Proposed Experiment: Consider a capillary tube, dipped in a container filled with water (Assume that the tube doesn't topple over or sink, it is fixed in its position somehow). It is obvious that we will observe some rise of water in the capillary, attributed to surface tension (popularly known as capillary rise).
Now, fill a dropper with soap solution. Add the solution dropwise (and slowly), to the mouth of the capillary, so that it falls on the meniscus drop by drop.
What happens next? Does the level of the capillary fall immediately, or does it take some time for it to happen? Could someone please explain the phenomenon properly? I've read that soap solution decreases the surface tension of water, and I concluded that addition of soap should lead to a decreased height of the column in the capillary.
P.S. For reference, here's something I learnt in Physics by Resnick Halliday and Krane:
For water at room temperature, the value of surface tension is 0.073 N/m. If we add a surface-active agent or surfactant, the surface tension reduces due to decrease in cohesive force between molecules. Quantitatively speaking, adding soap, reduces the surface tension to 0.025 N/m.
P.P.S. If possible, someone, please share a video of the experiment! I couldn't really find one online, so maybe y'all could record one and post it so all of us at Physics SE could see it happen! (After all, what better way is there to learn Physics than experiments?)