Coarse particles of ten different materials were subjected to oleate flotation in a monobubble Hallimond tube at pH=7.2. The best flotation was observed for calcite, fluorite, sphalerite, and ilmenite for which the maximum size of floating particles (D-max(1)), when floated individually, obeyed the Scheludko equation (D-max(1))(2) rho＇ = K = 0.160+/-0.007 g/cm where rho＇ is the density of particle in water and K is a constant. The oleate flotation of individual particles of germanium, silicon carbide, magnetite, and magnesite was smaller than that of calcite, fluorite, sphalerite, and ilmenite. Almost no flotation was recorded for quartz. The same materials were subjected to potation as a collection of particles and it was found that the maximum size of floating particles (D-max) depended not only on the hydrophobicity and the density of the particles but also on the amount of solids used in flotation. It was established that D-max can vary with the amount of solids from D-max(1) to a lowest value of D*(max). The potation of a collection of particles obeyed the equation: D*(max) rho＇ = L where L is a constant equal to 0.46+/-0.03 g/cm(2) for ilmenite, sphalerite, fluorite, and calcite. A comparison of D*(max) with D-max(1) provides an expression (D-max(1))(2)/D*(max) = K/L which can be used as a measure of interaction of coarse particles during flotation. For oleate flotation of fluorite, ilmenite, and sphalerite the interaction parameter K/L was equal to 0.35 cm.