Birch bark, which is found in many parts of the U.S., Canada, Europe and China, is a great way to start a campfire. Rich in terpenoids, the paper-thin material ignites easily. The heat it releases provides enough activation energy to set small twigs ablaze, which of course should be placed in a tee-pee arrangement, so as to let in more oxygen. All of this should take place in a pit surrounded by stones, not to let wind take heat away from the young fire and not to burn the forest down.
The hues of a flame are rarely constant for a second, a hint that something complex is occurring within them. There is a set of chain mechanisms involving intermediate molecules that are needed for subsequent steps. Many of the in-between products are radicals, reactive molecules with unpaired electrons. Radicals are often created in the high temperature regions of the flame, but…