This trick amazed and astounded us. Our friend Keith Riggs lit a candle, blew it out, and re-lit the candle by lighting the smoke, not the wick of the candle.
This trick was the subject of study for my cousin, Seth Thompson, in one of his chemistry classes at CSU. They were asked to break down why this event occurred on a molecular level. Here is his explanation:
1) When you are burning a candle, you are essentially vaporizing the liquid wax into a gas that is flammable. This vapor can then be used as fuel for the candle flame. It is this vaporized wax that fuels all candle flames used with conventional wax based candles.
2) If you blow out the candle, you have put out the flame on the wick but there is still vaporized wax that is in the air that can be used. You cannot see this vapor, but it will travel in the same direction as the smoke.
3) Therefore, as you hold a flame close to the smoke it will light the unused wax vapor that is in the smoke. It will then follow the fuel (wax vapor) all the way back to the candle wick where there will be enough fuel for the candle too continue burning like it was before you blew it out.