811 



Tf p ■ pL = f , T : Tic = ))}., V : vj. = n, I) : Vk = j? may be pul, the 

 lediiced equation of state, in consequence of the mentioned relations, 

 becomes : 



M + ~—\{n—^)=sm (6) 



Another set of equations is found by tlie introduction of the 



critical pressure coefficient /={-—]. But in this the dependence 



\pdljk 

 on the temperature of the quantity b must be taken into account. 

 We easily find (see p. 56 — 57 loc. cit.) : 



Pk{vk—h) \ vk—hk 



when ^'t represents — ( v~ I • Hence this becomes : 



r / r 



r — 1 \^ r — 1 



r 



If now the temperature-correction ^'t is represented by 7-, and 



r — 1 



r 



if we bear in mind that s would be the value of f, when b 



r— 1 *^ 



(or a) were no function of the temperature, which value we shall 



henceforth denote by f', we have the relation : 



in which 



^'=^^7, <^) 



In this / is therefore the quantity ( — ) determinable experiment- 



\dmjk 



ally, which, however, will not appear as such in the different 



relations. In them f' occurs systematically, which is connected with 



ƒ by the relation (5). Fortunately, however, (f is always very small, 



so that in a first approximation ƒ may be substituted for /'. But 



for the sake of accuracy we ha\e everywhere in what follows not 



identified f' with ƒ. 



When ph-\- "lüi} is substituted for R2\:{v/, — b/c) 



1 27 _ X, 27 

 follows from /' = RTici pic {vie —bi), so that we have also the relations 



f-'=TV-l^ü' («> 



