So now I think you will perceive the whole history of water with reference
to oxygen and the air, from what we have before said. Why does a piece of
potassium decompose water? Because it finds oxygen in the water. What is
set free when I put it in the water, as I am about to do again? It sets
free hydrogen, and the hydrogen burns; but the potassium itself combines
with oxygen; and this piece of potassium, in taking the water apart--the
water, you may say, derived from the combustion of the candle--takes away
the oxygen which the candle took from the air, and so sets the hydrogen
free; and even if I take a piece of ice, and put a piece of potassium upon
it, the beautiful affinities by which the oxygen and the hydrogen are
related are such, that the ice will absolutely set fire to the potassium.
I shew this to you to-day, in order to enlarge your ideas of these things,
and that you may see how greatly results are modified by circumstances.
There is the potassium on the ice, producing a sort of volcanic action.
It will be my place, when next we meet, having pointed out these anomalous
actions, to shew you that none of these extra and strange effects are met
with by us--that none of these strange and injurious actions take place
when we are burning, not merely a candle, but gas in our streets, or fuel
in our fireplaces, so long as we confine ourselves within the laws that
Nature has made for our guidance.
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