Influence of the Hellenic mind on the development of chemistry. Origin of the idea of the transmutation of metals. Philosophical foundation for the belief in alchemy. Alchemistic theory of the nature of metals. Origin of the conception of the Philosopher’s Stone. Geber. Association of alchemy with astrology. Rhazes. Avicenna. Chemical processes and substances known to the Arabian chemists. The Western Alchemists. Albertus Magnus. Roger Bacon. Raymond Lully. Arnoldus Villanovanus. Johannes de Rupecissa. George Ripley. Basil Valentine. CHAPTER IV THE PHILOSOPHER’S STONE 46 Alchemy in the Middle Ages. Association of religion with alchemy by the Christian Church. Alleged nature of the Philosopher’s Stone. Its character described. Its power. The Universal Medicine. The Elixir of Youth. The Alkahest. Opponents of alchemy: Erastius, Conringius, and Kircher. “The Hermes of Germany”: Rudolph II. Christian princes who had dealings with alchemists. Fate of certain alchemists. Persistency of alchemy and hermetic societies. Lord Bacon on alchemy. CHAPTER V IATRO-CHEMISTRY 57 Theories of the iatro-chemists. Paracelsus. Doctrine of the _tria prima_. The Paracelsian harmonies. Libavius. Van Helmont. Sylvius. Willis. Services of iatro-chemistry to science. Influence of iatro-chemistry on technology. Agricola. Palissy. Glauber. Chemical products made known by the alchemists. CHAPTER VI “THE SCEPTICAL CHEMIST”: THE DAWN OF SCIENTIFIC CHEMISTRY 70 The foundation of the Royal Society and other scientific academies. The appearance of “The Sceptical Chemist”: its attack on the doctrines of the Spagyrists. Boyle: his life and character. His services to learning. Kunkel. Becher. Mayow. Lemery. Homberg. Boerhaave. Stephen Hales. CHAPTER VII PHLOGISTONISM 91 Becher’s hypothesis of the _Terra Pinguis_. Its development into the theory of phlogiston. Stahl. Phlogiston, primarily a theory of combustion, becomes a theory of chemistry. Its general acceptance in Europe until the last quarter of the eighteenth century. Prominent phlogistians. Pott. Marggraf. Scheele: his discoveries. Duhamel. Macquer. Black: his essay on _Magnesia Alba_. Recognition of the individuality of carbon dioxide. Priestley: his life and character. His discoveries in pneumatic chemistry. His observations on the influence of vegetable life on the character of the atmosphere. Cavendish: his life and work. Discovery of composition of water. Influence of phlogistonism on the development of chemistry. Advances made during the period of phlogistonism. CHAPTER VIII LAVOISIER AND LA RÉVOLUTION CHIMIQUE 109