# Phenomenon where fumes can relight an extinguished flame

I lit a mosquito coil and used it to melt down small down candle wax which had fallen on the floor. The coil then produced some dense fumes. I directed the fumes to the flame of a candle. As soon the fumes reached the candle, my coil caught fire again and started burning. I mean the flame actually traveled the path of the fumes and re lit my mosquito coil. I just wanted to know what this phenomenon is called? Why does this happen?

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Welcome to Chemsitry.SE! This is an interesting question, and it has already attracted an answer. I edited your question to make it a little more readable and to remove some of your self-deprecating comments. You don't need to feel bad about something you don't know. I don't know what this phenomenon is either, nor how it works. –  Ben Norris Feb 22 '13 at 21:08
@BenNorris I tried to work with the title a bit, please reedit if you think I didn't capture the spirit of it. –  jonsca Feb 24 '13 at 22:26

## 1 Answer

It looks like you accidentally created a combustion mixture. I checked the Material Safety Data Sheet (MSDS) for several mosquito coils, and in addition to the insecticide, one of them also contained the oxidizer potassium nitrate $\ce{(KNO3)}$. The burning candle likely had some vaporized paraffin (fuel) in the flame, so when you directed the $\ce{KNO3}$ vapor into the flame, you had heat + fuel + oxidizer = combustion! You literally set that vapor on fire. I'd be careful with that: although the MSDS indicated a small amount of $\ce{KNO3}$ in the coil, you could still be injured if you were not prepared.

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To add to this, the reverse can also happen - it is quite easy to relight a very recently extinguished candle through its vapour. –  Richard Terrett Feb 23 '13 at 3:22
@trb456 thanks..but does the distance really matter in this? i mean suppose i stand somewhere far and direct those fumes will it still catch fire? is there a word for the vapor catching fire(is it some phenomenon?) –  sin Feb 23 '13 at 6:31
I don't think it matters specifically that the vapor caught fire. What matters are the conditions of the system: you provided an oxidizer in the vapor along with heat and fuel from the candle. That trio, no matter how it comes together, means combustion, which is why you need to be careful whenever you know you have two of the three in close proximity. –  trb456 Feb 23 '13 at 11:58