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Guillaume Rouelle, French Chemist
Guillaume Francois Rouelle (September 16, 1703 - August 3, 1770) was a French chemist and apothecary. In 1754 he introduced the concept of a base into chemistry, as a substance which reacts with an acid to give it solid form (as a salt). He is known as l'Ain̩ (the elder) to distinguish him from his younger brother, Hilaire Rouelle, who was also a chemist and known as the discoverer of urea. During 1742-68 he was a chemical demonstrator at the Jardin du Roi, Paris. He was an enthusiastic lecturer and taught most of the French chemists of the late 18th century; Denis Diderot, Antoine-Laurent de Lavoisier, Joseph Proust and Antoine-Augustin Parmentier. Rouelle believed in Stahl's incorrect phlogiston theory of combustion. Phlogiston was a flammable component of materials which was supposedly given off when they burned. This theory was disproved by Lavoisier. Rouelle was elected a foreign member of the Royal Swedish Academy of Sciences in 1749. He died in 1770 at the age of 66. Engraving from "Vies des savants illustres" by Louis Figuier. This image has been color enhanced.
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