The gas rises from the wick for a short time after the flame is blown out, and it is this gas which lights when you bring the match down toward the wick.
Experiment 71. Air used by flames.
FIG. 94
THE CANDLES GO OUT AND THE WATER RISES
Drop melted candle wax on a tin can cover and attach the bottoms of two candles to the cover (Fig. 94); use one candle about 4 inches long and another about 3 inches, stand them upright in a pan of water, light them, and invert a wide-mouthed bottle over them. Does some air escape at first due to expansion, do both candles go out, the taller one first, and does the water rise until the bottle is about one-fifth full?
FIG. 95
THE CORK RISES
Cut a piece of candle ½ inch long, float it on a flat cork or can cover in the pan of water, light it, and invert a fresh empty bottle over it (Fig. 95). Is the result similar?
The “why” of it
The water rises in the bottle because ⅕ of the air is used up by the burning candle. Air is ⅕ oxygen and ⅘ nitrogen. The oxygen unites with the burning gas of the candle and produces water vapor (H2O) and carbon dioxide (CO2); the nitrogen takes no part in the burning.