The angle of contact ($\theta$) is defined as the angle between the tangent to the liquid surface at the point of contact and the solid surface inside the liquid . According to the sources, if this angle is obtuse (greater than 90°), the cohesive forces between liquid molecules are stronger than the adhesive forces between the liquid and the solid . In this case, the liquid molecules are attracted strongly to themselves and weakly to the solid, and therefore the liquid does not wet the solid surface . A common example of this is mercury on glass, which forms an obtuse angle of contact and does not wet the surface .