This quantity was measured in experiments by Agnes Pockels using a homemade sliding trough (troff) that evolved into the Langmuir-Blodgett trough. This quantity is proportional to the force needed to lift a Wilhelmy plate or a du Nouy (10[3])ring. Three values of this quantity are related to the cosine of the (-5[1])contact angle by Young's relation, while this quantity times the subtracted reciprocals of two radii of curvature gives the pressure difference in the Young-Laplace (luh-PLOSS) equation. Mass is transferred along a gradient in this quantity in the (10[1])Marangoni effect, creating "wine tears." This quantity and adhesion cause interfaces to adopt a curved shape called a meniscus. For (10[3])10 points, name this force (10[1])that is "broken" by surfactants and allows certain insects to walk on (10[1])water. ■END■