A number of other interesting observations can be made:

After most of the cube has melted the weight of the water drop is sufficient to drag the ice cube down with it. ie the average density of the cube and drop is greater than that of the oil. Sometimes, as the cube and drop are sinking, the drop detaches itself from the cube and the cube floats back to the surface.

Small mini droplets occasionally break off from the main one as it descends forming a 'string of pearls' effect.

Water droplets may sit for some time on the water oil interface without coalescing with the body of the water.

When the coloured water droplets begin to coalesce with the water, the coloured water can be seen to sink as it mixes, because of its greater density.

There are interesting changes of shape in the water droplet as it forms, detaches itself from the cube and as it sinks.

Visual Tips

Water that has been dyed blue is easily seen in the pale yellow oil against a white background.


Teaching Tips

Repeat the demonstration with an uncoloured ice cube to show that the colouring makes no difference.