34 Mr. J. Kam on van der Waals* Equation and 



and as V e = 26, 



2a _ 1 



% 2 ~ 2b ; 

 whence 



9 9 



a= l h= s Yc ' 



as found in (15). 



Substituting V c in equation (A), V c = 2fr, we obtain 



2a _ E . T c 



96 2 ~~ 26 ' 

 whence 



T -9& •••"■• -^ 



As 5= |/3 (equation (8), p. 27), 



Tc= 2T ,Ot' (17) 



which is tbe identical form for the critical temperature as 

 found by van der Waals. 



Equation (9) p. 29, gives for T c the value 



2 P V 

 T c = ^j^, (18) 



and as V c = 3/3, we find in combination with (17) 

 6P c ./3 _ 8 a 

 U ~27 , £.R' 



or C= 8L^' oras / 3 =3^ 



p = — — a — p 



c 96' 2 ~(V c +6) 2 lc ' 



in accordance with the prece ling. 



It may be of interest to compare the above with an 

 experiment. 



In the case of carbonic acid, Andrews found for V c and P c : 



V c = -0066, 

 P c = 77 atmospheres. 

 We have, equation (15), p. 33, 



a=?V c = -007425, 



o 



and equation (8), p. 27, 



6=^V c =-0033. 



