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

annotated evaluation results showing constant parameter T_c and fitted parameters (top to bottom): a_1, a_2, a_3, a_4, a_5