Based on the static-friction model for solid-liquid-vapor contact line suggested by Adam and Jessop，one can calculate surface-tension coefficient of solids from the data of wetting angles, but the results depend on the friction condition adopted. Using the data reported on stainless steel and polypropylene samples as examples, we have compared the surface-tension coefficients given by the Mises yield condition and Amonton's friction law. It is found that only the latter pos sesses always the Wenzel behavior which claims an increase of surface-tension co efficient with surface roughness, as well as total wetting condition, namely rec eding angle vanishes when the difference of solid-liquid and solid-vapor coeffic ients equals that of liquid-vapor. This shows that the Amonton's law seems to be more reasonable for describing the static friction of contact line.