BTT, and thank you for a fascinating item. Ben also developed the beginnings of the modern battery and proved in Paris that a fellow in his 70's could cuckold a generation of young Frenchmen. My hero!
I believe he was the first to intuit that the charge in a Leyden jar remained on the glass container and proved it by statically charging the jar, dumping out its electrolyte and refilling to show that the cell remained fully charged until shorted to drain.