careful arrangement. Thus I cannot melt that piece of antimony by simply
putting it into the candle; but if I put it upon charcoal, and drive the
fiery current against it, there will be heat enough to melt it. The beauty
of the blowpipe is, that it sends hot air (making hot air by the
combustion of the flame) against the thing to be heated. I have only to
hold the antimony in the course of that current, and particle by particle
of the current impinges upon the antimony, and so we get it melted. You
now see it red-hot, and I have no doubt it will continue to burn if I
withdraw it from the flame and continue to force the air on it. Now, you
see it burning without any heat but that of its own combustion, which I am
keeping up by sending the air against it. It would go out in a moment if I
took away the current of air from it; but there it is burning, and the
more air I give it, by this or any other action, the better it is. So,
then, we have here not merely a mighty source of heat, but a means of
driving the heat forcibly against substances.

Let me shew you another experiment with a piece of iron. It will serve two
purposes--shewing you what the blowpipe does as a source of heat, and what
it does by sending that heat where it is wanted. I have taken iron in
contrast with silver or other metals, that you may see the difference of
action, and so be more interested in the experiment. Here is our fuel, the
coal-gas; and here our oxygen. Having thus my power of heat, I apply it to
the iron, which, as you see, soon gets red-hot. It is now flowing about
like a globule of melted mercury. But observe, I cannot raise any vapour:
it is now covered with a coat of melted oxide, and unless I have a great
power in my blowpipe, it is hardly possible to break through it. Now,
then, you see these beautiful sparks: you have not only a beautiful kind
of combustion, but you see the iron is being driven off, not producing
smoke, but burning in a fixed condition. How different this is from the
action of some other metals--that piece of antimony, for instance, which