Abstract: A small, compact plate reader is disclosed for microtitre plates. The reader comprises a totally enclosed housing (19), means e.g. a drawer (2) for receiving and inserting into the housing a microtitre plate (7) which is received into the housing between a light source and a photodetector positioned in vertical alignment above and below the microtitre plate. The light source and detector are mounted on a carriage movable in the housing along each of two orthogonal axes by means of the manual control knobs (10,11) on either side of the housing. The light source and detector are thus positionable with each of the wells of the microtitre plate in turn enabling absorbancy measurements to be made, and visually displayed by a digital display (9).

Abstract: A centrifuge comprises a rotor which tapers conically downwardly from a maximum diameter upper region to a central bottom opening through which a liquid entry pipe projects upwardly. An outlet end of the entry pipe is shrouded by a concentric cone which is mounted for rotation with the rotor. A flexible diaphragm is secured to the outlet end of the pipe and extends towards the cone so that liquid entering the rotor is directed to flow over an inwardly facing surface of the cone. By this means, the spin of the rotor is transmitted immediately to the liquid. During operation of the centrifuge, rapid changes in the rate of rotation of the rotor are effected so that solids which have separated from liquids in the rotor and have accumulated in the upper region are dislodged therefrom.

Abstract: A method of initiating an operation in dependence on the combined mass of an element and matter which is in or on the element can be used to remove matter which has accumulated on the rotor of a centrifuge. A substantial change is effected in the speed of rotation of the rotor and the rate of change is then measured. The operation is initiated when the rate of change is above or below a predetermined value.