From an early age, Boulton had interested himself in the scientific advances of his times. He discarded theories that electricity was a manifestation of the human soul, writing "we know tis matter & tis wrong to call it Spirit". He called such theories "Cymeras of each others Brain". His interest brought him into contact with other enthusiasts such as John Whitehurst, who also became a member of the Lunar Society. In 1758 the Pennsylvania printer Benjamin Franklin, the leading experimenter in electricity, journeyed to Birmingham during one of his lengthy stays in Britain; Boulton met him, and introduced him to his friends. Boulton worked with Franklin in efforts to contain electricity within a Leyden jar, and when the printer needed new glass for his "glassychord" (a mechanised version of musical glasses) he obtained it from Boulton.