This zinc plate has been allowed to corrode all the way through in places. The original batteries made to produce electricity in the 1830s were made by hanging a plate of copper and one of zinc in a solution of copper sulphate. Thomas Spencer observed that copper was deposited on the copper plate (the cathode, negative pole) and that the zinc (anode, positive pole) was etched.He and John Wilson patented this process in 1840.
This plate was made by shorting out such a battery.
