Abstract: The object of the present invention is the improvement of logarithmic amplifiers and/or converters and the applications of such devices in particular to photometric analyzer apparatuses.These amplifiers are characterized by the fact that they are linear with an amplification gain programmable by the .mu.P computer and that they may be preceded optionally by a reference voltage system.Application to the measurement of light transmitted by samples.

Abstract: A rotor, which has a center and a periphery, of a centrifuge analysis device. The rotor comprises, from the center of the periphery: central receptacles for liquids to be diluted before analysis; calibration vessels and overflow vessels disposed circumferentially adjacent to each other in respect to a circle concentric with the rotor; a mixing vessel communicating with each calibration vessel; and a plurality of measuring cells, each connected to the mixing vessel through a duct. Each calibration vessel is further provided with: a feed orifice through which it comunicates with one of the central receptacles; an exit orifice located in the wall of said calibration vessel opposite the feed orifice and permanently open; and an overflow orifice located at a position between said feed and exit orifices and through which the calibration vessel is connected to one of the overflow vessels.

Abstract: The present invention relates to a fractionating and observation cel of a liquid analysis device comprising a rotor, a central distribution cup or container for said liquid, and an assembly of cells on the periphery of the rotor, wherein the cells and the duct are formed by welding of two plastic pieces comprising said rotor, the liquid feed and gas evacuation duct is provided by the space existing between the two plastic pieces welded to each other by two welding seams along the edges of each duct, the opposite faces of the said pieces that constitute the duct with the said seams being left rough from molding.