= Liquid nitrogen
{wiki}
77K. Low enough for "high temperature <superconductors>" such as <yttrium barium copper oxide>, but for "low temperature superconductors", you need to go much lower, typically with <liquid helium>, which is likely much more expensive. TODO by how much?
\Video[https://www.youtube.com/watch?v=PEgm5NFXlFM]
{title=Where Do You Get Liquid Nitrogen? by The King of Random (2016)}
{description=He just goes to a medical gases shop in a local <industrial> estate and buys 20L for 95 dollars and brings it back on his own <Dewar> marked 35LD.}
\Video[https://www.youtube.com/watch?v=dCXkaQa53QQ]
{title=Making Liquid Nitrogen From Scratch! by <Veritasium> (2019)}
{description="From scratch" is perhaps a bit <clickbaity>, but I'll take it.}