Guillaume-François Rouelle

Guillaume François Rouelle (French pronunciation: [ɡijom fʁɑ̃swa ʁwɛl]; 15 September 1703 – 3 August 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 form a salt.

He is known as l'Aîné (the elder) to distinguish him from his younger brother, Hilaire Rouelle, who was also a chemist and known as the discoverer of urea.

Rouelle started as an apothecary. He later started a public course in his laboratory in 1738, in 1742 he was appointed experimental demonstrator of chemistry at the Jardin du Roi in Paris. he was especially influential and popular as a teacher, and taught many students among whom were Denis Diderot, Antoine-Laurent de Lavoisier, Joseph Proust and Antoine-Augustin Parmentier.

He was elected a foreign member of the Royal Swedish Academy of Sciences in 1749.

In addition to his investigation of neutral salts, he published papers on the inflammation of turpentine and other essential oils by nitric acid, and the methods of embalming practised in Ancient Egypt.