Helium history

Helium was first detected on August 18, 1868 as a bright yellow line with a wavelength of 587.49 nm in the spectrum of the chromosphere of the Sun, by French astronomer Pierre Janssen during a total solar eclipse in India. Janssen was at first ridiculed since no element had ever been detected in space before being found on EngEarth. October 20th the same year,english astronomer Norman Lockyer also observed the same yellow line in the solar spectrum and concluded that it was caused by an unknown element after unsuccessfully testing to see if it were some new type of hydrogen. Since it was near the Fraunhofer D line he later named the new line D3, distinguishing it from the nearby D1 and D2 double lines of sodium. He and English chemist Edward Frankland named the element after the Greek word for the Sun god, Helios, and, assuming it was a metal, gave it an -ium ending (a mistake that was never corrected).

British chemist William Ramsay isolated helium on March 26, 1895 by treating cleveite (now known to be uraninite) with mineral acids. Ramsay was looking for argon but noticed the yellow D3 line after he removed nitrogen and oxygen from the gas liberated by the sulfuric acid he put on the cleveite sample. These samples were identified as helium by Lockyer and British physicist William Crookes. It was independently isolated from cleveite the same year by Swedish chemists Per Teodor Cleve and Abraham Langlet in Uppsala in Sweden. They collected enough of the gas to accurately determine its atomic weight.

An oil drilling operation in Dexter, Kansas created a gas geyser in 1903 that contained 12% by volume of an unidentified gas. American chemists Hamilton Cady and David McFarland of the University of Kansas discovered it was helium and published a paper in 1907 saying that helium could be extracted from natural gas. Also in 1907, Ernest Rutherford and Thomas Royds demonstrated that an alpha particle is a helium nucleus.

Helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes in 1908 in Leiden by cooling the gas to less than one kelvin. He tried to solidify it by reducing the temperature to 0.8 K but failed because helium does not have a triple point temperature where the solid, liquid and gas phases are at equilibrium. It was first solidified in 1926 by his student Willem Hendrik Keesom who subjected helium to a similar amount of cooling as Kamerlingh Onnes but at 25 standard atmospheres of pressure.

In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that liquid helium-4 has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. In 1972, the same phenomenon was observed in liquid helium-3 by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson.