Viscosities of melts in the systems, Na₂O-P₂O₅, BaO-B₂O₃, Na₂O-B₂O₃ and Na₂O-SiO₂ were measured at 1000°C on the surface as well as in the bulk phase by using a modified rotating viscometer. For some melts, it was found that the viscosity on the surfaces is higher than that in the bulk phase. The highly viscous layer on the surface suggests that concentration of surface active component such as B₂O₃ in the system BaO-B₂O₃ is higher on the surface than in the bulk phase. Foaminess of the melts was also measured. It is concluded that higher viscosity of the melt itself is important, but not enough to stabilize the foam, and higher surface tension depression by the melt composition is also required.