Because the breath drives away the vapour of the grease which, becoming gaseous, supports the flame.
And because too rapid a flow of cold air reduces the temperature below the point at which combustion can be maintained.
260. Why will a gentle puff of breath, if given speedily after the flame is extinguished, rekindle it?
Because the oxygen of the air combines with the carbon and hydrogen that are still escaping from the heated wick, and re-lights it.
261. Why will not a similar puff rekindle the flame of a rushlight?
Because its wick retains but little heat, and holds a comparatively small amount of combustible matter in a volatile state.
262. Why is a fire, when it is very low, sometimes put out by blowing it?
Because the too rapid flow of cold air reduces the temperature of the burning mass.
263. Why will a piece of paper twisted like an extinguisher put out a candle?
Because, before the flame of the candle can ignite the paper, the oxygen contained within it is consumed, and the flame is suffocated.