A. Carbon (being very solid) requires a great degree of heat to make it unite with the oxygen of the air. When fresh coals are put on, their _under_ surface is heated before the upper surface; and one is _red_ (or in a state of combustion), while the other is _black_. 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. Q. _Why are there DARK and BRIGHT SPOTS in a CLEAR cinder FIRE?_ A. Because the _intensity_ of the combustion is _greater in some parts_ of the fire, than it is in _others_. Q. _Why is the intensity of the combustion so unequal?_ A. Because the air flies to the fire in various and unequal currents. Q. _Why do we see all sorts of GROTESQUE FIGURES in hot COALS?_ A. Because the _intensity_ of combustion is so _unequal_, (owing to the gusty manner in which the air flies to the fuel; and the various shades of red, yellow, and white heat mingling with the black of the unburnt coal), produce strange and fanciful resemblances. Q. _Why does PAPER BURN more readily than wood?_ A. Merely because it is of a _more fragile texture_; and, therefore, its component parts are more easily heated. Q. _Why does WOOD BURN more readily than coal?_ A. Because it is not so _solid_; and, therefore, its elemental parts are more easily separated, and made hot. Q. _When a FIRE is LIGHTED, why is PAPER laid at the BOTTOM, against the grate?_ A. Because paper (in consequence of its fragile texture), so very readily catches fire. Q. _Why is WOOD laid on the top of the paper?_ A. Because wood, (being more _substantial_), _burns longer_ than paper; and, therefore, affords a _longer contact of flame_ to heat the coals. Q. _Why would not paper do without wood?_ A. Because paper burns out so _rapidly_, that it would not afford sufficient _contact of flame_ to heat the coals to combustion. Q. _Why would not WOOD do WITHOUT shavings, straw, or paper?_