Coin current

Place several copper coins and pieces of sheet zinc of the same size alternately above one another, and between each metal pair insert a piece of blotting paper soaked in salt water. Electrical energy, which you can detect, is set free. Wind thin, covered copper wire about 50 times round a compass, and holds one of the bare ends on the last coin and one on the last zinc disk. The current causes a deflection of the compass needle.
In a similar experiment the Italian physicist Volta obtained a current. The salt solution acts on the metal like the sap in the potato in the previous experiment.