MICHIGAN ACADEMY OF SCIENCE. 
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Fig. 18. — Section of pipette holder shown in Fig. 17. 
1. Rubber stopper by means of which air tight connections are made between the glass pipette (4) 
and the body of the holder (5a). 
2. Union by which the two parts of the pipette (5a and 5b) are held together with the rubber dia- 
phragm (6) firmly clamped between them. 
3. Screw control: By turning this screw to the right the disc (7) is lowered and the rubber dia- 
phragm (6) made tense. Then a slight turn of the screw (3) to the left will draw liquids into the 
pipette, and a corresponding turn to the right will expel them. 
Fig. 19. — Taking up mixture without air bubbles. 
