Abstract: A mixer-feeder vessel for the percentagewise mixing of two or more liquids, particularly for offset printing presses, enables a fluid contained in the feeder vessel to be admitted to a fluid tank. A partial volume of the mixer-feeder vessel is subdivided into a predetermined number of chambers by means of partition walls, with the chambers arranged in adjacent relationship to form a row. The partition walls protrude from one wall of the vessel by a predetermined length into the vessel. In a wall opposite the one wall of the vessel there is provided an inlet-outlet port aligned with a first chamber of the row of chambers, so that when a liquid is supplied through the inlet-outlet port, the first chamber situated under the port is first filled and subsequently the remaining chambers along the row are filled in series. The opposite wall is spaced from confronting end sections of the partition walls by another length.