I p dv = I /i dv -f- I p di\ 



V 

 Tlie first pari I have developed before, and X ^= \ p dv—ET lo(f V 



'■'fk 

 ( y = co) is the .i'-function wliich has tlien been wrongly left out of 

 account. Tiiis function cannot be developed in the same manner as 

 the first integral, because the series used for that is no longer con- 

 vergent for large volumes; we must therefore turn to Kamerlingh 

 Onnes' empirical equation of state. 



When this equation of state is written in a reduced form, it also 

 represents the reduced equation of the isothermal of the mixture .c, 



at (he reduced temperature t ^ — , so that 



V 



I pdr = />.,i- i\iA \>dü = 

 I'rt i-'TIc 



Hence the neglected ,r-function is: 



\— — RT % vTh + — — + i T7 ~\ 1- 



7? VTk ^ V Tk 



and this may be developed again: 



X :=: X„ -f X, (,. - XTk) + X, {.,■ - .VTkY + 



\vhere the co-etllicients A',, X^, A', etc. are still functions of tempe- 

 rature. Fortunately the neglection of that function X has not influenced 

 the results in first approximation ; however in the formulae 4, 5, 

 12 and 13 of suppl. N". 7 we have to add 2 A', to the fiictor 

 RT 



