Experimental measurement of forces and energies associated with capillary rise in a vertical tube.

We examined the forces and energies associated with liquid rising in a capillary tube. Glass and polytetrafluorethylene (PTFE) tubes with diameter ranging from 0.5 to 1.4mm were brought into contact with ethylene glycol, glycerol or silicone oil to initiate rise. We measured the force generated by the rising liquids with a tensiometer and plotted them against rise height. From these plots, we estimated the change in potential energy. For a given liquid-solid combination, the change in potential energy was equal to the difference between the work of wetting and viscous dissipation in the bulk of the liquid; potential energy values were independent of tube diameter and ranged from 7 mJ/m(2) for silicone oil rising through PTFE to 33 mJ/m(2) for glycerol and glass.