Two useful modifications for the Seligson pipetting system.

The advantages of the Seligson pipette in a clinical laboratory are well known (Seligson, 1957; Saifer, Gerstenfeld, and Zymaris, 1958). It is usually attached to a burette for adding diluent. Mather (1960) modifies the stopcock of the pipette and attaches it to an automatic burette. In this laboratory, two devices have proved satisfactory in over two years' continuous service. (1) A 0.35 ml. Seligson pipette is attached to an "emil " double automatic 25 ml. pipette for preparing plasma dilutions for K+ estimation. The connexion is made with a short length of polythene tubing, of 2 mm. wall thickness. This makes a joint which is firm, but has some " give " if the pipette is knocked. If the glass tubing is roughened with emery paper there is less danger of it slipping out of the polythene. A turn of two stopcocks measures the plasma sample and dilutes it without further attention from the technician. The precision is shown in Table I.