Carl Wilhelm Scheele - Disproving The Theory of Phlogiston

Disproving The Theory of Phlogiston

Historians of science no longer question the role of Carl Scheele in the overturning of the phlogiston theory. It is generally accepted that he was the first to discover oxygen, among a number of prominent scientists (namely his esteemed colleagues Antoine Lavoisier, Joseph Black, and Joseph Priestley). In fact, it was determined that Scheele made the discovery three years prior to Priestley and at least several before Lavoisier. Joseph Priestley relied heavily on Scheele's work, perhaps so much so that he would not have made the discovery of oxygen on his own. Correspondence between Lavoisier and Scheele indicate that Scheele achieved interesting results without the advanced laboratory equipment that Lavoisier was accustomed to. Through the studies of Lavoisier, Joseph Priestley, Scheele, and others, chemistry was made a standardized field with consistent procedures. Although Scheele was unable to grasp the significance of his discovery of oxygen, his work was essential for the invalidation of the long-held theory of phlogiston.

Scheele's study of the gas not yet named oxygen was prompted by a complaint by Torbern Olof Bergman. Bergman informed Scheele that the saltpeter he had purchased from Scheele's employer produced red vapors when it came into contact with acid. Scheele's quick explanation for the vapors led Bergman to suggest that Scheele analyze the properties of manganese dioxide. It was through his studies of manganese dioxide that Scheele developed his concept of "fire air." He ultimately obtained oxygen by heating mercuric oxide, silver carbonate, magnesium nitrate, and other nitrate salts. Scheele wrote about his findings to Lavoisier who was able to see the significance of the results.