Abstract: An apparatus and method for serial dilution of liquid samples comprises a power-driven measuring valve having a rotatably mounted valve body provided with a single calibrated measuring passageway. During a dilution cycle the measuring passageway in different rotational positions of the valve body successively isolates a measured volume of a sample to be diluted and an equal volume of a first diluted solution of the sample which has been prepared by mixing the isolated undiluted volume of the sample with a measured volume of diluent. In a valve body position between said different rotational positions the measuring passageway is connected to form part of a rinsing flow system.

Abstract: Centrifugal batch separation of blood in a closed collapsible container is carried out by placing the container in a rigid casing in which the container is divided into two or more sections in that the casing constricts the container at one or more predetermined positions between the ends of the container. The casing with the container therein is then centrifuged, a gap-like passage between the container sections permitting rearrangement of the contents of the container so that each section will accommodate a blood fraction. After the centrifugation the fractions are isolated from each other. The volume of the cavity within the casing accommodating the radially outermost container section is matched with the hematocrit and the total blood volume by means of filler bodies.