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]