Watson: For surface tension s for the liquid/gas interface
ln(s/so) = a1 + åai ×Tri-1 ×ln(1-Tr) , where the summation is from i = 2 to nTerms -1
Tr = T/Tc, Tc is the critical temperature, and so = 1 N/m
ln(s/so) = a1 + åai ×Tri-1 ×ln(1-Tr) , where the summation is from i = 2 to nTerms -1
Tr = T/Tc, Tc is the critical temperature, and so = 1 N/m