A silica sample has been studied by vapor adsorption and by microcalorimetric methods. The combination of these two methods in the case of water allows us to calculate all the thermodynamic terms related to the adhesion on this silica. Adhesion between silica and miscellaneous solvents has been studied by immersion microcalorimetry. The silica is slightly hydrophobic, but the enthalpy of immersion into water is the most energetic one of all the solvents studied. It appears a clear graduation of the enthalpies of immersion due to the presence of delocalized electrons in the studied solvents. (C) 1994 Academic Press, Inc.