Fill a small narrow-necked bulb with port wine, or with water and
coloured spirit of wine, and put the bulb into a tall, narrow glass
jar, which is then to be filled up with cold water: immediately,
the coloured fluid will issue from the bulb, and accumulate on the
surface of the water in the jar, while colourless water will be seen
accumulating at the bottom of the bulb. By close inspection, the
descending current of the water may also be observed, and the coloured
and the colourless liquids be seen to pass each other in the narrow
neck of the bulb without mixing.
The whole of the coloured fluid will shortly have ascended, and the
bulb will be entirely filled with clear water.