In the case of water in axarrow glass tube, the force of adhesion between the water and glass molecules is greater than the cohesive force among water molecule, hence, water clings to the glass tube forming a concave meniscus. In the case of mercury, the cohesive force among its molecules is greater than the adhesive force, between mercury molecules and water molecules hence mercury molecules cling to each other forming a convex meniscus in the capillary glass tube.