Included rubber stopper centers glass capillary tube in the outer cylinder
Apparatus is comprised of an engraved 250-mm borosilicate glass capillary tube (graduated from 0 to 10 cm in 1-mm divisions) and an outer tube. Capillary tube is positioned in the center of the outer tube by means of a rubber stopper. Outer tube accomodates a pipette bulb to expel air.
250 mm borosilicate glass capillary tube, rubber stopper, and outer cylinder