Q. Which burns the quicker, a blazing fire, or a red hot one?
A. A blazing fire burns out the fuel quickest.
Q. Why do blazing coals burn quicker than red hot ones?
A. In red hot coals, only the mere surface is in a state of combustion, because the carbon is solid; but in a blazing fire, (where the gases are escaping), the whole volume of the coal throughout is in a state of decomposition.
Q. What is smoke?
A. Unconsumed parts of fuel (principally carbon), separated from the solid mass, and carried up the chimney by the current of hot air.
Q. Why is there more smoke when coals are fresh added, than when they are red hot?
A. Carbon (being solid), requires a great degree of heat to make it unite with oxygen, (or, in other words, to bring it into a state of perfect combustion): when coals are fresh laid on, more carbon is separated than can be reduced to combustion; and so it flies off in smoke.
Q. Why is there so little smoke with a red hot fire?
A. When a fire is red hot, the entire surface of the coals is in a state of combustion; so a very little flies off unconsumed, as smoke.