A set of data on dissolution of monodispersed silicate sand in a glass batch suddenly exposed to a constant temperature within the range from 1250-1410 deg C was analysed. It was found that: The fraction of sand dissolved in the stage of vigorous melting reactions increases rather irregularly with increasing temperature and linearly with decreasing initial grain radius and; The mass transfer coefficient does not change with time in the second stage of melting, but increases with increasing grain radius and surprisingly, decreases with increasing temperature for T1350 deg C. An attempt is made to explain this behaviour taking into consideration the initial heating rate, formation of intermediate crystalline compounds, evolution of batch gases and refining gases, and buoyant segregation of undissolved grains.