The automatic chemical analyzer includes a turntable adapted to hold a plurality of disposable cuvettes. An optical system adjacent to the turntable can perform tests on the contents of each cuvette as they are rotated on the turntable. A sample/reagent tray is rotatably mounted about an axis parallel to the turntable axis. A common probe arm pivoted about a third parallel axis mounts a pipette that can be moved along an arcuate path intersecting a cuvette access station on the turntable and at least one container access station on the sample/reagent tray for transferring liquids as required by specific test procedures. A wash/alignment station is provided to facilitate flushing on the pipette between liquid deliveries. Combined within it is an alignment plate that checks the radial position of the pipette relative to the probe arm axis and the elevation of the pipette tip relative to the supporting instrument framework. A capacitive sensing system is used to detect liquid level elevations during liquid transfers. It also is used for pipette alignment purposes.