The initial objective was to study the conditions under which certain alkyl surfactants are adsorbed on typical rock and/or soil minerals. Adsorption on only one mineral, kaolinite, was actually studied during the grant period. Only one mineral was studied because it was soon realized, after starting the research work, that meaningful results only could be obtained if one or at the most two minerals were studied in depth. Kaolinite was selected for study because of its common occurrence and because it appears to be the simplest of the clay minerals.