( 450 ) 



TABLE II. He. Individual virial coefficients. 

 Deviations of the pv^ from the calculated ones. 



1 0^ B 



l(.''C 



105 (0—C) 



+ 100° 35 ' L.^nCOT -)-0.C,7:{ +'i.i(', -^10 _t>i _-io I 4-t>2 



+ 2(1°. 00 •! .07^27;-! 40.a;{4 -f-O.-i;; , — 3 j +31 -36 i + s 



! 



0° . Ü.9!)970 +0. -)!':> +0.1 '2 --3) +sn 



— 103°. 57 ' C.^io:'!; +0 M37 +0 07 +11 — 7 



— 182^75 I o,;'.;w(;(i +o 17(; +0.01. 1 



-'216'. 56 i 0.206Ü3 +0.096 +0 02 



1 



+ 1 



— /.-) 



— 32 



— 8 



— 3 



(I 



+27 



§ 5. l)('t('ini)'initfi()ii, of the cr/'f/ca/ ft/npfratuir of hcliviti. 



From llie dala of lahle II we niav iirrive at a lir.st estitiialioii 

 concerning' llie ciilical lcni|)era(iire of lielinni, wIucIj will he fouji<l 

 from <leterniinati(>n,s of isoilierms wilhin the now accessiltle re.üion 

 of teni[)eratnrey. 



Kxtrapoiation pi-oves tiiat (he HovLÊ-poinl will lie in the nei,ii:h- 

 bonrhood of — 25()MJ. For hydrogen — 16(5° was fonnd for this. fcf. 

 Comm. K". 100"). If we assume 'Mf K. for the critical temperature 

 of liydroji;en, then follows from this for helium 



:/•/,.//, = 6^ A'. 



If this value of 7V is adoi)ted, the region (»f temperature — 217 

 to —183° for helium corresponds with that of 0' to +200^ for 

 hydrogen, liy a|)])]ying (he law of the corresponding states to the 

 slopes of the y>?'j-lines for the two suhstances in (he neighbourhood 

 of (hese e(juivalent limils of temperature, we arri\e at a slightly 

 lower value of the critical tem}>erature ^•iz. 



l\He = 5°.3 A'. 



This value !oo I tliiidc 1 may still consider as a highest limit for 

 the critical tem|»erature of He, as it seems i)robable to me, that He 

 with respect to H.^ will deviate from the law of the corresponding 

 states in this sense that the critical (emperatnre will be found lower- 

 than would follow from the application of this law (o corresponding 

 states for values of the reduced tem[)eratnres many times larger than 1. 

 \No\v there caji oidy be (piestion of a first estimation based on 

 determinations of isotherms. The determination of the isotherms of 

 — 253° and — 259°, which is in progress, will, I hope, soon lead 

 to a more reliable estimation. 



In conclusion I gladly express my thanks (t> Mr. C'. Hkaak for 

 his assistance in this investigation. 



(January 23, 1908). 



