Water climbs a clean glass capillary tube with a concave meniscus, while mercury in glass shows a convex meniscus depressed at the center. What comparison of forces explains the contrast?

Core Concept

Meniscus shape records the tug-of-war at the liquid-solid boundary. Polar glass hydrogen-bonds to water, so molecules at the wall feel a stronger upward adhesive pull than sideways cohesive pull, curling the surface upward and driving capillary rise. Mercury atoms bind each other strongly but adhere poorly to silicon dioxide, so cohesion dominates and the surface domes downward. Whichever force wins locally dictates whether the edge climbs or sinks.