Explosions: How We Shook the World Page #4

---

the reaction can happen more quickly, and as the reaction happens more quickly,

more heat's created, making the reaction go even faster and it's a runaway process.

Right.

With gas being produced so quickly and heat making it expand,

there's the potential for explosive force,

if I can channel it like the Chinese did.

This is my first attempt at a cannon.

I've decided to build it out of clear acrylic

so that we get to see what happens inside a cannon.

Now, I'll drop that on there.

That fits in nicely.

Got my cannonball.

So there it is. There's going to be an explosion in there.

That explosion will produce hot, expanding gas.

There'll be a big pressure rise in that part of the chamber.

That pressure will exert a force all around the container,

but these three sides should stay where they are.

This fourth side here, where the tennis ball is,

won't stay where it is, and that tennis ball will leave at

an undetermined speed that I suspect will be pretty quick.

Let's find out.

Three, two, one!

Yeah, that worked like a cannon should work.

Wow!

You can see how the gunpowder produces hot gases

at just the right rate

to push the ball out.

This technology quickly spread west, through the Middle East,

and by the 14th century, the Europeans had rockets and guns too.

But something else was happening - gunpowder was spreading beyond the battlefield.

Its power was being put to work in mines and engineering projects,

as Europe became more industrialised

and there was demand for more powerful and destructive explosions.

Gunpowder had reigned for 500 years,

but now its dominance was about to be challenged.

The middle of the 19th century provided a turning point

in the story of explosives.

I've had to come here, to the Defence Academy of the UK,

because we're going to make what they first discovered in 1846.

There was a growing tradition of pure scientific research in Europe,

with researchers trying to understand the chemical composition of natural substances.

One of these chemists was a German from a humble background called Christian Schonbein.

He was naive, unconventional and full of original ideas.

Working in Switzerland, he'd seen some unusual reactions with

concentrated acids and was keen to investigate them further.

One of those investigations was unwittingly to change the world of explosives forever.

Professor Jackie Akhavan has volunteered to show us

exactly what Schonbein did.

Jackie, what are we actually doing here?

OK, we're mixing nitric acid and sulphuric acid together

and then we're going to add some cotton wool to it,

to hopefully nitrate the cotton wool.

Schonbein didn't know it, but the cotton will be acting

Rate this script:0.0 / 0 votes