Needless to say, don't try this at home.
Reshared post from +Yonatan Zunger
Because making the invisible visible is beautiful. And because fire.
In almost any fire, only the topmost layer of the flammable material — the area in direct contact with oxygen — is actually on fire. Even there, it often isn't the body of the fuel which is burning; instead, the heat of the fire is causing a small amount of the fuel to evaporate, and it's the fuel vapor that burns.
(That's how both wood and gasoline fires work; in their solid and liquid states, respectively, the forces holding them in place are strong enough that they suppress the burning reaction. This is why it takes a while for wood to catch fire: you're using the fire to heat the wood enough to make it give off pre-soot, and that's what actually catches fire. If there's water, it will absorb a tremendous amount of the heat energy without itself heating up (see https://plus.google.com/+YonatanZunger/posts/hhDyY4DjuLv) and thus prevent the fire from spreading. This is why water is used to put out fires.)
There are a few exceptions, but they're unusual: things like monopropellant rocket fuels which contain both the fuel and the oxidizer inside them, thoroughly mixed, so that the entire thing can burn if ignited. But even in a normal rocket engine, it's only a small bit of the fuel that's burning at a time — or if not, you are having a big problem and you will not go to space today.
http://i.imgur.com/0w87emS , via +Effie Seiberg.
Very cool demonstration! But I have a scar on my left hand from when my brother tried something like this when we were kids. He needed surgery to get the glass splinters out of his abdomen.
@George – Yeah, it’s not something I’d recommend (even if I knew exactly what was being ignited). Too many variables.
Surprised enough oxygen could enter the bottle to keep the reaction going.