High-precision positive-displacement pipette having a nozzle with calibrated capillary channel and capable of disengageably fitting together with the free lower end of the pipette body. A piston fits tightly in the capillary channel and is controlled by a manually operable control rod equipped with a...http://www.google.de/patents/US4362064?utm_source=gb-gplus-sharePatent US4362064 - Positive-displacement pipette
