mixture) the pressure of the bromine gas in the mixture would be only
7/100ths of the normal pressure, or 53·2 millimetres. At this pressure
the boiling-point of bromine is about -5°, so that, on cooling to that
temperature, bromine would begin to show signs of liquefaction. This
is, however, still nearly 100° above the boiling-point of chlorine;
and there would therefore be no difficulty whatever in detecting such
a percentage of bromine in a mixture of chlorine and bromine gases on
cooling the mixture to a moderately low temperature.[30]

Argon has been liquefied. A sample of pure argon was sent by Professor
Ramsay to Professor Olszewski of Cracow, well known for his accurate
researches at low temperatures; and he found the boiling-point of argon
at atmospheric pressure to be -186·9°, and its melting-point to be
-189·6°. There was no appearance of liquid before the boiling-point
was reached, nor was there any alteration of temperature as the argon
boiled away, and these are signs of a single substance, not of a
mixture; moreover, the melting-point was a definite one; and here
again, mixtures never melt suddenly, but always show signs of softening
before melting. So far as this evidence goes, therefore, it points to
the conclusion that argon is not a mixture of two elements.

Other evidence may be sought for in the spectrum of argon, which was
carefully examined by Mr. Crookes. It consists of a great number of
lines, extending all through the spectrum, from far down in the red to
far beyond the visible violet; the invisible lines were examined by
the aid of photography, for ultraviolet light, although invisible to
the eye, impresses a photographic plate. The most striking feature of
this spectrum is the change which can be produced in it by altering the
intensity of the electric discharge which is passed through the tube
containing argon at a low pressure. By interposing a Leyden jar between
the secondary terminals of the induction-coil from which sparks are
taken through the gas, the colour of the light in the tube changes from
a brilliant red to an equally brilliant blue. A large number of lines
in the red spectrum disappear, on interposing
mixture) the pressure of the bromine gas in the mixture would be merely 
 7/100ths of the normal atmospheric pressure, or 53·2 millimetres. At this pressure 
 the boiling - point of bromine is approximately -5 °, so that, on cooling to that 
 temperature, bromine would begin to show sign of the zodiac of liquefaction. This 
 is, however, still nearly 100 ° above the boiling - detail of chlorine; 
 and there would therefore be no difficulty whatever in detect such 
 a percentage of bromine in a mixture of chlorine and bromine gases on 
 cooling the mix to a moderately low temperature.[30 ] 

 Argon has been liquefied. A sample of pure argon was send by Professor 
 Ramsay to Professor Olszewski of Cracow, well known for his accurate 
 researches at low temperature; and he found the boiling - point of argon 
 at atmospheric pressure to be -186·9 °, and its melting - detail to be 
 -189·6 °. There was no appearance of liquid before the boiling - point 
 was reached, nor was there any alteration of temperature as the argon 
 boiled aside, and these are signs of a single substance, not of a 
 mixture; moreover, the melting - point was a definite one; and here 
 again, mixtures never melt suddenly, but always show signs of softening 
 before melting. So far as this evidence goes, consequently, it point to 
 the conclusion that argon is not a mix of two chemical element. 

 Other evidence may be sought for in the spectrum of argon, which was 
 carefully examine by Mr. Crookes. It consist of a great number of 
 line, extending all through the spectrum, from far down in the red to 
 far beyond the visible violet; the invisible lines were examined by 
 the care of photography, for ultraviolet light, although invisible to 
 the eye, impresses a photographic plate. The most striking feature of speech of 
 this spectrum is the variety which can be grow in it by altering the 
 intensity of the electric discharge which is pass through the tube 
 containing argon at a low atmospheric pressure. By interposing a Leyden jar between 
 the secondary terminals of the trigger - coil from which sparks are 
 carry through the gas, the colour of the luminosity in the tube change from 
 a brilliant bolshevik to an equally bright blue. A large issue of lines 
 in the red spectrum disappear, on intervene
mixhure) the pressure of the bromine gas in the mieture wkuld be unly
7/100ths of the normal pressuce, oe 53·2 miolimetres. At this presrure
the bliling-pount id bromine ma about -5°, so tgwt, ou rooling to that
jemperature, tromine would teeiu to show signs of liquefaction. This
ys, howefeg, still nearly 100° abpde tgv noiling-point of chlorine;
and thers would therefore be no difficulty whatever in detfcting such
a percejtage of briminq in a mixturd of chlorpue and bromjne gases on
cooling the mixture to a moderateli moa temperaturx.[30]

Argon has been liquefied. D samplr of pure argok was sebt by Professor
Ramsay to Professor Olszgwski of Csaeow, well known for hiw qccurdte
raseafxher au lpw tempegatnres; and he found the voiling-point of argpn
wn atmospheric presstrq to be -186·9°, and its melting-point to be
-189·6°. Thege wzs no appearance of liqyid before the boilinh-point
was reached, nor was there any alteration of temperatgre aa tht qrgon
ciiped away, and these are signs of a single subseznve, not of a
mixtuve; moreover, the mektlnb-koint was a dewinite ons; and here
again, midtures gever melt sudqenlu, but always show signs of woftening
befjee melting. So far cs this evidznce gpes, tnerefore, it points to
thz concmusion that argon is vot a mixture of twp alements.

Other evidence may be soughv for in the spevtrum jf argon, wjich was
carefully examinfd by Ms. Crookes. Lt consists of a great number oh
kines, extendonc anl throuyh the spectrum, froi far down in jhe red tj
far ceyond the visiblx violet; the invisible litgs were examiied by
the aid of photogrxohy, for ultravoolet ligku, although invisible to
the ene, imkrssses a photogrckhix plate. The mosy sgrihijg fqdture of
this speztrjk is ghe change chkch van be produced in id by altering the
intenxiby of the electris discharge wnich is passed thrlugh vhe tuue
contsinyng argon at a low pressure. By interposlng a Leyden jaw bebweeg
the seconbary terminals of the induction-coil from which sparks are
jaken through the gas, uhe colour of the jight in dhe tube changes fron
a brilliant red uo an equally brilliant blue. D larhe number of lines
in the red spectrum disappear, on interposing
mixture) the pressure of the bromine gas mixture be only of the normal this the boiling-point of is about -5°, that, on cooling to that temperature, would begin to show signs of liquefaction. This is, however, still nearly 100° the boiling-point of chlorine; and there would therefore be no difficulty whatever in such percentage bromine a mixture of chlorine and bromine gases on cooling the mixture to a moderately low temperature.[30] has been liquefied. A sample of pure argon sent by Professor Ramsay Professor Olszewski of Cracow, well for accurate researches low and found the boiling-point argon at atmospheric pressure to be -186·9°, and its melting-point to be -189·6°. There was no appearance liquid before was reached, was any of temperature as boiled away, and these are signs substance, not of a mixture; moreover, the melting-point a definite and here again, mixtures never melt but always show signs of softening before melting. far as this evidence goes, therefore, it points to the conclusion that argon is not of two elements. Other may be sought in spectrum argon, was carefully by Mr. Crookes. It consists of a great number of lines, all through the spectrum, from far down in the red beyond visible violet; the lines were examined by aid photography, for ultraviolet light, to eye, plate. most feature of this spectrum the change which can be in it by altering discharge which is passed through the tube containing at a low pressure. By interposing a jar between the secondary terminals of the induction-coil from which sparks are through the colour of the light in the tube changes a brilliant red to equally brilliant blue. A large number of lines in red disappear, on
mixture) the pressure of the brOmine gas in The miXtuRe wOuLd be Only
7/100Ths of the normal PRessUre, or 53·2 millimetres. At this PressUrE
The bOIlIng-poInt of brOMiNE Is aBoUt -5°, So tHaT, On CooliNg tO that
teMperature, bRomInE would begin tO ShOw signs of lIquEfaction. This
Is, hOwever, StIll NEarly 100° AboVe the BoilinG-Point oF chlorine;
AnD There wOUld therEFOrE be nO difficulty whatevER iN Detecting such
a PercenTaGE oF BRomIne In a mixture Of ChlorINe and brOMiNE GAseS On
cooling the mIxture to a moDEraTely loW tEmpERature.[30]

argon HaS BeeN liquefied. A SampLe of pure aRgon waS Sent by PROfessor
ramsay To PRofEssoR olSzEwsKi OF CrACoW, weLL knOwn for hiS aCcUrate
ReseARCHEs at Low TempEratuRes; and he found The BoilINg-pOint oF argoN
at aTmOspheRic preSsure To Be -186·9°, and its melting-PoinT to be
-189·6°. TherE waS nO apPeArancE Of liquId bEfoRe the boIling-poINt
wAs REAChEd, nor was there any alTeRATiOn of tempEraturE As ThE Argon
boiLeD awAy, anD THese aRe siGNs Of a singlE substANcE, nOt of a
miXtUre; morEoVer, The MeltiNG-poiNt was a Definite One; anD Here
again, mixtuREs never melt suDDeNLY, bUT alwAys Show signs of SoftENing
BefoRE mEltINg. So fAr as tHiS EvIDence goes, therefore, iT pOints tO
the cOnclusion that Argon is not A MIXture of tWo elEMeNTs.

Other evidencE may bE sought for IN the specTrum oF argon, whIch was
carEFUlly examIneD by mr. CRooKES. IT consists of a gREAt nuMbEr of
linEs, eXtendinG alL thRouGh tHe Spectrum, fRom far doWn In ThE rEd tO
far bEYond the vIsIblE vIolEt; the INvisibLe linEs weRe ExAMinEd by
the AId OF PhotOgRaPhy, fOr uLtRavioLet lIGht, AlthougH invisiblE to
THe eyE, iMpResses a Photographic pLaTe. The most sTrIkiNg featURE of
this sPectrum is the change which CAn be proDucEd in iT by aLtering thE
inTensitY of THe elecTric diScharGe WhiCH Is pasSED tHroUgH the tube
coNTAinIng arGoN at a Low presSure. By interposing a lEydEn jar between
tHe sEconDARy TerMInALs oF tHE inDUCtion-coil from whIch sparks aRe
TAkEn through tHE gaS, tHe colouR of the lIght iN The tube Changes frOm
a brilliAnT red TO An eQually brilLiant bluE. A large nuMBer of LInEs
in tHe rEd specTrUm dIsappEar, on iNTerPosinG
mixture) the pressure of t he bromine  gasinthe  m ixtu re w ould be only
7 / 100t hs of the normal press ure,or 53·2 mi llime tres. A t  t h i s p re ss ure 
t h eboili ng- point o f bromineisab out -5°, sot ha t, on cool ing  to that
tem per ature,  b rom i ne wo uld  begi n to s h ow sig ns of liq ue f action .  This
i s ,  h owev er, still nearly1 00 °  above the boi ling-p oi n to f  ch lor ine;
and t he re wo u ld ther e fo r e ben o difficultywhatever in det ecting  s uch a perc entag eo f b romine in a  mix ture of c hlorin e  and br o mine ga ses on 
co oli ng t h emi xtu re toa  m ode r ate ly low t em pe ratur e.[3 0 ] Argo n h as b een l iquefied. A s amp le o f  pu re ar gon w as s en t byProfes sor
R am say to Professo r Ol szewski o f C ra cow ,wellk nown f orhis  accura te
rese a rch es a t  l ow temperatures; a nd h efound th e boil i ng -p o int of a rg onat a t m osphe ricp re ssure to  be -1 8 6· 9° , and i ts  melti ng -po int  to b e 
-18 9·6°.There wa s noa ppearance of l i quid before t h eb o il i ng-p oin t
was reach ed,n or w as t h er e a n y alt erati on of temperature as thear gon
bo iledaway, and the se are sig n s of a sin gles ub s tance, not ofa
mix ture; more o ver, the  melt ing-poin t was a d e f inite on e;and  he rea g ai n, mixtures n e v er m el t sudde nly , but a lwa yssho w s ig ns of sof tening
b ef or eme lti ng. S o  far asth isev ide nce g o es, th erefo re,it  p o int s to
th e  c o n clus io nthat  ar go n isnota  mi xture o f two ele men t s.
Ot he r evide nce may be so ug ht for inth e s pectru m of argon , which was
carefully e x aminedbyMr. C rook es. It co nsi sts of  ag reat n umberof
li ne s,e x tendi n g  a llth rough thes p ect rum,fr om f ar down  in the red to
far bey ond the visib leviol e t ;the in v isi bl e  li n e s were examined  by
the ai do fphotograph y , f or  ultrav iolet l ight, althoug h invisib le to
the  e ye,i m pre sses a pho tographi c plate.T he mo s tstrik ing  featu re  of 
this  spect r umis th e chan ge  which  canbe  produce d in it by altering the 
inten sityofthe elect ric dis charge wh ichis passedthr oug h the  tu b e
con tain i ng  ar g on at  a l o w pressur e .Byi n te rposing a L e y d enjar b etw e en
the  sec ondary terminalso f the inductio n-co i l  fr omw hich  s parks are
take n t hr o u gh the g as , the colou r of the  l i ght i n thetube c hangesf r om a bril lian t r ed to anequ al l y brill ia nt blue.A la rg e numb er ofl ines i n the red spectr um di s a ppear ,  on  inte rp osing
mixture) the_pressure of_the bromine gas in_the mixture_would_be only
7/100ths_of_the normal pressure,_or 53·2 millimetres._At this pressure
the boiling-point_of bromine is_about_-5°, so that, on cooling to that
temperature, bromine would begin to show signs of_liquefaction._This
is, however,_still_nearly_100° above the boiling-point of_chlorine;
and there would therefore be_no difficulty_whatever in detecting such
a percentage of bromine in_a_mixture of chlorine_and bromine gases on
cooling the mixture to a moderately_low temperature.[30]

Argon has been liquefied. A_sample of pure_argon_was_sent by Professor
Ramsay to_Professor Olszewski of Cracow, well known_for his accurate
researches at low temperatures;_and he found the boiling-point of argon
at_atmospheric pressure to be -186·9°, and_its melting-point to be
-189·6°. There_was no_appearance of liquid before the_boiling-point
was reached, nor_was there_any alteration of_temperature as the argon
boiled away, and_these are signs_of a single substance, not of_a
mixture;_moreover, the melting-point_was_a_definite one;_and here
again, mixtures_never_melt suddenly,_but_always show signs of softening
before melting._So_far as this evidence goes, therefore, it_points to
the conclusion that_argon_is not a mixture_of two elements.

Other evidence may_be sought for in the spectrum_of argon,_which was
carefully_examined by Mr. Crookes. It consists of a great number of
lines,_extending all through the spectrum, from_far down in the_red to
far_beyond_the visible violet;_the_invisible lines_were examined by
the aid of photography, for_ultraviolet light,_although invisible to
the eye, impresses a_photographic plate. The most_striking_feature of
this spectrum is the change_which can be produced in it_by altering the
intensity of the_electric_discharge_which is passed through the_tube
containing argon at a low pressure._By interposing a_Leyden jar between
the secondary terminals of the_induction-coil_from which sparks are
taken through the_gas,_the colour of the light in_the_tube_changes from
a brilliant red to_an equally brilliant blue. A large_number of lines
in the red spectrum disappear, on interposing