Fire can be one of man's worst enemies, or one of his best friends.
To find out about fire, let's talk to a scientist who has devoted his life to it, Dr.
Louis Allen Heard.
Dr.
Heard? Excuse me, but you startled me.
My goodness, doctor, do you do that often? No, only when I want to let off a little steam.
I see.
Dr.
Heard, just what is fire? Well, a fire results from a chemical reaction.
A fuel unites with oxygen.
Really, we need three things.
First, a fuel, then some oxygen, and third, sufficient heat to get the fire started.
If, for instance, I like this piece of tissue paper, it gets its oxygen from the air and burns up.
But if I take a piece of the same kind of paper and roll it up into a ball, the air has a hard time getting at it, so we don't get a fire.
Now, this block of wood won't burn very well because it has so little surface exposed to the oxygen.
But if we grind up some wood into some very fine sawdust, such as I have in this tube, and then blow this sawdust into an open flame, we get some real action.
Now, that's what happens in the dust explosion that you read about.
A man found that even oil is hard to burn, so he invented the wick to expose more of the oil to the air.
Now, this wick is made of glass, so it can't burn.
It just increases the surface of the fuel.
Nowadays, we do even better.
We spray the oil, and so get many tiny droplets, each surrounded by air.
This gives a good hot flame, as in the oil furnace.
Now, if I try to burn this steel bolt, it won't catch fire, and you didn't expect it would in the first place.
But if I take a piece of steel wool, even steel will catch fire if enough surface is exposed.
A fire is a result, really, of oxidation.
But here's an example of an oxidation that does not result in a fire.
It's going on in this mixture of liquids right now.
If I say a magic word like petroleum, now there's an oxidation without flame or smoke.
Most fires get their oxygen from the air, which contains about 20 percent oxygen and 80 percent nitrogen.
Now, this flash contains air, and we see that when the oxygen is all used up, the flame goes out.
But if we put this plant in a flash containing pure oxygen, it will burst at once from just a glow into a bright flame.
To build more useful fires, we sometimes take advantage of several of these principles.
Take magnesium, another metal which burns, brightly but kind of slowly.
To make it burn faster, we do two things.
Turn it into a very fine wire to expose more surface, and then surround it with pure oxygen, and you get a quick, very bright light.
That light has a valuable use.
Thank you.
Yes, a very valuable use indeed.
Now about starting the fire.
Some fuels take fire much more easily than others.
Here we are generating a gas called phospene.
The temperature of this room is sufficient to cause it to take fire.
It's too bad we can't use it in cars.
We could have automobiles running about blowing smoke rings at each other.
Scientific research can lead to many strange things.
Petroleum products can vary from peculiar stuff like this.
The gas, which you can't even see, but which is the most excellent fuel, and somewhere in between is the ideal fuel for your automobile.
Now here is a component from gasoline that we call heavy ends.
We'd like to burn this if we could because it contains lots of energy, but we can't even ignite it with a match.
And here is another fraction from gasoline that we call light ends, made up of small molecules which readily turn to vapor.
We can ignite this quite easily.
So we mix light ends and heavy ends to obtain the perfect blend.
A gasoline which is quick starting, it has lots of power.
Speaking of quick starting, here's a convenient fuel to have around the house when the electricity fails and you don't have a match.
Hmm, something wrong here.
Well, she certainly got a warm personality.
Now here's something that's much like a fire yet isn't a fire.
We mix sulfuric acid and table sugar, and in a moment we see steam and a black char of carbon.
That wasn't quite a fire, but we can burn sugar by mixing it with a substance containing oxygen.
No, no reaction.
Well, perhaps we need a catalyst.
A catalyst is a substance that speeds up chemical reactions between other substances.
I have here a very powerful catalyst, and I'll add just one drop of this powerful catalyst to the mixture.
The catalyst in this case is water.
You may have another catalyst handy that you don't know about.
Suppose we try to burn a lump of table sugar.
It doesn't take fire, but if we add a few cigarette ashes to it, they can't burn.
They've already burned, but they do contain something in the way of a catalyst that lets the sugar burn.
You can try this one yourself.
Up to here we've talked about fire, but not about any of the combustion.
If you burn gasoline, for instance, you get water and carbon dioxide.
Now here's an unusual type of combustion.
Hydrogen gas uniting with chlorine gas instead of with oxygen.
The I'll get the heat from this infrared lamp.
No reaction, so let's try ultraviolet light as a catalyst.
Well, the ultraviolet light caused an ultraviolet reaction.
Dr.
Hurd, tell me just what is the purpose of your research on fire? Well, it's very simple.
You see, in today's automobiles, it's actually fire power that drives your car.
An eight -cylinder engine at 60 miles an hour builds 9 ,600 fires every minute, and each fire must be just right.
From this research has come huge catalytic cracking units.
They are one reason why two gallons of today's gasoline do the work that took three gallons 30 years ago.
But now let's relax and blow some soap bubbles.
Funny, but I lose more fingers that way.
But I still hope that I can hold a paintbrush.
As usual, fire has the last word.
