"Andy Dingley" wrote in message
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On Fri, 07 Jan 2005 15:42:35 +0000, Grunff wrote:

It's very, very difficult to do on any kind of DIY budget :-)

No, many people have built LN2 refrigerators. It's hard to do it
efficiently, but refrigeration to this temperature isn't much harder
than making your own gas turbine.

Don't forget that Ohnes liquified helium in 1911 and discovered
superconductivity almost immediately afterwards. Nitrogen was back in
the 1880's. Now how much technology did any lab have back then that
you can't reproduce in a half-decent modern home workshop ?

Well the availability of whatever ore the Curies purified radium from is
presumably a little harder to get now :-)