Heike Kamerlingh Onnes Heike Kamerlingh Onnes Professor Heike Kamerlingh Onnes FRSFor HFRSE FCS ( (); 21 September 1853 – 21 February 1926) was a Dutch physicist and Nobel laureate. He exploited the Hampson–Linde cycle to investigate how materials behave when cooled to nearly absolute zero and later to liquefy helium for the first time, in 1908. He was also the discoverer of superconductivity in 1911. Kamerlingh Onnes was born in Groningen, Netherlands. His father, Harm Kamerlingh Onnes, was a brickworks owner. His mother was Anna Gerdina Coers of Arnhem. In 1870, Kamerlingh Onnes attended the University of Groningen. He studied under Robert Bunsen
Weiss magneton of the saturation magnetization at the temperature of liquid hydrogen in the laboratory of Heike Kamerlingh Onnes in Leiden. In 1911, Weiss announced that the molar moments of nickel and iron had the ratio of 3:11, from which he derived the value of a magneton. Weiss gave an address about the magneton at a conference in Karlsruhe in September 1911. Several theorists commented that the magneton should involve Planck's constant "h". By postulating that the ratio of electron kinetic energy to orbital frequency should be equal to "h", Richard Gans computed a value that was almost an order of magnitude