1729 -- Stephen Gray demonstrates the difference between conductors and non-conductors (insulators).
1732 -- C. F. du Fay Shows that all objects, except metals, animals, and liquids, can be electrified by rubbing them and that metals, animals and liquids could be electrified by means of an electrostatic generators
1737 -- C. F. du Fay and Francis Hauksbee the younger independently discover two kinds of frictional electricity: one generated from rubbing glass, the other from rubbing resin (later identified as positive and negative electrical charges).
1746 -- Leonhard Euler develops the wave theory of light refraction and dispersion
1747 -- William Watson, while experimenting with a Leyden jar, observes that a discharge of static electricity causes electric current to flow and develops the concept of an electrical potential (voltage).
1806 -- Alessandro Volta employs a voltaic pile to decompose potash and soda, showing that they are the oxides of the previously unknown metals potassium and sodium. These experiments were the beginning of electrochemistry.