Abstract: The method serves for the separation of solid materials out of a suspension and is, as a rule, implemented as a floatation method. The suspension (S) to be clarified is added tangentially from the outside at the periphery of a substantially cylindrical clarification volume (1). Damaging flow phenomena, such as for instance turbulence, are removed to the largest possible extent by flow means (2) which are applied prior to the entry of the suspension into the clarification volume so that an optimal flow takes place in the clarification volume (1). The flow is fed to the center of the clarification volume in a substantially spiral path (4), wherein the scum (6), which receives the materials to be separated out, forms on the surface. Various apparatuses for performing the method are proposed.