,an ,exam9ation ( "s ,me?ods ,employ$ 9 ,det]m9+ ! ,atomic ,weight ( ,cadmium4 ,a ,!sis ,pres5t$ to ! ,bo>d ( ,univ]sity ,/udies ( ! ,johns ,hopk9s ,univ]sity = ! ,degree ( ,doctor ( ,philosophy4 by ,john ,e4 ,bu*]4 #ahid ,cont5ts4 ,i4 ,introduction & ,hi/orical ,/atem5t #a ,,ii4 ,! ,oxalate ,me?od #c ,prep>ation ( ,pure ,cadmium #c ,prep>ation ( ,nitric ,acid #d ,purification ( ,wat] #d ,purification ( ,oxalic ,acid #e ,prep>ation ( ,cadmium ,oxalate #g ,proc$ure #h ,results #ac ,,iii4 ,! ,sulphide ,me?od #af ,prep>ation ( ,hydrog5 ,sulphide #af ,prep>ation ( ,nitrog5 #ag ,mode ( ,proc$ure #ah ,results #bd ,discussion ( ! ,results #bd ,discussion ( ! ,me?od #bf ,,iv4 ,! ,*loride ,me?od #cc ,prep>ation ( ,cadmium ,*loride #ce ,! ,filt]s #dh ,analytical ,process #eb ,results #eg ,discussion ( ! ,results #eh ,v4 ,! ,bromide ,me?od #fi ,prep>ation ( ,cadmium ,bromide & ,hydrobromic ,acid #gj ,me?od ( ,analysis #gh ,results #hj ,discussion ( ! ,results #hj ,,vi4 ,syn!ses ( ,cadmium ,sulphate #hb ,results #ij ,discussion ( ! ,results #ia ,,vii4 ,! ,oxide ,me?od #id ,results #if ,discussion ( ! ,results #ig ,det]m9ation ( ,error #ajd ,discussion ( ! ,oxalate ,me?od #aad ,,viii4 ,o!r ,me?ods #aai ,,ix4 ,conclusion #abb ,ackn[l$gem5t4 ,! au?or wi%es to ackn[l$ge 8 indebt$ness = advice & in/ruction to ,pr(essor ,morse at ^: sugge/ion & "u ^: guidance ?is "w has be5 c>ri$ on4 ,he also wi%es to express 8 ?anks = in/ruction to ,pr(essor ,rems5 9 ,*emi/ry1 ,pr(essor ,williams 9 ,m9]alogy1 ,dr4 ,ames 9 ,physics & ,mr4 ,hulburt 9 ,ma!matics4 ,introduction & ,hi/orical ,/atem5t4 ,! atomic weight ( cadmium has be5 inve/igat$ by a numb] ( *emi/s b ! results obta9$ v>y betwe5 wide limits4 ,! "w describ$ 9 ?is pap] 0 und]tak5 ) ! object ( f9d+ ! cause ( ! discrepancy 9 "s ( ! me?ods employ$4 ,a complete hi/orical /atem5t has be5 giv5 by ,morse & ,jones1 7,am]4 ,*em4 ,j\r41 #ad4 #bfa47 & x is only necess>y1 "h1 to give a summ>y = ! purpose ( ref]5ce3 ,ratio4 ,at4 ,wt4 ,cd4 #ahah1 ,/romey]1 ,cd 3 ,cd,o #aaa4dhc 7,s*weigg]s ,j\r4 #bb1 #ccf47 #aheg1 ,von ,hau]1 ,cd,s,o#d 3 ,cd,s #aaa4ice 7,j\r4 f4 ,prakt4 ,*emie #gb1 #cch47 #ahei1 ,dumas1 #a/ s]ies4 ,cd,cl#b 3 ,ag #aab4daf #b;d ,cd,cl#b 3 ,ag #aab4jjg 7,ann4 ,*im4 ,phys4 #c1 #ee1 #aeh47 #ahfj1 ,l5ss51 ,cd,c#b,o#d 3 ,cd,o #aab4jdc 7,j\r4 f4 ,prakt4 ,*em4 #gi1 #bha7 #ahhb1 ,hunt+ton & ,cooke1 ,cd,br#b 3 ,ag,br #aab4bci ,cd,br#b 3 ,ag #aab4bde 7,proce$+s ,am]4 ,acad4 #ag1 #bh7 #ahij1 ,p>tridge1 #a/ ,s]ies ,cd,c#b,o#d 3 ,cd,o #aaa4haf #b;d ,cd,s,o#d 3 ,cd,s #aaa4gbg #c;d ,cd,c#b,o#d 3 ,cd,s #aaa4faf 7,am]4 ,j\r4 ,sci4#c1 #dj1 #cgg7 #ahib1 ,morse & ,jones1 #a/ ,me?od1 ,cd 3 ,cd,o #aab4jgff #b;d ,cd,c#b,o#d 3 ,cd,o #aab4fcb #ahib1 ,torim] & ,smi?y ,cd,o 3 ,cd #aab4jee 7,zeit4 f4 ,anorg4 ,*em4 ,i4 #cfd7 ,9 ?is summ>y z well z 9 ! re/ ( ?is pap] ! foll[+ atomic weights are us$3 ,oxyg5 #af4jj ,sulphur #cb4jei ,c>bon #ab4jjc ,*lor9e #ce4de ,brom9e #gi4ie ,silv] #ajg4ic ,! ,oxalate ,me?od ,prep>ation ( ,pure ,cadmium4 8,cadmium met4 puriss4 galv4 r$uc01 obta9$ f ,s*u*>dt1 0 us$ = prep>+ pure cadmium4 ,x 0 heat$ to r$ness 9 a curr5t ( hydrog5 :i* _h be5 purifi$ by wa%+ ) bo? acid & alkal9e solutions ( potassium p]manganate4 ,?is treatm5t conv]t$ ! metallic p[d] into a b> :i* c\ld be di/ill$ 9 a vacuum4 ,! metal 0 !n di/ill$ n9e times 9 ! same mann] t ,morse & ,burton1 ,am]4 ,*em4 ,j\r4 #ab1 #bai1 _h di/ill$ z9c4 ,all di/illations 7 made sl[ly except ! la/ "o1 :i* 0 made q rapidly4 ,prep>ation ( ,nitric ,acid4 ,:5ev] pure nitric acid 0 requir$1 x 0 purifi$ by di/ill+ aga9/ a plat9um di% & collect+ ! di/illate 9 a small] "o ( ! same metal4 ,! nitric acid us$ 0 dilute & free f *lor9e4 ,purification ( ,wat]4 ,! wat] us$ 9 ?is "w 0 purifi$ by di/ill+ twice f an alkal9e solution ( potassium p]manganate1 always reject+ ! fir/ "p ( ! di/illate4 ,:5ev] wat] 0 ne$$ 9 ! prep>ation ( a pure comp\nd e4g4 cadmium oxalate1 oxalic acid1 cadmium nitrate1 etc41 x 0 subject$ to ! additional process ( be+ di/ill$ aga9/ a l>ge plat9um di% :i* 0 kept cool by plac+ ice inside x4 ,purification ( ,oxalic ,acid4 ,comm]cial oxalic acid 0 heat$ ) a fifte5 p]c5t solution ( hydro*loric acid until all 0 dissolv$4 ,! solution 0 !n w>m$ = tw5ty f\r h\rs4 ,on cool+1 cry/als ( oxalic acid sep>at$ out & ^! 7 wa%$ ) a little cold wat] to remove ! "m liquor4 ,!y 7 !n dissolv$ 9 hot n9ety-five p]c5t alcohol & all[$ to cry/allize sl[ly on cool+4 ,! acid 0 next cry/alliz$ f e!r 9 :i* x is only sp>+ly soluble4 ,aft] ?is x 0 boil$ ) wat] until ! odor ( e?yl acetate _h disappe>$4 ,f9ally x 0 recry/alliz$ ?ree times f wat] & dri$ 9 ! air at ord9>y temp]atures4 ,prep>ation ( ,cadmium ,oxalate4 ,a weigh$ piece ( cadmium 0 dissolv$ 9 nitric acid & ! excess ( acid evaporat$ (f4 ,! nitrite 0 !n dissolv$ 9 a l>ge quantity ( wat] & an equival5t am\nt ( oxalic acid 9 solution add$4 ,! oxalate sep>at$ 9 a few mom5ts z a cry/all9e precipitate4 ,x 0 collect$ on a porcela9 filt] & wa%$ ?or\ghly to remove nitric acid & ammonium nitrate4 ,a consid]able am\nt ( ammonium nitrate 0 =m$ dur+ ! solution ( ! cadmium 9 nitric acid4 ,! oxalate 0 f9ally dri$ 9 an air-ba? = fifty h\rs1 at #aej;,c4 ,proc$ure ,en\gh cadmium oxalate = a det]m9ation 0 plac$ 9 a weigh+ tube :i* _h be5 t>$ aga9/ a simil> vessel & dri$ at #aej;,c4 until ! weight rema9$ con/ant4 ,x 0 !n p\r$ into a weigh$ porcela9 crucible4 ,! tube & its t>e 7 n[ dri$ aga9 at ! same temp]ature to con/ant weight 9 ord] to avoid any error result+ f moi/ure be+ absorb$ by ! cadmium oxalate :i* adh]$ to ! weigh+-glass4 ,! crucibles us$ 9 ^! det]m9ations 7 arrang$ 9 ! same mann] z ^? employ$ by ,morse & ,jones 9 _! "w on ?is me?od4 ,a small porcela9 crucible on ^: edge 7 plac$ ?ree %ort plat9um wires b5t 9 ! %ape ( ! lett] ,u1 0 plac$ 9 a l>g] porcela9 crucible4 ,! plat9um wires prev5t$ ! lid f /ick+ to ! crucible aft] heat+ & also all[$ ! products ( decomposition to escape4 ,! glaze 0 remov$ f ! outside ( ! l>g] crucible ) hydr(luoric acid to avoid /ick+ :5 heat$ to a high temp]ature4 ,a second pair ( crucibles arrang$ 9 ! same mann] 0 t>$ aga9/ ! fir/ "o & 9 all cases treat$ l x4 ,aft] ! oxalate _h be5 p\r$ into ! weigh$ crucible1 x 0 decompos$ by plac+ ! crucible ) its cont5ts 9 a cyl9drical asbe/us cov]$ air-ba?1 & sl[ly rais+ ! temp]ature until ! mass beams uni=mly br[n 9 color4 ,9 ! la/ five det]m9ations1 ! temp]ature 0 n all[$ to exce$ #cjj;,c & aft] f =ty to eighty h\rs ! loss 9 weight 0 ab\t n9ety p]c5t ( ! am\nt calculat$ = complete decomposition4 ,9 ! fir/ f\r ! temp]ature 0 mu* high] & ! "t employ$ %ort]4 ,aft] ! oxalate _h be5 ?us treat$ nitric acid 0 add$ & ! cont5ts ( ! crucible dissolv$ completely4 ,! crucible 0 !n transf]r$ to a ba? con/ruct$ by plac+ a l>g] porcela9 crucible 9 a /ill l>g] "o ( iron & fill+ ! int]v5+ space ) s&4 ,x 0 sl[ly heat$ until ! nitric acid _h all evaporat$ & ! dry nitrate began to give (f r$ fumes4 ,! crucibles 7 !n remov$ to a simil> ba? conta9+ iron fil+s in/ead ( s&4 ,?is ba? 0 heat$ by means ( a s+le burn] z long z r$ fumes 7 obs]v$1 & !n = ab\t five h\rs ) a triple burn]4 ,f9ally1 ! crucibles 7 transf]r$ to a nickel crucible 9 ! bottom ( :i* a plate ( unglaz$ porcela9 0 plac$4 ,! nickel crucible :i* _h previ\sly be5 set tightly into a hole cut 9 an asbe/os bo>d 0 !n heat$ ov] ! bla/ lamp = two h\rs4 ,aft] ?is ! porcela9 crucible & cont5ts 7 weigh$ & !n reheat$ = half h\r p]iods z be=e until ?ree successive weigh+s rema9$ con/ant4 ,?is usually requir$ f ?ree to f\r h\rs ( bla/+4 ,9 all det]m9ations1 ! result+ product 0 te/$ = oxides ( nitrog5 ) potassium iodide1 />* & hydro*loric acid1 b none 0 f\nd4 ,all weigh+s 7 r$uc$ to ! vacuum /&>d on ! assumption ( #h4d = ! ,sp4 ,gr4 ( brass1 #ba4 = plat9um1 #c4ca = ! oxalate & #h4ae = cadmium oxide4 ,! results are3 ,cadmium ,oxalate4 ,cadmium ,oxide4 ,at4 ,wt4 ,cd4 ,i #a4igfgd #a4bfdad #aaa4gc ,,ii #a4idiab #a4bdfhb #aaa4hb ,,iii #a4ifghf #a4behhf #aaa4gg ,,iv #a4hgjii #a4aifge #aaa4gg ,v #a4ihida #a4bgbdb #aaa4gi ,,vi #a4cgeej 4#hgiid #aaa4he ,,vii #a4cccac 4#hecjh #aaa4ie ,,viii #a4iddej #a4bddeb #aab4jd ,,ix #b4jahdf #a4bibaj #aab4ji ,a glance at ^! results %[s t !re is a v>iation ( 4#cf ( a unit & t ! atomic weight 9 g5]al increases ) ! numb] ( det]m9ations4 ,9 ! fir/ f\r det]m9ations1 !re may h be5 loss ( cadmium by r$uction & subsequ5t volatilization1 b 9 ! lat] det]m9ations ?is is n probable4 ,x is believ$ t ! great] "p ( ! v>iation 0 due to imp]fect dehydration ( ! oxalate4 ,?is & o!r s\rces ( error 9 ?is me?od w be ref]r$ to lat]4 ,! nickel crucible us$ gave a slight sublimate on heat+1 ev5 aft] fifte5 h\rs' bla/+4 ,?is cond5s$ on ! porcela9 crucible z a br[ni% coat+ b1 z bo? ! crucible & its t>e 7 bla/$ = ! same l5g? ( "t1 x did n seem to *ange ! diff]5ce ( _! weights4 ,m ?an a doz5 nickel crucibles 7 tri$ b none 0 f\nd n to give a sublimate4 ,! am\nt 0 s slight t no attempt 0 made to det]m9e its nature4 ,! ,sulphide ,me?od4 ,?is me?od is bas$ on ! conv]sion ( cadmium oxalate into cadmium sulphide by heat+ 9 a curr5t ( hydrog5 sulphide4 ,! me?od has be5 us$ by ,p>tridge4 ,?is result 0 #aaa4fa = ! atomic weight ( cadmium4 ,prep>ation ( ,hydrog5 ,sulphide ,9 ! pres5t "w ?is gas 0 always prep>$ f potassium hydrosulphide :i* 0 made f b>ium sulphide 7comm]cial74 ,b>ium sulphide 0 treat$ ) dilute hydro*loric acid & ! result+ hydrog5 sulphide wa%$ ?or\ghly ) a solution ( potassium hydrosulphide & !n ) pure wat]4 ,x 0 !n pass$ into a /rong solution ( potassium hydroxide until ! lat] 0 saturat$4 ,:5 x 0 requir$1 x 0 set free f ?is solution by add+ dilute sulphuric acid & aga9 wa%+ ! result+ gas ) a /rong solution ( potassium hydrosulphide4 ,prep>ation ( ,nitrog54 ,:5ev] a curr5t ( nitrog5 0 requir$1 x 0 prep>$ by pass+ air ov] a lay] ( hot copp] gauze 9 a combu/ion tube4 ,a %ort lay] ( copp] oxide 0 fir/ introduc$1 !n ! copp] gauze & f9ally ano!r lay] ( copp] oxide4 ,! air 0 dri$ ) cau/ic pota% be=e ent]+ ! tube & ! nitrog5 obta9$ 0 also pass$ ?r\gh a long tube fill$ ) lumps ( ?is sub/ance be=e be+ us$4 ,mode ( ,proc$ure4 ,a numb] ( weigh+ tubes #adj millimetres long & #ac millimetres int]nal diamet] 7 made especially = ?is "w4 ,!y 7 always us$ 9 pairs1 "o be+ kept z a c\nt]poise4 ,a porcela9 boat ( su* dim5sions z j to slide into ! tube 0 plac$ 9 ea* "o4 ,= a det]m9ation1 a tube & its boat 7 t>$ ) ano!r tube & boat1 glass aga9/ glass & porcela9 aga9/ porcela9 until ! diff]5ce 9 weight 0 less ?an two t5?s ( a milligramme4 ,bo? boats 7 heat$ 9 a curr5t ( hydrog5 sulphide to incipi5t r$ness = ab\t "o h\r4 ,! curr5t ( hydrog5 sulphide 0 !n replac$ by "o ( nitrog51 9 :i* ! boats 7 cool$1 b :ile /ill w>m !y 7 transf]r$ to _! weigh+ tubes & all[$ to cool 9 a dessiccator conta9+ cau/ic pota% & weigh$4 ,be=e weigh+1 ! /opp]s ( ! weigh+ tubes 7 loos5$ = a mom5t 9 ord] to equalize ! int]nal & ext]nal pressure4 ,?is treatm5t 0 usually repeat$ two or ?ree times & ! diff]5ce 9 weight rema9$ p]fectly con/ant4 ,a portion ( cadmium oxalate suffici5t = a det]m9ation 0 plac$ 9 ! weigh$ boat & dri$ at #aej;,c4 ,! oxalate _h be5 prep>$ exactly l t us$ 9 ! oxalate me?od :i* has already be5 describ$4 ,! gas pressure 9 ! laboratory v>i$ v mu* :ile ?is me?od 0 "u inve/igation & great difficulty 0 exp]i5c$ 9 ma9ta9+ a con/ant temp]ature al?\gh a !rmoregulator 0 us$4 ,sometimes a specim5 ( oxalate :i* 0 suppos$ to be dry w\ld lose sev]al t5?s ( a milligramme :5 ! !rmomet] w\ld only h gone up to #afj;,c or #afe;,c = an h\r by accid5t4 ,"u ^! conditions ! dry+ 0 s unc]ta9 t only f\r det]m9ations 7 complet$ al?\gh _m 7 />t$4 ,! boat conta9+ ! oxalate :i* _h be5 dri$ & weigh$ 0 plac$ on supports ( unglaz$ porcela9 9 a combu/ion tube & a curr5t ( dry hydrog5 sulphide pass$ ov] x4 ,z soon z ! air 0 expell$1 ! tube1 :i* 0 9 a combu/ion furnace1 0 sl[ly heat$ until all ! oxalate seem$ to be decompos$ & !n rais$ to dull r$ness4 ,aft] ?is temp]ature _h be5 ma9ta9$ = ab\t an h\r1 ! sulphide 0 all[$ to cool to a temp]ature ( ab\t #bjj;,c4 & ! curr5t ( hydrog5 sulphide replac$ by dry nitrog51 us+ a ?ree-way /opcock4 ,:5 ne>ly cold ! boat 0 slipp$ into its weigh+-tube & weigh$1 ! same precautions be+ us$ z :5 weigh+ ! empty boat4 ,at ?is /age ! sulphide 0 always f "o to two milligrammes light] ?an at ! end ( ! det]m9ation4 ,x 0 reheat$ = p]iods ( "o h\r until ! weight rema9$ con/ant4 ,?is g5]ally requir$ f ?ree to five h\rs4 ,all weigh+s 7 r$uc$ to ! vacuum /&>d on ! basis ( #d4e = ! ,sp4 ,gr4 ( cadmium sulphide1 #c4ca = ! ,sp4 ,gr4 ( cadmium oxalate1 #h4d = ! ,sp4 ,gr4 ( brass weights & #ba = ! ,sp4 ,gr4 ( plat9um weights4 ,! results are z foll[s3 ,cd ,c#b,o#d ,cd,s ,at4 ,wt4 ,cd4 ,i4 #b4efcai #a4hdgaf #aab4be ,,ii4 #b4ahcfd #a4egcda #aab4ag ,,iii4 #b4aafdc #a4ebdfb #aab4je ,,iv4 #c4acaje #b4beehb #aab4ab ,! fir/ ?ree det]m9ations 7 made exactly z above describ$1 ! heat+ 9 hydrog5 sulphide be+ done 9 a ,bohemian glass combu/ion tube4 ,! hydrog5 sulphide 0 dri$ ) calcium *loride4 ,! f\r? det]m9ation 0 made "u some:at diff]5t conditions4 ,! boat conta9+ ! weigh$ oxalate 0 plac$ 9 a combu/ion tube :i* pass$ ?r\gh an asbe/us cov]$ air-ba?4 ,! air 0 displac$ by a curr5t ( dry hydrog5 sulphide & ! ba? sl[ly heat$4 ,:5 ! temp]ature _h ris5 to #baj;,c4 x 0 ma9ta9$ !re = ?ree h\rs1 & !n rais$ to #bej;,c4 = ?ree h\rs4 ,! sulphide !n weigh$ #b4bg grammes1 be+ #ad milligrammes heavi] ?an :5 ! det]m9ation 0 f9i%$4 ,x 0 replac$ 9 ! tube & reheat$ 9 a curr5t ( hydrog5 sulphide at a temp]ature ( #cjj;,c4 = f\r h\rs4 ,x 0 !n transf]r$ to a porcela9 tube & heat$ to r$ness = "o h\r4 ,x !n weigh$ #b4bedcg grammes1 be+ #a4de milligrammes light] ?an at ! end ( ! det]m9ation4 ,! weight did n become con/ant until x _h be5 heat$ six h\rs m to r$ness 9 a curr5t ( hydrog5 sulphide4 ,:5 ?is oxalate 0 sl[ly heat$ 9 ,h#b,s1 a small am\nt ( oxalic acid sublim$ to ! cold] "p ( ! tube1 b1 9 ! o!r cases :]e ! heat+ 0 m rapid1 only c>bon monoxide1 c>bon dioxide1 & wat] 7 obs]v$4 ,discussion ( ! ,me?od4 ,:5 hydrog5 sulphide is pass$ ?r\gh a r$-hot tube1 sulphur is deposit$ on ! cold] p>ts because at ?is temp]ature hydrog5 sulphide dissociates & ! elem5ts d n recomb9e on cool+4 ,9 ?is "w1 a fa9t sublimate 0 notic$ be=e com+ to ! zone ( sulphur deposit4 ,on exposure to air1 x deliquesc$ 9 a few m9utes =m+ small yell[ drops :i* _h a sal9e ta/e1 & gave te/s = potassium & sulphur4 ,! sublimate _h a yell[ color & 0 evid5tly =m$ by ! action ( sulphur on glass4 ,x seem$ to d no h>m1 b 9 ! f\r? det]m9ation an ef=t 0 made to avoid x by us+ a porcela9 tube in/ead ( a glass combu/ion tube = heat+ to r$ness 9 a curr5t ( hydrog5 sulphide4 ,! fact t sulphide ( cadmium 0 always too light aft] ! fir/ h\r's heat+ 9 hydrog5 sulphide proves t x mu/ h conta9$ "s oxide ( cadmium ev5 aft] ?is heat+4 ,oxide ( cadmium is readily absorb$ by ! glaze on porcela91 & "s error mu/ h be5 introduc$ 9 ?is way because x w\ld n be conv]t$ into sulphide aft] =m+ a silicate4 ,! effect ( ?is w\ld be to give a l[ result = ! atomic weight ( cadmium4 ,to get "s idea ( ! magnitude ( ?is error1 ! sulphide 0 p\r$ out ( ! boats us$ 9 ! fir/ & second det]m9ations4 ,!y 7 !n w>m$ ) nitric acid = a few mom5ts1 wa%$ 9 wat]1 & heat$ ov] ! bla/ lamp = a few m9utes4 ,! boats us$ z t>es 7 treat$ 9 exactly ! same mann]4 ,on weigh+1 ! boats 9 :i* ! oxalate 9 det]m9ations ,i & ,,ii _h be5 decompos$1 7 f\nd to be #a4ab milligrammes & 4#hb milligrammes heavi] respectively ?an at ! beg9n+ ( ! det]m9ations4 ,?is w\ld only introduce an error ( 4#jc ( a unit 9 ! atomic weight on acc\nt ( ! small diff]5ce 9 weight betwe5 ^! am\nts ( oxide & equival5t am\nts ( sulphide4 ,! boats 7 w>m$1 z above m5tion$1 ) nitric acid to remove any adh]+ sulphide4 ,?is might h decompos$ "s cadmium silicate at ! same "t1 & ! error due to cadmium oxide ?us be f\nd small] ?an x really is4 ,! foll[+ exp]im5t 0 made 9 ! hope ( avoid+ ! =mation ( cadmium silicate4 ,! glaze 0 remov$ f ! inside ( a porcela9 boat by hydr(luoric acid foll[$ by a ?or\gh sc\r+ ) s& & wat]4 ,! boat 0 !n heat$ 9 ! flame ( a bla/ lamp = sev]al m9utes1 t>$ aga9/ ano!r boat :i* 0 n treat$ ) hydr(luoric acid4 ,bo? 7 heat$ to r$ness 9 a curr5t ( hydrog5 sulphide = an h\r1 cool$1 weigh$1 & !n heat$ 9 hydrog5 sulphide = ano!r h\r1 & weigh$ aga94 ,! boat ga9$ #a4g milligrammes dur+ ?is second heat+1 %[+ t a boat ^: glaze has be5 remov$ by hydr(luoric acid c\ld n be us$ 9 ?is me?od4 ,?r\gh\t ?is "w1 great c>e 0 tak5 to exclude ! oxyg5 ( ! air f ! cadmium sulphide1 :ile hot4 ,! curr5t ( hydrog5 sulphide 9 :i* ! cadmium sulphide is heat$ mu/ n be too sl[1 o!rwise ! sulphur 9 ! dissociat$ gas w diffuse to ! cold] p>ts ( ! tube & cond5se1 ! residual gas becom+ v ri* 9 hydrog54 ,! hydrog5 w !n r$uce "s ( ! sulphide to metal1 caus+ loss by volatilization4 ,"o det]m9ation 0 lo/ 9 ?is way1 ov] two milligrammes ( ! sulphide be+ sublim$ out1 & x c\ld easily be detect$ on ! side ( ! tube4 ,x is believ$ t ! cause ( ! v>iations 9 ! f\r det]m9ations made by ?is me?od1 is due to imp]fect dehydration ( ! oxalate4 ,x did n seem advisable to cont9ue ?is "p ( ! "w any f>!r2 !re=e ! *loride me?od 0 tak5 up4 ,! ,*loride ,me?od4 ,hunt+ton _h det]m9$ ! ratios ( ,cd,br#b to ,ag,br & also ,cd,br#b to ,ag v c>efully1 obta9+ ! result #aab4bd = ! atomic weight ( cadmium4 ,morse & ,jones _h obta9$ #aab4jg = ?is con/ant by ! oxide me?od4 ,! object ( ! "w ab\t to be describ$ 0 to f9d ! cause ( ?is discrepancy if possible4 ,x 0 ?\ght advisable h[ev] to make "s det]m9ations ( ! ratio ( ,cd,cl#b to ,ag,cl be=e beg9n+ ! bromide me?od4 ,dumas1 9 #ahei1 us$ cadmium *loride to det]m9e ! atomic weight ( ! metal4 ,he did n e/abli% its ratio to silv] *loride b to silv] by titration4 ,he prep>$ cadmium *loride by dissolv+ ! metal 9 hydro*loric acid & melt+ ! result+ product 9 a plat9um capsule = five or six h\rs4 ,he made two s]ies ( ?ree det]m9ations4 ,! *loride us$ 9 ! fir/ s]ies 0 yell[ 9 places & n completely soluble4 ,! result 0 #aab4dgf4 ,! second s]ies 0 made ) *loride :i* 0 p]fectly :ite & soluble & gave #aab4jjg = ! atomic weight ( cadmium4 ,x is evid5tly m reliable ?an ! fir/ s]ies & ,dumas himself conclud$ t ! atomic weight is v ne> #aab4ja4 ,prep>ation ( ,cadmium ,*loride ,f\r diff]5t specim5s ( cadmium *loride 7 us$ 9 ?is "w & f ^! specim5s portions 7 tak5 = analysis4 ,^! portions 7 treat$ diff]5tly 9 diff]5t analyses1 !re=e x w be necess>y to give a brief descriptions ( !m & m5tion ! numb] ( ! det]m9ations1 9 :i* ea* "o 0 us$4 ,*loride ( cadmium 0 prep>$ 9 ! foll[+ mann]4 ,a solution ( pure hydro*loric acid 0 prep>$ by pass+ a curr5t ( hydro*loric acid gas into pure wat] :i* 0 conta9$ 9 a porcela9 crucible until no m 0 absolv$4 ,! wat] us$ _h be5 purifi$ by di/ill+ aga9/ a plat9um di% & ! hydro*loric acid gas 0 obta9$ by heat+ ord9>y conc5trat$ *emically pure hydro*loric acid 9 a di/ill+ bulb ^: neck _h be5 clos$ by fusion 9 ord] to avoid ! use ( a cork or rubb] /opp]4 ,hydro*loric acid ?us prep>$ w leave no residue on evaporation :5 air is exclud$ 7,/as1 ,aron/e9's ,g]man translation1 p4 #aaa74 ,a piece ( plat9um foil fre$ f iron by heat+ 9 ! vapors ( ammonium *loride z recomm5d$ by ,/as 7,aron/e9's translation1 p4 #aab7 0 introduc$ & a piece ( cadmium laid on x4 ,solution beg9s at once1 ! hydrog5 be+ lib]at$ on ! plat9um foil4 ,dur+ ! lat] "p ( ! process1 heat 0 appli$4 ,aft] all ( ! metal _h dissolv$1 ! solution 0 evaporat$1 ! plat9um foil hav+ previ\sly be5 remov$4 ,! cry/als ( cadmium *loride :i* sep>at$ 7 n dri$ b all[$ to rema9 slightly moi/ ) hydro*loric acid4 ,if no plat9um foil is us$1 ! solution ( ! pure metal becomes exce$+ly difficult1 unless a v l>ge excess ( acid is us$4 ,no objection c be rais$ to ! use ( plat9um foil = 9 mak+ fifty grammes ( cadmium *loride x co/ less ?an a t5? ( a milligramme & ev5 ?is c\ld probably h be5 avoid$ by us+ a some:at l>g] am\nt ( hydro*loric acid4 ,! foil 0 always kept subm]g$ 9 ! acid liquid4 ,! moi/ cry/als ( cadmium *loride 7 transf]r$ to a combu/ion tube pass+ ?r\gh an asbe/us cov]$ air-ba?1 & dri$ 9 a curr5t ( hydro*loric acid gas = sev]al h\rs at #cjj;,c4 ,! hydro*loric acid gas _h be5 pass$ ?r\gh a long calcium *loride tube to dry x1 al?\gh calcium *loride probably does n d ?is v ?or\ghly4 ,! hydro*loric acid gas 0 !n replac$ by a curr5t ( nitrog5 prep>$ z has already be5 describ$ "u ! sulphide me?od4 ,aft] ! curr5t ( nitrog5 _h be5 pass+ = ab\t half an h\r1 ! tube 0 all[$ to cool1 & ! *loride transf]r$ to ano!r combu/ion tube1 "o end ( :i* _h be5 seal$ 9 ! flame ( a bla/ lamp4 ,! o!r end 0 drawn out & atta*$ to a ,spr5gel m]cury pump4 ,aft] exhau/+1 ! *loride 0 sublim$ 9 ! vacuum4 ,?is takes place at a mod]ate temp]ature & ! sublimate has a beautiful cry/all9e /ructure & is p]fectly :ite4 ,! cry/all9e mass exposes s mu* surface t wat] is tak5 up v rapidly :5 expos$ to ! air4 ,?is action is s rapid t ! cry/als _c be transf]r$ to a weigh+-glass )\t introduc+ an appreciable error4 ,! :ole sample 0 accord+ly transf]r$ to a /opp]$ glass bottle :i* 0 kept "u a bell j> ) /icks ( cau/ic pota%4 ,?ree samples 7 prep>$ 9 ?is mann]1 ! fir/ be+ us$ 9 det]m9ation "o1 ! second 9 det]m9ations two to sev5 inclusive1 & ! ?ird 9 det]m9ations eight to n9ete5 inclusive4 ,! samples us$ 9 det]m9ations tw5ty & tw5ty-"o 7 prep>$ 9 ! foll[+ mann]3 ,ab\t ?ree grammes ( cadmium 7 plac$ 9 a combu/ion tube 9 :i* ?ree bridges 7z 9 ! di/illation ( pure cadmium7 _h be5 made4 ,a section may be repres5t$ ?us ,illu/ration ,! metal 0 plac$ 9 cavity ,a & a /ream ( *lor9e pass$ ?r\gh ! tube4 ,! *lor9e 0 prep>$ f potassium bi*romate & hydro*loric acid & dri$ by pass+ x ?r\gh a long tube conta9+ calcium *loride4 ,:5 ! air _h be5 displac$1 ! cadmium 0 heat$4 ,x fus$ & began to burn to ! *loride :i* p>tly fl[$ ov] ! bridge into cavity ,b & p>tly di/ill$ ov] into ?is cavity4 ,:5 ! reaction _h end$1 ! curr5t ( *lor9e 0 replac$ by "o ( dry nitrog51 & ! tube 0 all[$ to cool & ! *loride tak5 = analysis ,,xx4 ,! specim5 us$ 9 analysis tw5ty-"o 0 prep>$ 9 exactly ! same way1 only ! *lor9e us$ 0 obta9$ f manganese dioxide1 sodium *loride & sulphuric acid1 & 0 dri$ ) phosphor\s p5toxide in/ead ( calcium *loride4 ,! special treatm5t ( ! portions tak5 = analysis 0 z foll[s3 ,^? tak5 = det]m9ations ,i1 ,,ii & f ,,xi to ,,xix inclusive 7 plac$ 9 a plat9um boat & put into combu/ion tube4 ,a curr5t ( hydro*loric acid gas obta9$ by heat+ ! aque\s acid 0 pass$ ?r\gh ! tube4 ,! gas _h be5 dri$ by calcium *loride4 ,:5 ! air 0 displac$1 ! *loride 0 heat$ some:at high] ?an its fus+-po9t i4e4 to incipi5t r$ness1 & ma9ta9$ !re = a l5g? ( "t v>y+ f a few m9utes to m ?an an h\r4 ,! hydro*loric acid 0 !n displac$ by a curr5t ( nitrog51 & ! *loride all[$ to cool4 ,! boat ) ! *loride1 :ile /ill slightly w>m1 0 plac$ 9 a weigh+-tube1 cool$ 9 a d$icator conta9+ cau/ic pota% & weigh$4 ,! *loride ?us prep>$ is transp>5t & pres5ts only a small surface to ! air4 ,x takes wat] up s sl[ly t no error is introduc$ f ?is s\rce4 ,?is 0 te/$ 9 "o case by all[+ a boat conta9+ "s *loride ?us prep>$ to /& 9 ! air = a c]ta9 l5g? ( "t & not+ ! increase 9 weight4 ,x 0 q sl[4 ,9 sev]al cases specim5s ( *loride 7 te/$ = hydro*loric acid us+ tropaeol9 z an indicator4 ,x 0 always f\nd neutral4 ,! portions us$ = det]m9ations ,,iii & ,,vi to ,x inclusive 7 prep>$ 9 exactly ! same mann] z ! prec$+ ones except t ! hydro*loric acid gas 9 :i* !y 7 fus$ 0 n dri$ b us$ j z x came f ! aque\s acid4 ,9 "s cases ! plat9um boat 9 :i* ! *loride 0 fus$ 0 weigh$ be=e & aft] ! fusion4 ,! weight rema9$ un*ang$4 ,= det]m9ations ,,iv & ,v1 ab\t six grammes ( cadmium *loride 7 plac$ 9 a plat9um boat1 & m ?an two-?irds ( x di/ill$ out 9 a curr5t ( hydro*loric acid gas :i* _h n be5 dri$4 ,"p ( ! di/illate 0 collect$ aft] cool+ 9 nitrog5 & us$ 9 det]m9ation ,,iv :ile ! residue rema9+ 9 ! boat 0 us$ = det]m9ation ,v4 ,! me?od ( prep>+ ! *loride us$ 9 det]m9ations ,,xx & ,,xxi has already be5 describ$4 ,! ,filt]s4 ,?9k+ t a ,goo* crucible ) a plat9um sponge on ! bottom 9 place ( asbe/us w\ld be desirable = ?is "w "o 0 accord+ly made & answ]$ ! purpose v satisfactorily4 ,all det]m9ations 7 made by us+ su* filt]s4 ,c4 ,e4 ,munroe 7,*em4 ,news1 ,vol #eh1 p4 #aja7 has describ$ ! prep>ation ( ^! filt]s4 ,a plat9um ,goo* crucible 0 plac$ on a filt] pap] & "s ammonium platonic *loride :i* _h be5 ?or\ghly wa%$ introduc$ by susp5d+ x 9 alcohol & !n p\r+ ?is into x4 ,! precipitate settles to ! bottom =m+ a uni=m lay] & ! alcohol dra9s1 (f ?r\gh ! filt] pap]4 ,! crucible 0 !n dri$ sl[ly 9 an air-ba?4 ,aft] ?is x 0 transf]r$ to a porcela9 crucible & sl[ly heat$ until decomposition 0 complete4 ,9 ?is mann] a lay] ( plat9um felt is obta9$ :i* acts z a v effici5t filt]4 ,ano!r lay] ( d\ble *loride 0 !n decompos$ z be=e s t if !re 7 any imp]fections 9 ! fir/ lay] !y w\ld be cov]$ by ! second lay]4 ,! surface 0 smoo!d d[n by means ( a glass rod4 ,to prep>e a good filt] ! dry+ & subsequ5t heat+ %\ld be v sl[4 ,! heat+ mu/ n be at too high a temp]ature1 o!rwise ! felt becomes v compact & is useless = filt]+ purposes4 ,pressure produces ! same effect4 ,! filt]s 7 always treat$ ) /rong nitric acid1 wa%$ & reheat$ be=e be+ us$1 b 9 no case 0 *lor9e detect$ 9 ! nitric acid aft] ! wa%+1 nor any loss 9 weight ( ! crucible4 ,an objection to ! use ( ^! crucibles = ! purpose nam$ 0 f\nd 9 ! c\rse ( ?is "w1 b x w be discuss$ lat]4 ,! crucibles 7 always set 9 a l>ge weigh+-glass1 & ano!r weigh+-glass conta9+ an equal am\nt ( plat9um foil us$ z a t>e1 9 weigh+4 ,?is precaution 0 p]haps unnecess>y1 b at lea/ x did no h>m4 ,analytical ,process4 ,! weigh$ cadmium *loride 0 dissolv$ by plac+ ! boat conta9+ x 9 an ,erl5mey] flask conta9+ wat]4 ,! boat 0 !n wa%$1 dri$ & replac$ 9 its weigh+-tube4 ,on weigh+ aga91 ! loss 9 weight is equal to ! weight ( cadmium *loride tak54 ,all samples gave a p]fectly cle> solution except ^? us$ = det]m9ations ,,xx & ,,xxi4 ,a drop ( nitric acid 7#a3c7 0 add$ to ea* solution except 9 det]m9ation ,,xiv :]e ! cubic c5timetres 7 add$1 & 9 ,,xvi :]e t5 cubic c5timet]s 7 add$4 ,a solution ( silv] nitrate 0 !n add$ to precipitate ! *lor9e4 ,?is z well z ! subsequ5t wa%+ 0 done 9 a d>k-room illum9at$ by a s+le gas light ^: rays _h to pass ?r\gh a /rong solution ( neutral potassium *romate4 ,! precipitate 0 contract$ by w>m+ on ! wat]-ba?4 ,x 0 !n collect$ 9 ! prep>$ ,goo* crucibles & wa%$4 ,be=e filt]+1 ! flask conta9+ ! precipitate & "m-liquor 0 all[$ to cool4 ,silv] *loride is soluble 9 wat] to a consid]able ext5t b is reprecipitat$ by add+ an excess ( ei!r silv] nitrate or hydro*loric acid4 ,/as 7,ann4 de ,*em4 et ,phys4 #d1 #be1 #bb2 #e1 #c1 #ade2 #e1 #c1 #bhi47 inve/igat$ ?is v ?or\ghly4 ,cooke also did "s "w on x & us$ a dilute solution ( silv] nitrate to wa% ! *loride ?us prev5t+ solution 7,proc4 ,am]4 ,acad4 #ag1 #g474 ,9 ! above "w1 !re=e1 a solution conta9+ #j4aj grammes ( silv] nitrate p] lit] 0 fir/ us$1 foll[$ by "o only "o-t5? z /rong1 & f9ally pure wat] 0 us$4 ,only two or ?ree wa%+s c\ld be made ) wat] z ! *loride w5t into solution aft] ?is ow+ to ! removal ( ! silv] nitrate4 ,! la/ silv] nitrate solution us$ is s weak t any error introduc$ by n wa%+ x out completely is insignificant4 ,aft] wa%+1 ! silv] *loride 0 dri$ at temp]atures v>y+ f #aej;,c4 to #cjj;,c4 to con/ant weight4 ,a glass air-ba? 0 us$ 9 ord] to prev5t products f ! burn+ gas f com+ 9 contact ) ! *loride4 ,x 0 !n weigh$4 ,! quantity ( silv] nitrate us$ 9 ! det]m9ations 0 v>i$ v mu*4 ,! excess ov] :at 0 requir$ to precipitate ! *loride is giv5 9 ! table ( results 9 ^? cases 9 :i* x is kn[n4 ,! quantity ( wat] us$ 9 ea* det]m9ation is also giv5 :]e x is kn[n4 ,x is giv5 9 ! numb] ( cubic c5timetres us$ p] gramme ( cadmium *loride & does n include wa% wat]4 ,all weigh+s are r$uc$ to ! vacuum /&>d on ! basis t ,sp4 ,grs4 ( ,cd,cl#b #c4id & ,ag,cl #e4e4 ,! results are3 ,no4,cd,cl#b ,ag,cl ,h#b,o ,excess ,ag,n,o#c;,at4 ,wt4,melt$ 9 p] ,grm4 ,i #c4jiahcd4hchef #aab4cci ,dry ,h,cl ,,ii #b4bfajjc4eched #aab4cbi ,,iii #a4cegbib4abdca #aab4cbj,moi/ ,h,cl ,,iv #b4jeehbc4bagbg #aab4cci ,v #a4higgdb4igjda #aab4cjf ,,vi #c4ejcfge4dhdgc #h4ijaab4bhc ,,vii #b4gjbibd4bcjhg #bjj #a4giaab4cja ,,viii #d4bdbgf #f4fcih #cjj #h4ajaab4chg ,,ix #c4djbjje4cbcad #cjj #ah4ieaab4cfh ,x #d4fjfeig4bjchf #cjj #be4fbaab4dgb ,,xi #b4djhcb #aab4dcd ,dry ,h,cl ,,xii #b4aiaadc4dbgbd #aab4dcc ,,xiii #b4hdfbhd4dedgg #cjjd4de #c;cc4 ,,hno#caab4cai ,,xiv #b4efgdhd4jafea #cjj 4#ajaab4cii ,,xv #b4cajjcc4facgj #cjj4aj #aj;cc4 ,,hno#caab4djf ,,xvi #a4bejjha4iefeb #cjj #d4ffaab4cai ,,xvii #a4ifjaec4jfeda #cjj #c4bbaab4dff ,,xviii #b4bighgc4eicia #cjj #d4bgaab4ddh ,,xix #a4idbbgc4jchaa #cjj #c4faaab4dbc ,dry ,h,cl ,,xx #a4ajigfa4gcedg #aab4dga ,,xxi #a4fcjhjb4eejaf #aab4dgf -------------- ,av]age#aab4chc ,discussion ( ! ,results4 ,9 ! fir/ five det]m9ations1 ! analytical op]ations 7 conduct$ z ne>ly z possible alike1 b ! prep>ation ( ! portions ( cadmium *loride tak5 = analysis 0 v>i$ v mu* z w be se5 by ref]r+ back to ?is "p ( ?is pap]4 ,! results d n v>y m ?an #j4jae f _! av]age4 ,?is is v /rong evid5ce ( ! purity ( ! *loride us$ =1 if x conta9$ any impurity1 we %\ld h expect$ to v>y ! am\nt 9 ! diff]5t portions4 ,aft] ?is1 att5tion 0 paid especially to ! analytical process1 = x 0 ?\ght t !re probably 0 "s s]i\s error 9 ! me?od1 ! result be+ high] ?an any t _h previ\sly be5 obta9$1 if we exclude ,dumas' fir/ s]ies :i* he himself did n accept4 ,! conditions 7 v>i$ 9 _m ways to see h[ mu* ! result c\ld be influ5c$1 b "u no conditions 7 results z l[ z ,hunt+ton's av]age 7#aab4bd7 obta9$4 ,a numb] ( errors 7 f\nd 9 ! me?od dur+ ! "w1 b !y seem to neutralize ea* o!r to a great ext5t4 ,! m important ones w n[ be giv54 ,ne>ly e filtrate includ+ ! correspond+ wa% wat] 0 exam9$ = *lor9e aft] ! silv] & cadmium _h be5 precipitat$ by hydrog5 sulphide4 ,! excess ( hydrog5 sulphide 0 expell$ by boil+1 aft] ! addition ( "s nitric acid4 ,9 two cases an inv]t$ cond5s] 0 us$4 ,on add+ silv] nitrate a precipitate 0 always obta9$ %[+ ! pres5ce ( *lor9e4 ,c>e 0 always tak5 to filt] (f sulphur =m$ by ! oxidation ( hydrog5 sulphide1 be=e add+ ! silv] nitrate4 ,! precipitate 0 nev] v heavy1 & 0 n e/imat$ quantitatively4 ,x is evid5t t cadmium nitrate ex]ts a solv5t action on silv] *loride4 ,9 "s cases a v l>ge excess ( silv] nitrate 0 add$ b x did n *ange ! results m>k$ly4 ,silv] nitrate itself dissolv$ silv] *loride to "s ext5t4 ,! increase 9 insolubility1 if any1 on add+ an excess ( silv] nitrate is probably c\nt]balanc$ by ! increas$ error due to occlusion ( nitrates 9 ! silv] *loride4 ,/as 7,aron/e9's ,trans4 p4 #aef7 says x is impossible to contract silv] *loride or bromide 9 a solution conta9+ salts )\t !re be+ occlusion & t ! precipitate c only be fre$ f !m by divid+ up ! contract$ mass by %ak+ ) pure wat]4 ,?is 0 n done "h ow+ to ! solubility ( silv] *loride 9 pure wat]1 & ! complications introduc$ 9 ! analytical "p4 ,! occlusion ( nitrates by ! silv] *loride w\ld l[] ! atomic weight f\nd4 ,! silv] *loride obta9$ always d>k5$ on heat+ & conta9$ cadmium1 z 0 %[n 9 ! foll[+ mann]3 ,! lump ( silv] *loride 0 atta*$ to ! negative pole ( a cell & electrolyz$ 9 a ba? conta9+ dilute sulphuric acid4 ,! result+ metal 0 !n dissolv$ 9 nitric acid & ! silv] precipitat$ by add+ hydro*loric acid4 ,! filtrate 0 evaporat$ to expel ! nitric acid & ! residue tak5 up ) wat] & te/$ = cadmium ) hydrog5 sulphide4 ,an appreciable quantity 0 always f\nd4 ,?is me?od ( exam9ation does n %[ ! occlud$ silv] nitrate4 ,ano!r error :i* t5ds to l[] ! atomic weight f\nd is due to ! plat9um crucibles us$ = filt]+4 ,if a silv] nitrate solution is filt]$ ?r\gh su* a crucible !re w be an increase 9 weight due to silv] be+ deposit$4 ,?is takes place 9 acidifi$ solutions z well z 9 neutral ones4 ,wa%+ ) ammonia does n remove ! deposit1 b /rong nitric acid does1 ! wa%+s giv+ a te/ = silv]4 ,:e!r ! deposit+ ( silv] is due to ! action ( spongy plat9um 9 contact ) ! compact metal ( ! crucible or to "s impurity 9 ! plat9um sponge 0 n det]m9$1 b ! =m] seems by f> ! mo/ probable4 ,! increase 9 weight dur+ ! "t requir$ = filt]+ a det]m9ation mu/ h be5 q small h[ev]4 ,! samples ( cadmium *loride employ$ = det]m9ations ,,xx & ,,xxi 7 prep>$ by burn+ cadmium 9 a curr5t ( *lor9e4 ,! glass tube us$ 0 atta*$ some:at & ! solution ( ! *loride 0 v slightly turbid 9 ea* case4 ,! turbidity 0 s slight h[ev]1 t no v s]i\s error c\ld h result$ f x1 p>ticul>ly z x 0 probably p>tly c\nt]balanc$ by ! =mation ( "s potassium *loride4 ,= m accurate "w1 x %\ld h be5 made & r$i/ill$ 9 a porcela9 tube4 ,^! two samples 7 te/$ = free *lor9e ) potassium iodide & />* pa/e1 b none 0 f\nd4 ,"s ( ! specim5s ( *loride prep>$ by fusion 9 a curr5t ( hydro*loric acid 7 f\nd to be neutral1 us+ tropaeol9 z an indicator4 ,z ne>ly z c be judg$1 ! above errors w\ld probably c\nt]balance ea* o!r to a great ext5t1 & ?us give a fairly close approximation to ! atomic weight ( cadmium :5 ! av]age ( all ! det]m9ations is tak54 ,! value #aab4chc ?us obta9$ c only be reg>d$ z t5tative4 ,! ,bromide me?od4 ,hunt+ton 7,proc4 ,am]4 ,acad4 #aa4bh7 work+ "u ! direction ( ,j4 ,p4 ,cooke1 det]m9$ ! ratio ( cadmium bromide to silv] bromide & us+ ! total quantities = ! calculation ! result = ! atomic weight ( cadmium is #aab4bci4 ,he also det]m9$ ! ratio ( cadmium bromide to silv]1 obta9+ #aab4bde = ! atomic weight ( cadmium4 ,! "w :i* w n[ be describ$ 0 c>ri$ out v mu* l ! "w describ$ "u ! *loride me?od4 ,! ratio ( cadmium bromide to silv] bromide 0 inve/igat$4 ,prep>ation ( ,cadmium ,bromide & ,hydrobromic ,acid4 ,a l>ge quantity ( hydrobromic acid 0 prep>$ accord+ to ! me?od describ$ by ,dr4 ,edw>d ,r4 ,squibb 7,trans4 ( ,m$4 ,soc4 ( ! ,/ate ( ,n4 ,y474 ,"o "p ( wat] 0 add$ to sev5 p>ts ( /rong sulphuric acid 7,sp4 ,gr4 #a4hc7 & ! mixture cool$4 ,!n six p>ts ( potassium bromide 7 dissolv$ 9 six p>ts ( hot wat] & ! dilut$ sulphuric acid add$ to ?is hot solution4 ,x 0 set aside until cold 9 ord] to all[ ! sulphate ( potassium to cry/allize out4 ,! cry/als 7 dra9$ on a filt]-plate & quickly wa%$ ) two p>ts ( wat]4 ,! "m-liquor & wa%+ 7 !n di/ill$ until no m acid 0 obta9$ on fur!r heat+4 ,! acid ?us obta9$ 0 di/ill$ ?ree times f potassium bromide1 twice f cadmium bromide =m$ by add+ a piece ( pure cadmium to x1 & twice )\t ! addition ( any?+4 ,x 0 te/$ & f\nd to be free f sulphuric acid4 ,cadmium bromide 0 prep>$ f x1 9 exactly ! same way t ! cadmium *loride us$ 9 ! *loride me?od 0 prep>$ f pure metal & hydro*loric acid4 ,:ile ! cry/all9e mass ( cadmium bromide 0 /ill moi/1 x 0 transf]r$ to a comb9ation tube & dri$ at #cjj;,c = sev]al h\rs 9 a curr5t ( nitrog54 ,x 0 !n sublim$ 9 a vacuum z ! *loride _h be54 ,?is specim5 s]v$ = ! fir/ ?ree det]m9ations4 ,ab\t n9e grammes ( x 0 plac$ 9 a plat9um boat 9 a combu/ion tube1 & "p ( x di/ill$ 9 a curr5t ( nitrog54 ,! di/illate1 a portion ( :i* _h be5 te/$ ) tropaeol9 & f\nd neutral1 0 us$ = det]m9ation ,i4 ,! residue 9 ! boat 0 us$ = det]m9ation ,,ii4 ,ano!r portion ( ! ma9 sample 0 resublim$ 9 a vacuum & us$ 9 det]m9ation no4 ,,iii4 ,cadmium bromide is n hygroscopic or at lea/ only slightly1 !re=e ! sublim$ cadmium bromide c be transf]r$ to a weigh+-glass )\t tak+ up wat]4 ,?is _c be done 9 ! case ( ! *loride4 ,x is probable t ! hydrobromic acid z above prep>$ 0 p]fectly free f hydro*loric acid4 ,*lor9e 9 cadmium bromide w\ld cause ! atomic weight to be f\nd l[] ?an x really is4 ,x 0 ?\ght desirable1 h[ev]1 to prep>e an acid :i* w\ld c]ta9ly be free f *lor9e4 ,! me?od describ$ by ,/as 7,aron/e9's ,g]man translation1 p4 #aed47 0 employ$ ) ! additional precaution t ! above purifi$ acid 0 us$ to />t ) & all reag5ts employ$ _h be5 especially prep>$ s z to be free f *lor9e4 ,pure silv] 0 prep>$ accord+ to ,/as' description 7see ,aron/e9's translation1 page #cd1 also page #ajd7 by ! action ( ammonium sulphite on an ammoniacal solution ( silv] nitrate & copp] sulphate4 ,! silv] 0 dissolv$ 9 nitric acid free f *lor9e1 & !n sl[ly add$ to a dilute solution ( ! above-describ$ hydrobromic acid1 & ! precipitat$ silv] bromide ?or\ghly wa%$4 ,x 0 !n dige/$ = a long :ile 9 a /rong solution ( potassium bromide1 fir/ 9 ! cold1 !n by heat+4 ,! potassium bromide _h be5 made ?us3 ,twice recry/alliz$ potassium hydrog5 t>trate 0 heat$ 9 a plat9um di% 9 a muffle furnace until x 0 conv]t$ into c>bonate1 & ! excess ( c>bon burn$ (f4 ,x 0 !n dissolv$ 9 wat]1 filt]$ & neutraliz$ ) "s ( ! hydrobromic acid already describ$4 ,! c>bonate _h be5 te/$ = bo? sulphuric acid & *lor9e ) negative results4 ,aft] ! silv] bromide _h be5 dige/$ ) ! potassium bromide1 x 0 wa%$ v ?or\ghly1 susp5d$ 9 wat]1 & a curr5t ( hydrog5 sulphide pass$ into x4 ,?is conv]ts x into sulphide hydrobromic acid be+ lib]at$4 ,! acid 0 dra9$ (f on a porcela9 plate1 & !n di/ill$ a numb] ( times4 ,x 0 f9ally te/$ & f\nd to be p]fectly free f sulphates & also did n conta9 free brom9e4 ,hav+ />t$ ) an acid :i* 0 probably pure & subject$ x to ^! op]ations ) reag5ts free f *lor9e1 !re c be no d\bt z to ! purity ( ! result+ acid4 ,! hydrog5 sulphide us$ 0 prep>$ f potassium hydrosulphide z 9 ! sulphide me?od1 & wa%$ fir/ ) a solution ( ! hydrosulphide1 !n v ?or\ghly ) pure wat]4 ,f ! hydrobromic acid obta9$1 a specim5 ( cadmium bromide 0 prep>$ z be=e & sublim$ twice 9 a vacuum4 ,?is specim5 0 us$ = det]m9ations ,,iv & ,v4 ,me?od ( ,analysis4 ,! fir/ ?ree det]m9ations 7 made exactly l ^? 9 ! *loride me?od4 ,! la/ two 7 also made 9 ! same mann]1 only ! wa%+ ( ! precipitate 0 v>i$4 ,aft] ! silv] bromide _h be5 contract$ by w>m+ on a wat]-ba? x 0 wa%$ by decantation & !n agitat$ viol5tly ) cold wat] to remove occlud$ nitrates1 b x 0 !n s f9ely divid$ t x c\ld n be filt]$4 ,! artifice us$ by ,/as to contract x a second "t 0 to pass a curr5t ( /eam into ! milky liquid4 ,?is 0 tri$ "h1 b = "s reason or o!r did n "w v well1 & consid]able difficulty 0 _h 9 filt]+ x4 ,! results ( ! five det]m9ations are tabulat$ bel[4 ,all weigh+s are r$uc$ to ! vacuum /&>d on ! basis ( ,sp4 ,gr4 ( ,cd,br#b #d4f & ,sp4 ,gr4 ,ag,br #f4fb4 ,no4,cd,br#b ,ag,br ,h#b,o ,ex4 ,ag,n,o#c ,at4 ,wt4,rem>ks ,i #d4ciida #f4jgbjd #aab4dc;,di/illate ,,ii #c4ahjcj #d4chhca #aab4db,residue ,,iii #c4fjccf #d4igaej #aab4de,resublim$4 ,,iv #d4jdbdj #e4ehjfb #aab4bi ,v #c4fjeje #d4igeai #aab4ch ,av]age #aab4cid ,discussion ( ! ,results4 ,! fir/ ?ree specim5s 7 prep>$ "u widely diff]5t conditions yet ! results agree q closely4 ,! la/ two 7 prep>$ f ! repurifi$ hydrobromic acid4 ,if *lor9e _h be5 remov$ dur+ ! second purification we %\ld expect a high] result b ! results are l[]4 ,!re seems to be h>dly any d\bt t ?is is due to analytical errors r ?an a *ange 9 ! composition ( ! bromide4 ,:e!r ?is be true or n1 ! five det]m9ations all fall )9 ! limits obta9$ by ! *loride me?od & confirms x z fully z c be expect$4 ,! errors ( ! me?od are ! same z ^? ( ! bromide me?od1 only !y are probably less 9 mo/ cases4 ,"o filtrate 0 exam9$ = bromium1 b none 0 f\nd %[+ ! me?od to be m p]fect 9 ?is respect4 ,syn!ses ( ,cadmium ,sulphate4 ,x 0 next ?\ght ( exam9+ ! me?od bas$ on ! conv]sion ( cadmium sulphate into cadmium sulphide1 :i* has be5 us$ by von ,hau] ^: result is #aaa4id = ! atomic weight ( cadmium1 & m rec5tly by ,p>tridge :o obta9$ a mu* l[] result1 namely #aaa4gc4 ,!y dri$ cadmium sulphate 9 porcela9 boats1 & !n r$uc$ x to sulphide by heat+ 9 a curr5t ( hydrog5 sulphide4 ,! r$uction beg9s 9 ! cold & is probably complete or at lea/ ne>ly complete be=e ! temp]ature is suffici5tly high = cadmium sulphate to decompose into cadmium oxide1 = ! sulphate is v /able ) respect to heat4 ,?is be+ ! case1 probably no error results f ! =mation ( a silicate ( cadmium 9 ?is me?od4 ,! ma9 difficulty 9 ?is me?od w\ld be to prove t ! cadmium sulphate us$ is free f wat]4 ,nei!r von ,hau] nor ,p>tridge has done ?is because dry+ a sub/ance to a con/ant weight is n suffici5t evid5ce ( its anhydr\s "*1 especially if ! dry+ is done at a con/ant temp]ature4 ,?is has be5 %[n v cle>ly 9 ! case ( copp] sulphate1 by ,ri*>ds 7,proc4 ,am]4 ,acad4 ,sci4 #bf4 #bfc47 ,x 0 !re=e decid$ to attempt ! syn!sis ( cadmium sulphate1 hop+ to be able to fix a m9imum value = ! atomic weight ( cadmium4 ,a piece ( h>d glass tube 0 clos$ at "o end by fusion & ! o!r end drawn out into a small tube :i* 0 !n b5t twice at "r angles4 ,! l>ge "p 0 cut (f ne> ! beg9n+ ( ! small] tube1 & ! edges r\nd$ by fusion4 ,x 0 fill$ ) dilute sulfuric acid & heat$ = "s "t to remove soluble matt] f ! glass4 ,aft] remov+ ?is acid1 a weigh$ piece ( cadmium 0 introduc$ & an excess ( dilute sulphuric acid 7#a3 #c7 add$4 ,! tube conta9$ a small piece ( plat9um to aid ! solution ( ! cadmium4 ,dur+ ! process ( solution1 ! two p>ts ( ! glass tube 7 held toge!r by a rubb] b&1 & ! outlet ( ! small] tube dipp$ "u pure wat] conta9$ 9 a small tube clos$ at "o end4 ,illu/ration3 ,fig4 #b4 ,a section ( ! arrangem5t is %[n 9 figure #b4 ,solution 0 aid$ by ! application ( heat4 ,^! precautions 9 dissolv+ ! metal 7 tak5 to prev5t loss by spray+4 ,aft] ! metal _h be5 dissolv$1 ! solution & ! wat] ?r\gh :i* ! hydrog5 _h escap$ 7 transf]r$ to a porcela9 crucible4 ,an equal am\nt ( sulphuric acid 0 !n add$ to ! t>e & bo? 7 heat$ until fumes ( sulphuric acid ceas$ to come (f4 ,! crucible conta9+ ! dry sulphate 0 next plac$ an a porcela9 plate 9 a nickel crucible set 9 a hole 9 an asbe/os bo>d4 ,?is 0 plac$ ov] ! flame ( a ,buns5 burn]1 s t ! bottom ( ! nickel crucible 0 b>ely at a r$ heat4 ,! temp]ature on ! inside ( ?is ba? 0 consid]ably l[]4 ,aft] ! weight _h become ne>ly con/ant1 ! sulphate 0 te/$ = sulphuric acid by means ( /&>d alkali us+ tropaeol9 z an indicator4 ,x 0 f\nd acid1 b s slightly t no attempt 0 made to e/imate x4 ,result #aab4ce is prelim9>y4 ,ano!r syn!sis 0 made z foll[s3 ,a plat9um crucible1 lid & p]=at$ cone 7 place 9 a l>ge weigh+-glass & t>$ ) a simil> weigh+-glass conta9+ a plat9um crucible1 plat9um foil be+ add$ until ! weights 7 equal4 ,aft] ^! _h be5 accurately weigh$1 a weigh$ piece ( cadmium 0 add$ to ! "o conta9+ ! cone4 ,! cone 0 inv]t$ ov] ! piece ( metal on ! bottom ( ! plat9um crucible4 ,a consid]able excess ( dilute 7#a3 #c7 sulphuric acid 0 !n add$1 ! lid ^: edge 0 b5t d[n plac$ on ! crucible1 & ! weigh+-glass /opp]$ loosely4 ,?is 0 plac$ 9 an air-ba?1 & g5tly w>m$ dur+ ! lat] "p ( ! process ( solution4 ,!re is no difficulty 9 gett+ complete solution if a suffici5t excess ( acid is us$4 ,a v]tical section ( ! crucible & weigh+-glass is %[n 9 figure #c4 ,illu/ration3 #c ,?is arrangem5t avoids loss f spray+1 & ! necessity ( transf]r+ ! solution f a tube to a crucible z 9 ! fir/ exp]im5t4 ,an equal quantity ( sulphuric acid 0 add$ to ! crucible us$ z a t>e & evaporat$4 ,aft] ! metal _h be5 dissolv$1 ! plat9um cone 0 lift$ to "o side & ! excess ( acid evaporat$ (f4 ,x 0 !n heat$ 9 a glass air-ba? = a long "t at a temp]ature :i* 0 probably ab\t #djj;,c4 ,aft] ! weight _h become con/ant1 ! am\nt ( free sulphuric acid 0 e/imat$ by titration ) a /&>d alkali us+ tropaeol9 z an indicator4 #a4be milligrammes 7 f\nd & ?is weight 0 subtract$ f t f\nd at ! balance4 ,weigh+ 7 r$uc$ to ! vacuum /&>d1 assum+ ! ,sp4 ,grs4 ( cadmium & anhydr\s cadmium sulphate#a to be #h4ed & #c4j respectively4 ,! results 7 z foll[s3 ,footnote #a3 ,c\ld n f9d any record ( its ,sp4 ,gr41 #c4j is assum$4 ,cd ,cd,s,o#d ,at4 ,wt4 ,i4 7#aab4ce c only be reg>d$ z a prelim9>y exp]im5t7 ,,ii4 #a4aegha #b4adggf #aab4ce ,discussion ( ! ,results4 ,^! results agree fairly well ) ^? obta9$ by ! *loride & bromide me?ods4 ,! second exp]im5t is m tru/wor?y ?an ! fir/4 ,9 x1 we />t$ ) pure metal & ! manipulations 7 s simple t no s]i\s error c\ld h be5 made 9 !m4 ,h5ce x w only be necess>y to consid] ! end-product1 i4e41 ! cadmium sulphate4 ,! titration %[$ t ! sulphate 0 n basic ow+ to loss ( sulphur trioxide1 & aft] d$uct+ ! weight ( ! excess ( sulphuric acid we mu/ h left a weight ( cadmium sulphate :i* is equival5t to ! metal employ$4 ,! "q n[ is1 did x conta9 any?+ else & :at w\ld be its effect8 ,cle>ly ! effect ( wat] or any o!r impurity w\ld be to l[] ! atomic weight f\nd1 h5ce ! atomic weight mu/ be at lea/ z high z ! exp]im5t indicates4 ,z ! cadmium sulphate is deposit$1 at lea/ ! lat] "p ( x is f a /rong sulphuric acid solution1 x probably does n conta9 any wat] & 9 ?is case w\ld fix a maximum value z well z ! m9imum value1 & ?us det]m9e ! atomic weight4 ,x might be object$ to ! second exp]im5t t ! sulphuric acid f\nd may h be5 pres5t z ,,s#c & n z ,h#b,,s#d z 0 assum$4 ,?is seems highly improbable1 & ev5 if x 7 s ! error introduc$ w\ld be only ab\t 4#jc ( a unit 9 ! atomic weight4 ,z ! fir/ det]m9ation 0 f\nd practically neutral1 x does n apply to x at all4 ,! mo/ probable conclusion f ^! exp]im5ts is t ! atomic weight ( cadmium is ab\t #aab4ce4 ,a m ?or\gh /udy ( ?is me?od w\ld h be5 made if "t _h p]mitt$ x4 ,! ,oxide ,me?od4 ,z ! *loride & bromide me?ods & ! syn!sis ( cadmium sulphate all lead to approximately ! same high result1 x seem$ probable t ! oxide me?od :i* _h giv5 a mu* l[] result 7,morse ,jones #aab4jg7 mu/ be affect$ by "s error4 ,accord+ly x 0 exam9$ 9 ! mann] ab\t to be describ$4 ,a set ( crucibles 0 prep>$ z describ$ by ,morse & ,jones 9 _! "w on ?is me?od1 & 9 ! pres5t pap] "u ! oxalate me?od4 ,aft] !y _h be5 heat$ 9 a nickel crucible ov] a bla/ lamp & weigh$1 a weigh$ piece ( cadmium 0 introduc$ into ! small] inside crucible1 & dissolv$ 9 nitric acid ) ! aid ( heat4 ,an equal quantity ( nitric acid 0 add$ to ! t>e4 ,! acid 0 !n evaporat$ (f1 & ! result+ nitrate conv]t$ into oxide exactly z has already be5 describ$ "u ! oxalate4 ,! fir/ exp]im5t 0 made 9 ?is way & ! second "o exactly l x1 only ! porcela9 crucible us$ 0 ! "o :i* _h be5 employ$ 9 ! fir/ det]m9ation4 ,! glaze _h be5 remov$ by ! cadmium oxide ( ! fir/ det]m9ation1 & be=e us+ = ! second "o ! crucible 0 boil$ out ) nitric acid1 & heat$ to con/ant weight ov] a bla/ lamp z be=e4 ,det]m9ations ,,iii1 ,,iv & ,v 7 made 9 ! same way except t ! small inn] crucible 0 plat9um in/ead ( porcela94 ,all weigh+s 7 r$uc$ to ! vacuum /&>d on ! basis ( #h4ed = ! ,sp4 ,gr4 ( cadmium & #h4ae = ! ,sp4 ,gr ( cadmium oxide & #h4d = ! brass & #ba = ! plat9um weights4 ,! results are z foll[s3 ,cd ,cd,o ,at4 ,wt4 ,cd4 ,i4 #a4bfadb #a4ddadd #aab4aa ,,ii4 4#iighe #a4adjce #aab4jd ------------ ,av]age #aab4jh ,,iii4 #a4aacba #a4bgbdg #aaa4hd ,,iv4 #a4jbdab #a4agjed #aaa4ia ,v4 #b4hjiff #c4baaeb #aaa4hg ------------ ,av]age #aaa4hg ,! oxides result+ f ^! det]m9ations 7 always te/$ = oxides ( nitrog51 sometimes by us+ meta ph5yl5e diam9e & at o!r times by sulphanilic acid & naph?ylam9e sulphate1 b no traces 7 ev] f\nd4 ,! av]age ( ! det]m9ations made 9 porcela9 crucibles is #aab4jh4 ,morse & ,jones obta9$ ! same figure or1 if _! results are r$uc$ to ! vacuum /&>d1 #aab4jf1 by ! same me?od "u ! same conditions4 ,! results ( ! det]m9ations made 9 plat9um crucibles are equally con/ant1 b _! av]age is #aaa4hh be+ 4#bj ( a unit l[]4 ,!re=e1 m oxide is obta9$ :5 plat9um crucibles are us$ in/ead ( porcela9 ones4 ,9 two cases ! plat9um crucibles 7 weigh$ at ! end ( ! det]m9ations aft] ! cadmium oxide _h be5 remov$4 ,_! weight rema9$ un*ang$4 ,! mo/ probable explanation ( ^! facts seems to be t some?+ is reta9$ 9 ! oxide 9 bo? cases1 b t ! am\nt is great] 9 ! det]m9ation made 9 plat9um crucibles ?an 9 ^? 9 :i* porcela9 ones 7 employ$4 ,we %\ld expect ?is1 because 9 porcela9 crucibles "s ( ! oxide is absorb$ =m+ a silicate1 & any volatile impurity mu/ be expell$ f ?is "p ( ! oxide4 ,n f9d+ oxides ( nitrog51 x 0 ?\ght t gases probably nitrog5 & oxyg5 might be occlud$ al?\gh ,ri*>ds & ,rog]s 7,am]4 ,*em4 ,j\r4 #ae1 #efg47 _h exam9$ cadmium oxide prep>$ f ! nitrate & f\nd only a trace ( gas4 ,accord+ly two specim5s ( cadmium oxide obta9$ 9 ! above det]m9ations 7 p[d]$ 9 an agate mort> & boil$ ) wat] = "s "t 9 ord] to remove any adh]+ air4 ,!y 7 !n dissolv$ 9 dilute hydro*loric acid f :i* ! air _h be5 remov$ by boil+4 ,a small am\nt ( gas 0 f\nd 9 ea* case b n ne>ly en\gh to acc\nt = ! diff]5ce ( 4#ca unit 9 ! atomic weight ( cadmium betwe5 #aab4ch & ! oxide me?od4 ,9 fact n m ?an ab\t "o six? ( ! am\nt requir$ 0 f\nd4 ,x may be t ! p[d]+ ( ! oxide & !n boil+ up 9 wat] may h be5 to sev]e a treatm5t1 & t ! great] "p ( ! occlud$ gas escap$ dur+ ^! processes4 ,x seems t !re is at lea/ "s error due to occlud$ gases 9 me?ods involv+ ! decomposition ( cadmium nitrate to oxide1 b no satisfactory idea ( its magnitude c\ld be obta9$ f ^! two exp]im5ts z c>ri$ out4 ,! foll[+ exp]im5ts 7 !n made & !y seem to give def9ite evid5ce n only ( ! exi/5ce ( an error b also ( its magnitude4 ,c>bonate ( cadmium 0 made by dissolv+ pure cadmium 9 nitric acid1 add+ an excess ( ammonia & a small quantity ( ammonium c>bonate4 ,aft] /&+ = "s "t ! cadmium c>bonate 0 filt]$ (f & reject$4 ,! filtrate 0 treat$ ) an excess ( ammonium c>bonate & ! precipitat$ cadmium c>bonate all[$ to dige/ 9 x = "s "t4 ,aft] wa%+ by decantation sev]al times ! c>bonate 0 transf]r$ to a funnel conta9+ a porcela9 filt]-plate1 cov]$ ) a piece ( a%less filt] pap] ( slightly l>g] diamet]1 & wa%$ ?or\ghly4 ) wat]4 ,x 0 !n transf]r$ to a plat9um di%1 c>e be+ tak5 to avoid contam9ation ) filt] pap] & heat$ g5tly to conv]t x into oxide4 ,! result+ oxide 0 p[d]$ 9 an agate mort>1 return$ to ! plat9um di% & heat$ to incipi5t :it5ess = sev5 h\rs 9 a muffle furnace4 ,! temp]ature mu/ n be too high1 o!rwise ! oxide w di/ill readily leav+ no residue4 ,! oxide is slightly volatile at good r$ heat z 0 obs]v$ 9 try+ to make a det]m9ant at ?is temp]ature by ! oxide me?od4 ,a weigh$ portion ( ! oxide :i* _h be5 prep>$ f ! c>bonate 9 ! mann] describ$ 0 dissolv$ 9 a weigh$ porcela9 crucible & ! result+ nitrate conv]t$ into ! oxide aga9 by heat j z 9 ! oxide me?od4 ,?is con/itutes exp]im5t ,i4 ,exp]im5ts two & ?ree 7 made 9 exactly ! same way except t a plat9um crucible 0 us$ in/ead ( a porcela9 "o4 ,! results are3 ,initial ,wt4 ,f9al ,wt4 ,ga9 ,correspond+ ,error 9 ,at4 ,wt4 ,i4 #b4iedfi #b4iefej 4#jjjha 4#bd ,,ii4 #b4fggag #b4fghce 4#jjaag 4#ci ,,iii4 #c4jjbie #c4jjdbb 4#jjabg 4#ch ,z we />t$ ) cadmium oxide1 &1 aft] pass+ to ! nitrate1 conv]t$ x back into ! oxide1 ! weight %\ld rema9 un*ang$ if ! me?od is correct4 ,h[ev]1 ?is is n ! case1 b a l>ge increase 9 weight takes place4 ,! increase is l>g] 9 a plat9um crucible ?an 9 a porcela9 "o1 :i* acc\nts = ! fact t a l[] value = ! atomic weight is f\nd by ! oxide me?od :5 !y are us$4 ,! use ( a porcela9 crucible !re=e dim9i%es ! error1 b does n elim9ate x4 ,! explanation ( ?is has already be5 giv54 ,! oxides obta9$ 9 ^! ?ree exp]im5ts 7 te/$ = occlud$ gases 9 ! mann] already describ$1 b only small am\nts 7 f\nd4 ,bo? ( ^? made 9 plat9um crucibles 7 te/$ = nitrate ( cadmium ) bruc9e & sulphuric acid ) negative results4 ,to %[ t ! impurity 0 n conv]t$ into an ammonium salt :5 ! oxide 0 dissolv$ 9 hydro*loric acid1 a slight excess ( cau/ic pota% 0 add$ to ! solution1 ! precipitate all[$ to subside & ! clean1 sup]natant liquid te/$ = ammonia ) ,nessl]'s reag5t4 ,no ammonia 0 f\nd4 ,9 ord] to make ^! exp]im5ts z sev]e a te/ z possible1 a some:at high] temp]ature 0 employ$ ?an _h 9 ! five exp]im5ts describ$ "u ! oxide me?od4 ,?is 0 accompli%$ by bor+ out ! /opcocks ( ! bla/ lamp s t a l>g] supply ( gas 0 furni%$4 ,! two oxides 9 ! plat9um crucibles seem$ to be con/ant 9 weight1 b t 9 ! porcela9 crucible seem$ to lose 9 weight sl[ly4 ,! weight giv5 0 tak5 aft] f\r h\rs bla/+1 :i* is long] & at a high] temp]ature ?an 0 us$ 9 any ( ! five det]m9ations made by ! oxide me?od4 ,if ! cadmium oxide prep>$ f ! c>bonate reta9$ any c>bon dioxide1 x w\ld lose weight 9 be+ dissolv$ & reconv]t$ into oxide4 ,! above exp]im5ts !re=e seem to furni% v /rong evid5ce t !re is an error ( at lea/ 4#bd unit 9 ! oxide me?od :5 porcela9 crucibles are us$ & 4#ci ( a unit :5 plat9um ones are employ$4 if 4#bd ( a unit is add$ to #aab4jg ! result obta9$ :5 porcela9 crucibles are us$ we get #aab4ca & add+ 4#ci to #aaa4hg gives #aab4bf4 ,consid]+ ! small numb] ( exp]im5ts made1 ! fact t !y 7 made 9 su* a way z to give a l[ value 7num]ically7 = ! error r ?an a high "o1 & also t ! error is probably v>iable to "s ext5t1 especially :5 porcela9 crucibles are us$1 ! correct$ results agree z closely ) #aab4ch1 ! av]age ( ! *loride1 bromide & sulphate 7syn!tical7 me?ods z c\ld be expect$4 ,x mu/ also be borne 9 m9d t #aab4ch is only to be reg>d$ z an approximation to ! atomic weight ( cadmium4 ,! increase 9 weight obs]v$ 9 conv]t+ ! nitrate back into oxide might also be expla9$ by assum+ t ! cadmium oxide us$ 9 ! beg9n+ ( ! exp]im5ts 0 ri*] 9 metal ?an ! =mula ,cd,o indicat$ & t ! increase 9 weight is due to ?is excess ( metal be+ *ang$ to oxide4 ,! me?od ( prep>ation ( ! oxide f ! c>bonate & ! kn[n prop]ties ( cadmium oxide r5d] ?is view highly improbable1 & ! foll[+ two obs]vations r5d] x unt5able3 #a/4 ,if ?is 7 ! cause ( ! increase1 ! am\nt ( increase w\ld necess>ily be ! same 9 bo? plat9um & porcela9 crucibles1 :i* is n ! case4 ,illu/ration #bnd4 ,?ree grammes ( cadmium oxide made f ! c>bonate 7 dissolv$ 9 dilute hydro*loric acid f :i* ! air _h be5 expell$ by boil+4 ,! oxide1 :i* is v compact1 0 plac$ 9 a glass bulb :i* _h be5 bl[n at ! end ( a tube4 ,aft] displac+ ! air by fill+ ! entire app>atus ) rec5tly boil$ wat]1 ! exit ( ! tube 0 plac$ "u boil+ dilute hydro*loric acid1 & ! bulb heat$ until ! wat] boil$4 ,x 0 !n turn$ ov] s t ! /eam displac$ ne>ly all ! wat]4 ,on remov+ ! flame ! dilute hydro*loric acid at once fill$ ! bulb4 ,! exit tube 0 !n quickly plac$ "u a n>r[ tube fill$ ) m]cury & inv]t$ ov] m]cury 9 a di%4 ,! bulb 0 !n heat$ until ! oxide _h dissolv$4 ,by ?is me?od ! gas w\ld be boil$ out ( ! solution & collect$ 9 ! top ( ! n>r[ tube4 ,z only a v small am\nt ( /eam & dilute hydro*loric acid g ov] at ! same "t1 !re is no dang] ( ! gas =m$ be+ absorb$ to any consid]able ext5t4 ,x is well to put ! oxide into ! bulb be=e ! tube is b5d4 ,if ! hydro*loric acid is too /rong1 x mu/ be cool$ be=e ent]+ ! bulb z o!rwise ! reaction is too viol5t1 & ! exp]im5t may be lo/4 ,?is exp]im5t %[s t !re is no excess ( cadmium pres5t 9 ! oxide employ$ = no gas 0 f\nd4 ,if ?ree grammes ( ! oxide conta9$ en\gh metal to take up 4#jjabf grms4 ( oxyg51 4#jjjaf grms ( hydrog5 %\ld h be5 set free1 & its volume "u ord9>y conditions ( temp]ature & pressure w\ld h be5 ab\t #a4i cubic c5timetres4 ,?is exp]im5t w\ld also h %[n ! pres5ce ( c>bon dioxide if any _h be5 pres5t4 ,discussion ( ! ,oxalate ,me?od4 ,aft] hav+ done ! "w :i* has j be5 describ$1 we are 9 a position to turn to ! oxalate me?od1 :i* is ! fir/ me?od describ$ 9 ?is pap]4 ,x involves ! decomposition ( cadmium nitrate1 & is !re=e affect$ by an error f ?is s\rce1 only x is n z l>ge z 9 case ( ! oxide me?od4 ,if #b4iefej grammes ( cadmium oxide prep>$ 9 a porcela9 crucible conta9 4#jjjha grammes ( impurity1 an error ( 4#bd ( a unit w\ld be introduc$ 9 ! atomic weight z det]m9$ by ! oxide me?od or 4#aj 9 case ! oxalate me?od 7 employ$4 ,t is ! oxalate %\ld give ab\t #aab4dh = ! atomic weight ( cadmium1 b x really gives a v mu* l[] result4 ,morse & ,jones obta9$ #aab4jd 4#jce by x1 :ile ,p>tridge obta9$ #aaa4ha 4#jce by x4 ,if we take #aab4ch = ! atomic weight ( cadmium1 !re appe>s to be a second error ( 4#dd ( a unit 9 ! me?od z us$ by ,morse & ,jones1 :ile ,p>tridge's result indicates an error ( 4#eg ( a unit4 ,p>tridge only moi/5$ ! oxide obta9$ f ! oxalate ) a few drops ( nitric acid be=e mak+ ! f9al heat+1 & x seems probable !re=e t he made no appreciable error on acc\nt ( ! f9al oxide reta9+ products ( decomposition f cadmium nitrate4 ,! mo/ probable cause ( ?is l>ge error seems probably to be incomplete dehydration ( ! oxalate1 or r$uction to metal dur+ ! decomposition ( ! oxalate1 & subsequ5t volatilization ( "s ( x1 or a comb9ation ( bo? ( ^!4 ,! n9e det]m9ations giv5 9 ! e>li] "p ( ?is pap] ( c\rse v>y s mu* t !y are ( no value :atev] 9 det]m9+ ! atomic weight4 ,! reason t ! fir/ f\r are l[ is probably due 9 "p to sublimation ( cadmium1 = on dissolv+ ! result+ oxide 9 nitric acid a consid]able quantity ( metal 0 notic$ 9 ea* case4 ,9 ! o!rs1 ! temp]ature 0 kept l[]1 & ! decomposition took a long] "t4 ,no metal 0 obs]v$ on tak+ up 9 nitric acid4 ,to be c]ta9 ( :at ! cause ( error is w\ld require "s v c>efully conduct$ exp]im5ts1 b z !re are a numb] ( mu* m reliable me?ods = det]m9+ ! atomic weight ( cadmium1 x does n seem desirable to sp5d ! "t requir$ 9 mak+ !m4 ,x %\ld be m5tion$ t ,l5ss51 9 #ahfj1 fir/ employ$ ?is me?od4 ,he made ?ree det]m9ations4 #a4efig grms ( cadmium oxalate giv+ #a4jjdg grammes ( oxide1 :i* gives a value ( #aab4jdc = ! atomic weight ( cadmium 4 ,! diff]5ce betwe5 ! highe/ & l[e/ det]m9ation 0 4#cia ( a unit4 ,o!r ,me?ods ,a great deal ( "t 0 sp5t 9 try+ to effect a p>tial syn!sis ( cadmium bromide 9 exactly ! same mann] z _h be5 us$ 9 case ( cadmium sulphate4 ,no results 7 obta9$ because cadmium bromide is sl[ly volatile at #aej;,c1 ! temp]ature us$1 & reta9$ "s hydrobromic acid ev] aft] m ?an #ajj h\rs ( dry+4 ,"s "w 0 done 9 try+ to e/abli% ! ratio betwe5 silv] & ,cadmium by dropp+ a weigh$ piece ( cadmium into a solution ( silv] sulphate1 ! reaction be+3 ,cd ,ag#b,,s#d ,cd,s,o#d #b;,ag ,silv] nitrate _c be us$ because x becomes r$uc$ to nitrate ev5 at a temp]ature ( #j;,c41 z 0 %[n by its r$uc+ action on potassium p]manganate1 & by ! reaction ) meta-diamido b5z5e aft] ! reaction _h be5 complet$4 ,! ma9 difficulty ) ! me?od is t air mu/ be exclud$ 9 ord] to prev5t oxidation & solution ( "s ( ! precipitat$ silv]4 ,! silv] is p]fectly free f cadmium if an excess ( silv] sulphate is us$ & ! precipitat$ metal dige/$ ) x = "s "t4 ,s9ce ?is "p ( ! "w 0 done1 a pap] by ,mylius & ,fromm 7,b]4 #ahid1 #fcj7 appe>$ 9 :i* "o ( ! reactions /udi$ 0 t ( cadmium on silv] sulphate4 ,!y also f\nd ! result+ silv] free f cadmium4 ,! me?od seems v promis+1 b ! "w _h to be discont9u$ = lack ( "t4 ,conclusion4 ,i4 ,! "w on ! oxalate & sulphide me?ods describ$ 9 ?is pap] is ( no value = det]m9+ ! atomic weight ( cadmium4 ,x does n ev5 enable u to fix an approximate value4 ,,ii4 ,!re are a numb] ( errors 9 ! *loride & bromide me?ods z !y 7 us$ 9 ?is "w1 b !y are n v l>ge & p>tially comp5sate ea* o!r4 ,_! results1 #aab4chc & #aab4cif respectively1 may be reg>d$ z approximations to ! true value4 ,,iii4 ,! syn!sis ( cadmium sulphate z c>ri$ out is ( especial value 9 fix+ a m9imum value = ! atomic weight ( cadmium4 ,! result is #aab4ce1 agree+ closely ) t obta9$ by ! bromide & *loride me?ods4 ,,iv4 ,!re is an error 9 ! oxide me?od due to products ( decomposition ( ! nitrate be+ reta9$4 ,direct exp]im5ts gave 4#ci ( a unit = ?is :5 plat9um crucibles 7 us$ & 4#bd ( a unit :5 porcela9 ones 7 us$4 ,! calculat$ errors = porcela9 & plat9um crucibles are 4#cj & 4#ea ( a unit respectively1 if #aab4ch is assum$ z ! atomic weight ( ,cadmium4 ,v4 ,! av]age ( ! *loride1 bromide1 & sulphate me?ods is #aab4ch4 ,?is result is to be reg>d$ z t5tative & n z f9al s9ce ! ma9 object ( ?is "w has be5 to f9d ! cause ( ! discrepancy 9 "s me?ods employ$ 9 det]m9+ ?is con/ant1 r ?an to make an atomic weight det]m9ation4 ,biographical ,sket*4 ,john ,em]y ,bu*] 0 born ne> ,hanov]1 ,pa41 ,augu/ #ag1 #ahgb4 ,he ent]$ ,lehigh ,univ]sity 9 #ahhh & graduat$ 9 #ahia4 ,dur+ ! pa/ ?ree ye>s he has be5 a graduate /ud5t 9 ! ,johns ,hopk9s ,univ]sity4 ,subjects3 ,*emi/ry1 ,m9]alogy & ,ma!matics4 ---------------------------------------- -------------------------------- ,,transcrib]',s ,,notes #a4 ,sil5tly correct$ obvi\s typographical errors & v>iations 9 spell+4 #b4 ,reta9$ ar*aic1 non-/&>d1 & unc]ta9 spell+s z pr9t$4 #c4 ,enclos$ und]l9$ font 9 und]scores4 #d4 ,d5ot$ subscripts by an und]score be=e a s]ies ( subscript$ *>act]s enclos$ 9 curly braces1 e4g4 ,h#b,o4