  We perform a thermodynamic analysis of various contributions to the size
dependence of the contact angle cosine for axisymmetric and cylindrical sessile
droplets. This shows that a widely used method to determine the line tension
from the slope of the contact angle cosine dependence on the three-phase
contact line curvature (for axisymmetric droplets) provides a certain
combination of the line tension, adsorptions at the three interfaces, and the
macroscopic contact angle. To extract the leading-order contact-line-related
contribution and determine the line tension, we propose a simple technique
using contact angle size dependences for axisymmetric and cylindrical droplets
at the same conditions.
