Volta thought that the electricity was not in the dead frog but in the iron and copper. He experimented and found it to be so: whenever he brought together the iron and the copper, there was electricity; and this electricity made the dead frogs jerk their legs. Volta tried to produce electricity differently from what it had been produced before. Before that they used to get electricity by rubbing glass or sealing-wax. But Volta got electricity by uniting iron and copper. He tried to connect iron and copper and other metals, and by the mere combination of metals, silver, platinum, zinc, lead, iron, he produced electric sparks.
After Volta they tried to increase electricity by pouring all kinds of liquids—water and acids—between the metals. These liquids made the electricity more powerful, so that it was no longer necessary, as before, to rub in order to produce it; it is enough to put pieces of several metals in a bowl and fill it with a liquid, and there will be electricity in that bowl, and the sparks will come from the wires.
When this kind of electricity was discovered, people began to apply it: they invented a way of gold and silver plating by means of electricity, and electric light, and a way to transmit signs from place to place over a long distance by means of electricity.
For this purpose pieces of different metals are placed in jars, and liquids are poured into them. Electricity is collected in these jars, and is transferred by means of wires to the place where it is wanted, and from that place the wire is put into the ground. The electricity runs through the ground back to the jars, and rises from the earth by means of the other wire; thus the electricity keeps going around and around, as in a ring—from the wire into the ground, and along the ground, and up the wire, and again through the earth. Electricity can travel in either direction, just as one wants to send it: it can first go along the wire and return through the earth, or first go through the earth, and then return through the wire. Above the wire, in the place where the signs are given,