Air is a mixture of several
elements, mainly nitrogen, and
oxygen, and trace amounts
of the noble gases.
But this wasn't realised for
hundreds of years, and this is
because you can't see
these elements.
They're invisible.
But there's one element that has
such a beautiful colour in
the gas phase it was actually
named because of this.
And it was named by
Sir Humphry Davy.
Some experiments and
observations on a new
substance which becomes a
violet-colored gas by heat, by
Sir Humphry Davy, January
20, 1814.
"A new and very curious
substance has recently
occupied the attention
of chemists of Paris.
The substance appears as a
vapour of a beautiful violet
colour."
Davy notes that when the new
substance is exposed to liquid
ammonia a black powder is
formed which when dry,
fulminates by the slightest
contact or friction.
What he means is, when you
touch it, it explodes.
I'm trying to smear some of
this rather unpleasant
nitrogen triiodide, but it's
deeply unpleasant when dried
and incredibly unstable.
I've just come to check to
see how this is doing.
The problem is it needs to dry,
and it isn't going to
work until it's dried.
But the longer we leave it,
it could go off by itself.
So it's very nervous
at the moment.
[EXPLOSION]
[EXPLOSIONS]
Oh.
[INAUDIBLE].
But I felt that force right
in my stomach here.
That was a good cloud,
wasn't it?
So what we've just seen there is
the explosive decomposition
of nitrogen triiodide into
nitrogen gas and well, the
purple cloud of iodine vapour.
The explosion has sprayed
nitrogen triiodide everywhere,
so I feel rather sorry for
whoever is going to be in the
lecture theatre next.
[POPPING NOISES]
Ha, nothing's happening.
This is quite good though.
The suspense is good, isn't it?
Yeah.
Is it going to go?
Oh, your reaction is good.
[MUSIC PLAYING]
