02 March 2021


I dealt with liquid oxygen during my career, but never saw the actual substance.  Interesting that it has color*.
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which has continued to the present. Liquid oxygen has a pale blue color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet.
*discussed here and here.  "The transition responsible for the pale blue color of liquid oxygen is the simultaneous excitation of two molecules from triplet sigma to singlet delta. The double excitation avoids the spin forbiddeness." In other words, apparently it's some form of magic.


  1. Just make sure that magnet isn't flammable or oxidable. Cuz it'll go.

    Generally, you should be very afraid of liquid oxygen. It's not technically flammable itself, it's the exact and concentrated stuff that makes everything else extremely flammable.

  2. Fascinating !
    Any chance the blue colour helps give us blue skies ?
    Any chance it being paramagnetic (love that word) fuels the Southern Lights (Northern Lights from where you sit) ?

    1. Any chance the blue colour helps give us blue skies ?

      No. Completely unrelated. The sky is blue because of Raleigh scattering of solids in the air. NOAA explains:

      Also, do not forget the air is 80% nitrogen, only 20% oxygen. If any coloring of the sky were to come from the air, it would be the color of nitrogen. Liquid nitrogen is transparent.


    2. Any chance it being paramagnetic (love that word) fuels the Southern Lights (Northern Lights from where you sit) ?

      Also no. That's just the earth's magnetic field.

      Paramagnetism is a form of magnetism that's a bit weird from a daily-life- point of view, because paramagnets are only magnets when within another magnetic field. Basically, the magnetic properties of the atoms are so small that random (thermal) motion overwhelms it. But if you counter that by providing a magnetic field, or by lowering the temperature enough, it'll show up.

    3. Nepkarel, that's a wonderfully concise explanation of a term I was too lazy to look up. Thank you.

    4. You're very welcome. There's a whole world of something-magnets out there. They all are similar but different because scientists love diving into all the different options that exists. Sadly, wikipedia gets so technical these days that they confuse more than elucidate.

      Oddly, what seems to be the most commonly thought of form of magnetism, ferromagnetism, is actually kind of an oddball within the assembly from a scientific point of view. But don't think that you don't come across the other forms magnetisms outside of labs. They're hidden in all kinds of equipment.

  3. Fascinating, but of what use is liquid oxygen--is their practical uses? I don't understand "oxidizer," etc. Please educate me. Thank you.

    1. "Outside most hospitals is a large cryogenic container called a cryostat. This container usually holds many thousands of gallons of LOX to supply the hospital its piped oxygen. Why is it liquid oxygen? Again, LOX is the most space efficient method of storing oxygen. It would require hundreds of compressed oxygen cylinders to accomplish this job, and years ago hospitals converted to LOX."

      More here: https://www.elitecme.com/resource-center/respiratory-care-sleep-medicine/liquid-oxygen-applications-from-hospital-to-home

      Re "oxidizers" you could start with Wikipedia: https://en.wikipedia.org/wiki/Oxidizing_agent


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