Combustion Releases Phlogiston, an Invisible Fire-like Substance

For much of the 18th century, phlogiston theory was *the* dominant framework for understanding combustion, and Britannica's early editions dutifully recorded it. Phlogiston seemed to explain why wood loses mass when burned, and why some materials burn while others don't. The fatal flaw? Metals gain weight when burned, which contradicts the theory, yet phlogistonists invented epicycles like 'negative weight phlogiston' to preserve the model. Antoine Lavoisier's oxygen-based chemistry, published around 1785, offered precise measurements and consistency. The transition took decades because phlogiston had decades of institutional momentum behind it, but by the 1800s editions, Britannica's chemical articles had largely converted to the new paradigm.