Liquid helium of liquid water. Helium was first liquefied on July 10, 1908, by the Dutch physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands. At that time, helium-3 was unknown because the mass spectrometer had not yet been invented. In more recent decades, liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use in superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), Magnetoencephalography (MEG), and experiments in physics, such as low temperature Mössbauer spectroscopy. The temperature required to produce liquid helium is low because
Harm Kamerlingh Onnes Lorentz as a subject. One of these stained-glass windows contained a portrait of Hendrik Lorentz and formulas devised by him that describe the behavior of electrons. Other stained-glass windows show the instruments to measure the splitting of spectral lines of atoms under the influence of a magnetic field is measured, the so-called Zeeman effect. He also made portraits of the physicists Albert Einstein and Paul Ehrenfest. Harm Kamerlingh Onnes characterized his artistic work with the phrase "just messing around". In 1953 Kamerlingh Onnes with Bert Nienhuis Piet Wiegman, Dirk Hubers and Frans Wildenhain, took part of the exhibition "five contemporary