1. The increase in tensile strength and the elastic hysteresis are undoubtedly conditioned by the surface processes at the boundary of rubber and filler. 2. On freezing, the optimum increase in tensile strength is shifted toward a smaller volume loading. 3. Because of the considerable increase of viscosity of the medium upon freezing, the forces of friction increase to such a degree that they mask the usual relations existing between A, R, and H for all ingredients.