LXXIX.The cohesive force between solid surfaces and the surface energy of solids

Summary An expression is obtained for the cohesive force between two unequal spheres in geometrical contact. From the constant in this expression the surface energy of the solid may be computed. Results are obtained in agreement with the theory. The surface energies of freshly fused surfaces of quartz and sodium pyroborate are 33·8 and 69 ergs per sq. cm. In the case of borate spheres, however, the cohesion is probably due to a surface film of water.