Producing oxyhydrogen, the detonating gas. The external cylinder was filled with acidulated water (H2SO4). In the internal cylinder the current flowing through the platinum electrodes dissociated the surrounding water in hydrogen and oxygen, that were collected together by the tiny pipe and run through three ampoules whose function is not mentioned in the text (valve? exiccator?). The stoichiometric ratio was guaranteed as both gas came from the same amount of water and by exploding would regenerate it exactly. TRY AT YOUR OWN RISK!