A series of corrosion experiments was carried out using identical samples of a ceramic of known composition, structure, and density, which were subjected to a variety of simulated soil solutions. The action of the solutions was monitored by measuring their pH as a function of time at 25°C and 90°C. Under all conditions the pH stabilized rapidly. Microscopic and electron microscope studies showed the presence of reaction/alteration products that would account for the observed pH changes. The findings indicate that ancient ceramics that exhibit no physical deterioration will have below their surface a composition corresponding to the composition of the sherd at the time of its burial. -- AATA