566       Prof.  A.  W.  Porter  on  the  Inver  si  on- Points  for 
The  equation  to  this  isotherm,  with  the  numerical  values  of 
the  coefficients  inserted,  is 
pv  =  397930  +  3892300  logl0^±i*B-  ^^y 
Fig.  5. — Critical  Isotherm  of  Isopentane. 
HV 
xa 
\ 
200,000 
\ 
\ 
\ 
X; 
\ 
v       Van  der  Waais 
Critical 
!i 
'Z 
5                                     ■£ 
■r- 
.,   -4            "o 
3 
Vol 
Fluid  satisfying-  dotted  curve  would  have  one  inversion-point  only. 
Observed  values  0. 
The  comparison  between  experimental  and  calculated  values 
may  be  more  easily  made  by  means  of  the  following  table. 
V. 
V3. 
pv 
observed. 
V 
observed. 
p  calculated. 
Porter. 
Dieterici. 
42730 
26780 
25320 
23400 
14560 
4604 
3740 
2-4 
3 
4 
8 
20 
80 
100 
•7503 
•6931 
•6299 
•5 
•3684 
•2321 
•2154 
117790 
79380 
100080 
189680 
296800 
369120 
375000 
49080 
26460 
25020 
23710 
14840 
4614 
3750 
29627 
25433 
25020 
23778 
14752 
4614 
3748 
