The first experiments on electrical safety

This paper discusses the experiments conducted by physicist and physician Arsenne d´Arsonval on the effect of sinusoidal ac on the body, well before the era of electronics. d´Arsonval´s first experiments were on the effect of ac on muscle contraction using frog muscle. He contrived a most ingenious device, which displayed the voltage curve and the force of muscle contraction on a smoked-drum kymograph. By using this instrument, along with various alternators such as the Gramme machine, d´Arsonval was able to show that the muscular contraction force decreased with increasing frequency of the electric current. d´Arsonval then turned his attention to the effect of high-frequency ac on the human body. To this end, he created a spark-gap generator of the type described by Hertz in 1888. d´Arsonval demonstrated two important facts: 1) muscle contraction force decreased with increasing frequency of the current and 2) substantial current could be passed through the body and it produced a sensation of warmth. This he proved with conductive and capacitive coupling. By his experiments, d´Arsonval laid the foundation for two new medical techniques: 1) electrosurgery and 2) diathermy. Today both fields are well established in medicine