see how it glows! This is the glorious lime-light, which rivals the
voltaic-light, and which is almost equal to sunlight. I have here a piece
of carbon or charcoal, which will burn and give us light exactly in the
same manner as if it were burnt as part of a candle. The heat that is in
the flame of a candle decomposes the vapour of the wax, and sets free the
carbon particles they rise up heated and glowing as this now glows, and
then enter into the air. But the particles when burnt never pass off from
a candle in the form of carbon. They go off into the air as a perfectly
invisible substance, about which we shall know hereafter.
Is it not beautiful to think that such a process is going on, and that
such a dirty thing as charcoal can become so incandescent? You see it
comes to this that all bright flames contain these solid particles; all
things that burn and produce solid particles, either during the time they
are burning, as in the candle, or immediately after being burnt, as in the
case of the gunpowder and iron-filings, all these things give us this
glorious and beautiful light.
I will give you a few illustrations. Here is a piece of phosphorus, which
burns with a bright flame. Very well; we may now conclude that phosphorus
will produce, either at the moment that it is burning or afterwards, these
solid particles. Here is the phosphorus lighted, and I cover it over with
this glass for the purpose of keeping in what is produced. What is all
that smoke? That smoke consists of those very particles which are produced
by the combustion of the phosphorus. Here, again, are two substances. This
is chlorate of potassa, and this other sulphuret of antimony. I shall mix
these together a little, and then they may be burnt in many ways. I shall
touch them with a drop of sulphuric acid, for the purpose of giving you an
illustration of chemical action, and they will instantly burn[9]. [The
Lecturer then ignited the mixture by means of sulphuric acid.] Now, from
the appearance of things, you can judge for yourselves whether they
produce solid matter in burning. I have given you the train of reasoning
which will enable you to say whether they do or do not; for what is this
bright flame but the solid particles passing off?
[Illustration: Fig. 9.]
Mr. Anderson has in the furnace a very hot crucible, I am about to throw
into it some zinc filings, and they will burn with a flame like gunpowder.
I make this experiment because you can make it well at home. Now, I want
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