jgourlay
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Earth, Air, Fire, Water demo?
Gents:
I need a suggestion please. I am after a set of demonstrations that are short and safe that would allow me to demonstrate why the ancients would have
been driven to conclude that Earth, Air, Fire and Water were elements, and were the only elements.
I'd really be helpful if the demo could be done using clay pots instead of glass (for example) and with "chemicals" dug from the ground.
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not_important
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The thing is that the classical Four Elements, or in many cases Five Elements(*), where much more philosophical constructs with a seasoning of simple
observations or common knowledge tossed in, rather than any sort of experimentally driven model.
And the Elements were often considered as combinations of the basic pairs of opposing Properties: Hot/Cold and Wet/Dry. Fire is Hot+Dry, Air is
Hot+Wet, Earth is Cold+Dry, and Water Cold+Wet (obviously these relationships came from a warmer, dryer climate, not Ireland or Northern Europe.) Add
heat to water and it becomes steam - air, take wet from water and it becomes solid ice - earth.
The fifth Element comes about as a way to explain things that seem to fall outside of ordinary matter. Thought/Mind/Soul is one such thing. Another
is the stars or Heavens, ordinary matter is always changing while the starts do not.
So I don't see any experiments in the modern sense that would serve as evidence of Four Elements, outside of freezing and boiling water, burning wood
and coal (earth). You need the mind set that is looking for those simple relationships, the derivation from two pairs of opposites, in order to
interpret such observations as evidnece; ignoring that heat burns one type of Earth - wood or coal - to make hot+dry fire, yet melts other kinds of
Earth - metals - to give cold+wet Water (liquid metals).
(*) Earth, Water, Air, Fire, and variously Idea, Void, or Aether for most European through South Asian schools; for China Fire, Metal, Wood, Water,
and Earth as the fifth element. The Chinese view is centered around relationships of creating/generating and destroying/overcoming,
again some basic common knowledge taken up in philosophical abstraction. Wood parts Earth (think roots) and feeds/generates Fire, Fire melts Metal
and creates Earth as ashes.
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jgourlay
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I gotcha. I keep forgetting how allergic the ancients so often were to empiricism.
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blogfast25
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| Quote: | Originally posted by jgourlay
I gotcha. I keep forgetting how allergic the ancients so often were to empiricism. |
Oh, I wouldn't say that. Applying pure reason is not anti-empirical. It so happens that you need a lot of empiricism (centuries of it, actually!) to
unearth the true building blocks of nature, a work that is still in progress (see e.g. the LHC...)
The recognition of these basic "elements" stems from the realisation that everything must be made up of the same elementary building blocks, that was
quite a philosophical feat.
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Ozone
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Perhaps you could place a candle in a jar, light it and then put the lid on. It should go out very quickly (this can be fun if you go with the
phlogiston idea). Then light a candle in another jar (smaller jar) and pour the "de-phlogistinated" air from the sealed jar into it (the jar with the
lit candle). Because CO2 will displace the air, the candle should go out. Then pour some bromothymol blue into that jar and swirl it. It (if
sufficiently dilute) should go from blue-green to yellow (you can then explain the acidity of carbonic acid).
Fire, air and water, I suppose.
Cheers,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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not_important
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But phlogiston came about two millennia after the 4 or 5 elements concept, and was part of the set of theories that were displacing the 'prime
elements' or Principles of Salt, Sulfur and Mercury, which had modified and displace the Four Elements.
Phlogiston was actually fairly good science, a much more rational explanation of what we now call oxidation than anything preceding it. It was based
on qualitative experiments, the limits of which also crippled; quantitative experiments delt phlogiston its death blow.
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jgourlay
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Did "phlogiston" have something to do with blood? Or am I thinking "phlobotomist"?
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blogfast25
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| Quote: | Originally posted by jgourlay
Did "phlogiston" have something to do with blood? Or am I thinking "phlobotomist"? |
No, Wiki has a good entry about it. In essence the theory stated that on combustion, materials lost 'Phlogiston', leaving behind 'de-phlogistonated'
matter (the ashes, if you will).
As not_important stated, phlogiston theory, although incorrect, wasn't such bad science for its day. It was somewhat similar to Lavoisier's 'Caloric' theory which posited that heat transfer was the result of the flow of a fluid he called 'caloric' from hotter to cooler
bodies.
Ironically it was Lavoisier who convincingly debunked Phlogiston theory by showing that upon combustion materials actually combine with a gas
(oxygen), rather than lose the ethereal 'Phlogiston', yet his own Caloric theory was interesting but hopelessly wrong.
The history of science is almost as interesting as science itself...
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indigofuzzy
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The 4 (or 5) elements remain even today (in some circles) as a strong philosophical concept.
Some have "remapped" them to the phases of matter: Earth -> Solid, Water -> Liquid, Air -> Gas, Fire -> Plasma, Fifth Element ->
Vacuum, life force, Bose-Einstein Condensate (lotsa variation here)
Another school of thought takes a bit more of a Spiritual/Philosophical approach:
Earth: The quality of solidity and stability, and the physical nature of things.
Water: The quality of fluidity, and the emotional nature of things.
Air: The quality of inspiration, and the mental/philosophical nature of things
Fire: Energy, and the power of things.
"Fire" does stand in nicely as a general concept of energy, as most kinds of energy have a tendency to convert themselves to heat. 
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