Combustion was a type of chemical reaction in which an item was consumed by fire. Some forms of engines utilized combustion to operate. Byproducts of combustion included thermal radiation and carbon dioxide. In , Data reported several areas of combustion on the planet Gamma Hromi II, which Wesley Crusher simplified as indicating campfires. (TNG: "The Vengeance Factor" ) Powder burns were caused by the depositing of products of combustion on the skin and clothing of dead individuals, a fact Odo learned from reading 20th century crime novels. (DS9: "Field of Fire")