Source on Joseph Priestley

“Priestley thought he had stumbled across a crucial observation: "mephitic" air... was a conductor of electricity... only to discover in the coming weeks... condensed water in the glass... but the experiment led him to one of his most important contributions to the science of electricity: the addition of charcoal to the then short list of substances... capable of conduction, alongside water and metal.”

“Why did the problem of air become visible..? Why were Priestley, Boyle and Black able to see the question clearly enough..? ...because they had new tools. The air pump designed by Otto von Guericke and Boyle (...in collaboration with his assistant Robert Hooke...) were essential to Priestley's lab in Leeds. ...In a way, the air pump had enabled the entire field of pneumatic chemistry in the seventeenth century... [T]he air pump allowed you to... create a vacuum, which behaved markedly differently... even though air and the absence of air were visually indistinguishable.”

“The Royal Society... voted to award him the Copley Medal, the most prestigious scientific prize of its day, "on account of the many curious and useful Experiments contained in his observations on different kinds of Air." In receiving the prize, Priestley was joining the ranks of his friends Canton and Franklin... Only five years after they had encouraged him to turn his experimental hobbies into a serious vocation, Priestly had reached the highest pinnacle of scientific achievement.”