Q. What causes the combustion of the fuel?
A. The hydrogen gas of the fuel being set free, and excited by a piece of lighted paper, instantly unites with the oxygen of the air, and makes a yellow flame: this flame heats the carbon of the fuel, which also unites with the oxygen of the air, and produces carbonic acid gas.
Q. What is carbonic acid gas?
A. Only carbon (or charcoal) combined with oxygen gas.
Q. Why does fire produce heat?
A. 1st—By liberating latent heat from the air and fuel: and
2ndly—By throwing into rapid motion the atoms of matter.
Q. How is latent heat liberated by combustion?
A. When the oxygen of the air combines with the hydrogen of the fuel, the two gases condense into water; and latent heat is squeezed out, as water from a sponge.
Q. How are the atoms of matter disturbed by combustion?