Carl Wilhelm Scheele

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Carl Wilhelm Scheele (9 December 1742 – 21 May 1786) was a German-Swedish pharmaceutical chemist. Isaac Asimov called him "hard-luck Scheele" because he made a number of chemical discoveries before others who are generally given the credit. For example, Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, and chlorine before Humphry Davy.

Contents

Biography

Scheele was born in Stralsund, Western Pomerania, Germany (at the time under Swedish rule). Instead of becoming a carpenter like his father, Scheele decided to become a pharmacist. His career as a pharmacist began with his apprenticeship at an apothecary in Gothenburg when he was only fourteen years old. He retained this position for eight years before becoming an apothecary's clerk in Malmö. Then Scheele worked as a pharmacist in Stockholm, from 1770-1775 in Uppsala, and later in Köping.

Existing theories before Scheele

By the time he was a teenager, Scheele had learned the dominant theory of gases in the 1770s, the phlogiston theory. Phlogiston, classified as "matter of fire", was supposed to be released from any burning material, and when it was exhausted, combustion would stop. When Scheele discovered oxygen he called it "fire air" because it supported combustion, but he explained oxygen using phlogistical terms because he did not believe that his discovery disproved the phlogiston theory. Before Scheele made his discovery of oxygen, he studied air. Air was thought to be an element that made up the environment in which chemical reactions took place but did not interfere with the reactions. Scheele's investigation of air enabled him to conclude that air was a mixture of "fire air" and "foul air;" in other words, a mixture of two gases. He performed numerous experiments in which he burned substances such as saltpeter (potassium nitrate), manganese dioxide, heavy metal nitrates, silver carbonate and mercuric oxide. In all of these experiments, he isolated gas with the same properties; his "fire air," which he believed combined with phlogiston to be released during heat-releasing reactions. However, his first publication , A Chemical Treatise on Air and Fire, was not released until 1777, at which time both Joseph Priestley and Lavoisier had already published their experimental data and conclusions concerning oxygen and the phlogiston theory.

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