Abstract: The flotation apparatus comprising a container having a free liquid level of the fiber stock suspension which is fed essentially horizontally to the container by at least one infeed device. The infeed device contains at least one aeration element having an outlet cross-section located at a predetermined region which is 100 to 600 mm, preferably 50 to 250 mm, below the liquid level of the fiber stock suspension in the container. Between the end of the aeration element and the discharge mouth or opening of the infeed device which opens into the container there can be arranged an essentially horizontally extending starting path for quieting or stabilizing the flow of the fiber stock suspension. This starting path is provided at its initial region with an ascending cover member at which merges a channel having a free liquid level.