An experimental study of the melting of a vertical surface of a solid by a heated liquid pool of various densities was conducted. The heat transfer mode in the external fluid was by natural turbulent thermal convection. After the onset of melting, although the two media were miscible, the melt and external fluid did not intermix along their mutual vertical interface when densities of the two media were different. The melt flowed upward when the liquid pool was heavier, and downward otherwise. For these cases, the heat transfer to the solid surface was controlled by the flow of the melt layer. As the density of the liquid pool approached that of the melt, the melting rate decreased, assuming a minimum at a liquid-melt density ratio, ρ*, of about one. For ρ* < 1.1, the convective currents within the liquid pool became increasingly effective in the removal of the melt. The mixing of the two media increased, with maximum mixing occurring at ρ* ≈ 1. For this case, convection currents in the liquid pool became the controlling heat transfer mechanism.