Abstract: A proportioning head comprising a head plate, a multiplicity of pipette tips in plastic in a matrix array the tip apertures of which are disposed below the head plate and which are mounted at top of the head plate wherein the upper apertures of the pipette tips are accessible from the upper surface of the head plate, and a centering plate which has a multiplicity of centering holes in the same matrix array as have the pipette tips the inner diameter of which is tailored to the outer diameters of centering portions of the pipette tips disposed below the head plate in such a way that the centering plate is adapted to the pushed onto the centering portions while aligning the centering portions of the pipette tips onto the matrix array of the centering holes.

Abstract: A proportioning head comprising a head plate, a multiplicity of pipette tips in plastic in a matrix array the tip apertures of which are disposed below the head plate and which are mounted at top of the head plate wherein the upper apertures of the pipette tips are accessible from the upper surface of the head plate, and a centering plate which has a multiplicity of centering holes in the same matrix array as have the pipette tips the inner diameter of which is tailored to the outer diameters of centering portions of the pipette tips disposed below the head plate in such a way that the centering plate is adapted to the pushed onto the centering portions while aligning the centering portions of the pipette tips onto the matrix array of the centering holes.

Abstract: For the taking of liquid from large-volume, deep vessels by means of sucking vessels having short suction elements, a metered stand-by volume of liquid, which is accessible from above, is sucked from a volume of liquid of changing depth in the deep vessel and a defined sample of liquid is sucked from said stand-by volume at the same time. The auxiliary sucking device comprises a tube, which is adapted to be introduced into the deep vessel, and a check valve, which prevents a flow to the open bottom end of the tube. The tube is mounted on a bowl, which is adapted to be placed on the mouth of the deep vessel. The bowl preferably constitutes a portion of a housing in which the open top end of the tube is disposed close to the top wall of the housing. The top portion of the bowl contains an entrance opening, which is disposed above the stand-by volume of liquid, at least part of which is contained in the bowl.

Abstract: A plastic reaction vessel for holding a small quantity of liquid comprises a vessel body which has a body flange (4) surrounding an opening formed in the body, a cover, and a connecting strip (5) which is integral with the vessel body and the cover. Opposite to the connecting strip (5), the body flange (4) has a downwardly facing abutment surface (25), which is engageable by a hooklike extension (23), which is formed on the cover (6) and extends downwardly when the cover is closed. The connecting strip (5) comprises a hinge portion (12) between its opposite end portions. The cover comprise a cylindrical skirt, which is adapted to be inserted into the vessel body through the opening therein. A sealing lip (8) is provided on the outside of said skirt at that end thereof which is adapted to be inserted into the opening of the vessel body.