18th Century Pioneer

Henry Cavendish (1731 – 1810).  England.
 
Cavendish discovered for himself that the force between a pair of electrical charges is inverse to the square of the distance between them, a basic law of electrostatics subsequently established by Coulomb. Cavendish preceded Michael Faraday in demonstrating that the capacity of a condenser depends on the dielectric inserted between its plates. (A dielectric is non metallic). He used the concept of “potential” in developing the idea that all points on the surface of a good conductor are at the same potential with respect to a common reference, the Earth. This concept was important for the further development of electrical theory.

He discovered that the potential across conductors was directly proportional to the current through them, thus preceding the law proposed by Ohm in 1827. Cavendish also compared the electrical conductivity of equal solutions of electrolytes.

He did not publish his experiments on electricity. His research was subsequently repeated, after the discovery of his notebooks and manuscripts over a century later, by the Scottish mathematical physicist, James Clerk Maxwell, who devoted the last five years of his life to the task and published an annotated version of the electrical papers of Cavendish in 1879.

Reference:  Encyclopedia Britannica on line.