One of the main issues in the theory of flotation is the nature of the interaction of the collector reagent with the surface of the floated mineral. It has been established that during the flotation of wolframite and hübnerite in a sodium oleate solution, the pH of the pulp does not increase, but decreases. It has been suggested that as a result of the binding of more and more portions of fatty acid to the surface of the mineral in one solution of sodium oleate, the accumulation of not NaOH, but Na₂W0₄ occurs, which explains the decrease in pH. It has been suggested that the surface of the mineral extracts the fatty acid acyl ion from solution as a result of an exchange reaction between the acid or its soap and the surface of the mineral. Around the monomolecular layer of metallic soap, formed as a result of a chemical reaction on the surface of the mineral, a polymolecular film of undissociated oleic acid is formed, which causes flocculation of wolframite or hübnerite. In the flotation of pure minerals - wolframite and hübnerite - flocculation is a very significant reason for the success of flotation. Flotation of hübnerite with sodium oleate is less successful in comparison with flotation with oleic acid, which should be explained by the different flocculating ability of these reagents.