When the candle burns, a glass tube is inserted into the inner layer of the flame and smoke comes out.

In fact, when the candle burns, the unburned part below changes from solid to gas when heated, that is, smoke is solid particles condensed by candle vapor. So "ignite the smoke escaping from the glass nozzle with a burning match, and what you see is that" the smoke can be ignited. The possible substance in green smoke is gaseous paraffin.

Jing Rui Education Changning Tianshan Mountain