! quantity ( emanation 9 ! tube 0 at its maximum4 ,moreov]1 ! diffusion exp]im5ts1 already discuss$1 po9t to ! conclusion t ! emanation is ( high molecul> weight4 ,!re c ?us be no d\bt t ! helium is d]iv$ f ! emanation ( radium 9 consequ5ce ( *anges ( "s k9d occurr+ 9 x4 ,^! results 7 confirm$ lat] by o!r obs]v]s4 ,curie & ,dew>#cff p]=m$ ! foll[+ exp]im5t3 ,a weight ( ab\t #db gr4 ( radium bromide 0 plac$ 9 a qu>tz tube1 & ! tube exhau/$ until no fur!r gas came (f4 ,! radium 0 !n heat$ to fusion1 ab\t #bf c4c4 ( gas be+ lib]at$ 9 ! process4 ,! tube 0 !n seal$1 & "s weeks aft]w>ds ! spectrum ( ! gas lib]at$ 9 ! tube by ! radium 0 exam9$ by ,desl&res & f\nd to give ! entire spectrum ( helium4 ,! gas1 lib]at$ dur+ ! initial heat+ ( ! radium1 0 collect$ & f\nd to conta9 a l>ge am\nt ( emanation1 al?\gh ! gas _h be5 pass$ ?r\gh two tubes imm]s$ 9 liquid air4 ,! tube conta9+ ^! gases 0 v lum9\s & rapidly turn$ violet1 :ile m ?an half ( ! gases 0 absorb$4 ,! spectrum ( ! phosphoresc5t light 0 f\nd to be discont9u\s1 consi/+ ( ?ree nitrog5 b&s4 ,no sign ( ! helium spectrum 0 obs]v$1 al?\gh helium mu/ h be5 pres5t4 ,him/$t & ,mey]#cfg plac$ #ej mgrs4 ( radium bromide 9 a ,u tube connect$ ) a small vacuum tube4 ,! tube 0 c>efully exhau/$ & !n seal$ (f4 ,! spectrum ( hydrog5 & c>bon dioxide alone 0 obs]v$ = ?ree mon?s1 b aft] f\r mon?s ! r$1 yell[1 gre5 & blue l9es ( ! helium spectrum 7 visible4 ,! sl[ appe>ance ( ! helium spectrum 0 probably due to ! pres5ce 9 ! tube ( a consid]able quantity ( hydrog54 ,9 ano!r exp]im5t1 "s radium sulphate :i* _h be5 heat$ to a bright r$ heat 9 a qu>tz tube 0 connect$ ) a small vacuum tube4 ,aft] ?ree weeks1 "s ( ! l9es ( helium 7 cle>ly se51 & increas$ 9 brightness ) "t4 #bfh4 ,connection betwe5 helium & ! p>ticles4 ,! appe>ance ( helium 9 a tube conta9+ ! radium emanation may indicate ei!r t ! helium is "o ( ! f9al products1 :i* appe> at ! end ( ! s]ies ( radio-active *anges1 or t ! helium is 9 reality ! expell$ p>ticle4 ,! evid5ce at pres5t po9ts to ! latt] z be+ ! m probable explanation4 ,9 ! fir/ place1 ! emanation diffuses l a gas ( heavy molecul> weight1 & x appe>s probable t aft] ! expulsion ( a few p>ticles1 ! atomic weight ( ! f9al product is comp>able ) t ( ! emanation4 ,on ! o!r h&1 ! value ( e_/m det]m9$ = ! project$ p>ticle po9ts to ! conclusion t1 if x consi/s ( any kn[n k9d ( matt]1 x is ei!r hydrog5 or helium4 ,!re has be5 a t5d5cy to assume t ! helium produc$ f ! radium emanation is ! la/ trans=mation product ( t sub/ance4 ,! evid5ce1 h[ev]1 does n support ?is view4 ,we h se5 t ! emanation1 aft] ! initial rapid *anges1 is trans=m$ v sl[ly4 ,if ! helium 7 ! f9al product1 ! am\nt pres5t 9 ! emanation tube aft] a few days or weeks w\ld be insignificant1 s9ce ! product radium ,d int]v5es1 :i* takes #dj ye>s to be half trans=m$4 ,s9ce ! helium _c be ! f9al product ( ! s]ies ( *anges1 & s9ce all ! o!r products are radio-active1 & almo/ c]ta9ly ( high atomic weight1 x is difficult to see :at position ! helium atom occupies 9 ! s*eme ( trans=mation1 unless x be ! p>ticle expell$ dur+ ! successive *anges4 ,x is a matt] ( great difficulty to settle def9itely :e!r ! p>ticle is a project$ helium atom or n4 ,on acc\nt ( ! v small deflection ( ! rays 9 an electric field1 & ! complex nature ( ! radiation f radium1 an accurate det]m9ation ( ! value e_/m = ! p>ticle is beset ) difficulties4 ,x may be possible to settle ! "q by accurate measurem5ts ( ! volume ( gas 9 a tube1 fill$ orig9ally ) ! radium emanation4 ,s9ce ! emanation itself1 & two ( ! rapidly *ang+ products :i* result f x1 emit p>ticles1 ! f9al volume ( ! p>ticles1 if !y c exi/ 9 ! gase\s /ate1 w\ld be ?ree times ! volume ( ! emanation4 ,ramsay & ,soddy 7section #agb7 h made exp]im5ts ( ?is k9d1 b ! results obta9$ 7 v contradictory1 dep5d+ ^u ! k9d ( glass employ$4 ,9 "o case1 ! volume ( ! residual gases %rank almo/ to z]o1 9 ano!r ! initial volume increas$ to ab\t t5 times its initial value4 ,9 ! latt] exp]im5t a brilliant spectrum ( helium 0 obs]v$ 9 ! residual gas4 ,?is diff]5ce ( behavi\r is probably due to diff]5t degrees ( absorption ( helium by ! glass tubes4 ,if ! p>ticles are helium atoms1 we may expect t a l>ge proportion ( ! helium1 :i* is produc$ 9 a tube conta9+ ! radium emanation1 w be buri$ 9 ! wall ( ! glass tube2 = ! p>ticles are project$ ) suffici5t velocity to p5etrate "s di/ance into ! glass4 ,?is helium may ei!r rema9 9 ! glass1 or 9 "s cases rapidly diffuse out aga94 ,9 any case1 a fraction ( ! helium w\ld be lib]at$ :5 an int5se electric dis*>ge is pass$ ?r\gh ! tube4 ,ramsay & ,soddy h 9 "s in/ances obs]v$ t a slight am\nt ( helium is lib]at$ on heat+ ! walls ( ! tube 9 :i* ! emanation _h be5 /or$ = "s "t4 ,! volume ( helium produc$ p] ye> by #a gram ( radium c easily be calculat$ on ! assumption t ! p>ticle is 9 reality a helium atom4 ,x has be5 %[n t #be #aj p>ticles are project$ p] second f #a gram ( radium4 ,s9ce !re are #cf #aj molecules 9 "o cubic c5timetre ( any gas at /&>d pressure & temp]ature1 ! volume ( ! p>ticles releas$ p] second is #g #aj c4c4 & p] ye> #jbd c4c4 ,x has already be5 po9t$ out t1 on ?is hypo!sis1 ! volume ( helium releas$ by ! emanation is ?ree times ! volume ( ! latt]4 ,! am\nt ( helium to be obta9$ f ! emanation releas$ f #a gram ( radium 9 radio-active equilibrium is ?us ab\t #c cubic mms4 ,ramsay & ,soddy h tri$ to e/imate exp]im5tally ! probable volume ( helium produc$ p] second by "o gram ( radium4 ,! helium1 obta9$ f #ej mgrs4 ( radium bromide1 :i* _h be5 kept 9 solution 9 a clos$ vessel = #fj days1 0 introduc$ into a vacuum tube4 ,ano!r simil> tube 0 plac$ 9 s]ies ) x1 & ! am\nt ( ! helium 9 ! latt] adju/$ until on pass+ a dis*>ge ?r\gh ! two tubes 9 s]ies ! helium l9es 9 ea* tube 7 ( ab\t ! same brightness4 ,9 ?is way !y calculat$ t ! am\nt ( helium pres5t 0 #ja cubic mm4 ,on ?is e/imate1 ! am\nt ( helium produc$ p] ye> p] gram ( radium is ab\t #bj cubic mms4 ,we h se5 t ! calculat$ am\nt is ab\t #bdj cubic mms41 on ! assumption t ! p>ticle is a helium atom4 ,ramsay & ,soddy consid] t ! pres5ce ( argon 9 "o ( ! tubes may h s]i\sly int]f]$ ) ! correctness ( ! e/imation4 ,on acc\nt ( ! great unc]ta9ty atta*+ to e/imates ( ! above "*1 ! value d$uc$ by ,ramsay & ,soddy does n exclude ! probability t ! calculat$ volume may be ( ! "r ord] ( magnitude4 ,9 ord] to expla9 ! pres5ce ( helium 9 radium on ord9>y *emical l9es1 x has be5 sugge/$ t radium is n a true elem5t1 b a molecul> comp\nd ( helium ) "s sub/ance kn[n or unkn[n4 ,! helium comp\nd gradually breaks d[n1 giv+ rise to ! helium obs]v$4 ,x is at once obvi\s t ?is po/ulat$ helium comp\nd is ( a "* entirely diff]5t f t ( any o!r comp\nd previ\sly obs]v$ 9 *emi/ry4 ,weight = weight1 x emits dur+ its *ange an am\nt ( en]gy at lea/ "o million times great] ?an any molecul> comp\nd kn[n 7see section #bdi74 ,9 addition1 x mu/ be suppos$ t ! rate ( break+ up ( ! helium comp\nd is indep5d5t ( great ranges ( temp]ature--a result nev] be=e obs]v$ 9 any molecul> *ange4 ,! helium comp\nd 9 its break+ up mu/ give rise to ! peculi> radiations & also pass ?r\gh ! successive radio-active *anges obs]v$ 9 radium4 ,?us 9 ord] to expla9 ! production ( helium & radio-activity on ?is view1 a unique k9d ( molecule mu/ be po/ulat$--a molecule1 9 fact1 :i* is end[$ ) e s+le prop]ty :i* on ! dis9tegration !ory is ascrib$ to ! atom ( ! radio-elem5ts4 ,on ! o!r h&1 radium z f> z x has be5 exam9$1 has fulfill$ e te/ requir$ = an elem5t4 ,x has a well-m>k$ & *>act]i/ic spectrum1 & !re is no reason to suppose t x is n an elem5t 9 ! ord9>ily accept$ s5se ( ! t]m4 ,on ! !ory t ! radio-elem5ts are und]go+ atomic dis9tegration1 ! helium mu/ be consid]$ to be a con/itu5t ( ! radium atom1 or1 9 o!r words1 ! radium atom is built up ( p>ts1 "o ( :i*1 at lea/1 is ! atom ( helium4 ,! !ory t ! heavy atoms are all built up ( "s simple fundam5tal unit ( matt] or protyle has be5 advanc$ at v>i\s times by _m prom95t *emi/s & physici/s4 ,pr\t's hypo!sis t all elem5ts are built up out ( hydrog5 is an example ( ?is po9t ( view ( reg>d+ ! subject4 ,on ! dis9tegration !ory1 ! *anges occurr+ 9 ! radio-atoms involve an actual trans=mation ( ! atoms ?r\gh successive *anges4 ,?is *ange is s sl[ 9 uranium & ?orium t at lea/ a million ye>s w\ld be requir$ be=e ! am\nt ( *ange c\ld be measur$ by ! balance4 ,9 radium x is a million times fa/]1 b ev5 9 ?is case x is d\btful :e!r any appreciable *ange w\ld h be5 obs]v$ by ord9>y *emical me?ods = _m ye>s _h n ! possibility ( su* a *ange be5 sugge/$ f o!r l9es ( evid5ce4 ,! simil>ity ( ! p>ticles f ! diff]5t radio-elem5ts indicates t !y consi/ ( expell$ p>ticles ( ! same k9d4 ,on ?is view1 helium %\ld be produc$ by ea* ( ! radio-elem5ts4 ,its pres5ce 9 m9]als conta9+ ?orium1 = example 9 monazite s& & ! ,ceylon m9]al describ$ by ,ramsay1 indicates t helium may be a product ( ?orium z well z ( radium4 ,/rutt#cfh has rec5tly sugge/$ t mo/ ( ! helium obs]v$ 9 radio-active m9]als may be a decomposition product ( ?orium r ?an ( uranium & radium2 = he f9ds t m9]als ri* 9 helium always conta9 ?orium1 :ile _m uranium m9]als ne>ly free f ?orium conta9 little helium4 ,! evid5ce 9 support ( ?is view is1 h[ev]1 n altoge!r satisfactory1 = "s ( ! uranium m9]als 9 "q are second>y uranium m9]als 7see ,app5dix ,b71 deposit$ by ! action ( wat] or o!r ag5cies at a comp>atively late date1 & are also1 9 _m cases1 highly emanat+1 & consequ5tly c\ld n be expect$ to reta9 m ?an a fraction ( ! helium produc$ 9 !m4 ,tak+ ! view t ! p>ticles are project$ helium atoms1 we mu/ reg>d ! atoms ( ! radio-elem5ts z comp\nds ( "s kn[n or unkn[n sub/ance ) helium4 ,^! comp\nds break up spontane\sly1 & at a v sl[ rate ev5 9 ! case ( radium4 ,! dis9tegration takes place 9 successive /ages1 & at mo/ ( ! /ages a helium atom is project$ ) great velocity4 ,?is dis9tegration is accompani$ by an enorm\s emission ( en]gy4 ,! lib]ation ( su* a l>ge am\nt ( en]gy 9 ! radio-active *anges at once expla9s ! con/ancy ( ! rate ( *ange "u ! action ( any ( ! physical & *emical ag5cies at our comm&4 ,on ?is view1 uranium1 ?orium & radium are 9 reality comp\nds ( helium4 ,! helium1 h[ev]1 is held 9 su* /rong comb9ation t ! comp\nd _c be brok5 up by *emical or physical =ces1 &1 9 consequ5ce1 ^! bodies behave z *emical elem5ts 9 ! ord9>y accept$ *emical s5se4 ,x appe>s n unlikely t _m ( ! s-call$ *emical elem5ts may prove to be comp\nds ( helium1 or1 9 o!r words1 t ! helium atom is "o ( ! second>y units ) :i* ! heavi] atoms are built up4 ,9 ?is connection x is ( int]e/ to note t _m ( ! elem5ts diff] 9 _! atomic weight by f\r--! atomic weight ( helium4 ,if ! p>ticle is a helium atom1 at lea/ ?ree p>ticles mu/ be expell$ f uranium 7#bche7 to r$uce its atomic weight to t ( radium 7#bbe74 ,x is kn[n t five p>ticles are expell$ f radium dur+ its successive trans=mations4 ,?is w\ld make ! atomic weight ( ! f9al residue #bbe #bj #bje4 ,?is is v ne>ly ! atomic weight ( lead1 #bjfe4 ,i h1 = "s "t1 consid]$ x probable t lead is ! end or f9al product ( radium4 ,! same sugge/ion has rec5tly be5 made by ,boltwood#cfi4 ,?is po9t ( view is support$ by ! fact t lead is always f\nd 9 small quantity 9 all uranium m9]als1 & t ! relative proportions ( lead & helium 9 ! radio-active m9]als are ab\t ! same z w\ld be expect$ if lead & helium 7 bo? decomposition products ( radium4 ,dr ,boltwood has drawn my att5tion to ! fact t ! proportion ( lead 9 _m radio-active m9]als v>ies ) ! cont5t ( helium4 ,a m9]al ri* 9 helium 9 ne>ly all cases conta9s m lead ?an a m9]al poor 9 helium4 ,?is _c be consid]$1 at pres5t1 m ?an a speculation1 b ! facts z !y /& are v sugge/ive4 #bfi4 ,age ( radio-active m9]als4 ,helium is only f\nd 9 ! radio-active m9]als1 & ?is fact1 tak5 9 conjunction ) ! lib]ation ( helium by radium1 indicates t ! helium mu/ h be5 produc$ z a result ( ! trans=mation ( radium & ! o!r radio-active sub/ances conta9$ 9 ! m9]als4 ,n[ 9 a m9]al ab\t half ! helium is1 9 _m cases1 releas$ by heat & ! residue by solution4 ,x seems probable t ! helium produc$ ?r\gh\t ! mass ( ! m9]al is me*anically imprison$ 9 x4 ,moss#cgj f\nd t1 by gr9d+ pit*bl5de 9 vacuo1 helium is evolv$1 app>5tly %[+ t ! helium exi/s 9 cavities ( ! m9]al4 ,trav]s#cga has sugge/$ t1 s9ce helium is lib]at$ on heat+1 ! effect may be due to ! heat g5]at$ by gr9d+4 ,! escape ( ! helium f ! heat$ m9]al is probably connect$ ) ! fact obs]v$ by ,jaqu]od#cgb t helium passes ?r\gh ! walls ( a qu>tz tube1 heat$ above #ejj ,c4 ,! sub/ance ( ! m9]al probably possesses a simil> prop]ty4 ,trav]s consid]s t helium is pres5t 9 ! m9]al 9 a /ate ( sup]saturat$ solid solution1 b ! facts are equally well expla9$ by assum+ t ! helium is me*anically imprison$ 9 ! mass ( ! m9]al4 ,! sudd5 rise ( temp]ature obs]v$ 9 ! m9]al f]gusonite1 at ! "t ! helium is releas$1 has be5 f\nd to h no?+ to d ) ! pres5ce ( helium1 = x also takes place 9 m9]als n conta9+ helium4 ,! old view t helium 0 9 a /ate ( *emical comb9ation ) ! m9]al mu/ be ab&on$ 9 ! light ( ^! m rec5t exp]im5ts4 ,s9ce ! helium is only releas$ f "s m9]als by ! action ( high temp]atures & solution1 x appe>s probable t a l>ge proportion ( ! helium f\nd 9 ! m9]als is unable to escape "u normal conditions4 ,?us if ! rate ( production ( helium by ! radio-active sub/ance 7 def9itely kn[n1 x %\ld be possible to calculate ! age ( ! m9]al by obs]v+ ! volume ( helium lib]at$ f x by solution4 ,9 ! abs5ce ( su* def9ite in=mation1 an approximate calculation w be made to indicate ! ord] ( magnitude ( ! "t t has elaps$ s9ce ! m9]al 0 =m$ or 0 at a temp]ature l[ en\gh to prev5t ! escape ( ! helium4 ,let u take1 = example1 ! m9]al f]gusonite1 :i* 0 f\nd by ,ramsay & ,trav]s#cgc to evolve #aha c4c4 ( helium4 ,! f]gusonite conta9$ ab\t #g p] c5t4 ( uranium4 ,n[ uranium 9 old m9]als probably conta9s ab\t #h #aj ( its weight ( radium 7see section #bfb74 ,"o gram ( ! m9]al ?us conta9$ ab\t #ef #aj grams ( radium4 ,n[ if ! p>ticle is helium1 x has be5 %[n t #a gram ( radium produces #jbd c4c4 ( helium p] ye>4 ,! volume ( helium produc$ p] ye> 9 #a gram ( f]gusonite is ?us #ac #aj c4c4 ,assum+ t ! rate ( production ( helium has be5 uni=m1 ! "t requir$ to produce #aha c4c4 p] gram is ab\t #adj million ye>s4 ,if ! calculat$ rate ( production ( helium by radium is an ov]-e/imate1 ! "t is correspond+ly l5g!n$4 ,i ?9k t1 :5 ! con/ants requir$ = ^! calculations are m def9itely fix$1 ?is me?od w probably give fairly tru/wor?y in=mation z to ! probable age ( "s ( ! radio-active m9]als ( ! e>?'s cru/1 & indirectly z to ! age ( ! /rata 9 :i* !y are f\nd4 ,9 ?is connection x is ( int]e/ to note t ,ramsay#cgd f\nd t a ,ceylon m9]al1 ?orianite1 conta9$ z mu* z #ie c4c4 ( helium p] gram4 ,accord+ to ! analysis by ,dun/an1 ?is m9]al conta9s ab\t #gf p] c5t4 ( ?orium & #ab p] c5t4 ( uranium4 ,! unusually l>ge am\nt ( helium evolv$ f ?is m9]al w\ld indicate t x 0 =m$ at an e>li] date ?an ! f]gusonite previ\sly consid]$4 #bgj4 ,possible causes ( dis9tegration4 ,9 ord] to expla9 ! ph5om5a ( radio-activity1 x has be5 suppos$ t a c]ta9 small fraction ( ! radio-atoms und]goes dis9tegration p] second1 b no assumptions h be5 made z to ! cause :i* produces ! in/ability & consequ5t dis9tegration4 ,! in/ability ( ! atoms may be suppos$ to be br\ght ab\t ei!r by ! action ( ext]nal =ces or by t ( =ces inh]5t 9 ! atoms !mselves4 ,x is conceivable1 = example1 t ! application ( "s slight ext]nal =ce might cause in/ability & consequ5t dis9tegration1 accompani$ by ! lib]ation ( a l>ge am\nt ( en]gy1 on ! same pr9ciple t a detonator is necess>y to />t "s explosives4 ,x has be5 %[n t ! numb] ( atoms ( any radio-active product :i* break up p] second is always proportional to ! numb] pres5t4 ,?is law ( *ange does n ?r[ any light on ! "q1 = x w\ld be expect$ equally on ei!r hypo!sis4 ,x has n be5 f\nd possible to alt] ! rate ( *ange ( any product by ! application ( any kn[n physical or *emical =ces1 unless possibly x is assum$ t ! =ce ( gravitation :i* is n "u our control may influ5ce 9 "s way ! /ability ( ! radio-atoms4 ,x seems likely !re=e t ! cause ( ! disruption ( ! atoms ( ! radio-elem5ts & _! products resides 9 ! atoms !mselves4 ,accord+ to ! mod]n views ( ! con/itution ( ! atom1 x is n s mu* a matt] ( surprise t "s atoms dis9tegrate z t ! atoms ( ! elem5ts are s p]man5t z !y appe> to be4 ,9 accordance ) ! hypo!sis ( ,j4 ,j4 ,?omson1 x may be suppos$ t ! atoms consi/ ( a numb] ( small positively & negatively *>g$ p>ticles 9 rapid int]nal movem5t1 & held 9 equilibrium by _! mutual =ces4 ,9 a complex atom1 :]e ! possible v>iations 9 ! relative motion ( ! p>ts are v great1 ! atom may arrive at su* a phase t "o "p acquires suffici5t k9etic en]gy to escape f ! sy/em1 or t ! con/ra9+ =ces are mom5t>ily neutralis$1 s t ! "p escapes f ! sy/em ) ! velocity possess$ by x at ! in/ant ( its release4 ,sir ,oliv] ,lodge#cge has advanc$ ! view t ! in/ability ( ! atom may be a result ( radiation ( en]gy by ! atom4 ,l>mor has %[n t an electron1 subject to accel]ation1 radiates en]gy at a rate proportional to ! squ>e ( its accel]ation4 ,an electron mov+ uni=mly 9 a /raight l9e does n radiate en]gy1 b an electron1 con/ra9$ to move 9 a circul> orbit ) con/ant velocity1 is a p[]ful radiator1 = 9 su* a case ! electron is cont9u\sly accel]at$ t[>ds ! c5tre4 ,lodge consid]$ ! simple case ( a negatively *>g$ electron revolv+ r\nd an atom ( mass relatively l>ge b hav+ an equal positive *>ge & held 9 equilibrium by electrical =ces4 ,?is sy/em w radiate en]gy1 &1 s9ce ! radiation ( en]gy is equival5t to motion 9 a resi/+ m$ium1 ! p>ticle t5ds to move t[>ds ! c5tre1 & its spe$ consequ5tly increases4 ,! rate ( radiation ( en]gy w increase rapidly ) ! spe$ ( ! electron4 ,:5 ! spe$ ( ! electron becomes v ne>ly equal to ! velocity ( light1 accord+ to ,lodge1 ano!r effect sup]v5es4 ,x has be5 %[n 7section #hb7 t ! app>5t mass ( an electron increases v rapidly z ! spe$ ( light is approa*$1 & is !oretically inf9ite at ! spe$ ( light4 ,!re w be at ?is /age a sudd5 increase ( ! mass ( ! revolv+ atom1 &1 on ! supposition t ?is /age c be rea*$1 a consequ5t di/urbance ( ! balance ( =ces hold+ ! sy/em toge!r4 ,lodge consid]s x probable t1 "u ^! conditions1 ! p>ts ( ! sy/em w break asund] & escape f ! sph]e ( "o ano!r's influ5ce4 ,x seems probable t ! prim>y cause ( ! dis9tegration ( ! atom mu/ be look$ = 9 ! loss ( en]gy ( ! atomic sy/em due to electromagnetic radiation 7section #eb74 ,l>mor#cgf has %[n t ! condition to be fulfill$ 9 ord] t a sy/em ( rapidly mov+ electrons may p]si/ )\t loss ( en]gy is t ! vector sum ( ! accel]ations t[>ds ! c5tre %\ld be p]man5tly z]o4 ,:ile a s+le electron mov+ 9 a circul> orbit is a p[]ful radiator ( en]gy1 x is rem>kable h[ rapidly ! radiation ( en]gy dim9i%es if sev]al electrons are revolv+ 9 a r+4 ,?is has rec5tly be5 %[n by ,j4 ,j4 ,?omson#cgg1 :o exam9$ ma!matically ! case ( a sy/em ( negatively electrifi$ corpuscles1 situat$ at equal int]vals r\nd ! circumf]5ce ( a circle1 & rotat+ 9 "o plane ) uni=m velocity r\nd its c5tre4 ,= example1 he f\nd t ! radiation f a gr\p ( six p>ticles mov+ ) a velocity ( ( ! velocity ( light is less ?an "o-million? "p ( ! radiation f a s+le p>ticle describ+ ! same orbit ) ! same velocity4 ,:5 ! velocity is ( t ( light ! am\nt ( radiation is only #aj t ( a s+le p>ticle mov+ ) ! same velocity 9 ! same orbit4 ,results ( ?is k9d indicate t an atom consi/+ ( a l>ge numb] ( revolv+ electrons may radiate en]gy extremely sl[ly1 & yet1 f9ally1 ?is m9ute b cont9u\s dra9 ( en]gy f ! atom mu/ result ei!r 9 a re>rangem5t ( its compon5t p>ts into a new sy/em1 or ( an expulsion ( electrons or gr\ps ( electrons f ! atom4 ,simple models ( atoms to imitate ! behavi\r ( polonium 9 %oot+ out p>ticles1 & ( radium 9 %oot+ out p>ticles h be5 discuss$ by ,"l ,kelv9#cgh4 ,x is possible to devise c]ta9 /able arrangem5ts ( ! positively & negatively electrifi$ p>ticles1 suppos$ to con/itute an atom1 :i*1 on ! application ( "s di/urb+ =ce1 break up ) ! expulsion ( a "p ( ! sy/em ) great velocity4 ,j4 ,j4 ,?omson#cgi has ma!matically inve/igat$ ! possible /able arrangem5ts ( a numb] ( electrons mov+ ab\t 9 a sph]e ( uni=m positive electrification4 ,! prop]ties ( su* a model atom are v /rik+1 & indirectly sugge/ a possible explanation ( ! p]iodic law 9 *emi/ry4 ,he has %[n t ! electrons1 if 9 "o plane1 arrange !mselves 9 a numb] ( conc5tric r+s2 & g5]ally1 if !y are n con/ra9$ to move 9 "o plane1 9 a numb] ( conc5tric %ells l ! coats ( an onion4 ,! ma!matical problem is mu* simplifi$ if ! electrons are suppos$ to rotate 9 r+s 9 "o plane1 ! electrons 9 ea* r+ be+ arrang$ at equal angul> int]vals4 ,! ways 9 :i* ! numb] ( electrons gr\p !mselves1 = numb]s rang+ f #fj to #e at int]vals ( #e1 are %[n 9 ! foll[+ table3-- ,numb] #fj #ee #ej #de #dj #ce ( electrons ,numb] 9 #bj #ai #ah #ag #af #af successive r+s #af #af #ae #ad #ac #ab #ac #ab #aa #aj #h #f #h #g #e #d #c #a #c #a #a ,numb] #cj #be #bj #ae #aj #e ( electrons ,numb] 9 #ae #ac #ab #aj #h #e successive r+s #aj #i #g #e #b #e #c #a ,9 ! next table is giv5 ! possible s]ies ( arrangem5ts ( electrons :i* c h an out] r+ ( #bj3-- ,numb] #ei #fj #fa #fb #fc #fd #fe #ff #fg ( electrons ,numb] 9 #bj #bj #bj #bj #bj #bj #bj #bj #bj successive r+s #af #af #af #ag #ag #ag #ag #ag #ag #ac #ac #ac #ac #ac #ac #ad #ad #ae #h #h #i #i #aj #aj #aj #aj #aj #b #c #c #c #c #d #d #e #e ,! smalle/ numb] ( electrons :i* c h an out] r+ ( #bj is #ei1 :ile #fg is ! greate/4 ,! v>i\s arrangem5ts ( electrons c be classifi$ into families1 9 :i* ! gr\p+s ( ! electrons h c]ta9 features 9 common4 ,?us ! gr\p ( #fj electrons consi/s ( ! same arrangem5t ( electrons z ! gr\p ( #dj ) ! addition ( an out] r+ ( #bj electrons2 ! gr\p ( #dj is ! same z ! gr\p ( #bd ) an additional r+ outside2 & ! gr\p ( #bd 9 turn is ! same z ! gr\p ( #aa ) an extra r+4 ,a s]ies ( model atoms may be =m$ 9 ?is way1 9 :i* ea* atom is d]iv$ f ! prec$+ memb] by an additional r+ ( electrons4 ,su* atoms w\ld be expect$ to possess _m prop]ties 9 common1 & w\ld correspond to ! elem5ts 9 ! same v]tical column ( ! p]iodic table ( ,m5delef4 ,diff]5t arrangem5ts ( electrons v>y widely 9 /ability4 ,"s may acquire an extra electron or two & yet rema9 /able1 o!rs readily lose an electron )\t di/urb+ _! /ability4 ,! =m] w\ld correspond to an electro-negative atom1 ! latt] to an electro-positive4 ,c]ta9 arrangem5ts ( electrons are /able if ! electrons move ) an angul> velocity great] ?an a c]ta9 value1 b become un/able :5 ! velocity falls bel[ ?is value4 ,f\r electrons 9 motion1 = example1 are /able 9 "o plane1 b :5 ! velocity falls bel[ a c]ta9 critical value1 ! sy/em is un/able1 & ! electrons t5d to arrange !mselves at ! corn]s ( a regul> tetrah$ron4 ,j4 ,j4 ,?omson 7loc4 cit47 applies ?is prop]ty to expla9 :y an atom ( radio-active matt] breaks up1 z foll[s3-- 8,consid] n[ ! prop]ties ( an atom conta9+ a sy/em ( corpuscles 7electrons7 ( ?is k9d4 ,suppose ! corpuscles 7 orig9ally mov+ ) velocities f> exce$+ ! critical velocity2 9 consequ5ce ( ! radiation f ! mov+ corpuscles1 _! velocity w sl[ly--v sl[ly--dim9i%2 :51 aft] a long int]val1 ! velocity rea*es ! critical velocity1 !re w be :at is equival5t to an explosion ( ! corpuscles1 ! corpuscles w move f> away f _! orig9al position1 _! pot5tial en]gy w decrease1 :ile _! k9etic en]gy w increase4 ,! k9etic en]gy ga9$ 9 ?is way might be suffici5t to c>ry ! sy/em out ( ! atom1 & we %\ld h1 z 9 ! case ( radium1 a "p ( ! atom %ot (f4 ,9 consequ5ce ( ! v sl[ dissipation ( en]gy by radiation ! life ( ! atom w\ld be v long4 ,we h tak5 ! case ( ! f\r corpuscles z ! type ( a sy/em :i*1 l a top1 requires = its /ability a c]ta9 am\nt ( rotation4 ,any sy/em possess+ ?is prop]ty w\ld1 9 consequ5ce ( ! gradual dissipation ( en]gy by radiation1 give to ! atom conta9+ x radio-active prop]ties simil> to ^? conf]r$ by ! f\r corpuscles40 #bga4 ,heat ( ! sun & e>?4 ,x 0 po9t$ out by ,ru!r=d & ,soddy#chj t ! ma9t5ance ( ! sun's heat = long int]vals ( "t did n pres5t any fundam5tal difficulty if a process ( dis9tegration1 su* z occurs 9 ! radio-elem5ts1 7 suppos$ to be tak+ place 9 ! sun4 ,9 a lett] to ,nature 7,july #i1 #aijc7 ,w4 ,e4 ,wilson %[$ t ! pres5ce ( #cf grams ( radium 9 ea* cubic metre ( ! sun's mass 0 suffici5t to acc\nt = ! pres5t rate ( emission ( en]gy by ! sun4 ,?is calculation 0 bas$ on ! e/imate ( ,curie & ,laborde t #a gram ( radium emits #ajj gram-calories p] h\r1 & on ! obs]vation ( ,langley t ea* squ>e c5timetre ( ! sun's surface emits #hbh #aj gram-calories p] h\r4 ,s9ce ! av]age d5sity ( ! sun is #add1 ! pres5ce ( radium 9 ! sun1 to ! ext5t ( #be p>ts by weight 9 a million1 w\ld acc\nt = its pres5t rate ( emission ( en]gy4 ,an exam9ation ( ! spectrum ( ! sun has n s f> reveal$ any ( ! radium l9es4 ,x is kn[n1 h[ev]1 f spectroscopic evid5ce t helium is pres5t1 & ?is indirectly sugge/s ! exi/5ce ( radio-active matt] also4 ,x c readily be %[n#cha t ! abs5ce ( p5etrat+ rays f ! sun at ! surface ( ! e>? does n imply t ! radio-elem5ts are n pres5t 9 ! sun4 ,ev5 if ! sun 7 compos$ ( pure radium1 x w\ld h>dly be expect$ t ! rays emitt$ w\ld be appreciable at ! surface ( ! e>?1 s9ce ! rays w\ld be almo/ completely absorb$ 9 pass+ ?r\gh ! atmosph]e1 :i* corresponds to a ?ickness ( #gf c5timetres ( m]cury4 ,9 ! ,app5dix ,e ( ,?omson & ,tait's ,natural ,philosophy1 ,"l ,kelv9 has calculat$ ! en]gy lo/ 9 ! conc5tration ( ! sun f a condition ( inf9ite disp]sion1 & concludes t x seems 8on ! :ole probable t ! sun has n illum9at$ ! e>? = #ajj1jjj1jjj ye>s & almo/ c]ta9 t he has n done s = #ejj1jjj1jjj ye>s4 ,z = ! future we may say1 ) equal c]ta9ty1 t inhabitants ( ! e>? _c cont9ue to enjoy ! light & heat ess5tial to _! life = _m million ye>s long]1 unless s\rces n[ unkn[n to u are prep>$ 9 ! great /oreh\ses ( creation40 ,! discov]y t a small mass ( a sub/ance l radium c emit spontane\sly an enorm\s quantity ( heat r5d]s x possible t ?is e/imate ( ! age ( ! sun's heat may be mu* increas$4 ,9 a lett] to ,nature 7,sept4 #bd1 #aijc7 ,g4 ,h4 ,d>w9 drew att5tion to ?is probability1 & at ! same "t po9t$ out t1 on ,kelv9's hypo!ses1 8 e/imate ( ! duration ( ! sun's heat 0 probably mu* too high1 & /at$ t1 8,! lo/ en]gy ( ! sun1 suppos$ to be a homog5e\s sph]e ( mass ,m & radius a1 is 77,m_/a :]e is ! con/ant ( gravitation4 ,on introduc+ num]ical values = ! symbols 9 ?is =mula1 ,i f9d ! lo/ en]gy to be #bg #aj ,m calories :]e ,m is express$ 9 grams4 ,if we adopt ,langley's value ( ! sol> con/ant1 ?is heat suffices to give a supply = #ab million ye>s4 ,"l ,kelv9 us$ ,p\illet's value = t con/ant1 b if he _h be5 able to use ,langley's1 8 #ajj million w\ld h be5 r$uc$ to #fj million4 ,! discrepancy betwe5 my results ( #ab million & 8 ( #fj million is expla9$ by a conjectural augm5tation ( ! lo/ en]gy to all[ = ! conc5tration ( ! sol> mass t[>ds its c5tral p>ts40 ,n[ x has be5 %[n 7section #bff7 t "o gram ( radium emits dur+ its life an am\nt ( heat correspond+ to #af #aj gram-calories4 ,x has also be5 po9t$ out t !re is e reason to suppose t a simil> am\nt ( en]gy is resid5t 9 ! *emical atoms ( ! inactive elem5ts4 ,x is n improbable t1 at ! enorm\s temp]ature ( ! sun1 ! break+ up ( ! elem5ts into simpl] =ms may be tak+ place at a m rapid rate ?an on ! e>?4 ,if ! en]gy resid5t 9 ! atoms ( ! elem5ts is ?us available1 ! "t dur+ :i* ! sun may cont9ue to emit heat at ! pres5t rate may be at lea/ #ej times long] ?an ! value comput$ f dynamical data4 ,simil> consid]ations apply to ! "q ( ! age ( ! e>?4 ,a full discussion ( ! probable age ( ! e>?1 comput$ f its secul> cool+ f a molt5 mass1 is giv5 by ,"l ,kelv9 9 ,app5dix ,d ( ,?omson & ,tait's ,natural ,philosophy4 ,he has !re %[n t ab\t #ajj million ye>s aft] ! e>? 0 a molt5 mass1 ! gradual cool+ due to radiation f its surface w\ld acc\nt = ! av]age temp]ature gradi5t ( ,f4 p] foot1 obs]v$ to-day ne> ! e>?'s surface4 ,"s consid]ations w n[ be discuss$ :i* po9t to ! probability t ! pres5t temp]ature gradi5t obs]v$ 9 ! e>? _c be us$ z a guide to e/imate ! l5g? ( "t t has elaps$ s9ce ! e>? has be5 at a temp]ature capable ( support+ animal & vegetable life2 = x w be %[n t probably !re is suffici5t radio-active matt] on ! e>? to supply z mu* heat to ! e>? z is lo/ by radiation f its surface4 ,tak+ ! av]age conductivity ,k ( ! mat]ials ( ! e>? z #jjd 7,c4,g4,s4 units7 & ! temp]ature gradi5t ,t ne> ! surface z #jjjcg ,c4 p] cm41 ! heat ,q 9 gram-calories conduct$ to ! surface ( ! e>? p] second is giv5 by ,q #d,r,,kt1 :]e ,r is ! radius ( ! e>?4 ,let ,x be ! av]age am\nt ( heat lib]at$ p] second p] cubic c5timetre ( ! e>?'s volume ow+ to ! pres5ce ( radio-active matt]4 ,if ! heat ,q radiat$ f ! e>? is equal to ! heat suppli$ by ! radio-active matt] 9 ! e>?1 ,x 4 77,r #d,r,,kt1 or #c,,kt ,x ------ 4 ,r ,sub/itut+ ! values ( ^! con/ants1 ,x #g #aj gram-calories p] second #bb #aj gram-calories p] ye>4 ,s9ce #a gram ( radium emits #hgf1jjj gram-calories p] ye>1 ! pres5ce ( #bf #aj grams ( radium p] unit volume1 or #df #aj grams p] unit mass1 w\ld comp5sate = ! heat lo/ f ! e>? by conduction4 ,n[ x w be %[n 9 ! foll[+ *apt] t radio-active matt] seems to be di/ribut$ fairly uni=mly ?r\gh ! e>? & atmosph]e4 ,9 addition1 x has be5 f\nd t all sub/ances are radio-active to a feeble degree1 al?\gh x is n yet settl$ :e!r ?is radio-activity may n be due ma9ly to ! pres5ce ( a radio-elem5t z an impurity4 ,= example1 ,/rutt#chb obs]v$ t a plat9um plate 0 ab\t z active z a cry/al ( uranium nitrate1 or ab\t #b #aj z active z radium4 ,?is corresponds to a f> great] activity ?an is necess>y to comp5sate = ! loss ( heat ( ! e>?4 ,a m accurate d$uction1 h[ev]1 c be made f data ( ! radio-activity exhibit$ by matt] dug out ( ! e>?4 ,el/] & ,geitel#chc fill$ a di% ( volume #cc #aj c4c4 ) clay dug up f ! g>d51 & plac$ x 9 a vessel ( #cj litres capacity 9 :i* 0 plac$ an electroscope to det]m9e ! conductivity ( ! enclos$ gas4 ,aft] /&+ = sev]al days1 !y f\nd t ! conductivity ( ! air rea*$ a con/ant maximum value1 correspond+ to ?ree times ! normal4 ,x w be %[n lat] 7section #bhd7 t ! normal conductivity obs]v$ 9 seal$ vessels corresponds to ! production ( ab\t #cj ions p] c4c4 p] second4 ,! numb] ( ions produc$ p] second 9 ! vessel by ! radio-active e>? 0 ?us ab\t #b #aj4 ,?is w\ld give a saturation curr5t ?r\gh ! gas ( #bb #aj electromagnetic units4 ,n[ ! emanation f #a gram ( radium /or$ 9 a metal cyl9d] gives a saturation curr5t ( ab\t #cb #aj electromagnetic units4 ,el/] & ,geitel consid]$ t mo/ ( ! conductivity obs]v$ 9 ! gas 0 due to a radio-active emanation1 :i* gradually diffus$ f ! clay into ! air 9 ! vessel4 ,! increas$ conductivity 9 ! gas obs]v$ by ,el/] & ,geitel w\ld ?us be produc$ by ! emanation f #g #aj gram ( radium4 ,tak+ ! d5sity ( clay z #b1 ?is corresponds to ab\t #aj gram ( radium p] gram ( clay4 ,b x has be5 %[n t if #df #aj gram ( radium 7 pres5t 9 ea* gram ( e>?1 ! heat emitt$ w\ld comp5sate = ! loss ( heat ( ! e>? by conduction & radiation4 ,! am\nt ( activity obs]v$ 9 ! e>? is ?us ab\t ! "r ord] ( magnitude to acc\nt = ! heat emission requir$4 ,9 ! above e/imate1 ! pres5ce ( uranium & ?orium m9]als 9 ! e>? has n be5 consid]$4 ,moreov]1 x is probable t ! total am\nt ( radio-activity 9 ! clay 0 consid]ably great] ?an t calculat$1 = x is likely t o!r radio-active matt] 0 pres5t :i* did n give (f an emanation4 ,if ! e>? is suppos$ to be 9 a /ate ( !rmal equilibrium 9 :i* ! heat lo/ by radiation is suppli$ f radio-active matt]1 !re mu/ be an am\nt ( radio-active matt] 9 ! e>? correspond+ to ab\t #bgj million tons ( radium4 ,if !re 7 m radium ?an ?is 9 ! e>?1 ! temp]ature gradi5t w\ld be great] ?an t obs]v$ to-day4 ,?is may appe> to be a v l>ge quantity ( radium1 b rec5t det]m9ations 7section #bha7 ( ! am\nt ( radium emanation 9 ! atmosph]e /rongly support ! view t a l>ge quantity ( radium mu/ exi/ 9 ! surface soil ( ! e>?4 ,eve f\nd1 on a m9imum e/imate1 t ! am\nt ( emanation always pres5t 9 ! atmosph]e is equival5t to ! equilibrium am\nt d]iv$ f #ajj tons ( radium4 ,!re is e reason to believe t ! emanation f\nd 9 ! atmosph]e is suppli$ bo? by ! diffusion ( ! emanation f ! soil & by ! action ( spr+s4 ,s9ce ! emanation loses half its activity 9 f\r days1 x _c diffuse f any great dep?4 ,assum+ t ! radium is uni=mly di/ribut$ ?r\gh\t ! e>?1 ! quantity ( ! radium emanation produc$ 9 a ?9 %ell ( e>? ab\t ?irte5 metres 9 dep?1 is suffici5t to acc\nt = ! am\nt ord9>ily obs]v$ 9 ! atmosph]e4 ,i ?9k we may conclude t ! pres5t rate ( loss ( heat ( ! e>? might h cont9u$ un*ang$ = long p]iods ( "t 9 consequ5ce ( ! supply ( heat f radio-active matt] 9 ! e>?4 ,x ?us seems probable t ! e>? may h rema9$ = v long int]vals ( "t at a temp]ature n v diff]5t f t obs]v$ to-day1 & t1 9 consequ5ce1 ! "t dur+ :i* ! e>? has be5 at a temp]ature capable ( support+ ! pres5ce ( animal & vegetable life may be v mu* long] ?an ! e/imate made by ,"l ,kelv9 f o!r data4 #bgb4 ,evolution ( matt]4 ,al?\gh ! hypo!sis t all matt] is compos$ ( "s elem5t>y unit ( matt] or protyle has be5 advanc$ z a speculation at v>i\s times by _m prom95t physici/s & *emi/s1 ! fir/ def9ite exp]im5tal evid5ce %[+ t ! *emical atom 0 n ! smalle/ unit ( matt] 0 obta9$ 9 #ahig by ,j4 ,j4 ,?omson 9 8 classic rese>* on ! nature ( ! ca?ode rays produc$ by an electric dis*>ge 9 a vacuum tube4 ,we h se5 t ,sir ,william ,crookes1 :o 0 ! fir/ to demon/rate ! rem>kable prop]ties ( ^! rays1 _h sugge/$ t !y consi/$ ( /reams ( project$ *>g$ matt] & repres5t$--z he t]m$ x--a new or 8f\r? /ate ( matt]40 ,j4 ,j4 ,?omson %[$ by two di/9ct me?ods 7section #ej71 t ! ca?ode rays consi/$ ( a /ream ( negatively *>g$ p>ticles project$ ) great velocity4 ,! p>ticles behav$ z if _! mass 0 only ab\t ( ! mass ( ! atom ( hydrog51 :i* is ! lighte/ atom kn[n4 ,^! corpuscles1 z !y 7 t]m$ by ,?omson1 7 f\nd at a lat] date to be produc$ f a gl[+ c>bon filam5t & f a z9c plate expos$ to ! action ( ultra-violet light4 ,!y act$ z isolat$ units ( negative electricity1 &1 z we h se51 may be id5tifi$ ) ! electrons /udi$ ma!matically by ,l>mor & ,lor5tz4 ,n only 7 ^! electrons produc$ by ! action ( light1 heat1 & ! electric dis*>ge1 b simil> bodies 7 also f\nd to be emitt$ spontane\sly f ! radio-elem5ts ) a velocity f> great] ?an t obs]v$ = ! electrons 9 a vacuum tube4 ,! electrons produc$ 9 ^! v>i\s ways 7 all f\nd to c>ry a negative *>ge1 & to be app>5tly id5tical2 = ! ratio e_/m ( ! *>ge ( ! electron to its mass 0 9 all cases ! same )9 ! limits ( exp]im5tal error4 ,s9ce electrons1 produc$ f diff]5t k9ds ( matt] & "u diff]5t conditions1 7 9 all cases id5tical1 x seem$ probable t !y 7 a con/itu5t "p ( all matt]4 ,j4 ,j4 ,?omson sugge/$ t ! atom is built up ( a numb] ( ^! negatively *>g$ electrons comb9$ 9 "s way ) correspond+ positively *>g$ bodies4 ,on ?is view ! atoms ( ! *emical elem5ts diff] f "o ano!r only 9 ! numb] & arrangem5t ( ! compon5t electrons4 ,! removal ( an electron f ! atom 9 ! case ( ionization does n appe> to affect p]man5tly ! /ability ( ! sy/em1 = no evid5ce has s f> be5 obta9$ to %[ t ! passage ( an int5se electric dis*>ge ?r\gh a gas results 9 a p]man5t alt]ation ( ! /ructure ( ! atom4 ,on ! o!r h&1 9 ! case ( ! radio-active bodies1 a positively *>g$ p>ticle ( mass ab\t twice t ( ! hydrog5 atom escapes f ! heavy radio-atom4 ,?is loss appe>s to result at once 9 a p]man5t alt]ation ( ! atom1 & causes a m>k$ *ange 9 its physical & *emical prop]ties4 ,9 addition !re is no evid5ce t ! process is rev]sible4 ,! expulsion ( a p>ticle ) great velocity f an atom ( radio-active matt] also results 9 a trans=mation ( ! atom4 ,= example radium ,e emits a p>ticle1 &1 9 consequ5ce1 gives rise to a di/9ct sub/ance radium ,f 7polonium74 ,a case ( ?is k9d1 :]e ! expulsion ( a p>ticle ) great velocity causes a complete re>rangem5t ( ! p>ts ( an atom1 is probably q di/9ct f ! process :i* occurs dur+ ionization1 :]e a sl[ spe$ electron escapes f ! atom )\t app>5tly affect+ ! /ability ( ! atom left beh9d4 ,! only direct exp]im5tal evid5ce ( ! trans=mation ( matt] has be5 d]iv$ f a /udy ( ! radio-active bodies4 ,if ! dis9tegration !ory1 advanc$ to acc\nt = ! ph5om5a ( radio-activity1 is correct 9 ! ma9 ess5tials1 !n ! radio-elem5ts are und]go+ a spontane\s & cont9u\s process ( trans=mation into o!r & diff]5t k9ds ( matt]4 ,! rate ( trans=mation is sl[ 9 uranium & ?orium1 b is fairly rapid 9 radium4 ,x has be5 %[n t ! fraction ( a mass ( radium :i* is trans=m$ p] ye> is ab\t ( ! total am\nt pres5t4 ,9 ! case ( uranium & ?orium probably a million ye>s w\ld be requir$ to produce a simil> am\nt ( *ange4 ,?us ! process ( trans=mation 9 uranium & ?orium is f> too sl[ to be detect$ )9 a reasonable "t by ! use ( ! balance or spectroscope1 b ! radiations :i* accompany ! trans=mation c easily be detect$4 ,al?\gh ! process ( *ange is sl[ x is cont9u\s1 & 9 ! c\rse ( ages ! uranium & ?orium pres5t 9 ! e>? mu/ be trans=m$ into o!r types ( matt]4 ,^? :o h consid]$ ! possibility ( atoms und]go+ a process ( trans=mation h g5]ally ?\ght t ! matt] z a :ole w\ld und]go a progressive *ange1 ) a gradual alt]ation ( physical & *emical prop]ties ( ! :ole mass ( sub/ance4 ,on ! !ory ( dis9tegration ?is is n ! case4 ,only a m9ute fraction ( ! matt] pres5t breaks up 9 unit "t1 & 9 ea* ( ! successive /ages ?r\gh :i* ! dis9tegrat$ atoms pass1 !re is 9 mo/ cases a m>k$ alt]ation 9 ! *emical & physical prop]ties ( ! matt]4 ,! trans=mation ( ! radio-elem5ts is ?us a trans=mation ( a "p p] saltum1 & n a progressive *ange ( ! :ole4 ,at any "t aft] ! process ( trans=mation has be5 9 progress !re w ?us rema9 a "p ( ! matt] :i* is un*ang$1 &1 mix$ ) x1 ! products :i* h result$ f ! trans=mation ( ! rema9d]4 ,! "q naturally arises :e!r ! process ( degradation ( matt] is conf9$ to ! radio-elem5ts or is a univ]sal prop]ty ( matt]4 ,x w be %[n 9 *apt] ,,xiv t all matt]1 s f> exam9$1 exhibits ! prop]ty ( radio-activity to a slight degree4 ,x is v difficult1 h[ev]1 to make c]ta9 t ! obs]v$ radio-activity is n due to ! pres5ce 9 ! matt] ( a slight trace ( a radio-elem5t4 ,if ord9>y matt] is radio-active1 x is c]ta9 t its activity is mu* less ?an t ( uranium1 & consequ5tly t its rate ( trans=mation mu/ be excessively sl[4 ,!re is1 h[ev]1 ano!r possibility to be consid]$4 ,! *anges occurr+ 9 ! radio-elem5ts w\ld probably nev] h be5 detect$ if ! *ange _h n be5 accompani$ by ! expulsion ( *>g$ p>ticles ) great velocity4 ,x does n seem unlikely t an atom may und]go dis9tegration )\t project+ a "p ( its sy/em ) suffici5t velocity to ionize ! gas4 ,9 fact1 we h se5 t1 ev5 9 ! radio-elem5ts1 sev]al ( ! s]ies ( *anges 9 bo? ?orium1 radium1 & act9ium are unaccompani$ by ioniz+ rays4 ,! exp]im5tal results giv5 9 ,app5dix ,a /rongly support ?is po9t ( view4 ,x may ?us be possible t all matt] is und]go+ a sl[ process ( trans=mation1 :i* has s f> only be5 detect$ 9 ! radio-elem5ts on acc\nt ( ! expulsion ( *>g$ p>ticles ) great velocity dur+ ! *ange4 ,?is process ( degradation ( matt] cont9u+ = ages mu/ r$uce ! con/itu5ts ( ! e>? to ! simpl] & m /able =ms ( matt]4 ,! idea t helium is a trans=mation product ( radium sugge/s ! probability t helium is "o ( ! m elem5t>y sub/ances ( :i* ! heavi] atoms are compos$4 ,sir ,norman ,locky]1 9 8 int]e/+ book on 8,inorganic ,evolution10 has po9t$ out t ! spectra ( helium & ( hydrog5 pr$om9ate 9 ! hotte/ />s4 ,9 ! cool] />s ! m complex types ( matt] appe>4 ,sir ,norman ,locky] has bas$ 8 !ory ( evolution ( matt] on evid5ce ( a spectroscopic exam9ation ( ! />s1 & consid]s t temp]ature is ! ma9 factor 9 break+ up matt] into its simpl] =ms4 ,! trans=mation ( matt] occurr+ 9 ! radio-elem5ts is on ! o!r h& spontane\s1 & indep5d5t ( temp]ature ov] ! range exam9$4 ,footnote #ccc3 ,p]r91 ,revue ,sci5tifique1 ,april #ac1 #aija4 ,footnote #ccd3 ,becqu]el1 ,c4 ,r4 #acc1 p4 #igi1 #aija4 ,footnote #cce3 ,ru!r=d & ,mc,clung1 ,phil4 ,trans4 ,a1 p4 #be1 #aija4 ,footnote #ccf3 ,ru!r=d1 ,phil4 ,mag4 ,jan4 & ,feb4 #aijj4 ,footnote #ccg3 ,p4 ,curie1 ,c4 ,r4 #acf1 p4 #bbc1 #aijc4 ,footnote #cch3 ,ru!r=d1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #cci3 ,m4 & ,mme ,curie1 ,c4 ,r4 #acd1 p4 #he1 #aijb4 ,footnote #cdj3 ,ru!r=d & ,soddy1 ,trans4 ,*em4 ,soc4 #ha1 pp4 #cba1 #hcg1 #aijb4 ,phil4 ,mag4 ,sept4 & ,nov4 #aijb4 ,footnote #cda3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,april1 #aijc4 ,footnote #cdb3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #cdc3 ,ru!r=d1 ,phys4 ,zeit4 #d1 p4 #bce1 #aijb4 ,phil4 ,mag4 ,feb4 #aijc4 ,footnote #cdd3 ,ru!r=d1 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #cde3 ,curie & ,laborde1 ,c4 ,r4 #acf1 p4 #fgc1 #aijc4 ,footnote #cdf3 ,j4 ,j4 ,?omson1 ,nature1 p4 #fja1 #aijc4 ,footnote #cdg3 ,crookes1 ,c4 ,r4 #abh1 p4 #agf1 #ahii4 ,footnote #cdh3 ,f4 ,re1 ,c4 ,r4 p4 #acf1 p4 #acic1 #aijc4 ,footnote #cdi3 ,ri*>z & ,s*5ck1 ,b]l4 ,b]4 p4 #aajb1 #aijc4 ,s*5ck1 ,b]l4 ,b]4 p4 #cg1 #aijd4 ,footnote #cej3 ,arm/rong & ,l[ry1 ,proc4 ,roy4 ,soc4 #aijc4 ,*em4 ,news1 #hh1 p4 #hi1 #aijc4 ,footnote #cea3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #ceb3 ,boltwood1 ,nature1 ,may #be1 p4 #hj1 #aijd4 ,phil4 ,mag4 ,april1 #aije4 ,footnote #cec3 ,mc,coy1 ,b]4 d4 ,d4 ,*em4 ,ges4 ,no4 #aa1 p4 #bfda1 #aijd4 ,footnote #ced3 ,/rutt1 ,nature1 ,m>* #ag & ,july #g1 #aijd4 ,proc4 ,roy4 ,soc4 ,m>* #b1 #aije4 ,footnote #cee3 ,/rutt1 ,proc4 ,roy4 ,soc4 ,m>* #b1 #aije4 ,footnote #cef3 ,soddy1 ,nature1 ,may #ab1 #aijd2 ,jan4 #ai1 #aije4 ,footnote #ceg3 ,:e?am1 ,nature1 ,may #e1 #aijd2 ,jan4 #bf1 #aije4 ,footnote #ceh3 ,danne1 ,c4 ,r4 ,jan4 #bc1 #aije4 ,footnote #cei3 ,j4 ,j4 ,?omson1 ,nature1 ,april #cj1 p4 #fja1 #aijc4 ,footnote #cfj3 ,voll]1 ,phys4 ,zeit4 #e1 ,no4 #bd1 p4 #gha1 #aijd4 ,footnote #cfa3 ,ramsay & ,cooke1 ,nature1 ,aug4 #aa1 #aijd4 ,footnote #cfb3 ,eve1 ,nature1 ,m>* #af1 #aije4 ,footnote #cfc3 ,j4 ,j4 ,?omson1 ,int]national ,electrical ,congress1 ,/ ,l\is1 ,sept4 #aijd4 ,footnote #cfd3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 p4 #ehb1 #aijb2 pp4 #dec & #egi1 #aijc4 ,footnote #cfe3 ,ramsay & ,soddy1 ,nature1 ,july #af1 p4 #bdf1 #aijc4 ,proc4 ,roy4 ,soc4 #gb1 p4 #bjd1 #aijc2 #gc1 p4 #cdf1 #aijd4 ,footnote #cff3 ,curie & ,dew>1 ,c4 ,r4 #ach1 p4 #aij1 #aijd4 ,*em4 ,news1 #hi1 p4 #he1 #aijd4 ,footnote #cfg3 ,him/$t & ,mey]1 ,ann4 d4 ,phys4 #ae1 p4 #ahd1 #aijd4 ,footnote #cfh3 ,/rutt1 ,proc4 ,roy4 ,soc4 ,m>* #b1 #aije4 ,footnote #cfi3 ,boltwood1 ,phil4 ,mag4 ,april1 #aije4 ,footnote #cgj3 ,moss1 ,trans4 ,roy4 ,soc4 ,dubl91 #aijd4 ,footnote #cga3 ,trav]s1 ,nature1 p4 #bdh1 ,jan4 #ab1 #aije4 ,footnote #cgb3 ,jaqu]od1 ,c4 ,r4 p4 #ghi1 #aijd4 ,footnote #cgc3 ,ramsay & ,trav]s1 ,zeits*4 ,physik4 ,*em4 #be1 p4 #efh1 #ahih4 ,footnote #cgd3 ,ramsay1 ,nature1 ,april #g1 #aijd4 ,footnote #cge3 ,lodge1 ,nature1 ,june #aa1 p4 #abi1 #aijc4 ,footnote #cgf3 ,l>mor1 ,ae!r & ,matt]1 p4 #bcc4 ,footnote #cgg3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 p4 #fha1 ,dec4 #aijc4 ,footnote #cgh3 ,"l ,kelv91 ,phil4 ,mag4 ,oct4 #aijd4 ,footnote #cgi3 ,?omson1 ,phil4 ,mag4 ,m>*1 #aijd4 ,footnote #chj3 ,ru!r=d & ,soddy1 ,phil4 ,mag4 ,may1 #aijc4 ,footnote #cha3 ,see ,/rutt & ,joly1 ,nature1 ,oct4 #ae1 #aijc4 ,footnote #chb3 ,/rutt1 ,phil4 ,mag4 ,june1 #aijc4 ,footnote #chc3 ,el/] & ,geitel1 ,phys4 ,zeit4 #d1 ,no4 #ai1 p4 #ebb1 #aijc4 ,*em4 ,news1 ,july #ag1 p4 #cj1 #aijc4 ,,*apt] ,,xiv4 ,,radio-,,activity ,,( ,,! ,,atmosph]e ,,& ,,( ,,ord9>y ,,mat]ials4 #bgc4 ,radio-activity ( ! atmosph]e4 ,! exp]im5ts ( ,geitel#chd & ,c4 ,t4 ,r4 ,wilson#che 9 #aijj %[$ t a positively or negatively *>g$ conductor plac$ inside a clos$ vessel gradually lo/ its *>ge4 ,?is loss ( *>ge 0 %[n to be due to a small ionization ( ! air inside ! vessel4 ,el/] & ,geitel also f\nd t a *>g$ body expos$ 9 ! op5 air lo/ its *>ge rapidly1 & t ! rate ( dis*>ge 0 dep5d5t on ! locality & on atmosph]ic conditions4 ,a m detail$ description & discussion ( ^! results w be giv5 lat] 9 section #bhd4 ,9 ! c\rse ( ^! exp]im5ts1 ,geitel obs]v$ t ! rate ( dis*>ge increas$ slightly = "s "t aft] ! vessel _h be5 clos$4 ,he consid]$ t ?is might possibly be due to ! exi/5ce ( "s radio-active sub/ances 9 ! air1 :i* produc$ excit$ activity on ! walls ( ! vessel & s increas$ ! rate ( dissipation ( ! *>ge4 ,9 #aija ,el/] & ,geitel#chf tri$ ! bold exp]im5t ( see+ :e!r x 7 possible to extract a radio-active sub/ance f ! air4 ,! exp]im5ts ( ! writ] _h %[n t ! excit$ radio-activity f ! ?orium emanation c\ld be conc5trat$ on ! negative electrode 9 a /rong electric field4 ,?is result indicat$ t ! c>ri]s ( ! radio-activity _h a positive *>ge ( electricity4 ,el/] & ,geitel !re=e tri$ an exp]im5t to see :e!r positively *>g$ c>ri]s1 possess+ a simil> prop]ty1 7 pres5t 9 ! atmosph]e4 ,= ?is purpose a cyl9d] ( wire-nett+1 *>g$ negatively to #fjj volts1 0 expos$ = sev]al h\rs 9 ! op5 air4 ,! cyl9d] 0 !n remov$1 & quickly plac$ 9 a l>ge bell-j>1 inside :i* 0 plac$ an electroscope to detect ! rate ( dis*>ge4 ,x 0 f\nd t ! rate ( dis*>ge 0 increas$ to a slight ext5t4 ,9 ord] to multiply ! effect a wire ab\t #bj metres 9 l5g? 0 expos$ at "s height f ! gr\nd1 & 0 kept *>g$ to a high pot5tial by connect+ x to ! negative t]m9al ( an influ5ce ma*9e4 ,aft] exposure = "s h\rs1 ?is wire 0 remov$ & plac$ inside ! dissipation vessel4 ,! rate ( dis*>ge 0 f\nd to be increas$ _m times by ! pres5ce ( ! wire4 ,no increase 0 obs]v$ :5 ! wire 0 *>g$ positively in/ead ( negatively4 ,! results also %[$ t ! radio-active matt] c\ld be remov$ f ! wire 9 ! same way z f a wire made active by exposure 9 ! pres5ce ( ! ?orium emanation4 ,a piece ( lea!r moi/5$ ) ammonia 0 rubb$ ov] ! active wire4 ,on te/+ ! lea!r1 x 0 f\nd to be /rongly radio-active4 ,:5 a long wire 0 us$1 ! am\nt ( activity obta9$ on ! lea!r 0 comp>able ) t possess$ by a gram ( uranium oxide4 ,! activity produc$ on ! wire 0 n p]man5t1 b disappe>$ to a l>ge ext5t 9 ! c\rse ( a few h\rs4 ,! am\nt ( activity produc$ on a wire ( giv5 size1 expos$ "u simil> conditions1 0 indep5d5t ( ! mat]ial ( ! wire4 ,lead1 iron & copp] wires gave ab\t equal effects4 ,! am\nt ( activity obta9$ 0 greatly increas$ by expos+ a negatively *>g$ wire 9 a mass ( air :i* _h be5 undi/urb$ = a long "t4 ,exp]im5ts 7 made 9 ! great cave ( ,wolf5bttel1 & a v l>ge am\nt ( activity 0 obs]v$4 ,by transf]r+ ! activity to a piece ( lea!r x 0 f\nd t ! rays c\ld appreciably light up a scre5 ( b>ium plat9ocyanide 9 ! d>k#chg4 ,! rays also d>k5$ a photographic plate ?r\gh a piece ( alum9ium #ja mm4 9 ?ickness4 ,^! rem>kable exp]im5ts %[ t ! excit$ radio-activity obta9$ f ! atmosph]e is v simil> 9 "* to ! excit$ activity produc$ by ! emanations ( radium & ?orium4 ,no inve/igators h contribut$ m to our k ( ! radio-activity & ionization ( ! atmosph]e ?an ,el/] & ,geitel4 ,! exp]im5ts "h describ$ h be5 ! />t+-po9t ( a s]ies ( rese>*es by !m & o!rs on ! radio-active prop]ties ( ! atmosph]e1 :i* h l$ to a great ext5sion ( our k ( t important subject4 ,ru!r=d & ,allan#chh det]m9$ ! rate ( decay ( ! excit$ activity produc$ on a negatively *>g$ wire expos$ 9 ! op5 air4 ,a wire ab\t #ae metres long 0 expos$ 9 ! op5 air1 & kept *>g$ by an influ5ce ma*9e to a pot5tial ( ab\t #aj1jjj volts4 ,an h\r's exposure 0 suffici5t to obta9 a l>ge am\nt ( excit$ activity on ! wire4 ,! wire 0 !n rapidly remov$ & w\nd on a framework :i* =m$ ! c5tral electrode 9 a l>ge cyl9drical metal vessel4 ,! ionization curr5t = a saturation voltage 0 measur$ by means ( a s5sitive ,dolezalek electromet]4 ,! curr5t1 :i* is a measure ( ! activity ( ! wire1 0 f\nd to dim9i% accord+ to an expon5tial law ) ! "t1 fall+ to half value 9 ab\t #de m9utes4 ,! rate ( decay 0 indep5d5t ( ! mat]ial ( ! wire1 ( ! "t ( exposure1 & ( ! pot5tial ( ! wire4 ,an exam9ation 0 also made ( ! nature ( ! rays emitt$ by ! radio-active wire4 ,= ?is purpose a lead wire 0 made radio-active 9 ! mann] describ$1 & !n rapidly w\nd into ! =m ( a flat spiral4 ,! p5etrat+ p[] ( ! rays 0 te/$ 9 a vessel simil> to t %[n 9 ,fig4 #ag4 ,mo/ ( ! ionization 0 f\nd to be due to "s v easily absorb$ rays1 :i* 7 ( a slightly m p5etrat+ "* ?an ! rays emitt$ f a wire made active by ! radium or ?orium emanations4 ,! int5sity ( ! rays 0 cut d[n to half value by ab\t #jjja cm4 ( alum9ium4 ,! photographic action obs]v$ by ,el/] & ,geitel ?r\gh #ja mm4 ( alum9ium %[$ t "s p5etrat+ rays 7 also pres5t4 ,?is 0 aft]w>ds confirm$ by ,allan1 :o us$ ! electric me?od4 ,^! p5etrat+ rays are probably simil> 9 "* to ! rays f ! radio-elem5ts4 #bgd4 ,! excit$ activity produc$ on ! negatively *>g$ wire _c be due to an action ( ! /rong electric field on ! surface ( ! wire2 = v little excit$ activity is produc$ if ! wire is *>g$ to ! same pot5tial inside a clos$ cyl9d]4 ,we h se5 t ! excit$ activity produc$ on ! wire c be p>tially remov$ by rubb+ & by solution 9 acids1 &1 9 ?is respect1 x is simil> to ! excit$ activity produc$ 9 bodies by ! emanations ( radium & ?orium4 ,! v close simil>ity ( ! excit$ activity obta9$ f ! atmosph]e to t obta9$ f ! radium & ?orium emanations sugge/s ! probability t a radio-active emanation exi/s 9 ! atmosph]e4 ,?is view is confirm$ by a l>ge am\nt ( indirect evid5ce discuss$ 9 sections #bgf1 #bgg & #bhj4 ,assum+ ! pres5ce ( a radio-active emanation 9 ! atmosph]e1 ! radio-active effects obs]v$ receive a simple explanation4 ,! emanation 9 ! air gradually breaks up1 giv+ rise 9 "s way to positively *>g$ radio-active c>ri]s4 ,^! are driv5 to ! negative electrode 9 ! electric field1 & !re und]go a fur!r *ange1 giv+ rise to ! radiations obs]v$ at ! surface ( ! wire4 ,! matt] :i* causes excit$ activity w ?us be analog\s to ! active deposit ( radium & ?orium4 ,s9ce ! e>? is negatively electrifi$ ) reg>d to ! upp] atmosph]e1 ^! positive radio-active c>ri]s produc$ 9 ! air are cont9u\sly deposit$ on ! surface ( ! e>?4 ,ev]y?+ on ! surface ( ! e>?1 includ+ ! ext]nal surface ( build+s1 ! grass1 & leaves ( trees1 mu/ be cov]$ ) an invisible deposit ( radio-active mat]ial4 ,a hill1 or m\nta9 peak1 or any high mass ( rock or l&1 conc5trates ! e>?'s electric field at t po9t & consequ5tly w receive m excit$ radio-activity p] unit area ?an ! pla94 ,el/] & ,geitel h po9t$ out t ! great] ionization ( ! air obs]v$ 9 ! neighb\rhood ( project+ peaks receives a satisfactory explanation on ?is view4 ,if ! radio-active c>ri]s are produc$ at a uni=m rate 9 ! atmosph]e1 ! am\nt ( excit$ activity ,it1 produc$ on a wire expos$ "u giv5 conditions1 w1 aft] exposure = a "t t1 be giv5 by ,it ,i 7#a e-t 7 1 :]e ,i is ! maximum activity on ! wire & is ! con/ant ( decay ( ! excit$ activity4 ,s9ce ! activity ( a wire aft] removal falls to half value 9 ab\t #de m9utes1 ! value ( is #jib 7h\r74 ,"s exp]im5ts made by ,allan#chi are 9 r\gh agreem5t ) ! above equation4 ,accurate comp>ative results are difficult to obta9 on acc\nt ( ! incon/ancy ( ! radio-activity ( ! op5 air4 ,aft] an exposure ( a wire = sev]al h\rs1 ! activity rea*$ a practical maximum1 & 0 n mu* increas$ by cont9u$ exposure4 ,we h se5 7section #aia7 t ! c>ri]s ( ! active deposit ( radium & ?orium move 9 an electric field ) ab\t ! same velocity z ! ions4 ,we %\ld expect !re=e t a long wire *>g$ to a high negative pot5tial w\ld ab/ract ! active c>ri]s f ! atmosph]e = a consid]able di/ance4 ,?is does n appe> to be ! case1 = ,eve 7see section #bha7 has f\nd t ! c>ri]s are only ab/ract$ f ! air = a radius ( less ?an "o metre1 = a pot5tial ( ! wire ( #aj1jjj volts4 ,x seems probable t ! c>ri]s ( ! active matt] are deposit$ on ! num]\s f9e du/ p>ticles pres5t 9 ! air & ?us move v sl[ly ev5 9 a /rong electric field4 ,! am\nt ( excit$ activity produc$ on a wire1 support$ "s di/ance f ! surface ( ! e>?1 %\ld increase /eadily ) ! voltage1 = ! great] ! pot5tial1 ! great] ! volume ( air f :i* ! radio-active c>ri]s are ab/ract$4 ,! pres5ce ( radio-active matt] 9 ! atmosph]e w acc\nt = a consid]able portion ( ! ionization ( ! air obs]v$ ne> ! e>?4 ,?is important "q is discuss$ 9 m detail 9 section #bha4 #bge4 ,radio-activity ( fre%ly fall5 ra9 & sn[4 ,c4 ,t4 ,r4 ,wilson#cij tri$ exp]im5ts to see if any ( ! radio-active mat]ial f ! air 0 c>ri$ d[n by ra94 ,= ?is purpose a quantity ( fre%ly fall5 ra9 0 collect$1 rapidly evaporat$ to dryness 9 a plat9um vessel1 & ! activity ( ! residue te/$ by plac+ ! vessel 9 an electroscope4 ,9 all cases1 ! rate ( dis*>ge ( ! electroscope 0 consid]ably increas$4 ,f ab\t #ej c4c4 ( ra9 wat]1 an am\nt ( activity 0 obta9$ suffici5t to increase ! rate ( dis*>ge ( ! electroscope f\r or five times1 aft] ! rays _h trav]s$ a ?9 lay] ( alum9ium or gold-leaf4 ,! activity disappe>$ 9 ! c\rse ( a few h\rs1 fall+ to half value 9 ab\t #cj m9utes4 ,ra9 wat]1 :i* _h /ood = "s h\rs1 %[$ no trace ( activity4 ,tap wat]1 :5 evaporat$1 left no active residue4 ,! am\nts ( activity obta9$ f a giv5 quantity ( ra9 wat] 7 all ( ! same ord] ( magnitude1 :e!r ! ra9 0 precipitat$ 9 f9e or 9 l>ge drops1 by night or by day1 or :e!r ! ra9 0 te/$ at ! beg9n+ or at ! end ( a heavy ra9fall la/+ sev]al h\rs4 ,! activity obta9$ f ra9 is n de/roy$ by heat+ ! plat9um vessel to a r$ heat4 ,9 ?is & o!r respects x resembles ! excit$ activity obta9$ on negatively *>g$ wires expos$ 9 ! op5 air4 ,c4 ,t4 ,r4 ,wilson#cia obta9$ a radio-active precipitate f ra9 wat] by add+ a little b>ium *loride & precipitat+ ! b>ium ) sulphuric acid4 ,an active precipitate 0 also obta9$ :5 alum 0 add$ to ! wat]1 & ! alum9ium precipitat$ by ammonia4 ,! precipitates obta9$ 9 ?is way %[$ a l>ge activity4 ,! filtrate :5 boil$ d[n 0 q inactive1 %[+ t ! active matt] _h be5 completely remov$ by precipitation4 ,?is effect is q analog\s to ! production ( active precipitates f a solution conta9+ ! active deposit ( ?orium 7see section #ahe74 ,! radio-activity ( fre%ly fall5 sn[ 0 indep5d5tly obs]v$ by ,c4 ,t4 ,r4 ,wilson#cib 9 ,engl&1 & ,allan#cic & ,mc,lennan#cid 9 ,canada4 ,9 ord] to obta9 a l>ge am\nt ( activity1 ! surface lay] ( sn[ 0 remov$1 & evaporat$ to dryness 9 a metal vessel4 ,an active residue 0 obta9$ ) radio-active prop]ties simil> to ^? obs]v$ = fre%ly fall5 ra94 ,bo? ,wilson & ,allan f\nd t ! activity ( ra9 & sn[ decay$ at ab\t ! same rate1 ! activity fall+ to half value 9 ab\t #cj m9utes4 ,mc,lennan /ates t he f\nd a small] am\nt ( radio-activity 9 ! air aft] a prolong$ fall ( sn[4 ,s*mauss#cie has obs]v$ t drops ( wat] fall+ ?r\gh air ioniz$ by ,rntg5 rays acquire a negative *>ge4 ,?is effect is ascrib$ to ! fact t ! negative ions 9 air diffuse fa/] ?an ! positive4 ,on ?is view ! drops ( ra9 & flakes ( sn[ w\ld acquire a negative *>ge 9 fall+ ?r\gh ! air4 ,!y w\ld 9 consequ5ce act z collectors ( ! positive radio-active c>ri]s f ! air4 ,on evaporation ( ! wat] ! radio-active matt] w\ld be left beh9d4 #bgf4 ,radio-active emanations f ! e>?4 ,el/] & ,geitel obs]v$ t ! air 9 caves & cell>s 01 9 mo/ cases1 abnormally radio-active1 & %[$ v /rong ionization4 ,?is action might possibly be due to an effect ( /agnant air1 by :i* x produc$ a radio-active emanation f itself1 or to a diffusion ( a radio-active emanation f ! soil4 ,to te/ :e!r ?is emanation 0 produc$ by ! air itself1 ,el/] & ,geitel %ut up ! air = sev]al weeks 9 a l>ge boil]1 b no appreciable increase ( ! activity or ionization 0 obs]v$4 ,to see :e!r ! air imprison$ 9 ! capill>ies ( ! soil 0 radio-active1 ,el/] & ,geitel#cif put a pipe into ! e>? & suck$ up ! air into a te/+ vessel by means ( a wat] pump4 ,! app>atus employ$ to te/ ! ionization ( ! air is %[n 9 ,fig4 #ajc4 ,c is an electroscope connect$ ) a wire net1 ,z4 ,! active air 0 introduc$ into a l>ge bell-j> ( #bg litres capacity1 ! inside ( :i* 0 cov]$ ) wire nett+1 ,,mm4 ,! bell-j> re/$ on an iron plate ,,ab4 ,! electroscope c\ld be *>g$ by ! rod ,s4 ,! rate ( dis*>ge ( ! electroscope1 be=e ! active air 0 introduc$1 0 not$4 ,on all[+ ! active air to ent]1 ! rate ( dis*>ge increas$ rapidly1 ris+ 9 ! c\rse ( a few h\rs 9 "o exp]im5t to #cj times ! orig9al value4 ,!y f\nd t ! emanation produc$ excit$ activity on ! walls ( ! conta9+ vessel4 ,! air suck$ up f ! e>? 0 ev5 m active ?an t obs]v$ 9 caves & cell>s4 ,!re c ?us be little d\bt t ! abnormal activity obs]v$ 9 caves & cell>s is due to a radio-active emanation1 pres5t 9 ! e>?1 :i* gradually diffuses to ! surface & collects 9 places :]e ! air is n di/urb$4 ,results simil> to ^? obta9$ by ,el/] & ,geitel = ! air remov$ f ! e>? at ,wolf5bttel 7 also obta9$ lat] by ,eb]t & ,ew]s#cig at ,muni*4 ,!y f\nd a /rongly active emanation 9 ! soil1 &1 9 addition1 exam9$ ! v>iation ) "t ( ! activity due to ! emanation 9 a seal$ vessel4 ,aft] ! introduction ( ! active air into ! te/+ vessel1 ! activity 0 obs]v$ to increase = sev]al h\rs1 & !n to decay1 accord+ to an expon5tial law1 ) ! "t1 fall+ to half value 9 ab\t #cb days4 ,?is rate ( decay is m rapid ?an t obs]v$ = ! radium emanation1 :i* decays to half value 9 a little less ?an f\r days4 ,! increase ( activity ) "t is probably due to ! production ( excit$ activity on ! walls ( ! vessel by ! emanation4 ,9 ?is respect x is analog\s to ! increase ( activity obs]v$ :5 ! radium emanation is introduc$ into a clos$ vessel4 ,no def9ite exp]im5ts 7 made by ,eb]t & ,ew]s on ! rate ( decay ( ?is excit$ activity4 ,9 "o exp]im5t ! active emanation1 aft] /&+ 9 ! vessel = #adj h\rs1 0 remov$ by suck+ ord9>y air ( small activity ?r\gh ! app>atus4 ,! activity rapidly fell to ab\t half value1 & ?is 0 foll[$ by a v sl[ decrease ( ! activity ) "t4 ,?is result indicates t ab\t half ! rate ( dis*>ge obs]v$ 0 due to ! radiation f ! emanation & ! o!r half to ! excit$ activity produc$ by x4 ,! app>atus employ$ by ,eb]t & ,ew]s 9 ^! exp]im5ts 0 v simil> to t employ$ by ,el/] & ,geitel1 %[n 9 ,fig4 #ajc4 ,eb]t & ,ew]s obs]v$ t1 :5 ! wire net atta*$ to ! electroscope 0 *>g$ negatively1 ! rate ( dis*>ge obs]v$ 0 always great] ?an :5 x 0 *>g$ positively4 ,! diff]5ces obs]v$ betwe5 ! two rates ( dis*>ge v>i$ betwe5 #aj & #bj p] c5t4 ,a simil> effect has be5 obs]v$ by ,s>as91 ,tommas9a & ,mi*eli#cih = a wire made active by exposure to ! op5 air4 ,?is diff]5ce 9 ! rates ( dis*>ge = positive & negative electricity is probably connect$ ) ! pres5ce ( p>ticles ( du/ or small wat] globules susp5d$ 9 ! gas4 ,! exp]im5ts ( ,miss ,brooks 7section #aha7 h %[n t ! p>ticles ( du/ pres5t 9 ! air conta9+ ! ?orium emanation become radio-active4 ,a l>ge proportion ( ^! du/ p>ticles acquire a positive *>ge & are c>ri$ to ! negative electrode 9 an electric field4 ,?is effect w\ld increase ! rate ( dis*>ge ( ! electroscope :5 *>g$ negatively4 ,9 lat] exp]im5ts1 ,eb]t & ,ew]s notic$ t1 9 "s cases1 :5 ! air _h be5 kept 9 ! vessel = sev]al days1 ! effect 0 rev]s$1 & ! electroscope %[$ a great rate ( dis*>ge :5 *>g$ positively4 ,illu/ration3 ,fig4 #ajc4 ,j4 ,j4 ,?omson#cii has obs]v$ t ! magnitude ( ! ionization curr5t dep5ds on ! direction ( ! electric field1 if f9e wat] globules are susp5d$ 9 ! ioniz$ gas4 ,9 lat] exp]im5ts1 ,eb]t#djj f\nd t ! radio-active emanation c\ld be remov$ f ! air by cond5sation 9 liquid air4 ,?is prop]ty ( ! emanation 0 indep5d5tly discov]$ by ,eb]t be=e he 0 aw>e ( ! results ( ,ru!r=d & ,soddy on ! cond5sation ( ! emanations ( radium & ?orium4 ,to increase ! am\nt ( radio-active emanation 9 a giv5 volume ( air1 a quantity ( ! active air1 obta9$ by suck+ ! air f ! soil1 0 cond5s$ by a liquid air ma*9e4 ,! air 0 !n all[$ p>tially to evaporate1 b ! process 0 /opp$ be=e ! po9t ( volatilization ( ! emanation 0 rea*$4 ,?is process 0 repeat$ ) ano!r quantity ( air & ! residues add$ toge!r4 ,proce$+ 9 ?is way1 he 0 able to conc5trate ! emanation 9 a small volume ( air4 ,on all[+ ! air to evaporate1 ! ionization ( ! air 9 ! te/+ vessel increas$ rapidly = a "t & !n sl[ly dim9i%$4 ,eb]t /ates t ! maximum = ! emanation :i* _h be5 liquefi$ = "s "t 0 rea*$ e>li] ?an = fre% air4 ,! rate ( decay ( activity ( ! emanation 0 n alt]$ by keep+ x at ! temp]ature ( liquid air = "s "t4 ,9 ?is respect x behaves l ! emanations ( radium & ?orium4 ,j4 ,j4 ,?omson#dja f\nd t air bubbl$ ?r\gh ,cambridge tap wat] %[$ mu* great] conductivity ?an ord9>y air4 ,! air 0 drawn ?r\gh ! wat] by means ( a wat] pump into a l>ge gasomet]1 :5 ! ionization curr5t 0 te/$ ) a s5sitive electromet]4 ,:5 a rod *>g$ negatively 0 introduc$ into ?is conduct+ air x became active4 ,aft] an exposure = a p]iod ( #ae to #cj m9utes 9 ! conduct+ gas1 ! rod1 :5 introduc$ into a second te/+ vessel1 increas$ ! saturation curr5t 9 ! vessel to ab\t five times ! normal am\nt4 ,v little effect 0 produc$ :5 ! rod 0 un*>g$ or *>g$ positively = ! same "t4 ,! activity ( ! rod decay$ ) ! "t1 fall+ to half value 9 ab\t #dj m9utes4 ,! am\nt ( activity produc$ on a wire "u con/ant conditions 0 indep5d5t ( ! mat]ial ( ! wire4 ,! rays f ! rod 7 readily absorb$ 9 a few c5timetres ( air4 ,^! effects 71 at fir/1 ?\ght to be due to ! action ( ! small wat] drops susp5d$ 9 ! gas1 = x 0 well kn[n t air rapidly drawn ?r\gh wat] causes a tempor>y increase 9 its conductivity4 ,lat] results1 h[ev]1 %[$ t !re 0 a radio-active emanation pres5t 9 ,cambridge tap wat]4 ,?is l$ to an exam9ation ( ! wat]s f deep wells 9 v>i\s p>ts ( ,engl&1 & ,j4 ,j4 ,?omson f\nd t1 9 "s cases1 a l>ge am\nt ( emanation c\ld be obta9$ f ! well wat]4 ,! emanation 0 releas$ ei!r by bubbl+ air ?r\gh ! wat] or by boil+ ! wat]4 ,! gases obta9$ by boil+ ! wat] 7 f\nd to be /rongly active4 ,a sample ( air mix$ ) ! radio-active emanation 0 cond5s$4 ,! liquefi$ gas 0 all[$ to evaporate1 & ! e>li] & lat] portions ( ! gas 7 collect$ 9 sep>ate vessels4 ,! f9al portion 0 f\nd to be ab\t #cj times z active z ! fir/ portion4 ,an exam9ation ( ! radio-active prop]ties ( ! active gases s obta9$ has be5 made by ,adams#djb4 ,he f\nd t ! activity ( ! emanation decay$1 accord+ to an expon5tial law1 ) ! "t1 fall+ to half value 9 ab\t #cd days4 ,?is is n v diff]5t f ! rate ( decay ( ! activity ( ! radium emanation1 :i* falls to half value 9 a little less ?an f\r days4 ,! excit$ activity produc$ by ! emanation decay$ to half value 9 ab\t #ce m9utes4 ,! decay ( ! excit$ activity f radium is at fir/ irregul>1 b aft] "s "t falls (f1 accord+ to an expon5tial law1 dim9i%+ to half value 9 #bh m9utes4 ,tak+ into acc\nt ! unc]ta9ty atta*+ to measurem5ts ( ! v small ionization obs]v$ 9 ^! exp]im5ts1 ! results indicate t ! emanation obta9$ f well wat] 9 ,engl& is simil> to1 if n id5tical )1 ! radium emanation4 ,adams obs]v$ t ! emanation 0 slightly soluble 9 wat]4 ,aft] well wat] _h be5 boil$ = a :ile & !n put aside1 x 0 f\nd to recov] its p[] ( giv+ (f an emanation4 ,! am\nt obta9$ aft] /&+ = "s "t 0 nev] m ?an #aj p] c5t4 ( ! am\nt fir/ obta9$4 ,?us x is probable t ! well wat]1 9 addition to ! emanations mix$ ) x1 has also a slight am\nt ( a p]man5t radio-active sub/ance dissolv$ 9 x4 ,ord9>y ra9 wat] or di/ill$ wat] does n give (f an emanation4 ,bum/ead & ,:eel]#djc h made a v c>eful exam9ation ( ! radio-activity ( ! emanation obta9$ f ! surface wat] & soil at ,new ,hav51 ,connecticut4 ,! emanation1 obta9$ f ! wat] by boil+1 0 pass$ into a l>ge te/+ cyl9d]1 & measurem5ts ( ! curr5t 7 made by means ( a s5sitive electromet]4 ,! curr5t gradually rose to a maximum1 aft] ! introduction ( ! emanation1 9 exactly ! same way z ! curr5t increases 9 a vessel aft] ! introduction ( ! radium emanation4 ,! decay ( activity ( ! emanations obta9$ f ! wat] & soil 0 c>efully measur$1 &1 )9 ! limits ( exp]im5tal error1 agre$ ) ! rate ( decay ( activity obs]v$ = ! radium emanation4 ,! id5tity ( ! emanations f ! wat] & soil ) ! radium emanation 0 /ill fur!r e/abli%$ by exp]im5ts on ! rate ( diffusion ( ! emanation ?r\gh a por\s plate4 ,by comp>ative te/s x 0 f\nd t ! coeffici5t ( diffusion ( ! emanations f ! wat] & soil 0 ! same z = ! radium emanation4 ,also1 by comp>ison ( ! rate ( diffusion ( c>bonic acid1 x 0 f\nd t ! d5sity ( ! emanation 0 ab\t f\r times t ( c>bonic acid1 a result 9 good agreem5t ) t f\nd = ! radium emanation 7sections #afa & #afb74 ,bum/ead#djd has f\nd t a consid]able am\nt ( ?orium z well z radium emanation exi/s 9 ! air ( ,new ,hav54 ,= a ?ree h\r exposure 9 ! op5 air1 #c to #e p] c5t4 ( ! excit$ activity on ! wire is due to ?orium4 ,= a twelve h\r exposure1 ! ?orium activity 0 sometimes #ae p] c5t4 ( ! :ole4 ,on acc\nt ( ! comp>atively sl[ decay ( ! excit$ activity ( ?orium1 ! activity on ! wire aft] removal = ?ree or f\r h\rs 0 due almo/ entirely to ?orium4 ,! rate ( decay c\ld !n be measur$ accurately1 & 0 f\nd to be ! same z = a wire expos$ 9 ! pres5ce ( ! ?orium emanation4 ,dad\rian#dje has made an exam9ation ( ! und]gr\nd air 9 ,new ,hav51 & has f\nd t ?is too conta9s a l>ge quantity ( ! ?orium emanation4 ,a circul> hole ab\t #ej cms4 9 diamet] & #b metres deep 0 dug 9 ! gr\nd4 ,a numb] ( wires 7 w\nd on an insulat$ frame & susp5d$ 9 ! hole1 ! top ( ! hole !n be+ cov]$ ov]4 ,! wire 0 *>g$ negatively by a ,wim%ur/ ma*9e4 ,aft] a long exposure ! excit$ activity on ! wire dim9i%$ at a rate t %[$ x to be a mixture ( ! excit$ activities ( ?orium & radium4 ,a v l>ge am\nt ( "w has be5 done 9 exam9+ v>i\s hot & m9]al spr+s = ! pres5ce ( ! radium emanation1 & x is n possible "h to ref] m ?an briefly to a few ( ! v num]\s pap]s t h be5 publi%$ on ?is subject bo? 9 ,europe & ,am]ica4 ,h4 ,s4 ,all5 & ,"l ,bly?swood#djf h obs]v$ t ! hot spr+s at ,ba? & ,buxton gave (f a radio-active emanation4 ,?is 0 confirm$ by ,/rutt#djg1 :o f\nd t ! escap+ gases conta9$ ! radium emanation1 & also t ! mud deposit$ f ! spr+s conta9$ a trace ( radium salts4 ,^! results are ( consid]able int]e/1 = ,"l ,rayleigh has obs]v$ t helium is conta9$ among ! gases evolv$ by ! spr+s4 ,x appe>s probable t ! helium obs]v$ is produc$ f ! radium or radio-active deposits ?r\gh :i* ! wat] fl[s4 ,_m m9]al & hot spr+s :i* are fam\s = _! curative prop]ties h be5 f\nd to conta9 traces ( radium & also consid]able am\nts ( radium emanation4 ,x has be5 sugge/$ t ! curative prop]ties may be due to "s ext5t to ! pres5ce ( ^! m9ute quantities ( radium4 ,him/$t#djh f\nd t ! !rmal spr+s at ,bad5 ,bad5 conta9$ ! radium emanation1 :ile ,el/] & ,geitel#dji exam9$ ! deposits =m$ by ^! spr+s & f\nd !m to conta9 small quantities ( radium salts4 ,results ( a simil> "* 7 obta9$ = a numb] ( wat]s 9 ,g]many by ,dorn#daj1 ,s*5ck#daa1 & ,h4 ,ma*e#dab4 ,curie & ,laborde#dac h te/$ ! wat]s ( a l>ge numb] ( m9]al spr+s & f\nd t ! great majority conta9 ! radium emanation4 ,9 ?is connection1 x is ( int]e/ to note t ,curie & ,laborde f\nd v little emanation 9 ! wat]s ( ,sal9s-,m\ti]s1 :ile ,blanc#dad obs]v$1 on ! o!r h&1 t ! s$im5t f ! spr+ 0 v active4 ,a clos] exam9ation ( ?is deposit by ,blanc reveal$ ! fact t x conta9$ a consid]able quantity ( ?orium4 ,?is 0 prov$ by f9d+ t x gave out an emanation1 :i* lo/ half ( its activity 9 "o m9ute1 & produc$ excit$ activity1 :i* fell to half value 9 ab\t #aa h\rs4 ,boltwood#dae has te/$ a numb] ( samples ( spr+ wat] f diff]5t s\rces 9 ,am]ica & has f\nd t _m ( !m conta9 ! radium emanation4 ,mo/ ( ! results ^u ! am\nt ( radium emanation f diff]5t s\rces h be5 express$ 9 arbitr>y units )\t1 9 _m cases1 any comp>ative /&>d be+ giv54 ,boltwood 7loc4 cit47 has describ$ a satisfactory me?od = collect+ & te/+ ! emanation f diff]5t wat]s1 & has sugge/$ t ! rate ( dis*>ge obs]v$ by ! electroscope or ! electromet] %\ld be express$ 9 t]ms ( ! effect due to ! emanation lib]at$ on solution ( a def9ite weight ( ! m9]al uran9ite4 ,s9ce 9 e m9]al s f> exam9$1 ! am\nt ( radium pres5t is proportional to ! am\nt ( uranium1 su* a /&>d w\ld be suffici5tly def9ite = practical purposes4 ,! emanation lib]at$ f a few c5tigrams ( ! m9]al is suffici5t to give a conv5i5t rate ( dis*>ge ( an electroscope4 ,su* a me?od is pref]able to us+ a kn[n quantity ( a radium comp\nd z a /&>d1 s9ce x is difficult to "k ) c]ta9ty ! activity ( ! prep>ations ( radium :i* may be 9 ! possession ( ! diff]5t exp]im5t]s4 #bgg4 ,radio-activity ( con/itu5ts ( ! e>?4 ,el/] & ,geitel#daf obs]v$ t1 al?\gh 9 _m cases ! conductivity ( ! air 0 abnormally high 9 und]gr\nd enclosures1 ! conductivity v>i$ greatly 9 diff]5t places4 ,9 ! ,baumann ,cave1 = example1 ! conductivity ( ! air 0 n9e times ! normal1 b 9 ! ,ib]g ,cave only ?ree times ! normal4 ,9 a cell> at ,clau/hal ! conductivity 0 only slightly great] ?an ! normal1 b ! excit$ radio-activity obta9$ on a negatively *>g$ wire expos$ 9 x 0 only ( ! excit$ radio-activity obta9$ :5 ! wire 0 expos$ 9 ! free air4 ,!y conclud$ f ^! exp]im5ts t ! am\nt ( radio-activity 9 ! diff]5t places probably v>i$ ) ! nature ( ! soil4 ,obs]vations 7 !n made on ! conductivity ( ! air suck$ up f ! e>? at diff]5t p>ts ( ! c\ntry4 ,! clayey & lime/one soils at ,wolf5bttel 7 f\nd to be /rongly active1 ! conductivity v>y+ f f\r to sixte5 times ! normal am\nt4 ,a sample ( air f ! %ell lime/one ( ,wrzburg & f ! basalt ( ,wilhelm%he %[$ v little activity4 ,exp]im5ts 7 made to see :e!r any radio-active sub/ance c\ld be detect$ 9 ! soil itself4 ,= ?is purpose "s e>? 0 plac$ on a di% & introduc$ "u a bell-j>1 simil> to t %[n 9 ,fig4 #ajc4 ,! conductivity ( ! air 9 ! bell-j> increas$ ) ! "t1 ris+ to ?ree times ! normal value aft] sev]al days4 ,little diff]5ce 0 obs]v$ :e!r ! e>? 0 dry or moi/4 ,! activity ( ! soil seem$ to be p]man5t1 = no *ange 9 ! activity 0 obs]v$ aft] ! e>? _h be5 laid aside = eight mon?s4 ,attempts 7 !n made to sep>ate ! radio-active con/itu5t f ! soil by *emical treatm5t4 ,= ?is purpose a sample ( clay 0 te/$4 ,by extraction ) hydro*loric acid all ! calcium c>bonate 0 remov$4 ,on dry+ ! clay ! activity 0 f\nd to be r$uc$1 b x spontane\sly rega9$ its orig9al activity 9 ! c\rse ( a few days4 ,x seems probable1 !re=e1 t an active product _h be5 sep>at$ f ! soil by ! acid4 ,el/] & ,geitel consid] t an active sub/ance 0 pres5t 9 ! clay1 :i* =m$ a product m readily soluble 9 hydro*loric acid ?an ! active mat]ial itself4 ,!re seem$ to be a process ( sep>ation analog\s to t ( ,? ,x f ?orium by precipitation ) ammonia4 ,exp]im5ts 7 also made to see :e!r sub/ances plac$ 9 ! e>? acquir$ any radio-activity4 ,= ?is purpose samples ( pott]'s clay1 :it5+1 & heavy sp>1 wrapp$ 9 l951 7 plac$ 9 ! e>? #ej cms4 bel[ ! surface4 ,aft] an int]val ( a mon?1 ^! 7 dug up & _! activity exam9$4 ,! clay 0 ! only sub/ance :i* %[$ any activity4 ,! activity ( ! clay dim9i%$ ) ! "t1 %[+ t activity _h be5 excit$ 9 x by ! emanations pres5t 9 ! soil4 ,el/] & ,geitel#dag h f\nd t a l>ge quantity ( ! radio-active emanation c be obta9$ by suck+ air ?r\gh clay4 ,9 "s cases1 ! conductivity ( ! air 9 ! te/+ vessel 0 increas$ ov] #ajj times4 ,!y h also f\nd t ! s-call$ 8fango0--a f9e mud obta9$ f hot spr+s 9 ,battaglia1 ,nor!rn ,italy--gives (f ?ree or f\r times z mu* emanation z clay4 ,by treat+ ! fango ) acid1 ! active sub/ance pres5t 0 dissolv$4 ,on add+ "s b>ium *loride to ! solution1 & precipitat+ ! b>ium z sulphate1 ! active sub/ance 0 remov$1 & 9 ?is way a precipitate 0 obta9$ ov] #ajj times z active1 weight = weight1 z ! orig9al fango4 ,comp>isons 7 made ( ! rate ( decay ( ! excit$ activity1 due to ! emanation f fango1 ) t due to ! radium emanation1 & )9 ! limits ( error1 ! decay curves obta9$ 7 f\nd to be id5tical4 ,!re c ?us be no d\bt t ! activity obs]v$ 9 fango is due to ! pres5ce ( a small quantity ( radium4 ,el/] & ,geitel calculate t ! am\nt ( radium1 conta9$ 9 x1 is only ab\t "o-?\s&? ( ! am\nt to be obta9$ f an equal weight ( pit*bl5de f ,joa*im/hal4 ,v9c5ti & ,levi ,da ,z>a#dah h f\nd t ! wat]s & s$im5ts ( a numb] ( hot spr+s 9 ,nor!rn ,italy conta9 ! radium emanation4 ,el/] & ,geitel obs]v$ t natural c>bonic acid obta9$ f great dep?s ( old volcanic soil 0 radio-active1 :ile ,burton#dai f\nd t ! petroleum f a deep well 9 ,ont>io1 ,canada1 conta9$ a l>ge quantity ( emanation1 probably ( radium1 s9ce its activity fell to half value 9 #ca days1 :ile ! excit$ activity produc$ by ! emanation fell to half value 9 ab\t #ce m9utes4 ,a p]man5tly active deposit 0 left beh9d aft] volatilization ( ! oil1 indicat+ t probably "o or m ( ! radio-elem5ts 7 pres5t 9 m9ute quantity4 ,el/] & ,geitel#dbj h f\nd t ! active s$im5ts obta9$ f spr+s at ,nauheim & ,bad5 ,bad5 %[$ abnormal rates ( decay ( ! excit$ activity4 ,?is 0 f9ally trac$ to ! pres5ce 9 ! deposit ( bo? ?orium & radium4 ,by suitable *emical me?ods1 ! two active sub/ances 7 sep>at$ f ea* o!r & 7 !n te/$ sep>ately4 #bgh4 ,effect ( meteorological conditions ^u ! radio-activity ( ! atmosph]e4 ,! orig9al exp]im5ts ( ,el/] & ,geitel on ! excit$ radio-activity d]iv$ f ! atmosph]e 7 repeat$ by ,ru!r=d & ,allan#dba 9 ,canada4 ,x 0 f\nd t a l>ge am\nt ( excit$ radio-activity c\ld be d]iv$ f ! air1 & t ! effects 7 simil> to ^? obs]v$ by ,el/] & ,geitel 9 ,g]many4 ,?is 0 ! case ev5 on ! colde/ day 9 w9t]1 :5 ! gr\nd 0 cov]$ deeply ) sn[ & w9d 0 bl[+ f ! nor? ov] sn[-cov]$ l&s4 ,! results %[$ t ! radio-activity pres5t 9 ! air 0 n mu* affect$ by ! pres5ce ( moi/ure1 = ! air dur+ a ,canadian w9t] is extremely dry4 ,! greate/ am\nt ( excit$ activity on a negatively *>g$ wire 0 obta9$ 9 a /rong w9d4 ,9 "s cases ! am\nt produc$ = a giv5 "t ( exposure 0 t5 to tw5ty times ! normal am\nt4 ,a cold bright day ( w9t] usually gave m effect ?an a w>m dull day 9 summ]4 ,el/] & ,geitel#dbb h made a detail$ exam9ation ( ! effect ( meteorological conditions on ! am\nt ( excit$ radio-activity to be d]iv$ f ! atmosph]e4 ,= ?is purpose a simple portable app>atus 0 devis$ by !m & us$ = ! :ole s]ies ( exp]im5ts4 ,a l>ge numb] ( obs]vations 7 tak51 ext5d+ ov] a p]iod ( twelve mon?s4 ,!y f\nd t ! am\nt ( excit$ activity obta9$ 0 subject to great v>iations4 ,! extreme values obta9$ v>i$ 9 ! ratio ( #af to #a4 ,no direct connection c\ld be trac$ betwe5 ! am\nt ( ionization 9 ! atmosph]e & ! am\nt ( excit$ activity produc$4 ,!y f\nd t ! greate/ am\nt ( excit$ activity 0 obta9$ dur+ a fog1 :5 ! am\nt ( ionization 9 ! air 0 small4 ,?is result1 h[ev]1 is n necess>ily contradictory to ! view t ! ionization & activity ( ! air are to a c]ta9 ext5t connect$4 ,f ! exp]im5ts ( ,miss ,brooks on ! effect ( du/ 9 act+ z c>ri]s ( excit$ activity1 m excit$ activity %\ld be obta9$ dur+ a fog ?an 9 cle> air4 ,! p>ticles ( wat] become c5tres = ! deposit ( radio-active matt]4 ,! positive c>ri]s are ?us an*or$ & are n remov$ f ! air by ! e>?'s field4 ,9 a /rong electric field1 ^! small drops w be c>ri$ to ! negative electrode & manife/ _! activity on ! surface ( ! wire4 ,on ! o!r h&1 ! di/ribution ( wat] globules ?r\gh\t ! air causes ! ions 9 ! air to disappe> rapidly 9 consequ5ce ( _! diffusion to ! surface ( ! drops 7see section #ca74 ,= ?is reason ! d5s] ! fog1 ! small] w be ! conductivity obs]v$ 9 ! air4 ,l[]+ ! temp]ature ( ! air _h a decid$ influ5ce4 ,! av]age activity obs]v$ bel[ #j ,c4 0 #add times ! activity obs]v$ above #j ,c4 ,! height ( ! b>omet] 0 f\nd to ex]t a m>k$ influ5ce on ! am\nt ( excit$ activity to be d]iv$ f ! air4 ,! l[] ! b>omet] ! great] 0 ! am\nt ( excit$ activity 9 ! air4 ,! effect ( v>iation ( ! height ( ! b>omet] is intelligible1 :5 x is consid]$ t probably a l>ge proportion ( ! radio-activity obs]v$ 9 ! air is due to ! radio-active emanations :i* are cont9u\sly diffus+ f ! e>? into ! atmosph]e4 ,el/] & ,geitel h sugge/$ t a l[]+ ( ! pressure ( ! air w\ld cause ! air f ! gr\nd to be drawn up f ! capill>ies ( ! e>? into ! atmosph]e4 ,?is1 h[ev]1 ne$ n necess>ily be ! case if ! conditions ( ! escape ( ! emanation into ! atmosph]e are alt]$ by ! v>iation ( ! position ( und]gr\nd wat] or by a heavy fall ( ra94 ,! am\nt ( excit$ activity to be d]iv$ f ! air on ! ,baltic ,coa/ 0 only "o-?ird ( t obs]v$ inl& at ,wolf5bttel4 ,exp]im5ts on ! radio-activity ( ! air 9 mid-ocean w\ld be ( great importance 9 ord] to settle :e!r ! radio-activity obs]v$ 9 ! air is due to ! emanations f ! soil alone4 ,x is probable t ! radio-activity ( ! air at diff]5t po9ts ( ! e>? may v>y widely1 & may l>gely dep5d on ! nature ( ! soil4 ,saake#dbc has f\nd t ! am\nt ( emanation pres5t 9 ! air at high altitudes 9 ! valley ( ,arosa 9 ,switz]l& is mu* great] ?an ! normal am\nt at l[] levels4 ,el/] & ,geitel h obs]v$ t !re is also a l>g] numb] ( ions 9 ! air at high altitudes1 & sugge/ t ! curative effect ( !rmal spr+s & ! physiological actions ( ! air at high levels may be connect$ ) ! pres5ce ( an unusual am\nt ( radio-active matt] 9 ! atmosph]e4 ,simpson#dbd made exp]im5ts on ! am\nt ( excit$ activity at ,k>asjoh1 ,norway1 at a height ( ab\t #aej feet above sea level4 ,! sun did n rise above ! level ( ! horizon dur+ ! "t ! obs]vations 7 tak54 ,! av]age am\nt ( excit$ activity obta9$ f ! air 0 consid]ably great] ?an ! normal am\nt obs]v$ by ,el/] & ,geitel 9 ,g]many4 ,?is 0 ! m surpris+ z ! gr\nd 0 froz5 h>d & cov]$ ) deep sn[4 ,allan1 work+ 9 ,montreal1 ,canada1 e>ly obs]v$ t ! am\nt ( activity to be obta9$ f ! air 0 ab\t ! same 9 summ] z 9 w9t]1 al?\gh1 9 ! latt] case1 ! :ole e>? 0 deeply froz5 & cov]$ ) sn[1 & ! w9ds blew f ! nor? ov] sn[-cov]$ l&s4 ,"u su* conditions1 a dim9ution ( ! am\nt ( activity is to be expect$ s9ce ! diffusion ( ! emanation mu/ be ret>d$1 if n altoge!r /opp$1 by ! freez+ ( ! soil4 ,on ! o!r h&1 x appe>s difficult to escape f ! conclusion ( ,el/] & ,geitel t ! emanation pres5t 9 ! atmosph]e is evolv$ f ! e>? itself4 ,"s int]e/+ exp]im5ts h be5 made by ,mc,lennan#dbe on ! am\nt ( excit$ radio-activity to be d]iv$ f ! air :5 fill$ ) f9e spray4 ,! exp]im5ts 7 made at ! foot ( ! ,am]ican ,fall at ,niag>a4 ,an insulat$ wire 0 susp5d$ ne> ! foot ( ! ,fall1 & ! am\nt ( excit$ activity on ! wire comp>$ ) ! am\nt to be obta9$ on ! same wire = ! same exposure 9 ,toronto4 ,! am\nt ( activity obta9$ f ! air at ,toronto 0 g5]ally five or six times t obta9$ f ! air at ! ,falls4 ,9 ^! exp]im5ts x 0 n necess>y to use an electric ma*9e to *>ge ! wire negatively1 = ! fall+ spray kept ! insulat$ wire p]man5tly *>g$ to a pot5tial ( ab\t #gejj volts4 ,^! results indicate t ! fall+ spray _h a negative *>ge & electrifi$ ! wire4 ,! small am\nt ( ! excit$ radio-activity at ! ,falls 0 probably due to ! fact t ! negatively *>g$ drops ab/ract$ ! positively *>g$ radio-active c>ri]s f ! atmosph]e1 & 9 fall+ c>ri$ !m to ! riv] bel[4 ,on collect+ ! spray & evaporat+ x1 no active residue 0 obta9$4 ,su* a result is1 h[ev]1 to be expect$ on acc\nt ( ! m9ute proportion ( ! spray te/$ comp>$ ) t pres5t 9 ! air4 #bgi4 ,a v p5etrat+ radiation f ! e>?'s surface4 ,mc,lennan#dbf1 & ,ru!r=d & ,cooke#dbg indep5d5tly1 obs]v$ ! pres5ce ( a v p5etrat+ radiation inside build+s4 ,mc,lennan measur$ ! natural conductivity ( ! air 9 a l>ge clos$ metal cyl9d] by means ( a s5sitive electromet]4 ,! cyl9d] 0 !n plac$ inside ano!r & ! space betwe5 fill$ ) wat]4 ,= a ?ickness ( wat] betwe5 ! cyl9d]s ( #be cms4 ! conductivity ( ! air 9 ! inn] cyl9d] fell to ab\t #fc p] c5t4 ( its initial value4 ,?is result %[s t "p ( ! ionization 9 ! inn] cyl9d] 0 due to a p5etrat+ radiation f an ext]nal s\rce1 :i* radiation 0 p>tially or :olly absorb$ 9 wat]4 ,ru!r=d & ,cooke obs]v$ t ! rate ( dis*>ge ( a seal$ brass electroscope 0 dim9i%$ by plac+ a lead scre5 ar\nd ! electroscope4 ,a detail$ inve/igation ( ! decrease ( ! rate ( dis*>ge 9 ! electroscope1 :5 surr\nd$ by metal scre5s1 0 made lat] by ,cooke#dbh4 ,a ?ickness ( #e cms4 ( lead r\nd ! electroscope decreas$ ! rate ( dis*>ge ab\t #cj p] c5t4 ,fur!r increase ( ! ?ickness ( ! scre5 _h no effect4 ,:5 ! app>atus 0 surr\nd$ by #e tons ( pig-lead ! rate ( dis*>ge 0 ab\t ! same z :5 x 0 surr\nd$ by a plate ab\t #c cms4 ?ick4 ,an iron scre5 also dim9i%$ ! rate ( dis*>ge to ab\t ! same ext5t z ! lead4 ,by suitably arrang+ lead scre5s x 0 f\nd t ! radiation came equally f all directions4 ,x 0 ( ! same int5sity by night z by day4 ,9 ord] to be sure t ?is p5etrat+ radiation did n arise f ! pres5ce ( radio-active sub/ances 9 ! laboratory1 ! exp]im5ts 7 repeat$ 9 build+s 9 :i* radio-active sub/ances _h nev] be5 introduc$1 & also on ! op5 gr\nd f> remov$ f any build+4 ,9 all cases a dim9ution ( ! rate ( dis*>ge ( ! electroscope1 :5 surr\nd$ by lead scre5s1 0 obs]v$4 ,^! results %[ t a p5etrat+ radiation is pres5t at ! surface ( ! e>?1 aris+ p>tly f ! e>? itself & p>tly f ! atmosph]e4 ,! result is n surpris+ :5 ! radio-activity ( ! e>? & atmosph]e is tak5 into acc\nt4 ,! writ] has f\nd t bodies made active by exposure to ! emanations f ?orium & radium give out rays4 ,we may expect !n t ! v simil> excit$ radio-activity :i* is pres5t 9 ! e>? & atmosph]e %\ld also give rise to rays ( a simil> "*4 ,m rec5t "w1 h[ev] 7section #bhf71 indicates t ?is explanation is n suffici5t to expla9 all ! facts obs]v$4 #bhj4 ,comp>ison ( ! radio-activity ( ! atmosph]e ) t produc$ by ! radio-elem5ts4 ,! radio-active ph5om5a obs]v$ 9 ! e>? & atmosph]e are v simil> 9 "* to ^? produc$ by ?orium & radium4 ,radio-active emanations are pres5t 9 ! air ( caves & cell>s1 9 natural c>bonic acid1 & 9 deep well wat]1 & ^! emanations produce excit$ radio-activity on all bodies 9 contact ) !m4 ,! "q n[ arises :e!r ^! effects are due entirely to kn[n radio-elem5ts pres5t 9 ! e>? or to unkn[n k9ds ( radio-active matt]4 ,! simple/ me?od ( te/+ ?is po9t is to comp>e ! rate ( decay ( ! radio-active product 9 ! atmosph]e ) ^? ( ! kn[n radio-active products ( ?orium & radium4 ,a cursory exam9ation ( ! facts at once %[s t ! radio-activity ( ! atmosph]e is mu* m closely alli$ to effects produc$ by radium ?an to ^? due to ?orium4 ,! activity ( ! emanation releas$ f well wat]1 & also t suck$ up f ! e>?1 decays to half value 9 ab\t #cc days1 :ile ! activity ( ! radium emanation decays to half value 9 an int]val ( #cg to #d days4 ,consid]+ ! difficulty ( mak+ accurate det]m9ations ( ^! quantities1 ! rates ( decay ( ! activity ( ! emanations f ! e>? & f radium agree )9 ! limits ( exp]im5tal error4 ,a l>ge numb] ( obs]v]s h f\nd t ! radium emanation is pres5t 9 ! wat] ( !rmal spr+s & 9 ! s$im5t deposit$ by !m4 ,bum/ead & ,:eel] h %[n t ! emanation f ! soil & surface wat] ( ,new ,hav5 is id5tical ) t f radium4 ,if ! emanations f ! e>? & f radium are ! same1 ! excit$ activities produc$ %\ld h ! same rate ( decay4 ,! emanation f well wat] 9 ,engl& approximately fulfils ?is condition 7section #bgf71 b an obs]vation record$ by ,eb]t & ,ew]s 7section #bgf7 seems to %[ t ! excit$ activity due to ! emanation suck$ up f ! e>? decays at a v sl[ rate comp>$ ) t due to radium4 ,bum/ead has giv5 und\bt$ evid5ce t ! ?orium z well z ! radium emanation is also pres5t 9 ! atmosph]e at ,new ,hav51 :ile ,dad\rian has %[n t x is emitt$ by ,new ,hav5 soil4 ,blanc1 & ,el/] & ,geitel1 h also f\nd t ?orium is pres5t 9 ! s$im5t f "s !rmal spr+s4 ,if ! active matt] 9 ! atmosph]e consi/s ma9ly ( ! radium emanation1 ! active deposit on a negatively *>g$ wire1 expos$ 9 ! op5 air1 %\ld initially consi/ ( radium ,a1 ,b & ,c4 ,! curve ( decay %\ld be id5tical ) ! decay curve ( ! excit$ activity ( radium1 measur$ by ! rays1 t is1 !re %\ld be a rapid initial drop correspond+ to ! initial #c m9ute *ange1 !n a sl[ rate ( v>iation1 ! activity aft] sev]al h\rs decay+ to half value 9 ab\t #bh m9utes 7see section #bbb74 ,! rapid initial drop has be5 obs]v$ by ,bum/ead = ! air at ,new ,hav54 ,allan#dbi did n obs]ve ?is initial drop 9 ,montreal1 b f\nd ! activity fell to half value 9 ab\t #de m9utes1 reckon+ f a "t ab\t #aj m9utes aft] ! removal ( ! active wire4 ,?is is ab\t ! rate ( decay to be expect$ = ! active deposit ( radium ov] ! same int]val4 ,allan obta9$ evid5ce t !re 7 sev]al k9ds ( active matt] deposit$ on ! wire4 ,= example1 ! activity transf]r$ f ! active wire to a piece ( lea!r1 moi/5$ ) ammonia1 fell to half value 9 #ch m9utes2 = a piece ( absorb5t felt treat$ simil>ly1 ! activity fell to half value 9 #fj m9utes1 ! normal "t = ! untreat$ wire be+ #de m9utes4 ,x is probable t ?is v>iation ( ! rate ( decay is due to ! fact t unequal proportions ( radium ,b & ,c 7 transf]r$ f ! wire to ! rubb]4 ,if a great] proportion ( ,b ?an ( ,c 7 remov$1 ! decay w\ld be sl[] & vice v]sa4 ,! fact t ! activity ( ra9 & sn[ falls to half value 9 ab\t #cj m9utes is a /rong indication t ! radium emanation is pres5t 9 ! atmosph]e4 ,! active matt] ) ! ra9 & sn[ aft] /&+ "s "t w\ld consi/ ma9ly ( radium ,c & ?is %\ld decay expon5tially ) ! "t1 fall+ to half value 9 #bh m9utes4 ,on acc\nt ( ! rapid decay ( ! ?orium emanation--half value 9 "o m9ute--x is n likely t mu* ( ! activity ( ! atmosph]e c be ascrib$ to x4 ,its effect w\ld be mo/ m>k$ ne> ! surface ( ! soil4 ,!re c be little d\bt1 t a l>ge "p ( ! radio-activity ( ! atmosph]e is due to ! radium emanation1 :i* is cont9ually diffus+ into ! atmosph]e f ! pores ( ! e>?4 ,s9ce radio-activity has be5 obs]v$ 9 ! atmosph]e at all po9ts at :i* obs]vations h1 s f>1 be5 made1 radio-active matt] mu/ be di/ribut$ 9 m9ute quantities ?r\gh\t ! soil ( ! e>?4 ,! volatile emanations escape into ! atmosph]e by diffusion1 or are c>ri$ to ! surface 9 spr+ wat] or by ! escape ( und]gr\nd gases1 & cause ! radio-active ph5om5a obs]v$ 9 ! atmosph]e4 ,! obs]vation ( ,el/] & ,geitel t ! radio-activity ( ! air is mu* less ne> ! sea ?an inl& is expla9$ at once1 if ! radio-activity ( ! atmosph]e is due ma9ly to ! diffusion ( emanations f ! soil into ! air above x4 ,! r>e gases helium & x5on :i* exi/ 9 ! atmosph]e h be5 te/$ & f\nd to be non-radio-active4 ,! radio-activity ( ! air _c be ascrib$ to a slight radio-activity possess$ by ei!r ( ^! gases4 #bha4 ,am\nt ( ! radium emanation 9 ! atmosph]e4 ,x is a matt] ( great int]e/ to =m an e/imate ( ! am\nt ( radium emanation pres5t 9 ! atmosph]e1 = s9ce x comes f ! e>?1 x indirectly s]ves z a means ( e/imat+ ! am\nt ( radium :i* is di/ribut$ ov] a ?9 cru/ ( ! e>?4 ,"s exp]im5ts 9 ?is direction h be5 made by ,eve 9 ! laboratory ( ! writ]4 ,! exp]im5ts are n yet complet$ b ! results s f> obta9$ all[ u to calculate ! probable am\nt ( emanation p] cubic kilometre ( ! atmosph]e ne> ! e>?4 ,exp]im5ts 7 fir/ made ) a l>ge iron tank #aed cms4 squ>e & #gcj cms4 deep1 9 a build+ 9 :i* no radium or o!r radio-active mat]ial _h ev] be5 introduc$4 ,! saturation ionization curr5t = ! air 9 ! tank 0 fir/ measur$ by means ( an electroscope1 connect$ ) an insulat$ electrode pass+ up ! c5tre ( ! clos$ tank4 ,assum+ t ! ionization 9 ! tank 0 uni=m1 ! numb] ( ions produc$ p] c4c4 ( ! air 9 ! tank 0 f\nd to be #aj4 ,?is is a consid]ably l[] value ?an has usually be5 obs]v$ 9 a small clos$ vessel 7see section #bhd74 ,cooke obta9$ ! value #aj = a well clean$ brass electroscope1 surr\nd$ by lead1 :ile ,s*u/] obta9$ a value ab\t #ab = ! air 9 ! laboratory ( ,ow5s ,college1 ,man*e/]4 ,9 ord] to measure ! am\nt ( ! excit$ activity f ! tank1 a c5tral insulat$ wire 0 *>g$ negatively to ab\t #aj1jjj volts by a ,wim%ur/ ma*9e4 ,aft] two h\rs1 ! wire 0 remov$ & w\nd on an insulat$ frame connect$ ) a gold-leaf electroscope4 ,! rate ( decay ( ! activity on ! wire 0 f\nd to be ab\t ! same z = ! excit$ activity produc$ by ! radium emanation4 ,9 ord] to e/imate ! am\nt ( radium emanation pres5t 9 ! l>ge tank1 special exp]im5ts 7 made ) a small] tank 9 :i* a kn[n quantity ( ! radium emanation 0 introduc$ by employ+ a solution ( pure radium bromide ( kn[n conc5tration4 ,a c5tral wire 0 made ! negative electrode z be=e1 &1 aft] removal1 x 0 w\nd on ! frame & its activity te/$4 ,9 ?is way x 0 f\nd t ! am\nt ( radium emanation pres5t 9 ! l>ge tank1 9 ord] to produce ! excit$ activity obs]v$1 mu/ h be5 equal to ! equilibrium or maximum am\nt to be obta9$ f #ie #aj grams ( pure radium bromide4 ,! volume ( ! l>ge tank 0 #ag cubic metres1 s t ! am\nt ( emanation pres5t p] cubic metre 0 equival5t to t lib]at$ f #ef #aj grams ( radium bromide 9 radio-active equilibrium4 ,if ! am\nt ( ! emanation 9 ! tank is tak5 z ! av]age am\nt exi/+ 9 ! outside air1 ! am\nt ( radium emanation pres5t p] cubic kilometre ( ! air is equival5t to t suppli$ by #jef grams ( radium bromide4 ,= ! purpose ( calculation1 suppose ! emanation is uni=mly di/ribut$ ov] ! l& portion ( ! e>? 7 ( ! total surface71 & to ext5d to an av]age height ( #e kilometres4 ,! air ov] ! sea is n tak5 into acc\nt z its radio-activity has n be5 exam9$4 ,! total am\nt ( emanation pres5t 9 ! atmosph]e "u ^! conditions corresponds to t suppli$ by ab\t #djj tons ( radium bromide4 ,9 ord] to ma9ta9 ?is am\nt ( emanation 9 ! atmosph]e1 x mu/ be suppli$ at a con/ant rate f ! e>?'s surface4 ,s9ce ! great] am\nt ( ! emanation probably escapes into ! air by transpiration & diffusion ?r\gh ! soil1 ! emanation _c rea* ! surface except f a v ?9 lay] ( ! e>?4 ,! probable ?ickness ( ?is lay] c be e/imat$ if x is assum$ t ! pres5t loss ( heat f ! e>? is suppli$ f ! radio-active matt] conta9$ 9 x4 ,we h se5 7section #bga7 t1 on ?is hypo!sis1 !re mu/ be an am\nt ( active matt] 9 ! e>? correspond+ to ab\t #cjj million tons ( radium4 ,if ?is is suppos$ to be uni=mly di/ribut$1 a ?ickness ( lay] ( ab\t #ac metres w suffice to ma9ta9 ! calculat$ am\nt ( emanation 9 ! atmosph]e4 ,?is ?ickness ( lay] is ab\t ! ord] ( magnitude to be expect$ f g5]al consid]ations4 ,^! results lead indirectly to ! conclusion t a l>ge am\nt ( emanation does und\bt$ly exi/ 9 ! surface cru/ ( ! e>?4 ,exp]im5ts 7 also made by ,eve ) a l>ge z9c cyl9d] expos$ 9 ! op5 air4 ,volume = volume1 ! av]age am\nt ( excit$ activity d]iv$ f x 0 only ab\t "o-?ird ( t obta9$ f ! l>ge iron tank4 ,?is w\ld r$uce ! am\nt ( emanation1 previ\sly d$uc$1 to ab\t "o-?ird4 ,be=e su* calculations c be consid]$ at all def9ite1 x w be necess>y to make comp>ative measurem5ts ( ! am\nt ( emanation 9 ! atmosph]e at v>i\s p>ts ( ! e>?4 ,! air at ,montreal is n abnormally active1 s t ! calculations probably give ! "r ord] ( magnitude ( ! quantities4 ,eve also obs]v$ t ! am\nt ( activity to be obta9$ p] unit l5g? ( ! wire 9 ! z9c cyl9d] ( ab\t #gj cms4 9 diamet] 0 ab\t ! same z = a wire #e mms4 9 diamet] *>g$ to #aj1jjj volts 9 ! op5 air1 support$ #bj feet f ! gr\nd4 ,?is %[s t su* a pot5tial does n draw 9 ! c>ri]s ( excit$ activity :i* are m ?an half a metre away1 & probably ! range is ev5 less4 ,x is ( great importance to f9d h[ l>ge a proportion ( ! numb] ( ions produc$ 9 ! atmosph]e is due to ! radio-active matt] di/ribut$ ?r\gh\t x4 ,! results ( ,eve ) ! l>ge iron tank1 already ref]r$ to1 indicate t a l>ge proportion ( ! ionization 9 ! tank 0 due to ! radio-active matt] conta9$ 9 x1 = ! ratio ( ! excit$ activity on ! c5tral electrode to ! total ionization curr5t 9 ! tank 0 ab\t ( ! correspond+ ratio = a small] tank into :i* a supply ( ! radium emanation _h be5 introduc$4 ,?is result requires confirmation by exp]im5ts at o!r p>ts ( ! e>?1 b ! results po9t to ! conclusion t a l>ge "p1 if n all1 ( ! ionization at ! e>?'s surface is due to radio-active matt] di/ribut$ 9 ! atmosph]e4 ,a con/ant rate ( production ( #cj ions p] second p] c4c4 ( air1 :i* has be5 obs]v$ 9 ! op5 air at ! surface ( ! e>? 9 v>i\s localities1 w\ld be produc$ by ! pres5ce 9 ea* c4c4 ( ! air ( ! am\nt ( emanation lib]at$ f #bd #aj grams ( radium bromide 9 radio-active equilibrium4 ,x is n likely1 h[ev]1 t ! ionization ( ! upp] "p ( ! atmosph]e is due to ?is cause alone4 ,9 ord] to expla9 ! ma9t5ance ( ! l>ge positive *>ge1 :i* g5]ally exi/s 9 ! upp] atmosph]e1 !re mu/ be a /rong ionization ( ! upp] air1 :i* may possibly be due to ioniz+ radiations emitt$ by ! sun4 #bhb4 ,ionization ( atmosph]ic air4 ,a l>ge numb] ( measurem5ts h be5 made dur+ ! la/ few ye>s to det]m9e ! relative am\nt ( ionization 9 ! atmosph]e 9 diff]5t localities & at diff]5t altitudes4 ,measurem5ts ( ?is "* 7 fir/ und]tak5 by ,el/] & ,geitel ) a special type ( electroscope4 ,a *>g$ body expos$ to ! air 0 atta*$ to a portable electroscope1 & ! rate ( loss ( *>ge 0 obs]v$ by ! movem5t ( ! gold or alum9ium leaf4 ,! rates ( dis*>ge ( ! electroscope = positive & negative electricity 7 g5]ally diff]5t1 ! ratio dep5d+ on ! locality & ! altitude1 & on ! meteorological conditions4 ,?is app>atus is n suitable = quantitative measurem5ts & ! d$uctions to be drawn f ! obs]vations are ( necessity some:at indef9ite4 ,eb]t#dcj has design$ a portable app>atus 9 :i* ! numb] ( ions p] c4c4 ( ! air c be det]m9$ easily4 ,a con/ant curr5t ( air is drawn betwe5 two conc5tric cyl9d]s by means ( a fan actuat$ by a fall+ weight4 ,! inn] cyl9d] is insulat$ & connect$ ) an electroscope4 ,kn[+ ! capacity ( ! app>atus1 & ! velocity ( ! curr5t ( air1 ! rate ( movem5t ( ! gold-leaf af=ds a measure ( ! numb] ( ions pres5t 9 unit volume ( ! air drawn betwe5 ! cyl9d]s4 ,9 ?is way ,eb]t f\nd t ! numb] ( ions 9 ! air 0 some:at v>iable1 b on an av]age correspond$ to ab\t #bfjj p] c4c4 9 ! p>ticul> locality :]e ! measurem5ts 7 made4 ,?is is ! equilibrium numb] ( ions pres5t p] c4c4 :5 ! rate ( production balances ! rate ( recomb9ation4 ,if q is ! numb] ( ions produc$ p] second p] unit volume ( ! air & n is ! equilibrium numb]1 !n q n :]e is ! con/ant ( recomb9ation 7section #cj74 ,by a slight addition to ! app>atus ( ,eb]t1 ,s*u/]#dca has %[n t ! con/ant ( recomb9ation = ! p>ticul> sample ( air "u inve/igation c be det]m9$4 ,! value s obta9$ = air 9 ! neighb\rhood ( ,man*e/] 0 v>iable1 & two or ?ree times z great z = du/-free air4 ,! results ( "s prelim9>y measurem5ts %[$ t ! numb] ( ions pres5t p] c4c4 ( ! air 9 diff]5t localities v>i$ f #bcgj to #cffj1 :ile ! value ( q1 ! numb] ( ions produc$ p] c4c4 p] second1 v>i$ betwe5 #ab & #che4 ,ru!r=d & ,allan & ,eb]ts %[$ t ! ions 9 ! air _h ab\t ! same mobility z ! ions produc$ 9 air by ,rntg5 rays & radio-active sub/ances4 ,9 "s rec5t det]m9ations by ,ma*e & ,von ,s*weidl]#dcb1 ! velocity ( ! positive ion 0 f\nd to be ab\t #ajb cms4 p] second1 & t ( ! negative #abe cms41 = a pot5tial gradi5t ( "o volt p] cm4 ,langev9#dcc has rec5tly %[n t 9 addition to ^! swift mov+ ions1 !re are also pres5t 9 ! atmosph]e "s ions :i* travel extremely sl[ly 9 an electric field4 ,! numb] ( ^! sl[ly mov+ ions 9 ! air 9 ,p>is is ab\t #dj times z great z ! numb] ( ! swift] ions4 ,?is result is ( great importance1 = 9 ! app>atus ( ,eb]t ^! ions escape detection1 s9ce ! electric field is n /rong en\gh to c>ry !m to ! electrodes dur+ ! "t ( _! passage betwe5 ! cyl9d]s4 #bhc4 ,radio-activity ( ord9>y mat]ials4 ,x has be5 %[n t radio-active matt] seems to be di/ribut$ fairly uni=mly ov] ! surface ( ! e>? & 9 ! atmosph]e4 ,! v important "q arises :e!r ! small radio-activity obs]v$ is due to kn[n or unkn[n radio-elem5ts pres5t 9 ! e>? & atmosph]e1 or to a feeble radio-activity ( matt] 9 g5]al1 :i* is only readily detectable :5 l>ge quantities ( matt] are pres5t4 ,! exp]im5tal evid5ce is n yet suffici5t to answ] ?is "q1 b und\bt$ pro( has be5 obta9$ t _m ( ! metals %[ a v feeble radio-activity4 ,:e!r ?is radio-activity is due to ! pres5ce ( a slight trace ( ! radio-elem5ts or is an actual prop]ty ( ! metals !mselves w be discuss$ 9 m detail 9 section #bhf4 ,s*u/]#dcd has po9t$ out t e physical prop]ty hi!rto discov]$ = "o elem5t has be5 f\nd to be %>$ by all ! o!rs 9 v>y+ degrees4 ,= example1 ! prop]ty ( magnetism is mo/ /rongly m>k$ 9 iron1 nickel1 & cobalt1 b all o!r sub/ances are f\nd to be ei!r feebly magnetic or diamagnetic4 ,x might ?us be expect$ on g5]al pr9ciples t all matt] %\ld exhibit ! prop]ty ( radio-activity 9 v>y+ degrees4 ,on ! view develop$ 9 *apt] ,x41 ! pres5ce ( ?is prop]ty is an indication t ! matt] is und]go+ *ange accompani$ by ! expulsion ( *>g$ p>ticles4 ,x does n1 h[ev]1 by any means foll[ t because ! atom ( "o elem5t 9 ! c\rse ( "t becomes un/able & breaks up1 t1 !re=e1 ! atoms ( all ! o!r elem5ts pass ?r\gh simil> phases ( in/ability4 ,x has already be5 m5tion$ 7section #h71 t ,mme ,curie made a v ext5sive exam9ation ( mo/ ( ! elem5ts & _! comp\nds = radio-activity4 ,! electric me?od 0 us$1 & any sub/ance possess+ an activity ( ( t ( uranium w\ld c]ta9ly h be5 detect$4 ,) ! exception ( ! kn[n radio-elem5ts & ! m9]als conta9+ uranium & ?orium1 no o!r sub/ances 7 f\nd to be radio-active ev5 to t degree4 ,c]ta9 sub/ances l phosphorus#dce possess ! prop]ty ( ioniz+ a gas "u special conditions4 ,! air :i* is drawn ov] ! phosphorus is conduct+1 b x has n yet be5 settl$ :e!r ?is conductivity is due m]ely to ions =m$ at ! surface ( ! phosphorus or to ions produc$ by ! phosphorus nuclei or emanations1 z !y h be5 t]m$1 :i* are c>ri$ along ) ! curr5t ( air4 ,x does n h[ev] appe> t ! ionization ( ! gas is 9 any way due to ! pres5ce ( a p5etrat+ type ( radiation su* z is emitt$ by ! radio-active bodies4 ,le ,bon 7section #h7 obs]v$ t qu99e sulphate1 aft] be+ heat$ to a temp]ature bel[ ! melt+ po9t & !n all[$ to cool1 %[$ = a "t /rong phosphoresc5ce & 0 able rapidly to dis*>ge an electroscope4 ,! dis*>g+ action ( qu99e sulphate "u v>y+ conditions has be5 v c>efully exam9$ by ,miss ,gates#dcf4 ,! ionization c\ld n be obs]v$ ?r\gh ?9 alum9ium foil or gold-leaf1 b appe>$ to be conf9$ to ! surface ( ! sulphate4 ,! curr5t obs]v$ by an electromet] 0 f\nd to v>y ) ! direction ( ! electric field1 indicat+ t ! positive & negative ions _h v diff]5t mobilities4 ,! dis*>g+ action appe>s to be due ei!r to an ionization ( ! gas v close to ! surface by "s %ort ultra-violet light waves1 accompany+ ! phosphoresc5ce1 or to a *emical action tak+ place at ! surface4 ,?us1 nei!r phosphorus nor qu99e sulphate c be consid]$ to be radio-active1 ev5 "u ! special conditions :5 !y are able to dis*>ge an electrifi$ body4 ,no evid5ce 9 ei!r case has be5 f\nd t ! ionization is due to ! emission ( a p5etrat+ radiation4 ,no c]ta9 evid5ce has yet be5 obta9$ t any body c be made radio-active by exposure to ,rntg5 rays or ca?ode rays4 ,a metal expos$ to ! action ( ,rntg5 rays gives rise to a second>y radiation :i* is v readily absorb$ 9 a few c5timetres ( air4 ,x is possible t ?is second>y radiation may prove to be analog\s 9 "s respects to ! rays f ! radio-elem5ts4 ,! second>y radiation1 h[ev]1 ceases imm$iately ! ,rntg5 rays are cut (f4 ,vill>d#dcg /at$ t a piece ( bismu? produc$ a feeble photographic action aft] x _h be5 expos$ = "s "t to ! action ( ! ca?ode rays 9 a vacuum4 ,x has n h[ev] be5 %[n t ! bismu? gives out rays ( a "* simil> to ^? ( ! radio-active bodies4 ,! exp]im5ts ( ,ramsay & ,cooke on ! production ( app>5t activity 9 inactive matt] by ! radiations f radium h already be5 discuss$ 9 section #bfd4 ,! exi/5ce ( a v feeble radio-activity ( ord9>y matt] has be5 d$uc$ f ! /udy ( ! conductivity ( gases 9 clos$ vessels4 ,! conductivity is extremely m9ute1 & special me?ods are requir$ to det]m9e x ) accuracy4 ,a brief acc\nt w n[ be giv5 ( ! gradual gr[? ( our k on ?is important "q4 #bhd4 ,conductivity ( air 9 clos$ vessels4 ,s9ce ! "t ( ,c\lomb onw>ds sev]al inve/igators h believ$ t a *>g$ conductor plac$ inside a clos$ vessel lo/ its *>ge m rapidly ?an c\ld be expla9$ by ! conduction leak across ! insulat+ support4 ,matteucci1 z e>ly z #ahej1 obs]v$ t ! rate ( loss ( *>ge 0 indep5d5t ( ! pot5tial4 ,boys1 by us+ qu>tz insulators ( diff]5t l5g?s & diamet]s1 arriv$ at ! conclusion t ! leakage mu/ 9 "p take place ?r\gh ! air4 ,?is loss ( *>ge 9 a clos$ vessel 0 believ$ to be due 9 "s way to ! pres5ce ( du/ p>ticles 9 ! air4 ,on ! discov]y t gases become tempor>y conductors ( electricity "u ! influ5ce ( ,rntg5 rays & ! rays f radio-active sub/ances1 att5tion 0 aga9 drawn to ?is "q4 ,geitel#dch & ,c4 ,t4 ,r4 ,wilson#dci indep5d5tly attack$ ! problem1 & bo? came to ! conclusion t ! loss ( *>ge 0 due to a con/ant ionization ( ! air 9 ! clos$ vessel4 ,geitel employ$ 9 8 exp]im5ts an app>atus simil> to t %[n 9 ,fig4 #ajc4 ,! loss ( *>ge ( an ,exn] electroscope1 ) ! cyl9d] ( wire nett+ ,z atta*$1 0 obs]v$ 9 a clos$ vessel conta9+ ab\t #cj litres ( air4 ,! electroscope sy/em 0 f\nd to dim9i% 9 pot5tial at ! rate ( ab\t #dj volts p] h\r1 & ?is leakage 0 %[n n to be due to a want ( insulation ( ! supports4 ,wilson1 on ! o!r h&1 us$ a vessel ( v small volume1 9 ord] to "w ) air :i* c\ld be completely fre$ f du/4 ,9 ! fir/ exp]im5ts a silv]$ glass vessel ) a volume ( only #afc c4c4 0 employ$4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #ajd4 ,illu/ration3 ,fig4 #ajd4 ,! conductor1 ( :i* ! loss ( *>ge 0 to be measur$1 0 plac$ ne> ! c5tre ( ! vessel ,a4 ,x consi/$ ( a n>r[ /rip ( metal ) a gold-leaf atta*$4 ,! /rip ( metal 0 fix$ to ! upp] rod by means ( a small sulphur bead4 ,! upp] rod 0 connect$ ) a sulphur cond5s] ) an ,exn] electroscope ,b atta*$ to indicate its pot5tial4 ,! gold-leaf sy/em 0 initially *>g$ to ! same pot5tial z ! upp] rod & cond5s] by means ( a f9e /eel wire :i* 0 caus$ to t\* ! gold-leaf sy/em by ! attraction ( a magnet br\ght ne> x4 ,! rate ( movem5t ( ! gold-leaf 0 measur$ by means ( a microscope provid$ ) a micromet] eye-piece4 ,by keep+ ! upp] rod at a slightly high] pot5tial ?an ! gold-leaf sy/em1 x 0 ensur$ t ! loss ( *>ge ( ! gold-leaf sy/em %\ld n be due 9 any way to a conduction leakage across ! sulphur bead4 ,! me?od employ$ by ,wilson 9 ^! exp]im5ts is v c]ta9 & conv5i5t :5 an extremely small rate ( dis*>ge is to be obs]v$4 ,9 ?is respect ! electroscope measures ) c]ta9ty a rate ( loss ( *>ge mu* small] ?an c be measur$ by a s5sitive electromet]4 ,bo? ,geitel & ,wilson f\nd t ! leakage ( ! insulat$ sy/em 9 du/-free air 0 ! same = a positive z = a negative *>ge1 & 0 indep5d5t ( ! pot5tial ov] a consid]able range4 ,! leakage 0 ! same 9 ! d>k z 9 diffuse daylight4 ,! indep5d5ce ( leakage ( ! pot5tial is /rong evid5ce t ! loss ( *>ge is due to a con/ant ionization ( ! air4 ,:5 ! electric field act+ on ! gas exce$s a c]ta9 value1 all ! ions are c>ri$ to ! electrodes be=e recomb9ation occurs4 ,a saturation curr5t is rea*$1 & x w be indep5d5t ( fur!r increase ( ! electric field1 provid$1 ( c\rse1 a pot5tial suffici5tly high to cause a sp>k to pass is n appli$4 ,c4 ,t4 ,r4 ,wilson has rec5tly devis$ a /rik+ exp]im5t to %[ ! pres5ce ( ions 9 du/-free air :i* is n expos$ to any ext]nal ioniz+ ag5cy4 ,two l>ge metal plates are plac$ 9 a glass vessel connect$ ) an expansion app>atus simil> to t describ$ 9 section #cd4 ,on exp&+ ! air1 ! pres5ce ( ! ions is %[n by ! appe>ance ( a slight cl\d betwe5 ! plates4 ,^! cond5sation nuclei c>ry an electric *>ge1 & are app>5tly simil> 9 all respects to ! ions produc$ 9 gases by ,x rays1 or by ! rays f active sub/ances4 ,wilson f\nd t ! loss ( *>ge ( ! insulat$ sy/em 0 indep5d5t ( ! locality4 ,! rate ( dis*>ge 0 unalt]$ :5 ! app>atus 0 plac$ 9 a deep tunnel1 s t x did n appe> t ! loss ( *>ge 0 due to an ext]nal radiation4 ,f exp]im5ts already describ$1 h[ev] 7section #bgi71 x is probable t ab\t #cj p] c5t4 ( ! rate ( dis*>ge obs]v$ 0 due to a v p5etrat+ radiation4 ,?is exp]im5t ( ,wilson's indicates t ! int5sity ( ! p5etrat+ radiation 0 ! same 9 ! tunnel z at ! e>?'s surface4 ,wilson f\nd t ! ionization ( ! air 0 ab\t ! same 9 a brass vessel z 9 "o ( glass1 & came to ! conclusion t ! air 0 spontane\sly ioniz$4 ,us+ a brass vessel ( volume ab\t #dga c4c41 ,wilson det]m9$ ! numb] ( ions t mu/ be produc$ 9 air p] unit volume p] second1 9 ord] to acc\nt = ! loss ( *>ge ( ! insulat$ sy/em4 ,! leakage sy/em 0 f\nd to h a capacity ( ab\t #aa electro/atic units1 & lo/ its *>ge at ! rate ( #da volts p] h\r = a pot5tial ( #baj volts1 & #dj volts p] h\r = a pot5tial ( #abj volts4 ,tak+ ! *>ge on an ion z #cd #aj electro/atic units1 ?is corresponds to a production ( #bf ions p] second4 ,ru!r=d & ,allan#ddj repeat$ ! results ( ,geitel & ,wilson1 us+ an electromet] me?od4 ,! saturation curr5t 0 obs]v$ betwe5 two conc5tric z9c cyl9d]s ( diamet] #bee & #ge cms4 respectively & l5g? #aed cms4 ,x 0 f\nd t ! saturation curr5t c\ld practically be obta9$ ) a pot5tial ( a few volts4 ,saturation 0 h[ev] obta9$ ) a l[] voltage aft] ! air _h rema9$ undi/urb$ 9 ! cyl9d]s = sev]al days4 ,?is 0 probably due to ! gradual settl+ ( ! du/ orig9ally pres5t 9 ! air4 ,lat] obs]vations ( ! numb] ( ions produc$ 9 air 9 seal$ vessels h be5 made by ,patt]son#dda1 ,h>ms#ddb1 & ,cooke#ddc4 ,! results obta9$ by diff]5t obs]v]s are %[n 9 ! foll[+ table4 ,! value ( ! *>ge on an ion is tak5 z #cd #aj electro/atic units3 ,mat]ial ( ,numb] ( ions ,obs]v] vessel produc$ p] c4c4 p] second ,silv]$ #cf ,c4 ,t4 ,r4 ,wilson glass ,brass #bf ,z9c #bg ,ru!r=d & ,allan ,glass #ec to #fc ,h>ms ,iron #fa ,patt]son ,clean$ #aj ,cooke brass ,x w be %[n lat] t ! diff]5ces 9 ^! results are probably due to diff]5ces 9 ! radio-activity ( ! conta9+ vessel4 #bhe4 ,effect ( pressure & nature ( gas4 ,c4 ,t4 ,r4 ,wilson 7loc4 cit47 f\nd t ! rate ( leakage ( a *>g$ conductor v>i$ approximately z ! pressure ( ! air betwe5 ! pressures exam9$1 viz4 #dc mms4 & #gdc mms4 ( m]cury4 ,^! results po9t to ! conclusion t1 9 a good vacuum1 a *>g$ body w\ld lose its *>ge extremely sl[ly4 ,?is is 9 agreem5t ) an obs]vation ( ,crookes1 :o f\nd t a pair ( gold-leaves reta9$ _! *>ge = sev]al mon?s 9 a high vacuum4 ,wilson#ddd at a lat] date inve/igat$ ! leakage = diff]5t gases4 ,! results are includ$ 9 ! foll[+ table1 :]e ! ionization produc$ 9 air is tak5 z unity3 ,gas ,relative 7,relative ionization ionization7 _/ 7d5sity7 ,air #ajj #ajj ,hydrog5 #jahd #bg ,c>bon dioxide #afi #aaj ,sulphur #bfd #aba dioxide ,*lor(orm #dg #aji ,) ! exception ( hydrog51 ! ionization produc$ 9 diff]5t gases is approximately proportional to _! d5sity4 ,! relative ionization is v simil> to t obs]v$ by ,/rutt 7section #de7 = gases expos$ to ! influ5ce ( ! & rays f radio-active sub/ances1 & po9ts to ! conclusion t ! ionization obs]v$ may be due ei!r to a radiation f ! walls ( ! vessel or f ext]nal s\rces4 ,jaff#dde has made a c>eful exam9ation ( ! natural ionization 9 ! v heavy gas nickel-c>bonyl1 ,ni7,,co71 9 a small silv]$ glass vessel4 ,! ionization ( ?is gas 0 #ea times t ( air at normal pressure :ile its d5sity is #ei times t ( air4 ,! leak ( ! electroscope 0 ne>ly proportional to ! pressures except at l[ pressure1 :5 ! leak 0 some:at great] ?an w\ld be expect$ if ! pressure law held4 ,! fact t a gas ( su* high d5sity & complicat$ /ructure behaves l ! simpl] & light] gases is a /rong indication t ! ionization itself is due to a radiation f ! walls ( ! vessel & n to a spontane\s ionization ( ! gas4 ,patt]son#ddf exam9$ ! v>iation ( ! ionization ( air ) pressure 9 a l>ge iron vessel ( diamet] #cj cms4 & l5g? #bj cms4 ,! curr5t betwe5 a c5tral electrode & ! cyl9d] 0 measur$ by means ( a s5sitive ,dolezalek electromet]4 ,he f\nd t ! saturation curr5t 0 practically indep5d5t ( ! pressure = pressures great] ?an #cjj mms4 ( m]cury4 ,bel[ a pressure ( #hj mms4 ! curr5t v>i$ directly z ! pressure4 ,= air at atmosph]ic pressure1 ! curr5t 0 indep5d5t ( ! temp]ature up to #dej ,c4 ,) fur!r increase ( temp]ature1 ! curr5t began to increase1 & ! increase 0 m rapid :5 ! c5tral electrode 0 *>g$ negatively ?an :5 x 0 *>g$ positively4 ,?is diff]5ce 0 ascrib$ to ! production ( positive ions at ! surface ( ! iron vessel4 ,! results obta9$ by ,patt]son r5d] x v improbable t ! ionization obs]v$ 9 air is due to a spontane\s ionization ( ! enclos$ air3 = we %\ld expect ! am\nt ( ?is ionization to dep5d on ! temp]ature ( ! gas4 ,on ! o!r h&1 ^! results are to be expect$ if ! ionization ( ! enclos$ air is ma9ly due to an easily absorb$ radiation f ! walls ( ! vessel4 ,if ?is radiation _h a p5etrat+ p[] ab\t equal to t obs]v$ = ! rays ( ! radio-elem5ts1 ! radiation w\ld be absorb$ 9 a few c5timetres ( air4 ,) dim9ution ( pressure1 ! radiations w\ld trav]se a great] di/ance ( air be=e complete absorption1 b ! total ionization produc$ by ! rays w\ld /ill rema9 ab\t ! same1 until ! pressure 0 r$uc$ suffici5tly to all[ ! radiation to trav]se ! air space 9 ! vessel )\t complete absorption4 ,) /ill fur!r dim9ution ( pressure1 ! total ionization produc$ by ! radiation1 & 9 consequ5ce ! curr5t obs]v$1 w\ld v>y directly z ! pressure4 #bhf4 ,exam9ation ( ord9>y matt] = radio-activity4 ,/rutt#ddg1 ,mc,lennan & ,burton#ddh1 & ,cooke#ddi1 indep5d5tly obs]v$ ab\t ! same "t t ord9>y matt] is radio-active to a slight degree4 ,/rutt1 by means ( an electroscope1 obs]v$ t ! ionization produc$ 9 a clos$ vessel v>i$ ) ! mat]ial ( ! vessel4 ,a glass vessel ) a removable base 0 employ$ & ! vessel 0 l9$ ) ! mat]ial to be exam9$4 ,! foll[+ table %[s ! relative results obta9$4 ,! am\nt ( leakage obs]v$ is express$ 9 t]ms ( ! numb] ( scale divisions ( ! eye-piece pass$ ov] p] h\r by ! gold-leaf3 ,mat]ial ( ,leakage 9 l9+ ( scale divisions vessel p] h\r ,t9foil #cc ano!r #bc sample ,glass coat$ #ac ) phosphoric acid ,silv] #af *emically deposit$ on glass ,z9c #ab ,lead #bb ,copp] 7clean7 #bc 7oxidiz$7 #ag ,plat9um #bj1 #bi1 #ci 7v>i\s samples7 ,alum9ium #ad ,!re are ?us m>k$ diff]5ces 9 ! leakage obs]v$ = diff]5t mat]ials & also consid]able diff]5ces 9 diff]5t samples ( ! same metal4 ,= example1 "o specim5 ( plat9um caus$ ne>ly twice ! leakage ( ano!r sample f a diff]5t /ock4 ,mc,lennan & ,burton1 on ! o!r h&1 measur$ by means ( a s5sitive electromet] ! ionization curr5t produc$ 9 ! air 9 a clos$ iron cyl9d] #be cms4 9 diamet] & #acj cms4 9 l5g?1 9 :i* an insulat$ c5tral electrode 0 plac$4 ,! op5 cyl9d] 0 fir/ expos$ = "s "t at ! op5 w9d[ ( ! laboratory4 ,x 0 !n remov$1 ! top & bottom clos$1 & ! saturation curr5t ?r\gh ! gas det]m9$ z soon z possible4 ,9 all cases x 0 obs]v$ t ! curr5t dim9i%$ = two or ?ree h\rs to a m9imum & !n v sl[ly increas$ aga94 ,9 "o exp]im5t1 = example1 ! initial curr5t obs]v$ correspond$ to #cj on an arbitr>y scale4 ,9 ! c\rse ( f\r h\rs ! curr5t fell to a m9imum ( #ff1 & #dd h\rs lat] _h ris5 to a practical maximum ( #bd4 ,! initial decrease obs]v$ is probably due to a radio-activity ( ! enclos$ air or walls ( ! vessel1 :i* decay$ rapidly ) ! "t4 ,! decay ( ! excit$ activity produc$ on ! int]ior surface ( ! cyl9d] :5 expos$ to ! air 0 probably responsible = a "p ( ! decrease obs]v$4 ,mc,lennan ascribes ! increase ( curr5t ) "t to a radio-active emanation :i* is giv5 (f f ! cyl9d]1 & ionizes ! enclos$ air4 ,on plac+ l9+s ( lead1 t91 & z9c 9 ! iron cyl9d]1 consid]able diff]5ces 7 obs]v$ bo? = ! m9imum curr5t & also = ! f9al maximum4 ,lead gave ab\t twice ! curr5t due to z9c1 :ile t9 gave an int]m$iate value4 ,^! results are simil> 9 "* to ^? obta9$ by ,/rutt4 ,mc,lennan & ,burton also inve/igat$ ! effect ( dim9ution ( pressure on ! curr5t4 ,! cyl9d] 0 fill$ ) air to a pressure ( #g atmosph]es1 & all[$ to /& until ! curr5t rea*$ a con/ant value4 ,! air 0 !n all[$ to escape & ! pressure r$uc$ to #dd mms4 ( m]cury4 ,! curr5t 0 f\nd to v>y approximately z ! pressure ov] ! :ole range4 ,^! results are n 9 agreem5t ) ! results ( ,patt]son already describ$1 nor ) "s lat] exp]im5ts ( ,/rutt4 ,mc,lennan's results h[ev] po9t to ! conclusion t ! ionization 0 ma9ly due to an emanation emitt$ f ! metal4 ,s9ce ! air 0 rapidly remov$1 a proportionate am\nt ( ! emanation w\ld be remov$ also1 & x might ?us be expect$ t ! curr5t w\ld v>y directly z ! pressure4 ,if ?is is ! case ! curr5t ?r\gh ! gas at l[ pressures %\ld increase aga9 to a maximum if "t is all[$ = a fre% emanation to =m4 ,h4 ,l4 ,cooke1 us+ an electroscopic me?od1 obta9$ results v simil> to ^? giv5 by ,/rutt4 ,cooke obs]v$ t a p5etrat+ radiation 0 giv5 out f brick4 ,:5 a brass vessel conta9+ ! gold-leaf sy/em 0 surr\nd$ by brick1 ! dis*>ge ( ! electroscope 0 increas$ by #dj to #ej p] c5t4 ,?is radiation 0 ( ab\t ! same p5etrat+ p[] z ! rays f radio-active sub/ances4 ,! rays 7 completely absorb$ by surr\nd+ ! electroscope ) a %eet ( lead #b mms4 9 ?ickness4 ,?is result is 9 agreem5t ) ! obs]vation ( ,el/] & ,geitel1 already m5tion$1 t radio-active matt] 0 pres5t 9 clay fre%ly dug up f ! e>?4 ,cooke also obs]v$ t ! ionization ( ! air 9 a brass electroscope c\ld be r$uc$ to ab\t "o-?ird ( its usual value if ! int]ior surface ( ! brass 0 c>efully clean$4 ,by remov+ ! surface ( ! brass he 0 able to r$uce ! ionization ( ! enclos$ air f #cj to #aj ions p] c4c4 p] second4 ,?is is an important obs]vation1 & indicates t a l>ge proportion ( ! radio-activity obs]v$ 9 ord9>y matt] is due to a deposit ( radio-active matt] on its surface4 ,x has already be5 %[n t bodies :i* h be5 expos$ 9 ! pres5ce ( ! radium emanation reta9 a residual activity :i* decays extremely sl[ly4 ,!re c be no d\bt t ! radium emanation is pres5t 9 ! atmosph]e1 & ! expos$ surface ( matt]1 9 consequ5ce1 w become coat$ ) an invisible film ( radio-active matt]1 deposit$ f ! atmosph]e4 ,on acc\nt ( ! sl[ decay ( ?is activity x is probable t ! activity ( matt] expos$ 9 ! op5 air w\ld /eadily increase = a long int]val4 ,metals1 ev5 if !y are orig9ally inactive1 w\ld ?us acquire a fairly p]man5t activity1 b x %\ld be possible to get rid ( ?is by remov+ ! surface ( ! metal or by *emical treatm5t4 ,! rapid increase ( activity ( all matt] left 9 a laboratory 9 :i* a l>ge quantity ( emanation has be5 releas$ has be5 drawn att5tion to by ,eve#dej4 ,?is sup]ficial activity1 due to ! products radium ,d1 ,e1 & ,f1 0 ma9ly remov$ by plac+ ! metal 9 /rong acid4 ,a numb] ( exp]im5ts h be5 made by ,j4 ,j4 ,?omson1 ,n4 ,r4 ,campbell1 & ,a4 ,wood 9 ! ,cav5di% laboratory to exam9e :e!r ! radio-activity obs]v$ 9 ord9>y matt] is a specific prop]ty ( su* matt] or is due to ! pres5ce ( "s radio-active impurity4 ,an acc\nt ( ^! exp]im5ts 0 giv5 by ,pr(essor ,j4 ,j4 ,?omson 9 a discussion on ! ,radio-activity ( ,ord9>y ,matt] at ! ,briti% ,association meet+ at ,cambridge1 #aijd4 ,! results#dea1 z a :ole1 support ! view t ea* sub/ance gives out a *>act]i/ic type or types ( radiation & t ! radiation is a specific prop]ty ( ! sub/ance4 ,j4 ,j4 ,?omson#deb has made exp]im5ts to obs]ve ! action ( diff]5t sub/ances 9 cutt+ (f ! ext]nal v p5etrat+ radiation 7section #bgi7 obs]v$ by ,cooke & ,mc,lennan4 ,he f\nd t "s sub/ances cut (f ?is ext]nal radiation1 :ile o!rs _h little if any effect4 ,= example1 ! ionization 9 a clos$ vessel 0 r$uc$ #ag p] c5t4 by surr\nd+ x ) a ?ick lead envelope2 b1 on surr\nd+ x ) an equival5t absorb+ ?ickness ( wat]1 or wat] mix$ ) s&1 no s5sible dim9ution 0 obs]v$4 ,9 o!r exp]im5ts ,wood#dec f\nd t ! dim9ution ( ! ionization by a giv5 scre5 dep5d$ ^u ! mat]ial ( ! vessel4 ,= example1 ! ionization 9 a lead vessel1 surr\nd$ by a lead scre51 0 r$uc$ #aj p] c5t41 :ile 9 an iron vessel x 0 r$uc$ #bd p] c5t4 ,he concludes f 8 exp]im5ts t ! ionization obs]v$ 9 a clos$ vessel has a ?reefold orig94 ,"p ( x is due to an ext]nal p5etrat+ radiation1 "p to a second>y radiation set up by x1 :ile ! rema9d] is due to an intr9sic radiation f ! walls1 altoge!r indep5d5t ( ! ext]nal radiation4 ,9 "s exp]im5ts ( ,campbell#ded1 ! v>iation ( ! ionization curr5t betwe5 two p>allel plates 0 obs]v$ = a progressive increase ( ! di/ance betwe5 !m4 ,! effects obs]v$ are %[n 9 ,fig4 #aje4 ,! curves at fir/ rise rapidly1 !n b5d ov] & f9ally become a /raight l9e4 ,! knee ( ! curve is at a diff]5t di/ance = ! diff]5t sub/ances4 ,! %ape ( ^! curves indicates t two types ( radiation are pres5t1 "o ( :i* is readily absorb$ 9 ! gas :ile ! o!r1 a m p5etrat+ type ( radiation1 ext5ds ov] ! :ole di/ance betwe5 ! plates4 ,9 ano!r s]ies ( exp]im5ts1 "o side ( ! te/+ vessel 0 ( ?9 alum9ium1 & ! ionization curr5t 0 obs]v$ :5 an ext]ior scre5 0 br\ght up to x4 ,lead gave a consid]able increase1 b ! radiation f x 0 readily absorb$ by an int]pos$ scre54 ,! radiation emitt$ by c>bon & z9c 0 m ?an twice z p5etrat+ z f lead4 ,illu/ration3 ,fig4 #aje4 ,attempts 7 made to see :e!r a radio-active emanation 0 giv5 (f by dissolv+ solid sub/ances & !n keep+ ! solutions 9 a clos$ vessel & aft]w>ds te/+ ! activity ( ! air drawn f !m4 ,9 "s cases an emanation 0 obs]v$1 b ! am\nt v>i$ ) diff]5t specim5s ( ! same mat]ial2 9 o!rs no effect 0 detect$4 ,:5 l9+s ( diff]5t sub/ances 7 plac$ 9 a clos$ te/+ vessel1 ! ionization curr5t 9 mo/ cases fell at fir/1 pass$ ?r\gh a m9imum1 & !n sl[ly increas$ to a maximum4 ,= lead ! maximum 0 rea*$ 9 #i h\rs1 = t9 9 #ad & = z9c 9 #ah h\rs4 ,^! results indicate t an emanation is giv5 (f f ! metal1 & t ! am\nt rea*es a maximum value at diff]5t int]vals 9 ! v>i\s cases4 ,?is 0 confirm$ by an exam9ation ( a piece ( lead :i* 0 left 9 radium-free nitric acid4 ,tw5ty times ! normal effect 0 obs]v$ aft] ?is treatm5t4 ,?is is probably due to ! increase ( porosity ( ! lead :i* all[s a great] fraction ( ! emanation produc$ 9 ! metal to diffuse out ) ! gas4 ,! activity obs]v$ 9 ord9>y matt] is extremely small4 ,! l[e/ rate ( production ( ions yet obs]v$ is #aj p] cubic c5timetre p] second 9 a brass vessel4 ,suppose a sph]ical brass vessel is tak5 ( capacity #a litre4 ,! area ( ! int]ior surface w\ld be ab\t #dhj sq4 cms4 & ! total numb] ( ions produc$ p] second w\ld be ab\t #aj4 ,n[ x has be5 %[n1 9 section #beb1 t an p>ticle project$ f radium itself gives rise to #hf #aj ions be=e x is absorb$ 9 ! gas4 ,an expulsion ( "o p>ticle e #h seconds f ! :ole vessel1 or ( "o p>ticle f ea* squ>e c5timetre ( surface p] h\r w\ld ?us acc\nt = ! m9ute conductivity obs]v$4 ,ev5 if x 7 suppos$ t ?is activity is ! result ( a break+ up ( ! matt] compos+ ! vessel1 ! dis9tegration ( "o atom p] second p] gram1 provid$ x 0 accompani$ by ! expulsion ( an p>ticle1 w\ld fully acc\nt = ! conductivity obs]v$4 ,:ile ! exp]im5ts1 already ref]r$ to1 af=d /rong evid5ce t ord9>y matt] does possess ! prop]ty ( radio-activity to a feeble degree1 x mu/ n be =gott5 t ! activity obs]v$ is excessively m9ute1 comp>$ ev5 ) a weak radio-active sub/ance l uranium or ?orium4 ,! int]pretation ( ! results is complicat$1 too1 by ! pres5ce ( ! radium emanation 9 ! atmosph]e1 = we h se5 t ! surface ( e body expos$ to ! op5 air mu/ become coat$ ) ! sl[ly *ang+ trans=mation products ( ! radium emanation4 ,! di/ribution ( radio-active matt] ?r\gh\t ! con/itu5ts ( ! e>? r5d]s x difficult to be c]ta9 t any sub/ance1 h[ev] c>efully prep>$1 is fre$ f radio-active impurities4 ,if matt] 9 g5]al is radio-active1 x mu/ be und]go+ trans=mation at an excessively sl[ rate1 unless x be suppos$ 7see ,app5dix ,a7 t *anges ( a simil> "* to ^? obs]v$ 9 ! radio-elem5ts may occur )\t ! appe>ance ( _! *>act]i/ic radiations4 ,footnote #chd3 ,geitel1 ,phys4 ,zeit4 #b1 p4 #aaf1 #aijj4 ,footnote #che3 ,c4 ,t4 ,r4 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 #aa1 p4 #cb1 #aijj4 ,proc4 ,roy4 ,soc4 #fh1 p4 #aea1 #aija4 ,footnote #chf3 ,el/] & ,geitel1 ,phys4 ,zeit4 #b1 p4 #eij1 #aija4 ,footnote #chg3 ,el/] & ,geitel1 ,phys4 ,zeit4 #c1 p4 #gf1 #aija4 ,footnote #chh3 ,ru!r=d & ,allan1 ,phil4 ,mag4 ,dec4 #aijb4 ,footnote #chi3 ,allan1 ,phil4 ,mag4 ,feb4 #aijd4 ,footnote #cij3 ,c4 ,t4 ,r4 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 #aa1 p4 #dbh1 #aijb4 ,footnote #cia3 ,c4 ,t4 ,r4 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 #aa1 p4 #dbh1 #aijb2 #ab1 p4 #ag1 #aijc4 ,footnote #cib3 ,c4 ,t4 ,r4 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 #ab1 p4 #he1 #aijc4 ,footnote #cic3 ,allan1 ,phys4 ,rev4 #af1 p4 #ajf1 #aijc4 ,footnote #cid3 ,mc,lennan1 ,phys4 ,rev4 #af1 p4 #ahd1 #aijc4 ,footnote #cie3 ,s*mauss1 ,annal4 d4 ,phys4 #i1 p4 #bbd1 #aijb4 ,footnote #cif3 ,el/] & ,geitel1 ,phys4 ,zeit4 #c1 p4 #egd1 #aijb4 ,footnote #cig3 ,eb]t & ,ew]s1 ,phys4 ,zeit4 #d1 p4 #afb1 #aijb4 ,footnote #cih3 ,s>as91 ,tommas9a & ,mi*eli1 ,c4 ,r4 #aci1 p4 #iag1 #aije4 ,footnote #cii3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 ,sept4 #aijb4 ,footnote #djj3 ,eb]t1 ,sitz4 ,akad4 d4 ,wiss4 ,muni*1 #cc1 p4 #acc1 #aijc4 ,footnote #dja3 ,j4 ,j4 ,?omson1 ,phil4 ,mag4 ,sept4 #aijb4 ,footnote #djb3 ,adams1 ,phil4 ,mag4 ,nov4 #aijc4 ,footnote #djc3 ,bum/ead & ,:eel]1 ,am]4 ,j\rn4 ,sci5ce1 #ag1 p4 #ig1 ,feb4 #aijd4 ,footnote #djd3 ,bum/ead1 ,am]4 ,j\rn4 ,sci5ce1 #ah1 ,july1 #aijd4 ,footnote #dje3 ,dad\rian1 ,am]4 ,j\rn4 ,sci5ce1 #ai1 ,jan4 #aije4 ,footnote #djf3 ,h4 ,s4 ,all5 & ,"l ,bly?swood1 ,nature1 #fh1 p4 #cdc1 #aijc2 #fi1 p4 #bdg1 #aijd4 ,footnote #djg3 ,/rutt1 ,proc4 ,roy4 ,soc4 #gc1 p4 #aia1 #aijd4 ,footnote #djh3 ,him/$t1 ,ann4 d4 ,phys4 #ac1 p4 #egc1 #aijd4 ,footnote #dji3 ,el/] & ,geitel1 ,phys4 ,zeit4 #e1 ,no4 #ab1 p4 #cba1 #aijd4 ,footnote #daj3 ,dorn1 ,abh&l4 d4 ,natur4 ,ges4 ,halle1 #be1 p4 #ajg1 #aijd4 ,footnote #daa3 ,s*5ck1 ,!sis ,univ4 ,halle1 #aijd4 ,footnote #dab3 ,ma*e1 ,wi54 ,b]4 #aac1 p4 #acbi1 #aijd4 ,footnote #dac3 ,curie & ,laborde1 ,c4 ,r4 #ach1 p4 #aaej1 #aijd4 ,footnote #dad3 ,blanc1 ,phil4 ,mag4 ,jan4 #aije4 ,footnote #dae3 ,boltwood1 ,am]4 ,j\rn4 ,sci5ce1 #ah1 ,nov4 #aijd4 ,footnote #daf3 ,el/] & ,geitel1 ,phys4 ,zeit4 #d1 p4 #ebb1 #aijc4 ,footnote #dag3 ,el/] & ,geitel1 ,phys4 ,zeit4 #e1 ,no4 #a1 p4 #aa1 #aijc4 ,footnote #dah3 ,v9c5ti & ,levi ,da ,z>a1 ,atti d4 ,r4 ,in/it4 ,v5eto d4 ,sci5ze1 #ed1 p4 #ie1 #aije4 ,footnote #dai3 ,burton1 ,phil4 ,mag4 ,oct4 #aijd4 ,footnote #dbj3 ,el/] & ,geitel1 ,phys4 ,zeit4 #f1 ,no4 #c1 p4 #fg1 #aije4 ,footnote #dba3 ,ru!r=d & ,allan1 ,phil4 ,mag4 ,dec4 #aijb4 ,footnote #dbb3 ,el/] & ,geitel1 ,phys4 ,zeit4 #d1 p4 #ach1 #aijb2 #d1 p4 #ebb1 #aijc4 ,footnote #dbc3 ,saake1 ,phys4 ,zeit4 #d1 p4 #fbf1 #aijc4 ,footnote #dbd3 ,simpson1 ,proc4 ,roy4 ,soc4 #gc1 p4 #bji1 #aijd4 ,footnote #dbe3 ,mc,lennan1 ,phys4 ,rev4 #af1 p4 #ahd1 #aijc1 & ,phil4 ,mag4 #e1 p4 #dai1 #aijc4 ,footnote #dbf3 ,mc,lennan1 ,phys4 ,rev4 ,no4 #d1 #aijc4 ,footnote #dbg3 ,ru!r=d & ,cooke1 ,am]ic4 ,phys4 ,soc4 ,dec4 #aijb4 ,footnote #dbh3 ,cooke1 ,phil4 ,mag4 ,oct4 #aijc4 ,footnote #dbi3 ,allan1 ,phil4 ,mag4 ,feb4 #aijd4 ,footnote #dcj3 ,eb]t1 ,phys4 ,zeit4 #b1 p4 #fbb1 #aija4 ,zeits*r4 f4 ,lufts*iffahrt1 #d1 ,oct4 #aijb4 ,footnote #dca3 ,s*u/]1 ,proc4 ,man*e/] ,phil4 ,soc4 p4 #dhh1 ,no4 #ab1 #aijd4 ,footnote #dcb3 ,ma*e & ,von ,s*weidl]1 ,phys4 ,zeit4 #f1 ,no4 #c1 p4 #ga1 #aije4 ,footnote #dcc3 ,langev91 ,c4 ,r4 #adj1 p4 #bcb1 #aije4 ,footnote #dcd3 ,s*u/]1 ,briti% ,assoc4 #aijc4 ,footnote #dce3 ,j4 ,j4 ,?omson1 ,conduction ( ,electricity ?r\gh ,gases1 p4 #cbd1 #aijc4 ,footnote #dcf3 ,miss ,gates1 ,phys4 ,rev4 #ag1 p4 #dii1 #aijc4 ,footnote #dcg3 ,vill>d1 ,socit de ,physique1 ,july1 #aijj4 ,footnote #dch3 ,geitel1 ,phys4 ,zeit4 #b1 p4 #aaf1 #aijj4 ,footnote #dci3 ,c4 ,t4 ,r4 ,wilson1 ,proc4 ,camb4 ,phil4 ,soc4 #aa1 p4 #eb1 #aijj4 ,proc4 ,roy4 ,soc4 #fh1 p4 #aeb1 #aija4 ,footnote #ddj3 ,ru!r=d & ,allan1 ,phil4 ,mag4 ,dec4 #aijb4 ,footnote #dda3 ,patt]son1 ,phil4 ,mag4 ,augu/1 #aijc4 ,footnote #ddb3 ,h>ms1 ,phys4 ,zeit4 #d1 ,no4 #a1 p4 #aa1 #aijb4 ,footnote #ddc3 ,cooke1 ,phil4 ,mag4 ,oct4 #aijc4 ,footnote #ddd3 ,wilson1 ,proc4 ,roy4 ,soc4 #fi1 p4 #bgg1 #aija4 ,footnote #dde3 ,jaff1 ,phil4 ,mag4 ,oct4 #aijd4 ,footnote #ddf3 ,patt]son1 ,phil4 ,mag4 ,aug4 #aijc4 ,footnote #ddg3 ,/rutt1 ,phil4 ,mag4 ,june1 #aijc4 ,nature1 ,feb4 #ai1 #aijc4 ,footnote #ddh3 ,mc,lennan & ,burton1 ,phys4 ,rev4 ,no4 #d1 #aijc4 ,j4 ,j4 ,?omson1 ,nature1 ,feb4 #bf1 #aijc4 ,footnote #ddi3 ,cooke1 ,phil4 ,mag4 ,aug4 #f1 #aijc4 ,ru!r=d1 ,nature1 ,april #b1 #aijc4 ,footnote #dej3 ,eve1 ,nature1 ,m>* #af1 #aije4 ,footnote #dea3 ,see article 9 ,le ,radium1 ,no4 #c1 p4 #ha1 ,sept4 #ae1 #aijd4 ,footnote #deb3 ,j4 ,j4 ,?omson1 ,proc4 ,camb4 ,phil4 ,soc4 #ab1 p4 #cia1 #aijd4 ,footnote #dec3 ,wood1 ,phil4 ,mag4 ,april1 #aije4 ,footnote #ded3 ,campbell1 ,nature1 p4 #eaa1 ,m>* #ca1 #aijd4 ,phil4 ,mag4 ,april1 #aije4 ,,app5dix ,a4 ,,prop]ties ,,( ,,! ,,rays4 ,a brief acc\nt is giv5 "h ( "s inve/igations made by ! writ] on ! prop]ties ( ! rays f radium--inve/igations :i* 7 n complet$ 9 "t = ! results to be incorporat$ 9 ! text4 ,! exp]im5ts 7 und]tak5 prim>ily ) a view ( det]m9+ accurately ! value ( e_/m ( ! p>ticle f radium1 9 ord] to settle def9itely :e!r or n x is an atom ( helium4 ,9 ! previ\s exp]im5ts ( ! writ]1 ,becqu]el1 & ,des ,c\dres1 on ?is subject 7sections #hi1 #ij1 & #ia71 a ?ick lay] ( radium 9 radio-active equilibrium has be5 us$ z a s\rce ( rays4 ,bragg 7section #ajc7 has %[n t ! rays emitt$ f radium "u su* conditions are complex1 & consi/ ( p>ticles project$ ov] a consid]able range ( velocity4 ,9 ord] to obta9 a homog5e\s p5cil ( rays x is necess>y to use a v ?9 lay] ( a simple radio-active sub/ance z a s\rce ( rays4 ,9 ! exp]im5ts t foll[1 ?is condition 0 fulfill$ by us+ a f9e wire :i* 0 made active by exposure = sev]al h\rs 9 ! pres5ce ( a l>ge quantity ( radium emanation4 ,by *>g+ ! wire negatively ! active deposit 0 conc5trat$ ^u ! wire1 :i* 0 made int5sely active4 ,! active deposit initially conta9s radium ,a1 ,b1 & ,c4 ,! activity ( radium ,a practically disappe>s 9 ab\t fifte5 m9utes1 & ! radiation is !n due entirely to ! s+le product radium ,c1 s9ce radium ,b is a rayless product4 ,! activity ( radium ,c decreases to ab\t #ae p] c5t4 ( its initial value aft] two h\rs4 ,magnetic deflection ( ! rays4 ,! photographic me?od 0 employ$ to det]m9e ! deviation ( ! p5cil ( rays 9 a magnetic field4 ,! exp]im5tal arrangem5t is %[n 9 ,fig4 #ajf4 ,! rays f ! active wire1 :i* 0 plac$ 9 a slot1 pass$ ?r\gh a n>r[ slit & fell normally on a photographic plate1 plac$ at a kn[n di/ance above ! slit4 ,! app>atus 0 enclos$ 9 a brass tube :i* c\ld be exhau/$ rapidly to a l[ pressure by means ( a ,fleuss pump4 ,! app>atus 0 plac$ 9 a /rong uni=m magnetic field p>allel to ! plane ( ! slit4 ,! magnetic field 0 rev]s$ e t5 m9utes1 s t on develop+ ! plate two n>r[ b&s 7 obs]v$1 ! di/ance betwe5 :i* repres5t$ twice ! deviation f ! normal ( ! p5cil ( rays by ! magnetic field4 ,! wid? ( ! b& 0 f\nd to be ! same :e!r ! magnetic field 0 appli$ or n1 %[+ t ! p5cil ( rays 0 homog5e\s & consi/$ ( p>ticles project$ ) ! same velocity4 ,illu/ration3 ,fig4 #ajf4 ,by plac+ ! photographic plate at diff]5t di/ances f ! slit x 0 f\nd t ! rays1 aft] ent]+ ! magnetic field1 describ$ ! arc ( a circle ( radius equal to #dbj cms4 ,! /r5g? ( field ,h 0 #idgj ,c4,g4,s4 units1 s t ! value ( ,h = ! p>ticles expell$ f radium ,c is #cih1jjj4 ,?is is 9 good agreem5t ) ! maximum values ( ,h1 previ\sly f\nd = radium rays 7see section #ib74 ,! electric deviation ( ! rays f radium ,c has n yet be5 accurately measur$1 b an approximate det]m9ation ( e_/m = ! p>ticles c be obta9$ by assum+ t ! heat+ effect ( radium ,c is a measure ( ! k9etic en]gy ( ! p>ticles expell$ f x4 ,we h se5 9 section #bdf t ! heat+ effect ( ! radium ,c pres5t 9 "o gram ( radium 9 radio-active equilibrium is #ca gram calories p] h\r1 :i* corresponds to an emission ( en]gy ( #cf #aj ergs p] second4 ,n[ :5 radio-active equilibrium is rea*$1 ! numb] ( p>ticles expell$ f radium ,c p] second is equal to ! numb] ( p>ticles expell$ p] second f radium at its m9imum activity4 ,?is numb]1 n1 is #fb #aj 7section #ic74 ,!n mnv #cf #aj1 or 7m_/e7v #ajc #aj1 sub/itut+ ! value ( n1 & ! value ( ! ionic *>ge e4 ,! value ( e 9 ?is case has n be5 assum$1 s9ce n i_/e1 :]e i 0 ! measur$ curr5t due to ! *>ge c>ri$ by ! rays4 ,f ! magnetic deflection1 x is kn[n t 7m_/e7v #cih #aj4 ,f ^! two equations we obta9 v #bf #aj cms4 p] second4 e_/m #fe #aj electromagnetic units4 ,^! values are 9 surpris+ly good agreem5t ) ! previ\s values ( ! writ] & ,des ,c\dres 7section #ia74 ,on acc\nt ( ! unc]ta9ty atta*+ to ! value ( n1 n mu* weight c be atta*$ to ! det]m9ation by ?is me?od ( ! con/ants ( ! p>ticles4 ,decrease ( velocity ( ! p>ticles 9 pass+ ?r\gh matt]4 ,"s exp]im5ts 7 made to det]m9e ! velocity ( ! p>ticles f radium ,c aft] pass+ ?r\gh kn[n ?icknesses ( alum9ium4 ,! previ\s app>atus 0 employ$1 & ! di/ance betwe5 ! photographic b&s 0 obs]v$ = successive lay]s ( alum9ium foil1 ea* #jjjca cms4 ?ick1 plac$ ov] ! active wire4 ,! photographic plate 0 plac$ #b cms4 above ! slit1 & ! magnetic field ext5d$ #a cm4 bel[ ! slit4 ,! am\nt ( deviation ( ! rays is inv]sely proportional to _! velocity aft] trav]s+ ! alum9ium scre5s4 ,! impressions on ! plate 7 cle> & di/9ct1 & ab\t ! same 9 all cases1 %[+ t ! rays 7 /ill homog5e\s aft] pass+ ?r\gh ! alum9ium4 ,a cle> photographic impression 0 obta9$ = #ab lay]s ( foil1 b x 0 n f\nd possible to obta9 any effect ?r\gh #ac lay]s4 ,?is result %[s t ! photographic action ( ! rays1 l ! ioniz+ action1 ceases v abruptly4 ,! results obta9$ are %[n 9 ! foll[+ table4 ,assum+ t ! value ( e_/m is con/ant1 ! ?ird column gives ! velocity ( ! p>ticles aft] trav]s+ ! alum9ium4 ,?is is express$ 9 t]ms ( ,v1 ! velocity ( ! p>ticle :5 ! scre5s are remov$4 ,numb] ( ,di/ance ,velocity lay]s ( betwe5 ( alum9um b&s on ! p>ticles foil plate #j #adf mms4 #ajj ,v #e #aga #he #h #aia #gf #aj #bja #gc #ab #bbi #fd #ac ,no photographic effect ,! velocity ( ! p>ticle is ?us r$uc$ only ab\t #cf p] c5t4 ( its initial value :5 x fails to produce any action on ! photographic plate4 ,n[ ,bragg has %[n 7section #ajd7 t ! p>ticle produces approximately ! same numb] ( ions p] cm4 ( pa? 9 air ov] its :ole range4 ,consequ5tly1 ! simple/ assumption to make is t ! en]gy ( ! p>ticle is dim9i%$ by a con/ant am\nt 9 trav]s+ ea* lay] ( foil4 ,aft] pass+ ?r\gh #ab lay]s ! k9etic en]gy is r$uc$ to #da p] c5t4 ( ! maximum4 ,ea* lay] ( foil ?us absorbs #di p] c5t4 ( ! maximum en]gy4 ,! obs]v$ k9etic en]gy ( ! p>ticle aft] pass+ ?r\gh successive lay]s ( foil1 & ! value calculat$ on ! above assumptions1 are %[n 9 ! foll[+ table4 ,numb] ( ,obs]v$ ,calculat$ lay]s ( en]gy en]gy alum9um foil #j #ajj #ajj #e #gc #ge #h #eh #fa #aj #ec #ea #ab #da #da ,! exp]im5tal & !oretical values agree )9 ! limits ( exp]im5tal error4 ,we may ?us conclude1 z a fir/ approximation1 t ! same proportion ( ! total en]gy is ab/ract$ f ! p>ticles 9 pass+ ?r\gh equal di/ances ( ! absorb+ scre54 ,range ( ionization & photographic action 9 air4 ,! abrupt fall+ (f ( ! photographic impression aft] ! rays _h pass$ ?r\gh #ab lay]s ( foil sugge/$ t x might be directly connect$ ) ! correspond+ abrupt fall+ (f ( ! ionization 9 air1 s cle>ly br\ght out by ,bragg4 ,?is 0 f\nd to be ! case4 ,x 0 f\nd exp]im5tally t ! absorption 9 ea* lay] ( alum9ium foil 0 equival5t to t produc$ by a di/ance ( #ed cms4 ( air4 ,twelve lay]s ( foil ?us correspond$ to #fe cms4 ( air4 ,n[ ,bragg f\nd t ! rays f radium ,c ionize ! air = a di/ance #fg cms41 & t ! ionization !n falls (f v rapidly4 ,we may ?us conclude t ! rays cease to affect ! photographic plate at ! same velocity z t at :i* !y cease to ionize ! gas4 ,?is is a v important result1 &1 z we %all see lat]1 sugge/s t ! action on ! photographic plate is due to an ionization ( ! photographic salts4 ,! velocity ( ! p>ticles f ! diff]5t radio-active products c at once be calculat$1 kn[+ ! maximum range 9 air ( ! rays f ea* product4 ,! latt] h be5 exp]im5tally det]m9$ by ,bragg4 ,! velocity is express$ 9 t]ms ( ,v1 ! initial velocity ( ! p>ticles f radium ,c4 ,! rays f radium ,c are project$ ) a great] velocity ?an ! rays f ! o!r products ( radium4 ,product ,maximum ,velocity range ( ( p>ticles p>ticles 9 air ,radium #c cms4 #hb ,v ,emanation #ch or #dd #hg or #ij cms4 ,v ,rad4 ,a #dd or #ch #ij or #hg ,v ,rad4 ,c #fg #ajj ,v ,x is difficult to det]m9e f ! exp]im5ts :e!r ! range #ch cms4 belongs to ! rays f ! emanation or f radium ,a4 ,! mean velocity ( ! p>ticles is ?us #ij ,v1 & ! maximum v>iation = ! individual products does n v>y m ?an #aj p] c5t4 f ! mean value4 ,! results ( ,becqu]el1 discuss$ 9 section #ib1 at once receive an explanation on ! above results4 ,! p>ticles1 expell$ f radium 9 radio-active equilibrium1 h all ranges ly+ betwe5 #j & #fg cms4 ( air4 ,! velocity ( ! p>ticles :i* are able to produce a photographic impression v>ies betwe5 #fd ,v & ,v4 ,! p>ticles :i* h only a %ort range 9 air are project$ ) a small] velocity ?an ^? :i* h a great] range4 ,! =m] are 9 consequ5ce m b5t by a magnetic field4 ,x is ?us to be expect$ t ! app>5t curvature ( ! pa? ( rays 9 a uni=m magnetic field w be great] close to ! radium ?an at "s di/ance away4 ,range ( phosphoresc5t action 9 air4 ,"s exp]im5ts 7 also made to see :e!r ! action ( ! rays 9 produc+ lum9osity 9 sub/ances l z9c sulphide1 b>ium plat9ocyanide1 & willemite1 ceas$ at ! same di/ance z ! ioniz+ action4 ,a v active wire 0 plac$ on a movable plate1 ! di/ance ( :i* f a fix$ scre5 ( phosphoresc5t sub/ance c\ld be v>i$4 ,! di/ance at :i* ! phosphoresc5t action ceas$ c\ld be det]m9$ fairly accurately4 ,diff]5t ?icknesses ( alum9ium foil 7 !n plac$ ov] ! active wire1 & ! correspond+ di/ance at :i* ! lum9osity disappe>$ 0 measur$4 ,! results are %[n graphically 9 ,fig4 #ajg1 :]e ! ord9ates repres5t ! di/ance ( ! phosphoresc5t scre5 f ! active wire1 & ! abscissae ! numb] ( lay]s ( alum9ium foil1 ea* #jjjca cms4 ?ick4 ,illu/ration3 ,fig4 #ajg4 ,x is se5 t ! curve jo9+ ! po9ts is a /raight l9e4 #abe ?icknesses ( foil absorb$ ! rays to ! same ext5t z #fh cms4 ( air1 s t ea* ?ickness ( alum9ium correspond$ 9 absorb+ p[] to #ed cms4 ( air4 ,= a scre5 ( z9c sulphide1 ! phosphoresc5t action ceas$ at a di/ance ( air ( #fh cms41 %[+ t ! photographic & phosphoresc5t ranges ( ! rays 9 air 7 practically id5tical4 ,! exp]im5ts ) b>ium plat9ocyanide & willemite 7 m difficult1 z ! & rays f ! active wire produc$ a lum9osity comp>able ) t produc$ by ! rays4 ,fairly concordant results1 h[ev]1 7 obta9$ by introduc+ a ?9 %eet ( black pap] betwe5 ! active wire & ! scre54 ,if ! lum9osity 0 s5sibly *ang$1 x 0 conclud$ t ! rays /ill produc$ an effect1 & 9 ?is way ! po9t ( cessation ( phosphoresc5t action c\ld be approximately det]m9$4 ,= example1 ) eight ?icknesses ( foil ov] ! active wire ! additional ?ickness ( air requir$ to cut (f ! phosphoresc5t effect ( ! a rays 0 #be cms4 = willemite1 & #ba cms4 = b>ium plat9ocyanide4 ,! correspond+ di/ance = z9c sulphide 0 #bdj cms41 a value int]m$iate betwe5 ! o!r two4 ,s9ce eight lay]s ( foil are equival5t to #dc cms4 ( air1 ! ranges 9 air ( phosphoresc5t action = z9c sulphide1 b>ium plat9ocyanide1 & willemite correspond to #fg1 #fh1 & #fd cms4 respectively4 ,! diff]5ces obs]v$ are q likely to be due to exp]im5tal error4 ,discussion ( results4 ,we h se5 t ! ioniz+1 phosphoresc5t1 & photographic actions ( ! rays emitt$ f radium ,c cease aft] trav]s+ v ne>ly ! same di/ance ( air4 ,?is is a surpris+ result :5 x is rememb]$ t ! p>ticle1 aft] pass+ ?r\gh ?is dep? ( air1 /ill possesses a velocity ( at lea/ #fj p] c5t4 ( its initial value4 ,tak+ ! probable value ( ! initial velocity ( ! p>ticle f radium ,c z #be #aj cms4 p] sec41 ! ioniz+1 phosphoresc5t1 & photographic actions cease :5 ! velocity ( ! p>ticle falls bel[ #ae #aj cms4 p] second1 t is1 a velocity ( ab\t ( t ( light4 ,! p>ticle /ill possesses ne>ly #dj p] c5t4 ( its initial en]gy ( projection at ?is /age4 ,^! results %[ t ! prop]ty ( ! rays ( produc+ ionization 9 gases1 ( produc+ lum9osity 9 "s sub/ances1 & ( affect+ a photographic plate1 ceases :5 ! velocity ( ! p>ticle falls bel[ a c]ta9 fix$ value :i* is ! same 9 ea* case4 ,x seems reasonable1 !re=e1 to suppose t ^! ?ree prop]ties ( ! rays mu/ be ascrib$ to a common cause4 ,n[ ! absorption ( ! rays 9 gases is ma9ly a consequ5ce ( ! en]gy absorb$ 9 ! production ( ions 9 ! gas4 ,:5 ! p>ticles are completely absorb$ 9 ! gas1 ! same total am\nt ( ionization is produc$1 %[+ t ! en]gy requir$ to produce an ion is ! same = all gases4 ,on ! o!r h&1 = a con/ant s\rce ( radiation1 ! ionization p] unit volume ( ! gas is approximately proportional to its d5sity4 ,s9ce ! absorption ( ! rays 9 solid matt] is approximately proportional to ! d5sity ( ! absorb+ m$ium comp>$ ) air1 x is probable t ?is absorption is also a result ( ! en]gy us$ up 9 produc+ ions 9 ! solid matt] trav]s$1 & t ab\t ! same am\nt ( en]gy is requir$ to produce an ion 9 matt] :e!r solid1 liquid1 or gase\s4 ,x is probable1 !re=e1 t ! production ( ions 9 ! phosphoresc5t mat]ial & 9 ! photographic film w\ld cease at ab\t ! same velocity = :i* ! p>ticle is unable to ionize ! gas4 ,on ?is view1 !n1 ! exp]im5tal results receive a simple explanation4 ,! action ( ! rays 9 produc+ photographic & phosphoresc5t actions is prim>ily a result ( ionization4 ,?is ionization may possibly give rise to second>y actions :i* influ5ce ! effects obs]v$4 ,?is po9t ( view is ( int]e/ 9 connection ) ! orig9 ( ! 8sc9tillations0 obs]v$ 9 z9c sulphide & o!r sub/ances :5 expos$ to ! action ( ! rays4 ,?is effect is ascrib$ by ,becqu]el to ! cleavage ( ! cry/als "u ! bomb>dm5t ( ! p>ticles4 ,^! results1 h[ev]1 %[ t we mu/ look deep] = ! explanation ( ?is ph5om5on4 ,! effect is prim>ily due to ! production ( ions 9 ! phosphoresc5t mat]ial & n to direct bomb>dm5t1 = we h se5 t ! p>ticle produces no sc9tillations :5 x /ill possesses a l>ge am\nt ( k9etic en]gy4 ,x seems n unlikely t ! sc9tillations produc$ by ! rays mu/ be ascrib$ to ! recomb9ation ( ! ions :i* are produc$ by ! p>ticle 9 ! cry/all9e mass4 ,x is difficult to see h[ ?is ionization c\ld result 9 a cleavage ( ! cry/als4 ,?is close connection ( ! photographic & phosphoresc5t actions ( ! rays ) _! prop]ty ( produc+ ions1 raises ! "q :e!r photographic & phosphoresc5t actions 9 g5]al may n1 9 ! fir/ place1 be due to a production ( ions 9 ! sub/ance4 ,ionization curve = ! rays f radium ,c4 ,mr ,mc,clung1 work+ 9 ! laboratory ( ! writ]1 has rec5tly det]m9$ ! relative ionization p] unit pa? ( ! p>ticles project$ f radium ,c1 us+ ! me?od fir/ employ$ by ,bragg & discuss$ 9 section #ajd4 ,an active wire1 expos$ = sev]al h\rs to ! emanation f radium1 0 us$ z a s\rce ( rays4 ,! p>ticles 7 homog5e\s1 s9ce ! film ( radio-active matt] 0 extremely ?94 ,! relation betwe5 ! ionization obs]v$ ov] ! cross section ( ! n>r[ cone ( rays & ! di/ance f ! s\rce ( rays is %[n 9 ,fig4 #ajh4 ,illu/ration3 ,fig4 #ajh4 ,! curve exhibits ! same peculi>ities z ^? giv5 by ,bragg = a ?9 film ( matt] ( "o k9d4 ,! ionization ( ! p>ticle p] unit pa? increases sl[ly = ab\t #d cms4 ,!re is !n a m rapid increase j be=e ! p>ticle ceases to ionize ! gas1 & !n a rapid fall+ (f4 ,! ionization does n appe> to end s abruptly z is really ! case1 s9ce !re is a correction to be appli$ = ! angle subt5d$ by ! cone ( rays4 ,! maximum range ( ! rays 9 air 0 #fg cms41 a numb] 9 agreem5t ) t obta9$ by ,bragg by measurem5ts on ! range ( ! rays f radium4 ,^! results %[ t ! ionization p] unit pa? ( ! p>ticle increases at fir/ sl[ly & !n rapidly ) decrease ( velocity until ! rays cease to ionize ! gas4 ,en]gy requir$ to produce an ion4 ,f ! above results ! en]gy requir$ to produce an ion by collision ( ! p>ticle ) ! gas molecules c readily be d$uc$4 ,! p>ticles1 emitt$ f radium itself1 are initially project$ ) a velocity #hh,v :]e ,v is ! initial velocity ( projection ( ! p>ticles f radium ,c4 ,! p>ticles cease to ionize ! gas at a velocity #fd,v4 ,f ?is x c at once be d$uc$ t #dh ( ! total en]gy ( ! p>ticle1 %ot out by radium itself1 is absorb$ :5 x ceases to ionize ! gas4 ,assum+ t ! heat+ effect ( radium at its m9imum activity--#be gram calories p] h\r p] gram--is a measure ( ! k9etic en]gy ( ! expell$ p>ticles1 x c be calculat$ t ! k9etic en]gy ( ea* p>ticle is #dg #aj ergs4 ,! am\nt ( en]gy absorb$ :5 ! p>ticle j ceases to ionize ! gas is #bc #aj ergs4 ,assum+ t ?is en]gy is us$ up 9 ionization1 & rememb]+ t ! p>ticle f radium itself produces #hfjjj ions 9 its pa? 7section #beb71 ! av]age en]gy requir$ to produce an ion is #bg #aj ergs4 ,?is is equival5t to ! en]gy acquir$ by an ion mov+ freely betwe5 two po9ts diff]+ 9 pot5tial by #bd volts4 ,t[ns5d f\nd t fre% ions 7 produc$ by an electron = a correspond+ diff]5ce ( pot5tial ( #aj volts4 ,/>k1 f o!r data1 obta9$ a value #de volts1 :ile ,langev9 consid]s t #fj volts is an av]age value4 ,! value obta9$ by ,ru!r=d & ,mc,clung = ionization by ,x-rays 0 #age volts1 & is probably too high4 ,rayless *anges4 ,we h se5 t ! p>ticles f ! radio-active sub/ances are project$ ) an av]age velocity n m ?an #cj p] c5t4 great] ?an ! m9imum velocity1 bel[ :i* ! p>ticles are unable to produce any ioniz+1 photographic1 or phosphoresc5t action4 ,su* a conclusion sugge/s t ! prop]ty ( ! radio-active sub/ances ( emitt+ p>ticles has be5 detect$ because ! p>ticles 7 project$ slightly above ?is m9imum velocity4 ,a simil> dis9tegration ( matt] may be tak+ place 9 o!r sub/ances at a rate mu* great] ?an 9 uranium )\t produc+ mu* electrical effect1 provid$ ! p>ticles are project$ bel[ ! critical velocity4 ,! p>ticle1 on an av]age1 produces ab\t #ajj1jjj ions 9 ! gas be=e x is absorb$1 s t ! electrical effect obs]v$ is ab\t #ajj1jjj times z great z t due to ! *>ge c>ri$ by ! p>ticles alone4 ,x is n unlikely t ! num]\s rayless products :i* h be5 obs]v$ may und]go dis9tegration ( a simil> "* to ! products :i* obvi\sly emit rays4 ,9 ! rayless product ! p>ticle may be expell$ ) a velocity less ?an #ae #aj cms4 p] second & s fail to produce mu* electrical effect4 ,^! consid]ations h an important be>+ on ! "q :e!r matt] 9 g5]al is radio-active4 ,! prop]ty ( emitt+ p>ticles above ! critical velocity may well be a prop]ty only ( a special class ( sub/ances1 & ne$ n be exhibit$ by matt] 9 g5]al4 ,at ! same "t ! results sugge/ t ord9>y matt] may be und]go+ trans=mation accompani$ by ! expulsion ( p>ticles at a rate mu* great] ?an t %[n by uranium1 )\t produc+ appreciable electrical or photographic action4 ,,app5dix ,b4 ,,radio-,,active ,,m9]als4 ,^? natural m9]al sub/ances :i* possess m>k$ radio-active prop]ties h be5 f\nd to conta9 ei!r uranium or ?orium1 "o ( ^! elem5ts be+ always pres5t 9 suffici5t proportion readily to p]mit its *emical sep>ation & id5tification by ! ord9>y analytical me?ods#dee4 ,a l>ge numb] ( uranium & ?orium m9]als are kn[n at ! pres5t "t1 b !y are = ! mo/ "p f\nd v sp>+ly1 & "s ( !m h be5 obs]v$ to occur only 9 a s+le locality4 ,! *ief comm]cial s\rces ( uranium are uran9ite1 gummite1 & c>notite1 :ile ?orium is obta9$ almo/ exclusively f monazite4 ,ru!r=d & ,soddy 7,phil4 ,mag4 #fe1 #efa 7#aijc771 7 ! fir/ to call att5tion to ! important fact t ! relations betwe5 ! v>i\s radio-active sub/ances & ! o!r elem5ts c\ld be/ be det]m9$ f ! /udy ( ! natural m9]als 9 :i* ^! bodies occur1 s9ce ^! m9]als repres5t mixtures ( extreme antiquity1 :i* h rema9$ m or less undi/urb$ = almo/ c\ntless ages4 ,9 deal+ ) ^! matt]s1 h[ev]1 x is highly important t we br+ to our aid ! data furni%$ by geology & m9]alogy1 f :i* x is (t5 possible to det]m9e ! relative ages ( ! diff]5t sub/ances ) at lea/ a r\gh degree ( approximation4 ,?us1 = example1 if a c]ta9 m9]al occurs z a prim>y con/itu5t ( a rock ( remote geological p]iod1 x c safely be assum$ t its age is great] ?an t ( a simil> or diff]5t m9]al occurr+ 9 a lat] =mation4 ,x is1 moreov]1 q evid5t t ^? m9]als :i* are obvi\sly produc$ by ! decomposition & alt]ation ( ! prim>y m9]als1 ?r\gh ! action ( p]colat+ wat] & o!r ag5cies act+ f ! surface d[nw>d1 are ( less antiquity ?an ! prim>y m9]als f :i* !y orig9at$4 ,?r\gh ! application ( ^! consid]ations x %\ld1 9 g5]al1 be possible to arrange ! v>i\s m9]als r\ghly 9 ! ord] ( _! probable ages4 ,! mo/ famili> & widely kn[n uranium m9]al is uran9ite1 commonly call$ pit*bl5de1 :i* consi/s ess5tially ( uranium dioxide 7,,uo71 uranium trioxide 7,,uo71 & lead oxide 7,pb,o71 pres5t 9 v>y+ proportions4 ,! uran9ites c be di/+ui%$ z prim>y1 namely1 ^? :i* occur z a prim>y con/itu5t ( pegmatitic dikes & co>se granites1 & second>y1 :5 !y occur 9 metallif]\s ve9s associat$ ) ! sulphides ( silv]1 lead1 copp]1 nickel1 iron1 & z9c4 ,! =m] v>ieties are q frequ5tly cry/all9e 9 "*1 conta9 a l>g] proportion ( ! r>e e>?s & helium1 & h a high] specific gravity ?an ! latt]1 :i* are always massive & botryoidal4 ,! foll[+ are ! mo/ prom95t localities 9 :i* prim>y uran9ites occur3 #a4 ,nor? ,c>ol9a1 ,u4,s4,a4 7especially 9 ,mit*ell & ,yancey c\nties74 ,! uran9ite is f\nd 9 a co>se pegmatitic dike :i* is m9$ = ! mica con/itu5t4 ,! associat$ feldsp> ( ! dike is consid]ably decompos$ ?r\gh ! action ( meteoric wat]s & gases1 & ! uran9ite itself is l>gely alt]$ into ! second>y m9]als gummite & uranophane ?r\gh ! same ag5cies4 ,among ! associat$ prim>y m9]als are allanite1 zircon1 columbite1 sam>skite1 f]gusonite & monazite1 :ile ! second>y m9]als include gummite1 ?orogummite1 uranophane1 autunite1 phosphuranylite1 hat*ettolite1 & cyrtolite4 ,! geological p]iod ( ?is =mation is difficult to e/abli% ) c]ta9ty1 b is /at$ to be p]haps ,ar*ean1 or possibly to correspond ) ! close ( ! ,ordovician or ) ! ,p]mian4 #b4 ,connecticut1 ,u4,s4,a4 ,! be/ kn[n localities are ,gla/onbury1 :]e ! uran9ite is f\nd 9 ! feldsp> qu>ries1 & ,bran*ville1 :]e x occurs 9 an albitic granite4 ,bo? ( ^! localities h furni%$ f9e cry/als4 ,! geological p]iod probably corresponds ) ! close ( ! ,ordovician or ,c>bonif]\s eras1 & is /at$ to be c]ta9ly ,po/-,cambrian & ,pre-,triassic4 ,among ! associat$ m9]als are 7prim>y7 columbite1 7second>y7 torb]nite & autunite4 #c4 ,s\!rn ,norway1 p>ticul>ly 9 ! neighb\rhood ( ,moss4 ,"h uran9ite occurs 9 ! augite-sy5ite & pegmatite4 ,! v>ieties f\nd are kn[n z cleveite & brgg]ite1 & among ! prim>y associat$ m9]als are or?ite1 f]gusonite1 monazite1 & ?orite4 ,! p]iod is /at$ to be ,po/-,devonian4 #d4 ,llano ,c\nty1 ,texas4 ,! v>iety ( uran9ite kn[n z niv5ite is f\nd "h 9 a qu>tzose pegmatite1 associat$ ) ! prim>y m9]als gadol9ite1 allanite & f]gusonite1 & ! second>y m9]als cyrtolite1 yttrialite1 gummite1 & ?orogummite4 ,second>y uran9ite is f\nd at ,johanngeorg5/adt1 ,m>i5b]g & ,s*neeb]g 9 ,saxony1 at ,joa*im/hal & ,pribam 9 ,bohemia1 at ,cornwall 9 ,engl&1 & at ,black ,hawk1 ,colorado1 & 9 ! ,black ,hills1 ,s\? ,dakota1 9 ! ,unit$ ,/ates4 ,! exact geological p]iod ( mo/ ( ^! second>y occurr5ces is some:at unc]ta91 b !y are und\bt$ly v mu* lat] ?an ! prim>y occurr5ces m5tion$ above4 ,z a matt] ( g5]al int]e/ ! analysis ( a typical prim>y uran9ite 7,no4 #a7 & ( a typical second>y uran9ite 7,no4 #b7 is giv5 bel[#def3 ,no4 #a ,no4 #b ,gla/onbury1 ,johanngeorg5/adt1 ,conn4 ,saxony ,sp4 ,gr4 #iei #fhi ,,uo #bfdh #fjje ,,uo #egdc #bbcc ,th,o #igi 444 ,ce,o #jbe 444 ,la,o #jac 444 ,y,o #jbj 444 ,pb,o #cbf #fci ,ca,o #jjh #ajj ,he und4 und4 ,h,o #jfa #cag ,fe,o #jdj #jba ,si,o #jbe #jej ,al,o 444 #jbj ,bi,o 444 #jge ,cu,o 444 #jag ,mn,o 444 #jji ,mg,o 444 #jag ,na,o 444 #jca ,p,o 444 #jjf ,,s 444 #jai ,z,o 444 #bcd ,insoluble #jgj 444 ,! foll[+ li/ comprises ! m important radio-active m9]als1 ) _! approximate *emical composition & "s notes on _! occurr5ce & probable orig94 ,"n ,composition ,rem>ks ,uran9ite1 ,oxides ( ,occurs prim>y ,cleveite1 uranium & z a ,brgg]ite1 lead4 ,usually con/itu5t ( ,niv5ite1 conta9s rocks & ,pit*bl5de ?orium1 second>y 9 o!r r>e ve9s ) e>?s & metallif]\s helium4 sulphides ,uranium #ej-hj4 ,?orium #j-aj ,gummite 7,pb1 ,ca7 ,an alt]ation ,u,si,o product ( 4 #f;,h,o8 uran9ite4 ,uranium ,=m$ by ! #ej-fe action ( p]colat+ wat]s ,uranophane1 ,ca,o 4 #b,,uo ,an alt]ation ,uranotil 4 #b,si,o 4 product ( #f;,h,o uran9ite ,uranium ?r\gh #dd-ef gummite ,c>notite ,a vanadate ( ,occurs z a uranium & second>y potassium4 m9]al ,uranium impregnat+ a #db-ea por\s1 s$im5t>y s&/one4 ,f\nd 9 ,colorado & ,utah ,uranospha]ite ,bi,o 4 ,alt]ation #b,,uo 4 product ( #c;,h,o4 o!r uranium ,uranium #da m9]als ,torb]nite1 ,cu,o 4 #b,,uo ,cupr\ranite 4 ,p,o 4 #h;,h,o4 ,uranium #dd-ea ,autunite1 ,ca,o 4 #b,,uo ,calci\ranite 4 ,p,o 4 #h;,h,o4 ,uranium #de-ea ,uranocircite ,ba,o 4 #b,,uo 4 ,p,o 4 #h;,h,o4 ,uranium #df ,phosphuranylite #c,,uo 4 ,p,o 4 #f;,h,o4 ,uranium #eh-fd ,zun]ite ,cu,o 4 #b,,uo 4 ,z,o 4 #h;,h,o4 ,uranium #df ,uranosp9ite ,ca,o 4 #b,,uo 4 ,z,o 4 #h;,h,o4 ,uranium #di ,walpurgite #e;,bi,o 4 #c,,uo 4 ,z,o 4 #ab;,h,o4 ,uranium #af ,?orogummite ,,uo 4 ,a v>iety ( #c,th,o 4 gummite #c,si,o 4 #f;,h,o8 ,uranium #da ,?orite1 ,th,si,o4 ,a prim>y ,orangite1 ,uranium con/itu5t ( ,urano?orite #a-aj4 pegmatite ,?orium oxide dikes #dh-ga ,?orianite ,oxide ( ,occurs z a ?orium1 prim>y uranium1 ! con/itu5t ( r>e e>?s a pegmatite & lead4 dike 9 ,conta9s a ,ceylon4 relatively ,geological age l>ge probably proportion ( ,ar*ean helium4 ,uranium #i-aj4 ,?orium oxide #gc-gg ,sam>skite ,niobate & ,prim>y tantalate ( con/itu5t ( r>e e>?s4 pegmatite ,uranium #h-aj dikes ,f]gusonite ,metaniobate & tantalate ( r>e e>?s4 ,uranium #a-f ,eux5ite ,niobate & titanate ( r>e e>?s4 ,uranium #c-aj ,monazite ,phosphate ( ! r>e e>?s1 *iefly c]ium4 ,uranium #jc-jd ,footnote #dee3 ,an app>5t exception has be5 obs]v$ by ,danne 9 ! case ( c]ta9 lead m9]als :i* occur "u peculi> conditions at d',issy-l'vque1 ,france4 ,see p4 #dfe4 ,footnote #def3 ,hillebr&1 ,am4 ,j4 ,sci4 #dj1 #chd 7#ahij72 ibid4 #db1 #cij 7#ahia74 ,,index4 ,! numb]s ref] to ! pages4 rays discov]y (1 #ada nature (1 #ada magnetic deviation (1 #adb et seq4 electro/atic deviation (1 #adf velocity (1 #adh value ( e_/m =1 #adh *>ge c>ri$ by1 #aea et seq4 numb] ( p>ticles expell$ f "o gram ( radium1 #aee mass & en]gy (1 #aef orig9 (1 9 atomic dis9tegration1 #aeg sc9tillations produc$ by1 #aeh et seq4 absorption (1 by matt]1 #afa et seq4 increase ( absorption ) ?ickness ( matt] trav]s$1 #afc relative absorption ( rays f radio-elem5ts1 #afd absorption (1 by gases1 #afe et seq4 connection betwe5 absorption & d5sity1 #afi relation betwe5 ionization & absorption1 #agj !ory ( absorption (1 #agj et seq4 range ( ionization (1 #agb et seq4 complexity ( rays f radium1 #agd et seq4 effect ( ?ickness ( lay] ( radiat+ matt] on emission (1 #aie relative ionization produc$ by & rays1 #aif et seq4 phosphoresc5ce by rays1 #bjb et seq4 connection (1 ) radio-active *anges1 #bce1 #ddd et seq41 #dee f ! emanations1 #bfc emission ( en]gy f radio-elem5ts 9 =m ( rays1 #dai et seq4 connection ( heat emission ( radium ) rays1 #dba et seq4 numb] ( ions produc$ by an p>ticle1 #dcc abs5ce (1 9 rayless *anges1 #ded emission f active products1 #ded et seq4 loss ( weight due to expulsion (1 #dgc p>ticles consi/ ( helium1 #dgi et seq4 magnetic deflection (1 f radium ,c1 #edc velocity & e_/m =1 f radium ,c1 #edc et seq4 dim9ution ( velocity (1 9 pass+ ?r\gh matt]1 #ede dim9ution 9 velocity (1 9 pass+ ?r\gh alum9ium1 #ede velocity (1 :5 ionization ceases1 #ede et seq4 connection ( phosphoresc5t1 photographic1 & ionization effects produc$ by1 #edf et seq4 en]gy requir$ to produce an ion by rays1 #eea ,abraham app>5t mass ( mov+ *>g$ body1 #ga1 #abg ,absorption law (1 9 gases1 #fd et seq4 relative absorption ( 1 & rays by matt]1 #aaa connection betwe5 absorption & ionization1 #acd et seq41 #agj et seq4 ( rays by solids1 #acd et seq4 connection betwe5 absorption & d5sity = rays1 #acg ( rays 9 radio-active matt]1 #adj ( rays by solids1 #afa et seq4 ( rays 9 gases1 #afg1 #agj et seq4 connection betwe5 absorption & d5sity = rays1 #afi !ory (1 #agj et seq4 ( rays by solids1 #agi et seq4 connection betwe5 absorption & d5sity = rays1 #aha ( rays f ! emanations1 #bfc ( p5etrat+ rays f ! e>?1 #ebj1 #edj ,act9ium me?ods ( sep>ation (1 #bj et seq4 prop]ties (1 #ba simil>ity to 8emanat+ sub/ance0 ( ,giesel1 #ba possible connection ) radio-activity ( ?orium1 #bh emanation f1 #bdi excit$ activity produc$ by1 #caa effect ( magnetic field on excit$ activity f1 #cbd sep>ation ( act9ium ,x1 #cfe decay ( act9ium ,x1 #cfe s\rce ( act9ium emanation1 #cfe analysis ( active deposit (1 #cff radiations f products (1 #cfh p5etrat+ p[] ( & rays f1 #cfh products (1 #cfi table ( products (1 #ddi possible orig9 (1 #dfd ,act9ium ,a sep>ation & p]iod (1 #cfg et seq4 ,act9ium ,b p]iod (1 #cfh prop]ties (1 #cfh ,act9ium ,x sep>ation & decay (1 #cfd et seq4 production ( emanation by1 #cfe ,adams decay ( activity ( emanation f well wat]1 #eaa decay ( excit$ activity f ! emanation1 #eaa ,age ( radium1 #deg ( sun & e>?1 #dib et seq4 ,allan1 ,s4 ,j4 increase ) "t ( excit$ activity f atmosph]e1 #eje radio-activity ( sn[1 #ejf effect ( conditions on decay ( activity f air1 #eai1 #ebc ,allan & ,ru!r=d decay ( excit$ activity f ! atmosph]e1 #ejc ionization ( air 9 clos$ vessels1 #ecd ,all51 ,h4 ,s4 & ,"l ,bly?swood radium emanation 9 ,ba? spr+s1 #eac ,&]son & ,h>dy action ( radium rays on ! eye1 #bag ,arm/rong & ,l[ry radio-activity & phosphoresc5ce1 #ddd ,arnold rays f phosphoresc5t sub/ances1 #d ,as*k9ass & ,casp>i action ( radium rays on microbes1 #baf ,atmosph]e excit$ activity f1 #eja et seq4 radio-activity (1 due to emanations1 #ejd diffusion ( emanations into1 f ! e>?1 #ejg effect ( temp]ature1 pressure1 c4 on radio-activity (1 #eag et seq4 pres5ce ( v p5etrat+ radiation 91 #ebj comp>ison ( radio-activity (1 ) radio-elem5ts1 #eba et seq4 am\nt ( radium emanation 91 #ebd et seq4 ionization (1 due to radium emanation1 #ebf ,atom numb] ( p] c4c41 #ed dis9tegration (1 #bcd et seq4 complex nature (1 #bce *ang+ atoms1 #ddd et seq4 possible causes ( dis9tegration (1 #dhf evolution (1 #dif ,atomic weight ( radium by *emical me?ods1 #ag f spectroscopic evid5ce1 #ah emanations1 #bgc ( radio-elem5ts & connection ) radio-activity1 #dde rays discov]y (1 #aac magnetic deflection (1 #aad complexity (1 #aaf exam9ation by ! electrical me?od1 #aah effect (1 on a fluoresc5t scre51 #aai *>ge c>ri$ by !1 #abj et seq4 electro/atic deviation (1 #abd velocity (1 & value ( e_/m =1 #abf v>iation ( e_/m ) velocity (1 #abg et seq4 di/ribution ( velocity among/ p>ticles1 #aca absorption (1 #acd et seq4 v>iation ( absorption ) d5sity1 #acf et seq4 numb] ( p>ticles /opp$ by matt]1 #acg et seq4 v>iation ( int5sity (1 ) ?ickness ( lay]1 #adj second>y rays1 #ahi et seq4 relative ionization produc$ by & rays1 #aif relative en]gy emitt$ 9 =m ( & rays1 #aif et seq4 phosphoresc5t action (1 #bja et seq4 physical action produc$ by1 #bjg et seq4 *emical action (1 #bac physiological action (1 #baf f ,ur ,x1 #cdg f active deposit ( radium1 #cgg et seq4 significance ( appe>ance (1 only 9 la/ radio-active *anges1 #dee *ange ( weight due to expulsion (1 #dgc ,b>ium plat9ocyanide phosphoresc5ce (1 "u radium rays1 #bjc *ange ( col\r due to radium rays1 #bje ,b>kla pol>ization ( ,x rays1 #hj ,b>nes & ,ru!r=d heat+ effect ( radium emanation1 #dba1 #dbi connection ( heat+ effect ) radio-activity1 #dba heat+ effect ( active deposit1 #dbe heat+ effect ( rays1 #dbi heat+ effect ( emanation1 #dca division ( heat+ effect among active products1 #dcc ,b>y phosphoresc5ce "u radium rays1 #bjb ,bask]ville activity ( ?orium1 #bi phosphoresc5ce ( kunzite "u radium rays1 #bjc ,bask]ville & ,kunz phosphoresc5ce ( sub/ances "u radium rays1 #bjd ,beattie1 ,smolan & ,kelv9 dis*>g+ p[] ( uranium rays1 #g ,becqu]el rays f calcium sulphide1 #d rays f uranium1 #e et seq4 p]man5ce ( uranium rays1 #f dis*>g+ p[] ( uranium rays1 #f magnetic deflection ( radium rays by photographic me?od1 #aad et seq4 curvature ( radium rays 9 a magnetic field1 #aae et seq4 complexity ( radium rays1 #aaf et seq4 electro/atic deflection ( rays ( radium1 #abd et seq4 value ( e_/m = rays ( radium1 #abf et seq4 magnetic deviation ( rays ( radium & polonium1 #ade trajectory ( rays ( radium 9 magnetic field1 #adh sc9tillations due to cleavage ( cry/als1 #afj rays f radium1 #agi second>y rays produc$ by active sub/ances1 #ahg phosphoresc5ce produc$ by radium rays1 #bja conductivity ( p>aff9 "u radium radiation1 #baj effect ( temp]ature on uranium rays1 #baj *emical action ( radium rays1 #bad removal ( activity f uranium by precipitation ) b>ium1 #bai !ory ( radio-activity1 #dch ,bemont et ,m4 et ,mme ,curie discov]y ( radium1 #ac ,b]ndt spectrum ( polonium1 #bc ,blanc ?orium 9 s$im5ts f hot spr+s1 #ead ,bly?swood1 ,"l & ,all51 ,h4 ,s4 radium emanation 9 ,ba? spr+s1 #eac ,bdl&] & ,runge evolution ( gases f radium1 #bae ,boltwood orig9 ( radium1 #dfj am\nt ( radium 9 m9]als1 #dfj proportionality ( uranium & radium 9 m9]als1 #dfa production ( lead by uranium1 #dhd radium emanation 9 spr+ wat]1 #ead me?od ( /&>dization ( am\nt ( emanation 9 wat]s1 #ead ,boys rate ( dissipation ( *>ge1 #eca ,bragg & ,kleeman !ory ( absorption ( rays1 #agb et seq4 relation betwe5 ionization & absorption1 #agd et seq4 range ( rays 9 air1 #agd f\r sets ( rays f radium1 #agd et seq4 ,bronson use ( /eady deflection me?od ) an electromet]1 #ajd decay ( ?orium emanation1 #bdb decay ( excit$ activity f act9ium1 #cab ,brooks1 ,miss v>iation ( excit$ activity f ?orium = %ort exposures1 #cjd effect ( du/ on di/ribution ( excit$ activity1 #cje decay curves ( excit$ activity ( radium measur$ by & rays1 #cjg et seq4 decay curves ( excit$ activity f act9ium1 #cab ,brooks & ,ru!r=d absorption ( rays by matt]1 #afa comp>ison ( absorption ( rays f radio-elem5ts1 #afd diffusion ( radium emanation1 #bgj decay ( excit$ activity f radium1 #cjf ,bum/ead pres5ce ( ?orium emanation 9 atmosph]e1 #eab ,bum/ead & ,:eel] diffusion ( radium emanation1 #bgc emanation f surface wat] & ! soil1 #eab1 #ebb id5tity ( emanation f soil ) radium emanation1 #eab1 #ebb ,burton radium emanation 9 petroleum1 #eaf ,burton & ,mc,lennan p5etrat+ radiation f ! e>?1 #ebj radio-activity ( ord9>y mat]ials1 #ecg emanation f ord9>y matt]1 #ech ,campbell radio-activity ( ord9>y mat]ials1 #edj ,canal rays discov]y (1 #gh magnetic & electric deflection (1 #gh value ( e_/m =1 #gh simil>ity (1 to rays1 #aaj ,capacity ( electroscopes1 #hg ( electromet]s1 #id1 #ajb /&>ds (1 #ajb ,c>bonic acid radio-activity ( natural1 #eaf ,casp>i & ,as*k9ass action ( radium rays on microbes1 #baf ,ca?ode rays discov]y (1 #gc magnetic & electric deflection (1 #gd value ( e_/m =1 #ge radiation ( en]gy f1 #gi comp>ison (1 ) rays1 #abj absorption (1 by matt]1 #acf1 #acg see also rays ,caves radio-active matt] pres5t 9 air (1 #ead et seq4 radio-activity ( air (1 due to emanation f ! soil1 #eae ,*anges 7see ,trans=mations7 ,*>ge c>ri$ by ! ions1 #ej et seq4 negative *>ge c>ri$ by rays1 #abj measurem5t ( *>ge c>ri$ by rays1 #aba et seq4 positive *>ge c>ri$ by rays1 #ade measurem5t ( *>ge c>ri$ by rays1 #aea et seq4 ,*emical nature ( emanation1 #bfg ( active deposit1 #cab ,*emical actions ( radium rays production ( ozone1 #bac coloration ( glass & rock-salt1 #bac on phosphorus1 #bad on iod(orm1 #bad on globul91 #bad evolution ( hydrog5 & oxyg51 #bae ,*ild pot5tial gradi5t betwe5 electrodes1 #fe v>iation ( curr5t ) voltage = surface ionization1 #ff ,cl\ds =mation (1 by cond5sation ( wat] r\nd ions1 #df et seq4 diff]5ce betwe5 positive & negative ions 9 =mation (1 #di ,collie & ,ramsay spectrum ( emanation1 #bib ,collision ionization by1 #ci1 #eg numb] ( ions produc$ by rays p] cm4 ( pa?1 #dcd total numb] ( ions produc$ by collisions ( p>ticles1 #dcd ,coloration ( cry/als ( radif]\s b>ium1 #ae ( buns5 flame by radium1 #ae ( glass by radium rays1 #bac ( rock-salt1 fluor-sp> & potassium sulphate by radium rays1 #bac ,conc5tration ( excit$ activity on negative electrode1 #big activity ( radium indep5d5t (1 #dff ,cond5sation ( wat] r\nd ! ions1 #df et seq4 ( emanations1 #bgg exp]im5tal illu/ration (1 #bgi temp]ature (1 #bhj diff]5ce betwe5 po9t (1 = emanations ( ?orium & radium1 #bhc f air suck$ up f ! e>?1 #eaj ,conductivity ( gases expos$ to radiations1 #ca et seq4 v>iation (1 ) pressure1 #fa et seq4 v>iation (1 ) nature ( gas1 #fd comp>ison (1 = gases expos$ to 1 1 & rays1 #fd comp>ison (1 :5 expos$ to rays & to h>d ,x rays1 #ahd ( insulators1 #bji ( air 9 caves & cell>s1 #ejg et seq4 ( air 9 clos$ vessels1 #eca et seq4 v>iation (1 9 clos$ vessels ) pressure & nature ( gas1 #ecd v>iation (1 ) temp]ature = air 9 clos$ vessels1 #ecf increase (1 ) "t1 9 a clos$ vessel1 #ecg ,cons]vation ( radio-activity examples (1 #dfi et seq4 ,cooke1 ,h4 ,l4 p5etrat+ rays f ! e>?1 #ebj numb] ( ions p] c4c4 9 clos$ vessels1 #ecd radio-activity f ord9>y matt]1 #ecf ,cooke1 ,w4 ,t4 & ,ramsay radio-activity produc$ by radiations ( radium1 #dgb ,corpuscle 7see ,electron7 ,crookes1 ,sir ,w4 spectrum ( radium1 #ag spectrum ( polonium1 #bc nature ( ca?ode rays1 #gc nature ( rays1 #adb sc9tillations produc$ by radium1 #aeh sp9?>iscope1 #aeh numb] ( sc9tillations indep5d5t ( pressure & temp]ature1 #aei phosphoresc5ce ( diamond1 #bjd sep>ation ( ,ur ,x1 #bai !ory ( radio-activity1 #dda ,crookes & ,dew> abs5ce ( nitrog5 spectrum 9 phosphoresc5t light ( radium at l[ pressures1 #bjf ,cry/allization effect (1 on activity ( uranium1 #cdi ,curie1 ,mme p]man5ce ( uranium rays1 #f discov]y ( radio-activity ( ?orium1 #aj radio-activity ( uranium & ?orium m9]als1 #aa relative activity ( comp\nds ( uranium1 #ab coloration ( radium cry/als1 #ae spectrum ( radium1 #af discov]y ( polonium1 #bb nature ( a rays1 #adb absorption ( rays f polonium1 #afc second>y radiation te/$ by electric me?od1 #ahh sl[ly decay+ excit$ activity f radium1 #caa recov]y ( activity ( radium1 #cge bismu? made active by solution ( b>ium1 #dag ,curie1 ,p4 magnetic deviation ( radium rays by electric me?od1 #aad conductivity ( dielectrics "u radium rays1 #bji radio-activity ( radium unaffect$ by temp]ature1 #baj decay ( activity ( radium emanation1 #bdg discov]y ( excit$ radio-activity f radium1 #bie heat emission ( radium at l[ temp]ature & v>iation ( heat emission ) age ( radium1 #dai nature ( ! emanation1 #dci ,curie1 ,m4 et ,mme discov]y ( radium1 #ac *>ge c>ri$ by rays1 #aba lum9osity ( radium comp\nds1 #bje production ( ozone by radium rays1 #bac coloration ( glass by radium rays1 #bac !ory ( radio-activity1 #dci possible absorption by radio-elem5ts ( unkn[n radiations1 #ddb ,curie1 ,j4 et ,p4 qu>tz piezo-lectrique1 #aje et seq4 ,curie1 ,p4 et ,danne diffusion ( radio-active emanation1 #bgb decay ( excit$ activity f radium1 #cji decay curves ( radium & equation1 #cji occlusion ( radium emanation 9 solids1 #caj *anges 9 radium1 #cha effect ( temp]ature on active deposit1 #cij ,curie1 ,p4 & ,debi]ne evolution ( gas f radium1 #bae active gases evolv$ f radium1 #bea phosphoresc5ce produc$ by radium emanation1 #beb di/ribution ( lum9osity1 #beb rate ( production ( emanation indep5d5t ( pressure1 #bff effect ( pressure on am\nt ( excit$ activity1 #bff1 #cag ,curie & ,dew> production ( helium by radium1 #dgi ,curie1 ,p4 & ,laborde heat emission ( radium1 #dai orig9 ( heat f radium1 #ddj radium emanation 9 wat]s ( hot spr+s1 #ead ,curr5t ?r\gh gases1 #ca et seq4 v>iation (1 ) di/ance betwe5 ! plates1 #ei et seq4 v>iation (1 ) pressure ( gas1 #fa et seq4 v>iation (1 ) nature ( gas1 #fd measurem5t (1 by galvanomet]1 #hd measurem5t (1 by electroscope1 #he et seq4 measurem5t (1 by electromet]1 #ij et seq4 measurem5t (1 by qu>tz piezo-lectrique1 #aje ,dad\rian pres5ce ( ?orium emanation 9 ! e>?1 #eab ,danne on deposit ( radium n conta9+ uranium1 #dfe ,danne et ,curie diffusion ( radio-active emanation1 #bgb decay ( excit$ activity f radium1 #cji decay curves ( radium & equation1 #cji occlusion ( radium emanation 9 solids1 #caj *anges 9 radium1 #cha effect ( temp]ature on active deposit1 #cij ,danysz action ( radium rays on sk91 #baf ,d>w91 ,g4 ,h4 age ( sun1 #dib ,debi]ne act9ium1 #ba emanation f act9ium1 #bdi decay ( excit$ activity f act9ium1 #caa effect ( magnetic field on activity excit$ f act9ium1 #cbd b>ium made active by act9ium1 #dag ,debi]ne & ,curie evolution ( gas f radium1 #bae active gases evolv$ f radium1 #bea phosphoresc5ce produc$ by radium emanation1 #beb di/ribution ( lum9osity1 #beb rate ( production ( emanation indep5d5t ( pressure1 #bff effect ( pressure on am\nt ( excit$ activity1 #bff1 #cag ,decay ( activity ( ,? ,x1 #bba ( activity ( ,ur ,x1 #bbc significance ( law (1 #bbi effect ( conditions on ! rate (1 #bcb ( activity ( ?orium emanation1 #bda ( activity ( radium emanation1 #bdg ( activity ( act9ium emanation1 #bdi ( excit$ activity due to ?orium = long exposure1 #cjb ( excit$ activity due to ?orium = %ort exposure1 #cjd ( excit$ activity due to radium1 #cjf et seq4 excit$ activity ( sl[ decay due to radium1 #caa ( excit$ activity f act9ium1 #caa ( radium ,a1 ,b & ,c1 #cgg et seq4 ( radium ,d1 ,e & ,f1 #cig et seq4 ( heat+ effect ( emanation1 #dbc ( excit$ activity f atmosph]e1 #ejb ( activity ( ra9 & sn[1 #ejf ( emanation f ! e>?1 #ejh diff]5ces 91 ( excit$ activity f atmosph]e1 #eba et seq4 ,dem>ay spectrum ( radium1 #af ,deposit1 active connection (1 ) excit$ activity1 #cja physical & *emical prop]ties (1 #cab electrolysis (1 #cac effect ( temp]ature on1 #cae effect ( pressure on di/ribution (1 #cag transmission (1 by positive c>ri]s1 #cah et seq4 nom5clature (1 #cbh !ory ( *anges 91 #cca et seq4 !ory ( activity due to1 #ccg et seq4 !ory ( rayless *ange 91 #cda et seq4 ( ?orium1 #cjb et seq41 #cea et seq4 analysis (1 #cea rayless *ange 91 #ceb effect ( temp]ature on1 #ced p]iod ( products (1 #cee ( act9ium1 #caa et seq4 decay curves (1 #caa analysis (1 #cfg rayless *ange 91 #cfg p]iod ( products (1 #cfh radiations f1 #cfh ( radium1 #cgf et seq4 connection ( excit$ activity )1 #cjf g5]al analysis (1 #cgf et seq4 analysis (1 ( rapid *ange1 #cgg et seq4 analysis ( ray curves1 #cgg ray curves (1 #cgh ray curves (1 #cgi analysis ( ray curves1 #cha equations ( activity curves1 #chi effect ( temp]ature on1 #cij volatility (1 #cia ( sl[ trans=mation1 #caa1 #cig v>iation ( ray activity (1 #cih v>iation ( ray activity (1 #cii sep>ation ( con/itu5ts (1 #dja et seq4 successive products 91 #djb v>iation ( activity (1 = long p]iods1 #djg pres5ce 9 old radium1 #djh effect (1 on v>iation ( activity ( radium ) "t1 #dji pres5ce 9 pit*bl5de1 #daj connection ) radio-tellurium1 #daa connection ) polonium1 #daa1 #dab connection ) radio-lead1 #dac connection (1 ) radio-active induction1 #dae et seq4 heat emission (1 #dbe et seq4 use (1 to det]m9e numb] ( p>ticles f radium1 #dce use (1 z s\rce ( rays1 #edc ,des ,c\dres magnetic & electric deviation ( rays1 #adh det]m9ation ( e_/m = rays1 #adh ,dew> emission ( heat f radium 9 liquid hydrog51 #dbj ,dew> & ,crookes abs5ce ( nitrog5 spectrum 9 phosphoresc5t light ( radium at l[ pressures1 #bjf ,dew> & ,curie production ( helium by radium1 #dgi ,dielectrics condition (1 "u radium rays1 #bji ,diffusion ( ions1 #ea et seq4 ( radium emanation into gases1 #bgj ( ?orium emanation into gases1 #bge ( radium emanation into liquids1 #bgf ,dis*>ge action ( rays on sp>k & electrodeless1 #bjh ,dis9tegration acc\nt ( !ory (1 #bcd1 #cbe1 #dde li/ ( products (1 #ddi rate (1 9 radio-elem5ts1 #deg emission ( en]gy 9 consequ5ce (1 #dgd et seq4 helium a product (1 #dgf et seq4 possible causes (1 #dhf et seq4 ( matt] 9 g5]al1 #dif et seq4 ,dissipation ( *>ge 9 caves & cell>s1 #ead et seq4 9 clos$ vessels1 #eca effect ( pressure & nature ( gas on1 #ecd et seq4 effect ( mat]ial ( vessel on1 #ecf et seq4 ,dolezalek electromet]1 con/ruction (1 #id et seq4 ,dorn *>ge c>ri$ by rays1 #abb electro/atic deflection ( rays f radium1 #abd discov]y ( radium emanation1 #bdf effect ( moi/ure on emanat+ p[] ( ?orium1 #bee electrolysis ( radium solution1 #cac loss ( weight ( radium1 #dgd radium emanation 9 spr+s1 #eac ,drey] & ,salomons5 coloration ( qu>tz by radium rays1 #bac ,dun/on analysis ( ?orianite1 #dhf ,durack ionization by collision ( electrons ( great velocity1 #aga ,du/ effect (1 on recomb9ation ( ions1 #db effect (1 on di/ribution ( excit$ activity1 #cje ,e>? am\nt ( radium 91 #dic et seq4 age (1 #dif excit$ activity deposit$ on1 #ejd activity conc5trat$ on peaks (1 #ejd emanation f1 #ejg v p5etrat+ radiation f1 #ebj ,eb]t cond5sation ( emanation f ! e>?1 #eaj app>atus = det]m9+ numb] ( ions p] c4c4 9 air1 #ebg velocity ( ions 9 air1 #ebh ,eb]t & ,ew]s emanation f ! e>?1 #ejh ,electrolysis sep>ation ( radio-tellurium by1 #be ( solutions ( active deposit1 #cac ( radium solutions1 #cac ( ?orium solutions1 #cad ,electromet] description (1 #ij et seq4 use (1 9 measurem5ts1 #ij con/ruction (1 #ia et seq4 ,dolezalek1 #id adju/m5t & scre5+ (1 #ie special key =1 #ig application (1 to measurem5ts ( radio-activity1 #ig et seq4 measurem5t ( curr5t by1 #ajj capacity (1 #aja use ) /eady deflection1 #ajc use ) qu>tz piezo-lectrique1 #aje ,electron def9ition (1 #ef production (1 "u diff]5t conditions1 #gf et seq4 id5tity ( rays ) electrons1 #abj et seq4 v>iation ( app>5t mass ( electron ) velocity1 #abg et seq4 evid5ce t mass ( electron is electromagnetic1 #abi et seq4 diamet] (1 #aca ,electroscope description (1 us$ by ,curie1 #he con/ruction (1 = accurate measurem5ts1 #hf use (1 9 measurem5ts ( m9ute curr5ts1 #hf ( ,c4 ,t4 ,r4 ,wilson1 #hi use (1 9 measur+ conductivity ( air 9 clos$ vessels1 #eca et seq4 use (1 = det]m9+ radio-activity ( ord9>y matt]1 #ecg ,el/] & ,geitel radio-active lead1 #bg effect ( magnetic field on conductivity produc$ 9 air by rays1 #aac sc9tillations produc$ by active sub/ances1 #aeh action ( radium rays on sp>k1 #bjh photo-electric action ( body1 col\r$ by radium rays1 #bad radio-active matt] 9 e>?1 #did discov]y ( excit$ activity 9 atmosph]e1 #eja emanations f ! e>?1 #ejg radio-activity ( air 9 caves1 #ejg radio-activity ( ! soil1 #eae radio-activity ( fango1 #eaf v>iation ( radio-activity 9 atmosph]e ) meteorological conditions1 #eag effect ( temp]ature & pressure on atmosph]ic radio-activity1 #eah ,emanation ( ?orium1 discov]y & prop]ties (1 #bch me?ods ( measurem5t (1 #bdj decay ( activity (1 #bda effect ( ?ickness ( lay] on am\nt (1 #bdc increase (1 ) "t to a maximum1 #bde ( radium1 #bdf decay ( activity (1 #bdg ( act9ium1 prop]ties (1 #bdi ( radium1 phosphoresc5ce produc$ by1 #bea rate ( emission (1 #bed effect ( conditions on rate ( emission (1 #bee reg5]ation ( emanat+ p[]1 #bef cont9u\s rate ( production (1 #beg s\rce ( ?orium emanation1 #bfa s\rce ( radium & act9ium emanation1 #bfc radiations f1 #bfc effect ( pressure on production (1 #bfe *emical nature (1 #bfg exp]im5ts to illu/rate gase\s nature (1 #bfh rate ( diffusion ( radium emanation1 #bfi rate ( diffusion ( ?orium emanation1 #bge diffusion (1 into liquids1 #bgf cond5sation (1 #bgg temp]ature ( cond5sation (1 #bhj volume (1 f "o gram ( radium & ?orium1 #bhh measurem5t ( volume (1 f radium1 #bhi dim9ution ( volume (1 #bij spectrum ( emanation1 #bib connection betwe5 emanation & excit$ activity1 #bih effect ( removal (1 on activity ( radium1 #cga et seq4 fraction ( activity ( radium due to1 #cgd effect ( rate ( escape (1 on activity ( radium1 #cgd heat emission (1 #dbj1 #dca v>iation ( heat emission ) "t1 #dba et seq4 enorm\s emission ( en]gy f emanation1 #dca radio-activity ( atmosph]e due to emanations1 #ejd suck$ up f ! e>?1 #ejg 9 caves1 #ejg et seq4 rate ( decay ( activity (1 f ! e>?1 #ejh cond5sation (1 f ! atmosph]e1 #eaj 9 well wat] & spr+s1 #eaj et seq4 f 8fango10 #eaf effect ( meteorological conditions on am\nt (1 9 atmosph]e1 #eag et seq4 f metals1 #ech ,emanat+ p[] measurem5t (1 #bed effect ( conditions on1 #bee reg5]ation (1 #bef ,emanium or 8emanat+ sub/ance0 ( ,giesel 7see ,act9ium7 discov]y (1 #ba sep>ation & prop]ties (1 #ba simil>ity (1 to act9ium1 #ba emanation f1 #bdi excit$ activity produc$ by1 #caa action ( an electric field on1 #cbc ,en]gy ( p>ticle1 #aef ( p>ticle1 #aif comp>ison (1 = & p>ticles1 #aif emitt$ f radium 9 =m ( heat1 #dai et seq4 emission (1 f ! emanation1 #dca emission (1 f radio-active products ( radium1 #dcc total emission (1 f #a gram ( radio-elem5ts1 #dgd et seq4 lat5t /ore (1 9 matt]1 #dge ,eve conductivity ( gases expos$ to ,x rays1 #fd conductivity ( gases expos$ to ,x rays & rays1 #ahc1 #ahd second>y rays produc$ by & rays1 #ahi et seq4 magnetic deflection ( second>y rays f rays1 #aic v>iation ( activity ( radium ) conc5tration1 #dfg am\nt ( radium emanation 9 ! atmosph]e1 #ebd et seq4 ionization due to emanation 9 atmosph]e1 #ebf et seq4 ,evolution ( matt] evid5ce (1 #dig ,ew]s & ,eb]t emanation f ! e>?1 #ejh ,excit$ radio-activity discov]y & prop]ties (1 #bie et seq4 conc5tration (1 on negative electrode1 #big connection (1 ) ! emanations1 #bih removal (1 by acids1 #cjj decay (1 due to ?orium1 #cjb decay (1 = %ort exposure to ?orium1 #cjd effect ( du/ on di/ribution (1 #cje decay curves = diff]5t times ( exposure1 #cjf et seq4 decay (1 f radium1 #cjf decay curves (1 measur$ by rays1 #cjh decay curves (1 measur$ by rays1 #cji decay curves (1 f act9ium1 #caa ( radium1 ( v sl[ decay1 #caa effect ( solution on1 #cab electrolysis ( active solutions1 #cac effect ( temp]ature on1 #cae v>iation ) electric field1 ( am\nt (1 #caf effect ( pressure on di/ribution (1 #cag transmission (1 #cah f act9ium & emanium1 #cbc heat emission due to1 #dbe et seq4 f ! atmosph]e1 #eja et seq4 decay (1 #ejb due to emanation 9 atmosph]e1 #ejd di/ribution (1 on surface ( ! e>?1 #ejd conc5tration (1 on prom95ces ( ! e>?1 #ejd ( ra9 & sn[1 #ejf produc$ by emanation f tap wat]1 #eaj effect ( meteorological conditions on am\nt (1 #eag et seq4 am\nt (1 at ,niag>a ,falls1 #ebj rate ( decay (1 dep5d5t on conditions1 #ebb et seq4 ,exn] & ,has*ek spectrum ( radium1 #ag ,eye action ( radium rays on1 #bag ,fehrle di/ribution ( excit$ activity on a plate 9 electric field1 #cah ,fluoresc5ce produc$ 9 sub/ances by radium rays1 #ah produc$ 9 sub/ances by radium & polonium rays1 #bja et seq4 ,fog l>ge am\nt ( excit$ activity dur+1 #eah ,=* loss ( weight ( radium1 #dgd rays relative conductivity ( gas expos$ to & h>d ,x rays1 #fd1 #ahd discov]y (1 #agi absorption (1 by matt]1 #agi et seq4 connection betwe5 absorption (1 & d5sity1 #ahb discussion ( nature ( rays1 #ahb et seq4 second>y rays produc$ by rays1 #ahi measurem5t ( radio-activity by means (1 #ddb1 #dfg cons]vation ( radio-activity measur$ by1 #dga ,gases evolv$ by radium1 #bae pres5ce ( helium 9 gases f radium1 #baf ,gates1 ,miss ,f4 effect ( temp]ature on excit$ activity1 #cae dis*>ge ( qu99e sulphate1 #ecj ,geitel natural conductivity ( air 9 clos$ vessels1 #eja1 #eca ,geitel & ,el/] radio-active lead1 #bg effect ( magnetic field on conductivity produc$ by radium rays1 #aac sc9tillations produc$ by active sub/ances1 #aeh action ( radium rays on sp>k1 #bjh photo-electric action ( bodies col\r$ by radium rays1 #bad radio-active matt] 9 e>?1 #did discov]y ( radio-active matt] 9 atmosph]e1 #eja emanations f ! e>?1 #ejg radio-activity ( air 9 caves1 #ejg radio-activity ( ! soil1 #eae radio-activity ( fango1 #eaf v>iation ( radio-activity ( air ) meteorological conditions1 #eag effect ( temp]ature & pressure on radio-activity 9 atmosph]e1 #eah ,giesel coloration ( buns5 flame by radium1 #ae sep>ation ( radium by cry/allization ( bromide1 #ae emanat+ sub/ance1 #ba radio-active lead1 #bg magnetic deviation ( rays1 #aac decrease ) "t ( lum9osity ( radio-active scre51 #bje spectrum ( phosphoresc5t light ( emanium due to didymium1 #bjf1 #bjg coloration ( bodies by radium rays1 #bac evolution ( gases f radium1 #bae action ( radium rays on ! eye1 #bag emanation f ! emanat+ sub/ance1 #bej lum9osity produc$ by radium emanation1 #bea decay ( excit$ activity ( emanium1 #cab activity ( radium dep5d5t on age1 #cga bismu? made active by radio-active solution1 #dag temp]ature ( radium bromide above air1 #dbj ,gim+ham & ,rossignol decay ( ?orium emanation1 #bdb ,glass coloration produc$ 91 by radium rays1 #bac phosphoresc5ce produc$ 91 by emanation1 #beb ,glew simple =m ( sp9?>iscope1 & sc9tillations1 #aei ,globul9 action ( radium rays on1 #bad ,godlewski effect ( cry/allization on activity ( uranium1 #cdi diffusion ( uranium ,x1 #cej sep>ation ( act9ium ,x1 #cfe s\rce ( act9ium emanation1 #cfe recov]y & decay curves ( act9ium1 #cff p5etrat+ p[] ( & rays f act9ium1 #cfh radiations f active products1 #cfh ,gold/e9 canal rays1 #gh coloration ( bodies by radium rays1 #bac ,gond]1 ,h(mann1 & ,wlfl prop]ties ( radio-active lead1 #bg1 #dac ,gri] & ,ru!r=d magnetic deviation ( rays ( ?orium1 #aad relative curr5t due to & rays1 #aie nature ( rays f ,ur ,x1 #cdg ,h>dy coagulation ( globul9 by radium rays1 #bad ,h>dy & ,miss ,willcock coloration ( iod(orm solutions by radium rays1 #bad ,h>dy & ,&]son action ( radium rays on ! eye1 #bag ,h>ms numb] ( ions p] c4c4 9 clos$ vessel1 #ecd ,h>tmann spectrum ( phosphoresc5t light ( emanium1 #bjf ,has*ek & ,exn] spectrum ( radium1 #ag ,heat rate ( emission (1 f radium1 #dai et seq4 emission (1 f radium at l[ temp]atures1 #dbj connection ( heat emission ) ! radio-activity1 #dba et seq4 s\rce ( heat en]gy1 #dba et seq4 rate ( emission (1 aft] removal ( ! emanation1 #dbb et seq4 rate ( emission (1 by emanation1 #dbc1 #dca v>iation ) "t ( heat emission ( radium1 & ( its emanation1 #dbc heat+ effect ( ! emanation1 #dbc1 #dca heat+ effect ( active deposit1 #dbe proportion ( heat+ effect due to radio-active products1 #dcc orig9 (1 9 radium1 #ddb et seq4 total heat emission dur+ life ( radio-elem5ts1 #dgd et seq4 heat+ ( e>? by radio-active matt]1 #dic ,heaviside app>5t mass ( mov+ *>g$ body1 #ga1 #abg ,helium produc$ by radium & its emanation1 #dgf et seq4 am\nt (1 f radium1 #dhj orig9 (1 #dhj ,helmholtz & ,ri*>z action ( ions on /eam jet1 #dg ,hempt9ne action ( rays on sp>k & electrodeless dis*>ge1 #bjh ,h5n+ resi/ance ( radium solutions1 #bjh effect ( voltage on am\nt ( excit$ activity1 #caf ,h5n+ & ,kohlraus* conductivity ( solutions ( radium bromide1 #bjh ,h]tz electric deviation ( ca?ode rays1 #gc ,heydweil] loss ( weight ( radium1 #dgd ,him/$t action ( radium rays on sel5ium1 #bjh radium emanation 9 spr+s ( ,bad51 #eac ,him/$t & ,mey] production ( helium by radium1 #dgi ,him/$t & ,nagel action ( radium rays on ! eye1 #bag ,h(mann1 ,gond]1 & ,wlfl prop]ties ( radio-active lead1 #bg1 #dac ,h(mann & ,/rauss radio-active lead1 #bg ,h(mann & ,z]ban connection ( activity ( ?orium ) uranium1 #bi ,hugg9s1 ,sir ,w4 & ,lady spectrum ( phosphoresc5t light ( radium bromide1 #bje ,hydrog5 production (1 by radium rays1 #bae ,induc$ radio-activity 7see ,excit$ radio-activity7 ,induction radio-active1 #bd mean+ & examples (1 #dae et seq4 ,insulators conduction (1 "u radium rays1 #bji ,iod(orm coloration produc$ 91 by radium rays1 #bad ,ionization !ory (1 to expla9 conductivity ( gases1 #ca et seq4 by collision1 #ci1 #eg v>iation (1 ) pressure ( gas1 #fa et seq4 v>iation (1 ) nature ( gas1 #fd comp>ison (1 produc$ by rays1 #aaa1 #aid production (1 9 insulators1 #bji total1 produc$ by #a gram ( radium1 #dcc et seq4 natural ionization ( gases1 #eca et seq4 connection (1 ) phosphoresc5t & photographic actions1 #edi ,ions 9 explanation ( conductivity ( gases1 #ca et seq4 production (1 by collision1 #ci1 #eg rate ( recomb9ation (1 #dj et seq4 mobility (1 #db et seq4 diff]5ce betwe5 mobility ( positive & negative1 #dc et seq4 cond5sation ( wat] ar\nd1 #df et seq4 diff]5ce betwe5 positive & negative1 #di *>ge c>ri$ by1 #ej diffusion (1 #ea et seq4 *>ge on an ion same z on hydrog5 atom1 #ed numb] (1 produc$ p] c4c41 #ed size & nature (1 #ee et seq4 def9ition (1 #ef et seq4 velocity acquir$ by1 betwe5 collisions1 #eh en]gy requir$ to produce1 #eh1 #eea comp>ative numb] (1 produc$ 9 gases1 #fe di/urbance ( pot5tial gradi5t by movem5t (1 #fe production (1 9 insulators1 #bji numb] (1 produc$ by p>ticle1 #dcc numb] produc$ p] c4c4 9 clos$ vessels1 #ecc et seq4 ,joly motion ( radium 9 an electric field1 #baa absorption ( radium rays by atmosph]e1 #dib 7see foot-note7 ,kaufmann velocity ( ca?ode rays1 #ge v>iation ( e_/m ) velocity ( electron1 #abg et seq4 ,kelv9 !ory ( radio-activity1 #dda age ( sun & e>?1 #dib1 #dic ,kelv91 ,smolan & ,beattie dis*>g+ p[] ( uranium rays1 #g ,kleeman & ,bragg !ory ( absorption ( rays1 #agb et seq4 relation betwe5 ionization & absorption1 #agd et seq4 range ( rays 9 air1 #agd f\r sets ( rays f radium1 #agd et seq4 ,kohlraus* conductivity ( wat] alt]$ by radium rays1 #bjh ,kohlraus* & ,h5n+ conductivity ( solutions ( radium bromide1 #bjh ,kunz phosphoresc5ce ( willemite & kunzite1 #bjc ,kunz & ,bask]ville phosphoresc5ce ( sub/ance "u radium rays1 #bjd ,kunzite phosphoresc5ce (1 "u radium rays1 #bjc ,laborde & ,curie heat emission ( radium1 #dai orig9 ( heat f radium1 #ddj radium emanation 9 wat]s ( hot spr+s1 #ead ,langev9 coeffici5t ( recomb9ation ( ions1 #da velocity ( ions1 #de et seq4 en]gy requir$ to produce an ion1 #eh second>y radiation produc$ by ,x rays1 #ahg sl[ mov+ ions 9 air1 #ebh ,l>mor radiation !ory1 #gg radiation ( en]gy f mov+ electron1 #gi /ructure ( ! atom1 #aeg ,lead1 radio-active prep>ation (1 #bf radiations f1 #bf ,le ,bon rays f bodies expos$ to sunlight1 #e dis*>g+ p[] ( qu99e sulphate1 #i1 #ecj ,l5>d ionization ( gases by ultra-violet light1 #i action ( ions on a /eam jet1 #dg p5etrat+ p[] ( ca?ode rays1 #gc negative *>ge c>ri$ by ,l5>d rays1 #abj absorption ( ca?ode rays proportional to d5sity1 #acf1 #acg ,l]*1 von *emical prop]ties ( active deposit ( ?orium1 #cac electrolysis ( solution ( active deposit1 #cac effect ( temp]ature on excit$ activity1 #cae tempor>y activity ( active deposit f ?orium1 #dae ,locky] inorganic evolution1 #dii ,lodge1 ,sir ,oliv] electronic !ory1 #fi in/ability ( atoms1 #dhg ,lor5tz /ructure ( atoms1 #aeg ,l[ry & ,arm/rong radio-activity & phosphoresc5ce1 #ddd ,lum9osity ( radium comp\nds1 #bje *ange (1 9 radium comp\nds ) "t1 #bje spectrum ( phosphoresc5t light f radium bromide1 #bjf ( radium comp\nds unaffect$ by temp]ature1 #baj ,ma*e radium emanation 9 hot spr+s1 #eac ,ma*e & von ,s*weidl] velocity ( ions 9 air1 #ebh ,mak[] diffusion ( radium emanation1 #bgd diffusion ( ?orium emanation1 #bgf ,m>ckwald prep>ation ( radio-tellurium1 #be rate ( decay ( radio-tellurium1 #daa ,mass app>5t mass ( electron1 #ga1 #abg v>iation ( mass ( electron ) spe$1 #abg et seq4 ( p>ticle1 #adg et seq4 ,mat]ials radio-activity ( ord9>y1 #ebh1 #ecf et seq4 ,matteucci rate ( dissipation ( *>ge 9 clos$ vessels1 #eca ,mc,clelland absorption ( rays1 #aha second>y rays f & rays f radium1 #aib ,mc,clung coeffici5t ( recomb9ation ( ions1 #da conductivity ( gases expos$ to ,x rays1 #fd ionization by rays f radium ,c1 #eej ,mc,clung & ,ru!r=d en]gy requir$ to produce an ion1 #eh v>iation ( curr5t ) ?ickness ( lay] ( uranium1 #aie e/imate ( en]gy radiat$ f radio-elem5ts1 #dah radiation ( en]gy f radium1 #dch ,mc,lennan absorption ( ca?ode rays1 #fe radio-activity ( sn[1 #ejf excit$ radio-activity at ,niag>a ,falls1 #eai ,mc,lennan & ,burton p5etrat+ radiation f ! e>?1 #ebj radio-activity ( ord9>y mat]ials1 #ecg emanation f ord9>y matt]1 #ech ,metabolon def9ition (1 #ddf table ( metabolons1 #ddi radio-elem5ts z metabolons1 #deg ,meteorological conditions effect (1 on radio-activity ( atmosph]e1 #eag ,me?ods ( measurem5t 9 radio-activity1 #hb et seq4 comp>ison ( photographic & electrical1 #hc et seq4 description ( electrical1 #hd et seq4 ,mey] & ,him/$t production ( helium by radium1 #dgi ,mey] & ,s*weidl] magnetic deviation ( rays by electrical me?od1 #aac absorption ( rays ( radium by matt]1 #acf activity proportional to am\nt ( uranium1 #aie emanation f uranium1 #cdh effect ( cry/allization on activity ( uranium1 #cdi rate ( decay ( radio-tellurium1 #daa ,m9]als1 radio-active con/ant ratio ( radium to uranium1 #dei et seq4 li/ ( m9]als1 #dfa age (1 #dhe composition (1 #eed et seq4 ,mobility ( ions1 #dc et seq4 ,moi/ure effect (1 on velocity ( ions1 #dc1 #de effect (1 on emanat+ p[]1 #bee ,molecule numb] (1 9 #a c4c4 ( hydrog51 #ed ,molecul> weight ( radium emanation1 #bgc ( ?orium emanation1 #bge ,nagel & ,him/$t action ( radium rays on ! eye1 #bag ,niew5gl[ski rays f sulphide ( calcium1 #d ,nom5clature ( successive products1 #cbh et seq4 ,numb] ( molecules p] c4c4 ( hydrog51 #ed ( ions produc$ 9 gas by active sub/ances1 #ee ( p>ticles expell$ f #a gram ( radium1 #abd ( p>ticles emitt$ p] gram ( radium1 #aee ( ions produc$ p] c4c4 9 clos$ vessels1 #ecd ,occlusion ( emanation 9 ?orium & radium1 #beh ( radium emanation by solids1 #caj ,ow5s saturation curr5t affect$ by du/1 #db p5etrat+ p[] ( rays indep5d5t ( comp\nd1 #afd absorption ( rays v>ies directly z ! pressure ( gas1 #afi effect ( air curr5ts on conductivity produc$ by ?orium1 #bch ,oxyg5 *ange into ozone1 by radium rays1 #bac production (1 f radium solutions1 #bae ,ozone production (1 by radium rays1 #bac ,p>aff9 objection to1 z an insulator1 #if conductivity (1 "u radium rays1 #baj ,pas*5 di/ribution ( velocity among/ p>ticles1 #aca et seq4 abs5ce ( magnetic deflection ( rays1 #ahc rays & electrons1 #ahe heat+ effect ( rays1 #ahf1 #dbi ,patt]son numb] ( ions p] c4c4 9 clos$ vessel1 #ecd natural conductivity ( air due to an easily absorb$ radiation1 #ecf effect ( temp]ature on natural conductivity ( air1 #ecf ,peck & ,will[s action ( radium rays on sp>k1 #bjh ,pegram electrolysis ( ?orium solutions1 #cad tempor>y activity ( sub/ances sep>at$ f ?orium1 #dae ,p5etrat+ p[] comp>ison (1 = 1 & rays1 #aaa v>iation 91 ( rays1 #acd et seq4 v>iation (1 ) d5sity = rays1 #acg comp>ison (1 = rays f radio-elem5ts1 #afd v>iation (1 ) d5sity = rays1 #afi v>iation (1 ) d5sity = rays1 #ahb ,p5etrat+ radiation f ! e>? & atmosph]e1 #ebj ,p]r9 *>ge c>ri$ by ca?ode rays1 #gc !ory ( radio-activity1 #dcg ,phosphoresc5ce production (1 by radium1 #ai production (1 by radium & polonium rays1 #bja et seq4 comp>ison (1 produc$ by & rays1 #bjb ( z9c sulphide1 #bjb ( b>ium plat9ocyanide1 #bjc ( willemite & kunzite1 #bjc produc$ by radium emanation 9 sub/ances1 #bjc1 #beb dim9ution (1 ) "t1 #bje ( radium comp\nds1 #bje spectrum ( phosphoresc5t light ( radium bromide1 #bje spectrum ( phosphoresc5t light ( 8emanium10 #bjf production ( by heat 7!rmo-lum9esc5ce71 #bjg use (1 to illu/rate cond5sation ( emanations1 #bgi connection ( ) ionization1 #edg et seq4 ,phosphorus action ( radium rays on1 #bad ionization produc$ by1 #ebi ,photo-electric action produc$ by radium rays 9 c]ta9 sub/ances1 #bad ,photographic me?od1 advantages & disadvantages (1 #hc relative photographic action ( rays1 #hc connection ( photographic action ) ionization1 #edf ,physical action ( radium rays on sp>ks1 #bjh on electrodeless dis*>ge1 #bjh on sel5ium1 #bjh on conductivity ( insulators1 #bji ,physiological action ( radium rays production ( burns1 #baf effect on bact]ia1 #baf effect on eye1 #bag ,piezo-lectrique ( qu>tz description (1 #aje ,pit*bl5des comp>ison ( radio-activity (1 #aa radio-elem5ts sep>at$ f1 #ac et seq4 radium cont9ually produc$ f1 #dei con/itution (1 #eeg ,pol>ization ( uranium rays abs5ce (1 #g ,polonium me?ods ( sep>ation (1 #bb rays f1 #bc decay ( activity (1 #bc discussion ( nature (1 #bd simil>ity to radio-tellurium1 #bf magnetic deviation ( rays f1 #adf1 #aej sl[ mov+ electrons1 #aec increase ( absorption ) ?ickness ( matt] trav]s$1 #afc connection (1 ) radium ,f1 #daa ,pot5tial requir$ to produce saturation1 #cb et seq4 fall ( pot5tial ne$$ to produce ions at ea* collision1 #eh gradi5t due to movem5t ( ions1 #fe ,pre*t & ,runge spectrum ( radium1 #ag atomic weight ( radium1 #ah heat+ effect ( radium1 #dbj ,pressure effect (1 on velocity ( ions1 #df effect (1 on curr5t ?r\gh gases1 #fa et seq4 production ( emanation indep5d5t (1 #bfe effect (1 on di/ribution ( excit$ activity1 #cag effect (1 on natural conductivity ( air 9 clos$ vessels1 #ecd ,products1 radio-active li/ (1 f radio-elem5ts1 #ddi prop]ties (1 #ddi am\nt ( 9 radium1 #deb et seq4 radiations f1 #dee ,qu>tz piezo-lectrique use (1 9 measurem5t ( curr5t1 #aje ,qu99e sulphate dis*>g+ p[] (1 #ecj phosphoresc5ce (1 #ecj ,radiations emitt$ by uranium1 #h emitt$ by ?orium1 #aj emitt$ by radium1 #ah emitt$ by act9ium1 #ba emitt$ by polonium1 #bc me?od ( measurem5t (1 #hb et seq4 me?ods ( comp>ison (1 #ajh ?ree k9ds (1 #aji analogy to rays f a ,crookes tube1 #aaj relative ioniz+ & p5etrat+ p[] (1 #aaa difficulties ( comp>ative measurem5t (1 #aab rays1 #aac rays1 #ada rays1 #agi second>y rays1 #ahg comp>ison ( ionization ( & rays1 #aid phosphoresc5t effect (1 #bja et seq4 physical actions (1 #bjg et seq4 *emical actions (1 #bac et seq4 physiological actions (1 #baf f ! emanation1 #bfc f ,ur ,x1 #cdg connection (1 ) heat emission1 #dba et seq4 f diff]5t active products1 #dee cons]vation ( en]gy ( ea* specific type (1 #dfi et seq4 ,radio-lead connection (1 ) polonium1 #daa et seq4 connection (1 ) radium ,d1 #dac ,radio-tellurium rate ( decay (1 #daa connection ( ) radium ,f1 #daa ,radium discov]y (1 #ac sep>ation (1 #ac spectrum (1 #af atomic weight (1 #ag radiations f1 #ah comp\nds (1 #ai nature ( radiations f1 #aji rays f1 #aac rays f1 #ada rays f1 #agi second>y rays f1 #ahg production ( phosphoresc5ce by1 #bja et seq4 spectrum ( phosphoresc5t light (1 #bjf physical actions (1 #bjg et seq4 *emical actions (1 #bac et seq4 physiological actions (1 #baf emanation f1 #bdf prop]ties ( emanation f1 #bdg et seq4 *emical nature ( emanation f1 #bfg diffusion ( emanation f1 #bfi cond5sation ( emanation f1 #bgg am\nt ( emanation f1 #bhh volume ( emanation f1 #bhi spectrum ( emanation f1 #bib excit$ radio-activity f1 #bie et seq4 decay ( excit$ activity f1 #cjf et seq4 diff]5ce 9 prop]ties ( radium & ! emanation1 #cbg nom5clature ( products1 #cbh !ory ( successive *anges 91 #ccj alt]ation ( activity (1 by removal ( emanation1 #cga et seq4 recov]y ( activity (1 aft] removal ( emanation1 #cgb effect ( escape ( emanation on recov]y ( activity (1 #cgd non-sep>able activity (1 #cge p]iod & prop]ties ( radium ,a1 ,b & ,c1 #cgf et seq4 analysis ( active deposit ( rapid *anges ( radium1 #cgg analysis ( ray curves1 #cha et seq4 analysis ( ray curves1 #chf et seq4 equations ( activity curves1 #chi effect ( temp]ature on active deposit (1 #cij relative activity due to products (1 #cie active deposit ( sl[ trans=mation1 #cig physical & *emical prop]ties ( radium ,d1 ,e & ,f1 #cih et seq4 effect ( temp]ature on active deposit ( sl[ *ange1 #dja sep>ation ( radium ,f by bismu?1 #djb products (1 #djb et seq4 rate ( trans=mation ( radium ,d1 #djd et seq4 v>iation ( ! activity ( ! active deposit ov] long p]iods ( "t1 #djg am\nts ( radium ,d1 ,e & ,f 9 old radium1 #djh v>iation ( activity (1 ) "t1 #dji products ( 9 pit*bl5de1 #daj orig9 ( radio-tellurium1 #daa orig9 ( polonium1 #daa1 #dab orig9 ( radio-lead1 #dac tempor>y activity ( inactive matt] sep>at$ f pit*bl5de1 #dae et seq4 heat emission (1 #dai et seq4 heat emission ( emanation f1 #dbj1 #dca heat+ effects due to products (1 #dcc !ories ( radio-activity (1 #dcg et seq4 discussion ( !ories ( radio-activity (1 #dda et seq4 en]gy ( radiations1 n d]iv$ f ext]nal s\rce1 #ddb et seq4 !ory ( radio-active *ange1 #ddd et seq4 li/ ( active products (1 #ddi am\nt ( products (1 #deb rate ( *ange (1 #deg life ( radium1 #deg orig9 (1 #dei et seq4 production (1 by uranium1 #dei et seq4 am\nt ( 9 #a gram ( uranium1 #dfa am\nt (1 9 m9]als1 #dfa radio-activity (1 indep5d5t ( conc5tration1 #dff et seq4 disappe>ance (1 #dfg life (1 indep5d5t ( conc5tration1 #dfh cons]vation ( radio-activity (1 #dfi et seq4 loss ( weight (1 #dgc exp]im5ts to det]m9e loss ( weight (1 #dgd total emission ( en]gy f #a gram (1 #dgd et seq4 production ( helium f1 #dgf helium1 dis9tegration product (1 #dgi et seq4 am\nt ( helium f1 #dhj possible causes ( dis9tegration (1 #dhf et seq4 am\nt (1 to acc\nt = heat ( sun1 #dia possible connection ( ) heat ( sun1 #dia possible connection ( ) heat ( e>?1 #dic probable am\nt (1 9 e>?1 #die am\nt (1 9 atmosph]e1 #die1 #ebd pres5ce (1 9 atmosph]e1 #eba et seq4 ,radium ,a decay curve (1 #cgh radiation f1 #cha effect (1 on activity curves1 #chf et seq4 connection ) lat] *anges1 #cib activity suppli$ by1 #cic ,radium ,b abs5ce ( rays 91 #cha effect (1 on activity curves1 #cha et seq4 effect ( temp]ature on1 #cij volatility (1 #cij abs5ce ( heat+ effect (1 #dcc nature ( rayless *ange 91 #ded1 #eeb ,radium ,c radiations f1 #cha analysis ( ray curves (1 #cha et seq4 analysis ( ray curves (1 #chf et seq4 effect ( temp]ature on1 #cij activity suppli$ by1 #cid et seq4 heat+ effect (1 #dbe use (1 z a s\rce ( rays1 #dce explosive nature ( *ange 91 #def magnetic deflection ( rays f1 #edc velocity & value ( e_/m = rays f1 #edd ,radium ,d orig9 ( "n (1 #cgf connection (1 ) active deposit1 #djc p]iod ( trans=mation (1 #djf effect (1 on v>iation ( activity1 #djg pres5ce 9 old radium1 #djh effect (1 on activity ( old radium1 #dji pres5ce 9 pit*bl5de1 #daj connection ) radio-lead1 #dac am\nt (1 9 #a ton ( uranium1 #ded ,radium ,e effect ( temp]ature on1 #dja connection (1 ) ray activity active deposit1 #djc1 #djj connection ) radio-lead1 #dac ,radium ,f v>iation ( activity due to1 #cih effect ( temp]ature on1 #dja sep>ation (1 on bismu? plate1 #djb connection ) active deposit1 #djc v>iation ( activity (1 ov] long p]iods ( "t1 #djg pres5ce 9 old radium1 #dji effect (1 on activity ( old radium1 #dji pres5ce 9 pit*bl5de1 #daj connection ) radio-tellurium1 #daa connection ) polonium1 #daa1 #dab connection ) radio-lead1 #dac ,ra9 radio-activity (1 #eje decay ( activity (1 #ejf ,ramsay1 ,sir ,w4 am\nt ( helium 9 ?orianite1 #dhf ,ramsay & ,collie spectrum ( emanation1 #bib ,ramsay & ,cooke radio-activity produc$ by radiation f radium1 #dgb ,ramsay & ,soddy evolution ( gas f radium1 #bae production ( hydrog5 & oxyg5 f radium1 #bae *emical nature ( ! emanation1 #bfh gase\s nature ( ! emanation1 #bfh volume ( emanation1 & *ange ) "t1 #bhi helium f radium emanation1 #bia am\nt ( helium produc$ by radium1 #dhj ,ramsay & ,trav]s am\nt ( helium 9 f]gusonite1 #dhf ,rayless *anges discussion (1 #ded1 #eeb ,re1 ,f4 !ory ( radio-activity1 #dda ,recomb9ation ( ions1 #dj et seq4 con/ant (1 #db ,recov]y ( activity ( ?orium aft] removal ( ,? ,x1 #bba ( activity ( uranium aft] removal ( ,ur ,x1 #bbc significance ( law (1 #bbd effect ( conditions on rate (1 #bcb ( activity ( radium aft] removal ( emanation1 #cgb ( heat+ effect ( radium1 #dbc ,reflection no evid5ce ( direct reflection = uranium rays1 #g diffuse reflection ( rays1 #g ,refraction no evid5ce (1 = uranium rays1 #g ,reg5]ation ( emanat+ p[]1 #bef ,ri*>z & von ,helmholtz action ( ions on /eam jet1 #dg ,ri*>z & ,s*5ck !ory ( radio-activity1 #dda ,rossignol & ,gim+ham decay ( ?orium emanation1 #bdb ,runge spectrum ( radium1 #ag ,runge & ,bdl&] evolution ( gas f radium1 #bae ,runge & ,pre*t spectrum ( radium1 #ag atomic weight ( radium1 #ah heat+ effect ( radium1 #dbj ,russel photographic action ( sub/ances1 #hc ,saake am\nt ( emanation 9 air at high altitudes1 #eai ,salomons5 & ,drey] coloration ( qu>tz by radium rays1 #bac ,saturation curr5t mean+ (1 #cc et seq4 application (1 to measurem5ts ( radio-activity1 #hd measurem5t (1 #ajj et seq4 ,s*5ck radium emanation 9 spr+s1 #eac ,s*5ck & ,ri*>z !ory ( radio-activity1 #dda ,s*midt discov]y ( radio-activity ( ?orium1 #aj ,s*midt & ,wi$emann !rmo-lum9esc5ce1 #bjg ,s*u/] numb] ( ions p] c4c4 9 air ( ,man*e/]1 #ebh radio-activity ( matt]1 #ebi ,s*weidl] & ,ma*e velocity ( ions 9 air1 #ebh ,s*weidl] & ,mey] magnetic deviation ( rays by electrical me?od1 #aac absorption ( rays ( radium by matt]1 #acf activity proportional to am\nt ( uranium1 #aie emanation f uranium1 #cdh effect ( cry/allization on activity ( uranium1 #cdi rate ( decay ( radio-tellurium1 #daa ,sc9tillations discov]y (1 9 z9c sulphide scre51 #aeh connection (1 ) rays1 #aeh illu/ration (1 by sp9?>iscope1 #aeh cause (1 #afj production (1 by action ( electric field1 #afj ,se>le app>5t mass ( mov+ *>g$ body1 #ga1 #abg ,second>y rays exam9ation (1 by photographic me?od1 #ahg exam9ation (1 by electrical me?od1 #ahh production (1 by & rays1 #ahi et seq4 f diff]5t mat]ials1 #aia am\nt (1 dep5ds ^u atomic weight1 #aib magnetic deflection (1 #aic ,seitz absorption ( electrons by matt]1 #acg et seq4 ,sel5ium action ( radium rays on1 #bjh ,simon value ( e_/m = ca?ode rays1 #ge1 #abi ,simpson am\nt ( excit$ activity 9 nor? ( ,norway1 #eai ,slat]1 ,miss effect ( temp]ature on active deposit ( ?orium1 #ced ,smolan1 ,beattie & ,kelv9 dis*>g+ p[] ( uranium rays1 #g ,sn[ radio-activity (1 #ejf decay ( activity (1 #ejg ,soddy comp>ison ( photographic & electrical action ( uranium rays1 #hc nature ( rays f ,ur ,x1 #cdg production ( radium f uranium1 #dfc ,soddy & ,ramsay evolution ( gas f radium1 #bae production ( hydrog5 & oxyg5 f radium1 #bae *emical nature ( ! emanation1 #bfh gase\s nature ( ! emanation1 #bfh volume ( ! emanation1 & *ange ) "t1 #bhi helium f radium emanation1 #bia am\nt ( helium produc$ by radium1 #dhj ,soddy & ,ru!r=d sep>ation ( ,? ,x1 #bbj decay ( activity ( ,? ,x1 #bba recov]y ( activity ( ?orium fre$ f ,? ,x1 #bba decay ( activity ( ,ur ,x1 #bbc recov]y ( activity ( uranium fre$ f ,ur ,x1 #bbc explanation ( decay & recov]y curves1 #bbd rate ( production ( ,? ,x1 #bbg !ory ( decay ( activity1 #bbi influ5ce ( conditions on rate ( decay & recov]y ( activity1 #bcc dis9tegration hypo!sis1 #bcd decay ( activity ( radium emanation1 #bdg measurem5ts ( emanat+ p[]1 #bed effect ( temp]ature1 moi/ure1 & solution1 on emanat+ p[]1 #bee reg5]ation ( emanat+ p[]1 #bef con/ant rate ( production ( emanation ( radium & ?orium1 #beg s\rce ( ?orium emanation1 #bfa radiations f ! emanation1 #bfd *emical nature ( emanation1 #bfg cond5sation ( emanations ( radium & ?orium1 #bgg temp]ature ( cond5sation ( emanation1 #bgh effect ( successive precipitations on activity ( ?orium1 #ceh recov]y ( activity ( radium1 #cgb !ory ( radio-activity1 #dci !ory ( radio-active *ange1 #dde cons]vation ( radio-activity1 #dfi ,soil radio-activity (1 #ejg et seq4 diff]5ce 9 activity (1 #ejh et seq4 ,solution coloration (1 by radium1 #ae ( active deposit 9 acids1 #cab electrolysis ( active1 #cac ,s\rce ( ?orium emanation1 #bfa ( radium & act9ium emanations1 #bfc ,sp>k action ( radium rays on1 #bjh ,spectrum sp>k spectrum ( radium1 #ae1 #af flame spectrum ( radium1 #ag effect ( a magnetic field on spectrum ( radium1 #ag ( polonium1 #bc ( phosphoresc5t light ( radium bromide1 #bjf ( emanation1 #bib ( helium 9 radium gases & emanation1 #dgg ,sp9?>iscope description (1 #aeh ,spr+s emanation f wat] (1 #eac ,/>k en]gy to produce an ion1 #eh ,/oney1 ,john/one use ( t]m electron1 #gf ,/rauss & ,h(mann radio-active lead1 #bg ,/rutt conductivity ( gases = radiation1 #fc1 #fd conductivity ( gases produc$ by rays1 #fd1 #ahc negative *>ge c>ri$ by rays1 #abb et seq4 absorption ( rays proportional to d5sity1 #acf nature ( rays1 #adb attempt to measure *>ge ( rays1 #aec con/ant ratio ( uranium to radium 9 m9]als1 #dfb connection ( ?orium ) helium1 #dhc absorption ( radium rays f sun by atmosph]e1 #dib pres5ce ( radium 9 ,ba? wat]s1 #eac radio-activity ( ord9>y matt]1 #ecf ,sun effect ( radium 91 #dia age (1 #dib ,temp]ature effect (1 on int5sity ( radiations f uranium & radium1 #baj effect (1 on lum9osity1 #baj rate ( decay ( radium emanation unaffect$ by1 #bdi ( cond5sation ( emanations1 #bhc rate ( decay ( ?orium emanation unaffect$ by1 #bhg effect (1 on excit$ activity1 #cae effect (1 on active deposit ( ?orium1 #ced effect (1 on active deposit ( act9ium1 #cfh effect (1 on active deposit ( rapid *ange ( radium1 #cij effect (1 on active deposit ( sl[ *ange1 #dja ( radium above surr\nd+ space1 #dai effect (1 on am\nt ( excit$ activity 9 atmosph]e1 #eah effect (1 on natural ionization ( air1 #ecf ,!ories ( radio-activity1 review (1 #dcg et seq4 discussion (1 #dda et seq4 dis9tegration !ory1 #dde et seq4 ,!rmo-lum9esc5ce1 #bjg ,?omson1 ,j4 ,j4 relation betwe5 curr5t & voltage = ioniz$ gases1 #cd diff]5ce betwe5 ions z cond5sation nuclei1 #di *>ge on ion1 #ej magnetic field produc$ by an ion 9 motion1 #fi app>5t mass ( electron1 #ga action ( magnetic field on mov+ ion1 #gb det]m9ation ( e_/m = ca?ode /ream1 #gc orig9 ( ,x rays1 #hj sl[ velocity electrons f radio-tellurium1 #aec *>ge c>ri$ by rays1 #aed !ory ( radio-activity1 #ddj cause ( heat emission f radium1 #ddb /ructure ( atom1 #dhg possible causes ( dis9tegration ( radium1 #dhg nature ( electrons1 #dif emanation f tap-wat] & deep wells1 #eaj radio-activity ( ord9>y mat]ials1 #eci ,?omson1 ,j4 ,j4 & ,ru!r=d ionization !ory ( gases1 #ca et seq4 ,?orium discov]y ( radio-activity (1 #aj emanation f1 #aa prep>ation ( non-radio-active ?orium1 #bi nature ( radiations f1 #aji rays f1 #aad rays f1 #ada rays f1 #ahj sep>ation ( ,? ,x f1 #bbj recov]y ( activity (1 #bba dis9tegration (1 #bcd emanation f1 #bch prop]ties ( emanation f1 #bci diffusion ( emanation f1 #bge cond5sation ( emanation f1 #bgg excit$ radio-activity f1 #bie et seq4 analysis ( active deposit (1 #cea et seq4 rayless *ange 91 #ceb explanation ( initial portion ( decay curve1 #ceh explanation ( initial portion ( recov]y curve1 #ceh effect ( successive precipitations on1 #ceh recov]y curve aft] l>ge numb] ( precipitations1 #cei products (1 #cfc non-sep>able activity (1 #cfc radiations f active products (1 #cfc division ( activity among/ active products (1 #cfc rate ( emission ( en]gy by1 #dcb !ories ( radio-activity (1 #dch discussion ( !ories ( radio-activity1 #dda et seq4 s\rce ( en]gy ( radiations1 #ddb et seq4 !ory ( radio-active *ange1 #ddd et seq4 table ( radio-active products (1 #ddi rate ( *ange (1 #deh life (1 #deh cons]vation ( radio-activity (1 #dfi total emission ( en]gy f #a gram (1 #dge possible causes ( dis9tegration (1 #dhf et seq4 ,?orium ,a p]iod & prop]ties (1 #ceb et seq4 abs5ce ( rays 91 #ceb effect ( temp]ature on1 #ced ,?orium ,b p]iod & prop]ties (1 #ceb et seq4 effect ( temp]ature on1 #ced radiations f1 #cfc ,?orium ,x me?ods ( sep>ation (1 #bbj law ( decay ( activity (1 #bba law ( recov]y ( activity (1 #bba !ory to expla9 production (1 #bbd mat]ial nature (1 #bbf cont9u\s production (1 #bbg explanation ( decay ( activity (1 #bbi effect ( conditions on ! rate ( *ange (1 #bcc dis9tegration hypo!sis to expla9 production (1 #bcd m9ute am\nt (1 produc$1 #bcg effect ( successive sep>ations (1 on activity ( ?orium1 #ceh et seq4 analysis ( decay & recov]y curves (1 #ceh radiations f1 #cfc ,tommas9a sc9tillations produc$ by electrification1 #afj ,t[ns5d ions by collision1 #ci1 #eg coeffici5t ( recomb9ation1 #da diffusion ( ions1 #ea et seq4 comp>ison ( *>ge on ion ) t on hydrog5 atom 9 electrolysis1 #ec numb] ( molecules p] c4c4 ( gas1 #ed ionization by collision = diff]5t spe$s1 #aga ,trans=mations1 successive !ory (1 #cbe et seq4 nom5clature (1 #cbh activity due to1 #ccg detection ( a rayless *ange 91 #cda 9 uranium1 #cdf et seq4 9 ?orium1 #cea et seq4 9 act9ium1 #cfd et seq4 9 radium1 #cga et seq4 li/ (1 #ddi orig9 ( radium 91 #dei helium1 a result (1 #dgf et seq4 possible cause (1 #dhf et seq4 application (1 to evolution ( matt]1 #dig et seq4 ,transmission ( excit$ radio-activity ( radium & ?orium1 #cah et seq4 ( excit$ radio-activity ( act9ium1 #cbc ,trav]s & ,ramsay am\nt ( helium 9 f]gusonite1 #dhf ,troo/ rays f hexagonal bl5de1 #d ,uranium discov]y ( radio-activity (1 #e p]si/5ce ( radiations (1 #f dis*>g+ p[] ( rays1 #g abs5ce ( reflection1 refraction & pol>ization1 #g exam9ation ( uranium m9]als1 #aa et seq4 relative activity ( comp\nds ( uranium1 #ab nature ( radiations f1 #aji rays f1 #aad rays f1 #ada rays f1 #ahj sep>ation ( ,ur ,x f1 #bai recov]y ( activity (1 #bai *anges 91 #cdf et seq4 non-sep>able activity (1 #cdg radiations f ,ur ,x1 #cdg et seq4 me?od ( measurem5t ( activity ( ,ur ,x1 #cdg emission ( en]gy by1 #dah !ories ( radio-activity (1 #dcg et seq4 discussion ( !ories ( radio-activity1 #dda et seq4 s\rce ( en]gy ( radiation1 #ddb et seq4 !ory ( radio-active *ange1 #ddd et seq4 table ( active products1 #ddi rate ( *ange (1 #deh life (1 #deh radium probable product (1 #dei et seq4 am\nt ( radium 91 #dfj et seq4 am\nt (1 9 radio-active m9]als1 #dfa gr[? ( radium 91 #dfc cons]vation ( radio-activity (1 #dfi total emission ( en]gy f #a gram (1 #dge possible causes ( dis9tegration (1 #dhf et seq4 ,uranium ,x sep>ation (1 by ,crookes1 #bai sep>ation (1 by ,becqu]el1 #bai decay ( activity (1 #bbc recov]y ( activity (1 #bbc !ory to expla9 production (1 #bbd et seq4 mat]ial nature (1 #bbf explanation ( decay ( activity (1 #bbi *anges 91 #cdf et seq4 radiations f1 #cdg et seq4 me?od ( measurem5t ( radiations f1 #cdg effect ( cry/allization on activity (1 #cdi diffusion (1 #cej ,velocity ( ions 9 electric field1 #db et seq4 diff]5ce betwe51 ( positive & negative ions1 #dc et seq4 ( p>ticle or electron1 #abf et seq4 v>iation ( mass ( electron )1 #abg ( p>ticle1 #adh ( transmission ( c>ri]s ( excit$ activity1 #cbj et seq4 ( ions 9 atmosph]e1 #ebh ,vill>d discov]y ( rays f radium1 #agi alt]ation ( ,x ray scre5 ) "t1 #bje activity produc$ by ca?ode rays1 #ecj ,v9c5ti & ,levi ,da ,z>a radium emanation 9 spr+ wat]s1 #eaf ,voll] v>iation ( activity ( radium ) conc5tration1 #dfg ,volume ( radium emanation1 calculation (1 #bhi decrease (1 ( radium emanation1 #bij ,walk]1 ,g4 ,w4 !ory ( electromet]1 #ij ,walkh(f action ( radium rays on sk91 #baf ,wall/abe diffusion ( radium emanation into liquids1 #bgf ,wat] emanation f1 #eaj et seq4 decay ( activity ( emanation f1 #eaa et seq4 ,wat]-falls am\nt ( excit$ activity produc$ at ,niag>a1 #ebj electrification produc$ ne>1 #ebj ,watts1 ,m>%all atomic weight ( radium1 #ah ,wei*]t velocity ( ca?ode rays1 #gf ,weight loss ( by radio-elem5ts1 #dgc attempts to measure loss ( 9 radium1 #dgd ,:eel] & ,bum/ead diffusion ( radium emanation1 #bgc emanation f surface wat] & ! soil1 #eab1 #ebb id5tity ( emanation f soil ) radium emanation1 #eab1 #ebb ,:e?am effect ( val5cy ( ion on colloidal solutions1 #bae production ( radium f uranium1 #dfc ,wi$emann !rmo-lum9esc5ce1 #bjg ,wi$emann & ,s*midt !rmo-lum9esc5ce1 #bjg ,wi5 value ( e_/m = canal rays1 #gh positive *>ge ( canal rays1 #gh am\nt ( *>ge c>ri$ by rays1 #abd ,willcock1 ,miss & ,h>dy coloration ( iod(orm solution by radium rays1 #bad ,willemite phosphoresc5ce (1 "u radium rays1 #bjc use (1 to %[ cond5sation ( emanation1 #bgi ,will[s & ,peck action ( radium rays on sp>k1 #bjh ,wilson1 ,c4 ,t4 ,r4 ions z nuclei ( cond5sation1 #dg et seq4 diff]5ce betwe5 positive & negative ions z cond5sation nuclei1 #di equality ( *>ges c>ri$ by positive & negative ions1 #ej con/ruction ( electroscope1 #hf1 #hh natural ionization ( air 9 vessels1 #eja radio-activity ( ra9 & sn[1 #eje1 #ejf loss ( *>ge 9 clos$ vessels1 #eca et seq41 #ecd pres5ce ( ions 9 du/-free air %[n by cond5sation1 #ecc numb] ( ions produc$ p] c4c41 #ecc effect ( pressure & nature ( gas on ionization 9 seal$ vessels1 #ecd ,wilson1 ,h4 ,a4 *>ge on ion1 #ea ,wilson1 ,w4 ,e4 radium 9 sun1 #dia ,wlfl1 ,h(mann & ,gond] prop]ties ( radio-active lead1 #bg1 #dac ,wood1 ,a4 radio-activity ( ord9>y mat]ials1 #edj ,z>a1 ,levi ,da & ,v9c5ti radium emanation 9 spr+ wat]s1 #eaf ,zeeman action ( magnetic field on light1 #gg ,zel5y velocity ( ions1 #db et seq4 diff]5ce ( velocity ( ions1 #de pot5tial gradi5t betwe5 electrodes1 #fe ,z]ban & ,h(mann connection ( activity ( ?orium ) uranium1 #bi ,z9c ,sulphide sc9tillations produc$ 9 by rays1 #aeh cause ( lum9osity (1 #afj1 #edi ,,cambridge3 ,,pr9t$ ,,by ,,john ,,clay1 ,m4,a4 ,,at ,,! ,,univ]sity ,,press4 ,,cambridge ,,physical ,,s]ies4 ,conduction ( ,electricity ?r\gh ,gases4 ,by ,j4 ,j4 ,,?omson1 ,d4,sc41 ,,ll4,d41 ,ph4,d41 ,f4,r4,s41 ,fell[ ( ,tr9ity ,college & ,cav5di% ,pr(essor ( ,exp]im5tal ,physics4 ,demy #hvo4 viii #efh pp4 #afs4 ,,cont5ts4 ,i4 ,electrical ,conductivity ( ,gases 9 a normal /ate4 ,,ii4 ,prop]ties ( a ,gas :5 9 ! conduct+ /ate4 ,,iii4 ,ma!matical ,!ory ( ! ,conduction ( ,electricity ?r\gh a ,gas conta9+ ,ions4 ,,iv4 ,effect produc$ by a ,magnetic ,field on ! ,motion ( ! ,ions4 ,v4 ,det]m9ation ( ! ,ratio ( ! ,*>ge to ! ,mass ( an ,ion4 ,,vi4 ,det]m9ation ( ! ,*>ge c>ri$ by ! ,negative ,ion4 ,,vii4 ,on "s ,physical ,prop]ties ( ,gase\s ,ions4 ,,viii4 ,ionisation by ,inc&esc5t ,solids4 ,,ix4 ,ionisation 9 ,gases f ,flames4 ,x4 ,ionisation by ,light4 ,photo-,electric ,effects4 ,,xi4 ,ionisation by ,rntg5 ,rays4 ,,xii4 ,becqu]el ,rays4 ,,xiii4 ,sp>k ,dis*>ge4 ,,xiv4 ,! ,electric ,arc4 ,,xv4 ,dis*>ge ?r\gh ,gases at ,l[ ,pressures4 ,,xvi4 ,!ory ( ! ,dis*>ge ?r\gh ,vacuum ,tubes4 ,,xvii4 ,ca?ode ,rays4 ,,xviii4 ,rntg5 ,rays4 ,,xix4 ,prop]ties ( ,mov+ ,electrifi$ ,bodies4 ,supplem5t>y ,notes4 ,index4 ,times4--8,x is difficult to ?9k ( a s+le bran* ( ! physical sci5ces 9 :i* ^! advances are n ( fundam5tal importance4 ,! physici/ sees ! relations betwe5 electricity & matt] laid b>e 9 a mann] h>dly hop$ = hi!rto4444 ,! work]s 9 ! field ( ,sci5ce are to-day reap+ an unp>allel$ h>ve/1 & we may congratulate ourselves t 9 ?is field at lea/ we m ?an hold our own among ! nations ( ! _w40 ,a ,treatise on ! ,!ory ( ,solution1 includ+ ! ,ph5om5a ( ,electrolysis4 ,by ,,william ,,cecil ,,dampi] ,,:e?am1 ,m4,a41 ,f4,r4,s41 ,fell[ ( ,tr9ity ,college4 ,demy #hvo4 x #dhh pp4 #ajs4 net4 ,a!num4--8,! *oice & arrangem5t ( ! matt] includ$ are alike excell5t4444 ,mr ,:e?am's book is probably ! mo/ complete & satisfactory treatise on ! subject 9 any language & z su* is sure to enjoy a wide popul>ity40 ,nature4--8,! treatm5t ?r\gh\t is *>act]is$ by great cle>ness1 especially 9 ! physical & ma!matical portions1 s t ! volume may be w>mly recomm5d$ to /ud5ts ( *emi/ry40 ,,cambridge ,,physical ,,s]ies4 ,,cont5ts ,,( ,,mr ,,:e?am',s #8,,solution ,,& ,,electrolysis4' ,i4 ,!rmodynamics4 ,,ii4 ,! ,phase ,rule4 ,,iii4 ,! ,phase ,rule4 ,two ,compon5ts4 ,solutions4 ,,iv4 ,solubility4 ,v4 ,osmotic ,pressure4 ,,vi4 ,vap\r ,pressures & ,freez+ ,po9ts4 ,,vii4 ,!ories ( ,solution4 ,,viii4 ,electrolysis4 ,,ix4 ,conductivity ( ,electrolytes4 ,x4 ,galvanic ,cells4 ,,xi4 ,contact ,electricity & ,pol>ization4 ,,xii4 ,! ,!ory ( ,electrolytic ,dissociation4 ,,xiii4 ,diffusion 9 ,solutions4 ,,xiv4 ,solutions ( ,colloids4 ,additions4 ,table ( ,electro-*emical ,prop]ties ( ,aque\s ,solutions4 ,electricity & ,magnetism3 an ,elem5t>y ,text-book1 ,!oretical & ,practical4 ,by ,r4 ,t4 ,,glazebrook1 ,m4,a41 ,f4,r4,s41 ,director ( ! ,national ,physical ,laboratory & ,fell[ ( ,tr9ity ,college1 ,cambridge4 ,cr[n #hvo4 ,clo?4 #a-ddj pp4 #gs4 #f;d4 ,a!num4--8,if ! nature ( ! book be tak5 into consid]ation1 x w be f\nd unusually free f ! influ5ce ( ! exam9ation _s4 ,! writ+ is bright & int]e/+1 & w /imulate a desire1 we ?9k1 = fur!r /udy40 ,gu>dian4--8,e s*oolma/] & tea*] :o has "u consid]ation ! selection ( a text-book = 8 bett] /ud5ts %\ld mo/ c]ta9ly look into ?is book4 ,! in=mation is ev]y:]e absolutely s\nd & reliable40 ,,preface4 ,"s words are p]haps necess>y to expla9 ! publication ( ano!r book deal+ ) ,elem5t>y ,electricity4 ,a consid]able portion ( ! pres5t "w has be5 9 type = a long "t2 x 0 us$ orig9ally z a "p ( ! practical "w 9 ,physics = ,m$ical ,/ud5ts at ! ,cav5di% ,laboratory 9 connexion ) my lectures1 & 0 exp&$ by ,mr ,wilb]=ce & ,mr ,fitzpatrick 9 "o ( _! ,laboratory ,note-books ( ,practical ,physics4 ,:5 ,i ceas$ to deliv] ! fir/ ye> c\rse ,i 0 ask$ to pr9t my lectures = ! use1 prim>ily1 ( ! ,/ud5ts att5d+ ! practical classes2 ! lectures on ,me*anics1 ,heat & ,light h be5 9 type = "s ye>s4 ,o!r claims on my "t h prev5t$ ! issue ( ! pres5t volume until n[1 :5 x appe>s 9 response to ! promise made sev]al ye>s ago4 ,mean:ile ! subject has *ang$2 b :ile ?is is ! case ! elem5t>y laws & measurem5ts on :i* ! sci5ce is bas$ rema9 unalt]$1 & ,i tru/ ! book may be f\nd ( s]vice to o!rs besides my successors at ! ,cav5di% ,laboratory4 ,! book is to be us$ 9 ! same way z its pr$ecessors4 ,! app>atus = mo/ ( ! ,exp]im5ts is ( a simple "* & c be suppli$ at no great exp5se 9 consid]able quantities4 ,?us ! ,exp]im5ts %\ld all1 z f> z possible1 be c>ri$ out by ! memb]s ( ! class1 ! tea*] %\ld base 8 reason+ on ! results actually obta9$ by 8 pupils4 ,t5 or twelve ye>s ago ?is me?od 0 f> f common2 ! importance to a ,s*ool ( a ,physical ,laboratory is n[ m g5]ally recogniz$2 x is ) ! hope t ! book may be ( value to ^? :o are endeav\r+ to put ! me?od 9 practice t x is issu$ n[4 ,heat & ,light4 ,an ,elem5t>y ,text-book1 ,!oretical & ,practical1 = ,colleges & ,s*ools4 ,by ,r4 ,t4 ,,glazebrook1 ,m4,a4 ,cr[n #hvo4 #es4 ,also 9 sep>ate volumes3 ,heat4 #bcj pp4 #cs4 ,light4 #bac pp4 #cs4 ,me*anics & ,hydro/atics4 ,an ,elem5t>y ,text-book1 ,!oretical & ,practical1 = ,colleges & ,s*ools4 ,by ,r4 ,t4 ,,glazebrook1 ,m4,a4 ,cr[n #hvo4 #hs4 #f;d4 ,also 9 sep>ate volumes3 ,"p ,i4 ,dynamics4 #bef pp4 #ds4 ,"p ,,ii4 ,/atics4 #ahb pp4 #cs4 ,"p ,,iii4 ,hydro/atics4 #baf pp4 #cs4 ,,extracts ,,f ,,press ,,notices4 8,s*ools & ,colleges w c]ta9ly b5efit by adopt+ ?is book = _! /ud5ts40 ,nature4 8,mr ,glazebrook's volumes on ,heat & ,light deal ) ^! subjects f ! exp]im5tal side & x is difficult to admire suffici5tly ! +5uity & simplicity ( _m ( ! exp]im5ts )\t los+ sight ( ! skill & judgm5t ) :i* !y are arrang$40 ,saturday ,review4 8,! books almo/ cov] ! advanc$ /ages ( ! ,s\? ,k5s+ton prospectus & _! use c c]ta9ly be recomm5d$ to all :o wi% to /udy ^! subjects ) intellig5ce & ?or\ghness40 ,s*oolma/]4 8,mr ,glazebrook's great practical exp]i5ce has enabl$ him to treat ! exp]im5tal aspect ( ! book ) unusual p[] & x is 9 ?is t ! great value ( ! book z comp>$ ) mo/ ( ! ord9>y manuals consi/s40 ,educational ,review4 8,! book is v simply & concisely writt51 is cle> & me?odic 9 arrangem5t4444 ,we recomm5d ! book to ! att5tion ( all /ud5ts & tea*]s ( ?is bran* ( physical sci5ce40 ,educational ,news4 8,we wi% ,mr ,glazebrook e success on ! ext5sion ( 8 practical sy/em to all ! ,colleges & ,s*ools ( ! c\ntry4 ,x is ! only way 9 :i* ! int]e/ ( ! /ud5t c be awak5$ & ! /udy ( ! subject made popul> & real40 ,te*nical ,_w4 8,x w be especially appreciat$ by tea*]s :o possess ! necess>y app>atus = exp]im5tal illu/rations40 ,a!num4 8,text-books on ?is subject are g5]ally too simple or too elaborate = a conception ( elem5t>y me*anical pr9ciples4 ,?is book _c fail to recomm5d itself !re=e = a fir/ c\rse prelim9>y to ! /udy ( physical sci5ce4 ,no o!r book pres5ts 9 ! same space ) ! same cle>ness & exactness s l>ge a range ( me*anical pr9ciples40 ,physical ,review4 8,m>k$ ability has be5 %ewn 9 ! developm5t ( ! subject ( ,/atics 9 ! pres5t volume4444 ,! collect$ examples = /ud5ts' ex]cises are excell5t40 ,glasg[ ,h]ald4 ,g5]al ,editors3 ,f4 ,h4 ,,neville1 ,m4,a41 ,f4,r4,s4 & ,w4 ,c4 ,d4 ,,:e?am1 ,m4,a41 ,f4,r4,s4 ,me*anics4 ,by ,,john ,,cox1 ,m4,a41 ,f4,r4,s4,c41 ,macdonald ,pr(essor ( ,exp]im5tal ,physics 9 ,mc,gill ,univ]sity1 ,montreal4 ,demy #hvo4 pp4 xiv #ccb4 #is4 ,net4 ,a!num4--8,x may reasonably be hop$ t ?is endeav\r to bridge ov] ! gulf :i* has hi!rto sep>at$ !ory f practice 9 respect ( ! pr9ciples ( me*anics1 by %[+ _! intimate connexion1 & to pres5t ! subject 9 a m liv+ & attractive =m1 by draw+ att5tion to ! gradual /ages & me?ods by :i* ! e>ly inve/igators discov]$ ! laws :i* gov]n ! sci5ce1 w meet ) ! success :i* x des]ves40 ,! ,/udy ( ,*emical ,composition4 ,an ,acc\nt ( its ,me?od & ,hi/orical ,developm5t1 ) illu/rative quotations4 ,by ,,ida ,,freund1 ,/aff ,lectur] & ,associate ( ,newnham ,college4 ,demy #hvo4 xvi #fej pp4 #ahs4 ,net4 ,saturday ,review4--8,writt5 f a broad1 philosophical /&po9t1 we "k ( no book m suit$ = ! /ud5t ( *emi/ry :o has atta9$ a s\nd g5]al k ( ! sci5ce1 & is n[ ready to appreciate a critical discussion ( ! me?ods by :i* ! results he has le>nt h be5 built up1 !reby fitt+ himself = ! real _w ( inve/igation on 8 own acc\nt40 ,a ,treatise on ! ,!ory ( ,alt]nat+ ,curr5ts4 ,by ,,alex&] ,,russell1 ,m4,a41 ,m4,i4,e4,e4 ,vol4 ,i4 ,demy #hvo4 pp4 #djh4 #abs4 ,net4 ,vol4 ,,ii4 ,9 ! ,press4 ,scotsman4--8,! volume is n only ri* 9 its own sub/antive tea*+1 b well suppli$ ) ref]5ces to ! m remote au?orities ^u its subject4 ,x op5s an important & valuable contribution to ! !oretical lit]ature ( electrical eng9e]+40 ,radio-activity4 ,by ,e4 ,,ru!r=d1 ,d4,sc41 ,f4,r4,s41 ,f4,r4,s4,c41 ,macdonald ,pr(essor ( ,physics1 ,mc,gill ,univ]sity1 ,montreal4 ,demy #hvo4 pp4 x #djj4 #ajs4 #f;d4 ,net4 ,a!num4--8,engli% /ud5ts h _h to wait till n[ = any connect$ & detail$ acc\nt ( ?is new bran* ( physics f ! p5 ( "o :o has a fir/ h& k ( x40 ,nature4--8,! arrangem5t ( ! matt] & its treatm5t are ?r\gh\t admirable40 ,! ,!ory ( ,exp]im5tal ,electricity4 ,by ,w4 ,c4 ,d4 ,,:e?am1 ,m4,a41 ,f4,r4,s41 ,fell[ ( ,tr9ity ,college4 ,demy #hvo4 #hs4 ,net4 ,,cambridge ,,univ]sity ,,press ,,w>eh\se1 ,c4 ,f4 ,,clay1 ,,manag]1 ,london3 ,,ave ,,m>ia ,,lane1 ,glasg[3 #ej1 ,,well+ton ,,/reet4 ,,also ,london3 ,h4 ,k4 ,,lewis1 #acf1 ,,g[] ,,/reet1 ,w4,c4 ,transcrib]'s ,notes3 ,inconsi/5t spell+ & hyph5ation 7 made consi/5t only :5 a pr$om9ant =m 0 f\nd 9 ?is book4 ,text t 0 9 italics is enclos$ by und]scores 7italics74 ,text t 0 9 bold face is enclos$ by equals signs 7bold74 ,footnotes h be5 mov$ to foll[ ! 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"n1 & "nexpression means t expression is a subscript to ! "n4 ,_m p>5!ses are add$ to all[ an expression to be transcrib$ on "o l9e4