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
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 combus