( 58.^ ) 



\ . A sliulil ('orroclioii iiiiist of (•oiii'sc Ito applied In llio calciila- 

 lioiis ot' § .') in ('(»iis(Mpioii('c of tlic \ ariahilil v of /),, A„ w illi llic tciii- 

 |K'i-atiir('. Vov llic assiiinptioii llial A,, rcMiiaiiis coiislaiil pleads also 

 llie ('ii'ctiiiislaiice. tlial accoi-diiiü- lo aii observation of D. IJkktiiki.ot 

 the e.\|)crinienl vic^lds the wilne '2,93 a 2,9(S lor tlie ratio hetweeii 

 tlie teniporatnre at whicli a uas in exti-eme rai'elaclion follows the 

 law of l)()Vi,F,, and the critical tein|(eratnre; lor which i-atio the sn|>- 

 posilion that />,, is constant o\'cr this large teinperalnre inléi-\al ') leads 

 to tlu^ valnc 2,9. If wo assume this same sn|)position, wo shall 

 liiid A,/ to bo ocpial to. circa 920 also h)r the ci'itical isothermal. 

 Ihit />„ will be fonnd to be coiisiderabl v higher than at 0°. W(? saw- 

 above that the diiroroJico amounts to 77 nnits for 99' dillbi-ence in 

 teni[)eratniv. We shall therefore lind />„ at — 242° C^ from the eipiation : 



9 J. 9 



h = 4G3 -f ^^- X 77 = 408 + 188 r= 051. 

 99 



If thoi-ofore wo pnt A^ = 920 and />„ = ()50, then in the first place 



h,j is no lonuor ocpial lo 2 />„, bnt to: 



h,,z= 1,415 A„. 



The variabilitv of A is therefore mnch smaller than at O"", and in 

 conso(pionce of this tlu^ cpiaiititios j-?^ and ^3., will also bo fonnd to be 

 mnch smaller, and the ci-itical (piaidities .will approach still more 

 closolv to the normal \alnos. 



The (niantit\ /< =r — - is hei-o =2,41 , and the \alno of 



• A,/— />„ 0.415 



./; = — ot (Mpiat ion A ceases accordinuh to be 0,709, bnt becomes 



V'n — ^'J 

 0,8.52. Iji conso(pienco of this wo lind : 



f>:-K 



= 1/ 0,852 =z 0,923, 



Irom w liicli tollows: 



/>/, =z 0,977 h„ = 899. 



For /•/,. and for /:?! -[- i^.^ nvo lind (comp. § 3): 



rt = 2,87 /./.. ; ,A + i^. = <>'<>--^2«- 

 So we find : 



/y, =r 2.87 A/, {= 2.80 h„ -= 3.97 A„) =: 2579. 



a N'olnmo w liich is reached at 0^ ('. at a prossnre of ± .5.50 atm. 



The valnes of ji, and /:?.j taken separately are: 



[l—.vy 

 /I = — = 0.0117 ; /?, = 0.01 11. 



') Zio VAN niiii \Va.\ls, I.e. ill, p. ii'i-7. 



