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.