He discovered and named "diamagnetism" prior to his work in electrochemistry, where his namesake constant gives the number of coulombs in a mole of electrons.  
The first to liquefy chlorine, this scientist's namesake rotator is useful in optical isolators.  He discovered and named "diamagnetism" prior to his work in electrochemistry, where his namesake constant gives the number of coulombs in a mole of electrons.  He had to take five years off in the early 1840s due to headaches that may have been caused by mercury poisoning, but he came roaring back and gave an 1846 lecture on "Ray Vibrations" that became the basis for Maxwell's electromagnetic theory of light.  The discoverer of benzene, he argued that equal currents gave rise to equal amounts of decomposition, which summarizes his first law of electrolysis.  FTP, name this British scientist, best known for his work in physics indicating that a change in magnetic flux induces an electromotive force.
The first to liquefy chlorine, this scientist's namesake rotator is useful in optical isolators.  
Michael Faraday