Imagine an isolated cilindrical Leyden jar. A Leyden jar is something like a big capacitor, and normally, the external plate is grounded as we charge. But now, imagine this Leyden jar is not grounded, and you go charging the external plate. Finally, you'll have excess charge on the external plate. Now imagine you connect externally the external and the internal plate. Will the excess charge hold on the external plate, or will it spread along both plates?