[Limpet Chicken]

I never said it can't be done, only that it hasn't been done to best of my knowledge, and probably cannot be done with the technology we currently possess.

[AWK]

Melting point for solid helium is 0.92 Kelvin (at normal pressure). This temperature can be easily achieved in labs where helium is liqudified (critical temperature about 5 Kelvins). Helium crystallizes in the closest packing mode.

[Limpet Chicken]

I stand corrected, I just did a quick search, and it seems it's possible, http://pfwww.kek.jp/outline/instr/topog.html
the link mentions something called quantum crystal, is it possible that a fifth state of matter has been discovered?

[gregpawin]

What's more of a concern with using liquid helium, after you've shelled out a few hundred bucks for a tank, is not leaving the top open.  All the other gases will form a layer of frozen air on top of the helium, yes frozen oxygen, nitrogen, and the rest.  Then you've got a problem.  Eventually, that helium's gonna warm up and expand.  If you don't do something soon, the thing's a huge bomb.  Usually, what's done is that they try to break through the crust with a metal pole at first, but if its too thick, they have to drill through the side of the tank, which I can't image how'd they'd avoid not freezing themselves when the liquid helium comes out.

What's interesting about oxygen, is that its paramagnetic.  It'll be attracted to magnetic fields.

What's interesting about hydrogen, I think its hydrogen, is that they believe there's a metallic form that comes after solidifying it.  They're waiting for it to turn from clear, to shiny like a metal, though I'm not so sure about the progress of that.

[Corvettaholic]

On the subject of really cold gases... I have some experiments I would like try in the field of cooling using liquid nitrogen. I've heard its cheap and readily available, but where should I start my hunt and will a simple thermos work for buying some?

[gregpawin]

I'm sure you can just look them up in the yellow pages.  You can hold the liquid itself in most common thermos but I don't think you can pull up and ask for some, like gas.  They'd want you to buy a considerable amount I would think, because the smaller the container, the faster its going to boil away.  I think it costs around a buck a liter.

[Limpet Chicken]

I just HAVE to get me a tank of liquid nitrogen soon, for my phosphorus experiments

The matallic hydrogen is made i think, is to have a STRONG tube, with a high explosive charge at each end, then an amount of liquid hydrogen in the middle with a metal projectile either side if the liquid H, when the HE's are simultaneously fired, it gets compressed enough to make hydrogen metal, I'm not sure if it STAYS metal though after exposure to normal pressure though.

[xALmoN]

i'm sure the after the shockwave passes.. the solid probably melts then boils away . is expansion exothermic or endothermic again? i think its endothermic, right? wouldnt compressing it in a thick enough glass cylinder then cooling it be better? or am i not making any sense..