The First Demonstration: Proof That Air Is a Substance
This lecture demonstration is the first recorded in history. The demonstration was performed in 440 B.C. by the Greek physician Empedocles to confirm his belief that air is a "substance." With minor changes, this demonstration can be repeated.
Prove that air is a substance.
Empedocles observed that "the water rushes into the large opening as the air rushes out of the small." Because air prevented the water from entering, air must, indeed, be a substance.
Large clear plastic aquarium
1. Fill a large clear plastic aquarium almost full of water.
2. Add a few drops of food coloring to make the level more visible.
3. Place your finger over the opening in the stem of a glass funnel and place the large open end of the funnel in the water.
4. Notice that the water does not enter the funnel.
5. Remove your finger from the opening - water rushes into the large opening as the air rushes out of the small.
Explain that since air prevented the water from entering, it must indeed be a substance. Probing questions to ask students would be (1) Why do you think such a simple demonstration was important in thge year 440 B.C.? (2) Would you give the same explanation as Empedocles? (3) What is a demonstration?
Water may be flushed down the drain.
On the basis of this observation, Empedocles developed a "water clock." This clock was a conical container with a small hole in the top and a larger hole in the bottom. The cone sank in a certain amount of time, so it could be used as a crude time piece.
Ironically, this first demonstration can easily be documented and attributed to Empedocles more that 2300 years ago, although the origins of more recent demonstrations are much more difficult to trace.
By modern standards, this demonstration seems very simple and obvious. However, it was not the custom of early "scientists" to do experiments or demonstrations. This simple demonstration by Empedocles caused other Greek physicians to begin thinking about the role of air in breathing and other processes.