Combustion is the process of burning a substance to create heat, and often, light. It involves a chemical reaction between a fuel and an oxidizing agent which is usually oxygen. Combustion is typically associated with fire--the first chemical reaction that people discovered how to create and control more than a million years ago. Besides using fire for cooking, people learned to harden clay into pottery, produce metal from ores found in the ground, and melt metals together to make new materials. Because fire was capable of bringing about such dramatic changes, the ancient Greeks and early chemists (called alchemists) considered fire to be one of the four basic elements of nature from which all other things are made.

Before the Middle Ages, Arabic tribes conquered much of Asia and Africa, and their culture inherited many Greek scientific ideas. At the height of Arabic power during the 700s, an...