I make this experiment because you can make it well at home. Now, I want
you to see what will be the result of the combustion of this zinc. Here it
is burning--burning beautifully like a candle, I may say. But what is all
that smoke, and what are those little clouds of wool which will come to
you if you cannot come to them, and make themselves sensible to you in the
form of the old philosophic wool, as it was called? We shall have left in
that crucible, also, a quantity of this woolly matter. But I will take a
piece of this same zinc and make an experiment a little more closely at
home, as it were. You will have here the same thing happening. Here is the
piece of zinc, there [pointing to a jet of hydrogen] is the furnace, and
we will set to work and try and burn the metal. It glows, you see: there
is the combustion, and there is the white substance into which it burns.
And so, if I take that flame of hydrogen as the representative of a
candle, and shew you a substance like zinc burning in the flame, you will
see that it was merely during the action of combustion that this substance
glowed--while it was kept hot; and if I take a flame of hydrogen, and put
this white substance from the zinc into it, look how beautifully it glows,
and just because it is a solid substance.
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