Bill: I’m Bill Hammack . . .
Don: . . . and I’m Don DeCoste.
Bill: And we created this lecture series Michael
Faraday’s The Chemical History of a Candle
with Alex Black, a chemistry undergraduate
at the time at the University of Illinois,
and this commentary track is intended to enhance
and enrich the lecture by looking at some
of the larger issues that Faraday is going
to touch on.
Don: You know, and Faraday lets us know right
away that this is more than just about a candle
he tells us that there is no better window
into science than studying the candle.
He is going to hint at and discuss a lot of things, chemical reactions, density, the nature of
gases, capillary action, and if you haven’t
watched these lectures yet or read these — spoiler
coming up here — by the last lecture, he
is going to compare human respiration to the
combustion of a candle. And Bill and I’ve
found it very useful to rewatch these lectures
again, knowing that he is going to do that,
because it’s really fascinating to see the
logic that he uses and how he goes about leading
us naturally to this point.
Bill: And the way he does this is by asking
questions and making observations, and so
he is actually modelling the scientific method
or scientific process for us. In fact, in
the lecture, he is going to come back and
explicitly tell us that he is doing this.
Don: And I think something to make more explicit
from Faraday about this part that I really
like, is that the heat serves two purposes
– it melts the wax, which is more obvious,
but it also then by causing the convection
currents, it allows the air to flow over the
candle, and it cools down the wax on the outside.
So it heats and cools at the same time, allowing
the candle to keep its shape.
Bill: So now Faraday’s next sentence is
one of my favorites and really captures something
really important in the lectures.
Faraday: The same force of gravity, which holds
worlds together, holds this fluid in a horizontal position, and if the cup be not horizontal,
of course the fluid will run away in guttering.
Bill: And we’ll see Faraday make this point
again and again throughout the lecture the
point that science gives us a uniform explanation for nature.
Don: And this is probably a good time to talk
about the language and our choice. You just
heard the phrase “if the cup be not horizontal,”
obviously we decided to keep Faraday’s original
language. You’ll hear many other examples
of this in the coming lectures. We decided
to do this for a few reasons, one, historically,
we wanted to keep the language, he is also
very poetic in a lot of places, but is also
very vivid. In the same passage we heard him
use the phrase “holds worlds together,”
and that really tells us what’s going on,
but it’s a very vivid way of saying that.
Bill: In addition to being vivid, there’s
also a precision to it even though it’s
not always what we would call strictly scientific
language today.
Don: And I really like the way that Faraday
makes segues and makes transitions. He talks
first of all that the utility of a candle
is what’s important, and that’s actually
its beauty, not what it looks like, but how
it acts. And then he also looks at candles
like these are bad burning candles, and he
finds some beauty in those too, and that beauty
is, we can learn something about burning by
a negative result.
Bill: Yeah, indeed as scientists we can learn
from any result, and in fact, in beautiful
language, Faraday makes that same point right
about here.
Faraday: We come here to be scientists, and
my hope you will always remember that whenever
a result happens, especially if it be new,
you should say, what is the cause, why does
it occur, and you will in the course of time,
find out the reason.
Bill: So this really nicely sums up the nature
of science, and it’s a theme that really
permeates all of these lectures.
Don: And, of course, part of this nature is
to ask a question, and the question doesn’t
always lead to an answer and leads to another
question. So he asks a question about the
chemical change that occurs in a candle, and
that leads him to wonder about the physical
change, and that is, how does that wax get
up to the flame.
Bill: You just mentioned physical and chemical
changes, and those are going to be really
important throughout the lecture, and let’s
listen to how Michael Faraday discusses chemical
and physical changes in a very colloquial,
yet still precise language.
Faraday: Especially when you come to learn
what a vigorous thing flame is, what power
it has of destroying the wax itself when it
gets hold of it, and of disturbing its proper
form if it comes only too near.
Don: And so the flame does two things then,
the flame melts the wax, and that’s a physical
change, and Faraday uses the term “disturbing
its proper form,” which lets us know it’s
actually going then from a solid to a liquid.
The flame also allows the wax to react with
the oxygen as we’ll find out.
Bill: Yeah, yeah, it destroys the wax and
then turns the wax into something new as we’ll
find out, we had carbon dioxide and water
as products of the flame.
Don: And so this is a chemical reaction. Now,
when students are first learning chemistry,
this difference between chemical and physical
change is a difficult one. It helps if the
students think about the molecules, and Faraday
provides language and helps us view it this
way, destroying, destroying the molecules,
and just disturbing the molecules changing the form.
Bill: And Faraday will return to these chemical
and physical changes in every lecture.
Don: And so this is one example of something
that we changed that Faraday did. It’s same
idea but with different materials. Faraday
used rattan cane and camphor because he had
the materials in his time, and we decided
instead to use a salt column and alcohol to
show capillary action of a fluid.
Bill: You know, and this is one of our favorite
demonstrations of Faraday’s. It’s just,
it’s so vivid. Don just said just a minute
ago, it was good looking and good working,
and you really can understand how a part of
a candle works after you see this.
Bill: And so let’s return to Michael Faraday here because he just summarizes this so aptly.
Faraday: The fluid has risen by the capillary
action of the salt, just as it does through
the wick in the candle.
Don: So another thing about the language.
We mentioned a little bit ago that we decided
to keep his language for certain, for reasons,
historical reasons, it’s very vivid and
so on. Obviously the language he just said,
that we had him just say, the capillary action
of the salt, those were our words because
as we mentioned, we changed the demonstration
to include a salt column. And so we did this
when we needed to do this. We kept his language
as much as possible, if we needed to change
a demonstration or we needed to say something
in a slightly different way, we changed the
language slightly.
Bill: So, now the demonstration that we just
saw and the one that’s coming up, are used
to show that the fuel used by the candle is
vaporous, so in that experiment, where he
turned the candle over, the liquid would come
down on the flame, and the candle cannot burn,
the liquid fuel has to become vaporous first.
And then this experiment coming up is a very
famous one where he is going to relight the
vapor. And I should note that both of these
experiments are little difficult to do when
we turn the candle over that took a number
of tries and you’re going to see me lighting
the vapor here in just a second and this was
certainly not a single take that we used to
do this, that we did this in, and in fact,
what’s interesting is Faraday in the later
lectures does even more fantastic things in
piping that vapor around through a glass tube
and relighting it . . . things just … things
I find just truly astonishing. So, in the
section that’s coming up Michael Faraday
just gets lyrical about science. And you can
really see or hear his enthusiasm come through,
and so I think we should just let him speak
for a moment here.
Faraday: Where you have  such beauty and brightness
is nothing, but combustion or flame can produce.
You have the glittering beauty of gold and
silver, and the still higher luster of jewels
like the ruby and diamond, but none of these
rival the brilliancy and beauty of flame.
What diamond can shine like flame, it owes
its luster at night time to the very flame
shining upon it. The flame shines in darkness,
but the light which the diamond has is as
nothing until the flame shine upon it when
it is brilliant again. The candle alone shines
by itself and for itself, and for those who’ve
arranged the materials.
Don: Let’s be Faraday here for a moment
and make all the observations we can. The
wick is bright at the end, it’s black down
the length of it up to where the wax is, and
the flame only touches up to where the wax
is and the flame is multicoloured as well.
Bill: Of course what he did was he used . . . turned
this all into questions and used that to motivate
a scientific investigation into how a candle
works.
Don: And so if you know where Faraday is going
with this, he just dropped a couple of really
big hints. He mentioned the phrase, ignition
is not so perfect, which is talking about
incomplete combustion, which he’ll get into
more about not being able to burn the carbon
completely; he used the phrase matter rising
about it, which is the carbon dioxide, which
takes up almost an entire lecture; and used
the phrase “which you do not see” which
is the first hint that that he’s going to,
you know, work at getting the invisible visible for us.
Bill: Yeah, in fact that’s going to come
up again and again throughout the lectures.
This is the first example using the shadows
where he makes the invisible visible, but
we’ll see examples of that throughout the
lectures.
Don: And this is one of the many times I think
both Bill and I were just fascinated by what
we saw, in that we actually see a shadow of
a flame, which never occurred to me that we
could do that, and what’s great about this,
as Faraday points out, is that the darkest
part of the shadow is actually the brightest
part of the flame.
Bill: And it’s worth making a tie to the
later lectures in that here he makes the observation
that the brightest part of the flame shows
up darkest in the shadow, but he also explained
in later lectures, that’s because there’s
incandescent particles, carbon particles that
are what give a flame its brightness.
Don: And in that last clip, we used some special
effects, so we could take photographs of the
flames above those candles. And we did this
because Faraday actually said that. He said
that we have to photograph these in order
to find out everything concerning them.
Bill: We were very surprised to hear him mention
photographs, and we found out that he was
very interested in photography, and in fact,
at the Royal Institution in January 1839,
he made the first public announcement in Britain
of the new art, which was to become photography.
Don: So now let’s listen to Faraday, as
he explains this demonstration that he used
with this sufficiently large flame.
Faraday: You have the air creeping in over
the edge of the dish forming these tongues.
Why, because through the force of the current,
and the irregularity of the action of the
flame, it cannot flow in one uniform stream.
The air flows in so irregularly that you have
what would otherwise be a single image broken
up into a variety of forms, and each of these
little tongues has an independent existence
of its own. Indeed I might say you have here
a multitude of independent candles.
Bill: Now, with that phrase “a multitude
of independent candles,” Faraday introduces
a kind of reasoning that he’ll use more
often throughout the remaining lectures, it’s
reductionism. In other words, it’s a way
to look for a unity in nature by reducing
it to some essential elements, and actually
making a philosophical point that these elements
are identical.
Don: And by elements here, we mean principles.
Notice, he’s not saying that this large
flame is of like independent candles, he is
saying you have here a multitude of independent
candles. So instead of just being an analogy,
he is actually equating the two.
Bill: And I think this is a good reminder
at the end of the lectures that while the
lectures appear to be about a candle, and
then ultimately about respiration that really
these lectures are an extended study in the
scientific method, in how you reason as a
scientist and how you ask questions. And in
fact at the very end here, he asks a series
of questions that then will be answered in
later lectures. And so as you’ll see here
at the end, this video series has a companion
volume, a companion book that goes with it,
it contains transcripts of all the lectures.
Don: And it also contains the lecture guides
written in contemporary language and includes
as well a set of activities that you could
do at home or at school.
Bill: And you’ll notice that there’s a
free PDF at the website, and that also you
can buy hardbound copies and paperbound copies
and electronic version. So I’m Bill Hammack.
Don: I am Don DeCoste.
Bill: And thanks for listening.
