Considerations on combustion and fire behaviour of materials: A change of mind during the 18th century

Abstract

Our knowledge of fire has advanced rapidly over the last few decades to a point where we now have a good understanding of the complex interactions between combustion chemistry, fluid dynamics and heat transfer. It took many centuries before the basic principles were resolved and we should not forget the remarkable achievements of early generations of scientists in the 17th and 18th centuries. This article traces the ideas that led to the development of our understanding oxidation, combustion and fire, from the age of the alchemist to the discovery of oxygen at the end of the 18th century. Fire was first understood in terms of its chemical aspect before its thermal one, but the discovery took time, as earlier theories adopted by alchemists were only replaced at the end of the 17th century by the ‘phlogiston’ theory from Becher and Stahl. This theory has been replaced less than a century after by the actual theory of oxidation, established on the basis of a rigorous theoretical and experimental work from Lavoisier and the discovery of oxygen by Priestley. In a few years, this theory passed from being marginal and resisted strongly by partisans of phlogiston, to being the only one commonly adopted. This history is an excellent example of how science advances, with conflicting theories being tested until one gains general acceptance after careful experimental work and subjection to the peer-review process.