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