Robert Boyle

Published the book that helped end alchemy — then lobbied Parliament to legalize transmutation so he could keep trying.

The Sceptical Chymist (1661) attacked the four-element theory and the three-prime Paracelsian theory, and argued chemistry needed to be built from reproducible experiments on definite substances — the founding text of modern chemistry. Boyle's gas law followed. So did the Royal Society norms of public, repeatable demonstration. And Boyle privately ran transmutation experiments his whole life, exchanged letters with Newton about a "philosophical mercury," and successfully lobbied to repeal the 1404 statute that had made transmutation illegal in England. The public methodology revolution stuck. The private gold project never delivered.