Several motivations, improved procedures, and different contexts: The first liquefactions of helium around the world

Helium was the last member of the list of the so-called permanent gases to be liquefied. The main reasons for that were the very late discovery of the element on the earthʹs surface and its boiling point, the lowest of all substances. This account of the earliest and different methods for its liquefaction reveals, both chronologically and geographically, the technical developments involved. An effort is made to show how the availability of the natural resource, together with political circumstances and economic limitations, had different roles in specific moments of the entire history.