1746, Mei Sen Brock of Leiden University in the Netherlands invented the "Leiden bottle" for collecting charges. He wants to find a way to save electricity, because he sees that the electricity he collects can easily disappear in the air.

One day, he hung a bucket in the air, connected the motor, led it out of the bucket with a copper wire and immersed it in a glass bottle filled with water. He asked an assistant to hold a glass bottle in one hand, while Mei Sen Brock shook the motor vigorously.

At this time, his assistant accidentally hit the other person's hand with a barrel. He suddenly felt a strong electric shock and cried. Mei Sen Brock then switched places with his assistant and asked him to shake the motor. He held the water bottle in one hand and touched the bucket in the other.

1780, when Italian anatomist luigi galvani dissected a frog, he accidentally touched the frog's thigh with different metal instruments in his hand, and the muscles of the frog's leg twitched immediately, as if stimulated by electric current, but if only one metal instrument was used to touch the frog, there would be no such reaction. Galvani believes that this phenomenon is due to a kind of electricity generated in animals, which he calls "bioelectricity".

Galvani's discovery aroused great interest of physicists, who competed to repeat the experiment of flail Vanni, trying to find a way to generate current. After many experiments, Italian physicist Volt thinks that Galvani's bioelectricity theory is incorrect. The reason why frog muscle can generate current is probably that some liquid in the muscle is at work. To prove his point, Volt immersed two different kinds of metal sheets in different solutions for experiments.

It is found that as long as one of the two kinds of metal sheets reacts with the solution, an electric current can be generated between the metal sheets.