or 



( 140 ) 



v,=K^{z + L_i:j(i_^_jj 



Siibstitiitinj>- these values and putting ^^ = ?ii^o we get tlie eqimtioji 



71 (n — 1) 



I T 



If we put 71 = 2, tlieii we get z= — for — -:=0,8 



1 T 



2 3= — „ — :rz0,7 



5 Tk 

 1 T 



6 T/, ' 



1 T 



— rrr0,615. 



7 " 7 



For A^ery small ^■ahles of z we may neglect z' compared to unity 

 and we ma}^ calculate the value of z from the approximated equation : 



8 T _ 1z 



1 T 1 



which equation yields the value of c = — for —-=-—. For such 



small values of z we have : — = 1, = and — ^ . 



V-h, h, l-^Z h, 1 + 2 



We will assume that for all tempei-atures belo^v 0,6 Tk the vapour 



phase may be considered to have a sufficient degree of rarefaction 



for follo^ving the gaslaws ; therefore A\'e may assume z to lia\'e a 



1 1 ^ f l',i\ 



value below — . If we choose z = — , then we find for ( — 1 the 



value 4 ^ =4 — or ^ = 2,56. With this value 



\rj \\-^2z) 25 



we have : 



Zoo 27 i-^]— -^ ' --^- ^=:Zor/ 27X20,5 A u 0.11. 



It is true that this value is smaller than /<>(/ 27"-, but it ai)proaches 

 sufficiently to that value. The fact that it is smaller than /o</ 2 7 Ms in 

 perfect agreement with the circumstance that for the quantity ƒ in 



the formula — log — ^=f — ^ — according to the experiments at low 



