Words enter language and sometimes words disappear-often as quickly as they appeared. In the transition from the ancient ideas of the ‘four elements’ of earth, air, fire and water, to the modern Periodic table, scientists struggled to understand basic chemical reactions such as oxidation. In 1730 the word phlogiston entered the scientific vocabulary, meaning a hypothetical inflammatory principle, formerly believed to exist in all combustible matter, and later extended to cover reactions such as oxidation. The word came from Modern Latin around 1702, which came from the Ancient Greek word phlogiston(1610s in this sense), neuter of phlogistosmeaning burnt up, inflammable, from phlogizein, to set on fire, burn, which came from from phlox (genitive phlogos) flame, blaze. The theory was propounded by German chemist George Ernst Stahl in 1702, denied by French chemist Antoine Lavoisier by 1775, defended by English theologian and chemist Joseph Priestley but generally abandoned by 1800. When Lavoisier composed the word oxygen in 1777 (in French, oxygen entered English in 1790), he was reacting to and rejecting the idea of phlogiston, composing his word from the Ancient Greek word oxys meaning sharp or acid and the -gene suffix used to indicate the origin or formation of something. The word was meant to mean ‘acidifying principle’ because it was considered essential in the formation of acids, though has since been shown not to be true. In fact, when Priestley isolated oxygen for the first time in 1774 he called it deplhogisticated air, but Lavoisier’s endeavors meant the end of the phlogiston.
Image of iron oxidation courtesy Dustin Jamison, used with permission under a Creative Commons 3.0 License.