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
What Katy Did School (set in Hanover, New Hampshire); "What Katy Did Next", in which a new friend of Katy's takes her on a once-in-a-lifetime trip to Europe; "Clover", in which Katy is married and Clover accompanies her brother Phil to Colorado after he falls ill; and "In the High Valley", which shows the lives of a handful of young people living in the High Valley in Colorado, including Clover, Elsie and their husbands. What Katy Did What Katy Did is an 1872 children's book written by Sarah Chauncey Woolsey under her pen name Susan Coolidge. It follows the adventures of a twelve-year-old