It was the German Ewald von George Kleist (1700-1748) who discovered the condenser in 1745 in an attempt to build a machine for producing sparks.
Some months later the Dutch physicist Pieter van Musschenbroek (1692-1761), a professor at the University of Leyden, attempted to produce sparks from water. A certain Andreas Cunaeus, perhaps one of his students who had witnessed the experiment, tried to repeat it on his own. He electrified the water contained in a glass jar that he was holding in his hand, placing the end of a metal rod inside the water in contact with one of the poles of an electrostatic generator.
On putting down the jar he was holding in one hand, he tried to extract the metal rod with the other and received a shock, which in his opinion was far stronger than what could be expected with the power of the machine he was using, and the jar fell from his hand and broke on the floor.
Musschenbroek, on being informed by Cunaeus, immediately repeated the experiment and received a shock so strong that in a letter to Rèamur, he wrote that he would not repeat the experiment for the entire French kingdom. Independently of Cunaeus and Musschenbroek, Kleist performed those experiments and discovered the condenser by chance: the plates were the water and the experimenter's hand, while the dielectric was the glass of the jar.
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