Some of mankind's best moments have been set around a fire – learning to cook, campfire stories, and s'mores. But on a chemical level, what is occurring? What processes is the wood that is burning undergoing? When wood is being heated to a level much higher than the boiling point of water, chemical degradation begins to occur.
If you continue to heat the wood, or increase the temperature that is is subjected to, the wood will begin to blacken and char. Considering that the fire has a good amount of oxygen to continue fueling it, wood will ignite when temperatures hit 500 degrees Fahrenheit. Should there be a lack of oxygen, gases will be driven off without a combustion, causing destructive distillation, otherwise known as pyrolysis, which produces charcoal. Add some oxygen and both the charcoal and wood will burn together; but until the temperatures reach 1,100 degrees Fahrenheit, not all of the gases will burn. Ignited gases can produce extremely high temperatures of up to 2,000 degrees Fahrenheit.
So how did wood come to be? It originally came from molecules synthesized by energy taken from the sun, which fueled the necessary chemical reactions to stimulate tree growth. These chemicals break down in instances of heat, and the energy within the tree is released as heat as well. When it comes to measuring fuel wood, the most widely recognized form of measurement is the standard cord, which is a four foot long pile stacked four feethigh and eight feet wide. An average cord contains about 80 cubic feet of solid wood and can weigh anywhere from one to two tons.
Most do not really need this much wood, so in cases of firewood, it is usually cut down to shorter lengths and sold in what is called a face cord, a four foot high by eight feet wide stack. Depth is equal to length. Almost all wood can be used well for fuel, so it is up to you to decide which you want to use. Keep in mind that different woods have different aromas, flame colors, and value. Make sure that the wood you choose is adequately dried to produce a great flame.