Leiden University at the university. The learning and reputation of Jacobus Gronovius, Herman Boerhaave, Tiberius Hemsterhuis and David Ruhnken, among others, enabled Leiden to maintain its reputation for excellence down to the end of the 18th century. At the end of the nineteenth century, Leiden University again became one of Europe's leading universities. At the world’s first university low-temperature laboratory, professor Heike Kamerlingh Onnes achieved temperatures of only one degree above absolute zero of −273 degrees Celsius. In 1908 he was also the first to succeed in liquifying helium and can be credited with the discovery of the superconductivity in metals. The
Mieczysław Wolfke K. Kamerlingh-Onnes and (later) Willem Keesom studied the dielectric constant of liquid helium at various temperatures. The theoretical experiments led him to the discovery of two liquid phases of helium and solidification of helium what Mieczysław Wolfke considered as the third of his greatest achievements. In the early thirties Wolfke started to organize the separated Institute of Low Temperatures at Warsaw University of Technology, even running the first installation. In 1927 Wolfke worked on the liquid helium dielectric constant and in the next year on the association in liquid dielectrics. He also started cooperation with the Polish Army in Temporary