Abstract: A reagent kit adapted for being used in an automatic analytical apparatus. The reagent kit comprises at least a first reagent container and a second reagent container which have the same height, a kit cover for covering and for holding the upper parts of said at least two reagent containers together, a first tray for holding the bottom part of the first reagent container, and a second tray for holding the bottom part of the second reagent container. Reagent containers are so configured and dimensioned that when they are assembled together they fill the entire space comprised between kit cover and the trays with exception of a tubular volume which allows air circulation through said reagent kit. The sum of the height of the side walls of the kit cover and the height of the side walls of the trays is smaller than the height of the reagent containers.

Abstract: A closure device for a test tube to be used with an ultra-centrifuge comprising an insertion member, the insertion member including a bottom section which is adopted to be inserted into the test tube and has an outer diameter substantially equal to the inner diameter of the test tube and an upper section which extends upwardly from the test tube and has an outer diameter greater than the inner diameter of the said test tube, an abutment positioned outside of the test tube about the upper edge thereof, said abutment being adopted under the influence of centrifugal force to press against the outer surface of the upper edge of the test tube.