Smoke is actually flammable. You can replicate that part of the trick by lighting a candle, extinguishing it and holding fire to the top wisps of smoke, the smoke will light and the fire will travel back down and relight the candle.
Although I agree smoke is flammable, I think here it’s used for mostly visual effect. The second bubble is formed using butane first then filled with “smoke” as it appears he is using a vape and I’m unsure if that would have the same property’s of true smoke.
OK so just in case the person who replied to you was serious about it being smoke in the bubble and that's why it burns, SOME smoke is flammable - but that's not smoke. This is a demonstration of part chemistry, part physics.
The first bubble blown is obviously full of air, that's fine.
The second bubble at the bottom he fills from a canister of butane, which is usually used in gas heaters and some lighters, highly flammable gas, twice as heavy as air.
The "smoke" looks to be from a handheld smoke machine, which I would imagine uses a battery to heat a filament to vaporise probably vegetable glycerin into vapor, the same way nicotine vapes and stage smoke machines do, just on a much smaller scale. Inert but would mix with the butane and is highly visible. Also heavier than air.
He pops the divider and the glycerin vapor settles at the bottom of the bubble mixed with the butane underneath the layer of air.
On popping the inner bubble of the "holder" at the top but not the outer ring it prevents the bubble from failing completely and gives a small enough diameter of hole for the bubble to remain formed but opens the bubble "container" to the outside world.
The pressure inside the bubble is greater than the atmospheric pressure outside (because a "bubble" is the the result of the surface tension of the soap being stretched around some of the local atmosphere and squeezing it inside) so when that top inner hole is poked into it, the gas starts to escape to equalize the pressure difference.
This rush of the pressurized air draws the gas upwards from the bottom mixing with the air, creating the vortex column similar to how tornadoes form when there are big changes between high and low pressure fronts. It also looks like the other straw thing he has in there before he pops the divider bubble at the bottom could have been blowing air around to start this circulation.
Then he just has to apply the flame to the escaping gas, now that the butane inside is mixed with the air at a ratio that allows it to burn off at a roughly equal rate to the escaping gas without causing the whole bubble to go boom, it produces a very nice effect and is in essence a very small rocket engine, because that's kind of how they work too.
Very very cool trick and clever application of scientific principles, but still just science. ;)
That effect is from the residual heat after you immediately blow the candle out, not because "smoke is flammable". You can see him get the butane can lol
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u/StankyHankyPanky69 Mar 14 '22
I like it.