The potato and wires produce an electric current in the same way as a torch battery, but only a very weak one. The sap of the potato reacts with the metals in a chemical process and also produces electrical energy. We speak of a galvanic cell because the Italian doctor Galvani first observed this process in a similar experiment in 1789. Coin Current Place several copper coins and pieces of sheet zinc of the same size alternately on top of one another. Between each metal pair of zinc and copper insert a piece of blotting paper soaked in salt water.
Electrical energy is set free.
Wind thin, covered copper wire about 50 times round a compass, and hold one of the bare ends on the last copper coin and one on the last zinc disk. The current causes the compass needle to move away from the wound wires. 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 Potato Battery Experiment. Destroyed Metal by Decomposition Put a piece of aluminum foil with a copper coin on it into a glass of water, and let it stand for a day.