> No, colloids aren't a phase in their own right, but a combination of things in two different phases. I think the Monkey means things like Helium in its superfluid state. Or maybe not.
>
> winter"Some chemistry knowledge"mute

I don't know colloids, or superfluid helium (I'm a chemical engineer, not a chemist!) but I can describe supercritical dense phase fluids to you.

Supercritical fluids occur above the critical point (Tc,Pc) of any substance. A supercritical fluid exhibits the characteristics of both vapor and liquid, and behaves in a lot of ways like a very dense gas.

One might ask, "Above the critical point? With respect to which axis?" That's a hard question to answer. Of course, I only work with petroleum fluids, and in that case, I believe a fluid with a pressure above Pc but a temperature below Tc can have supercritical behaviour, but a very high temperature is still required. A much higher pressure may also be required.

Anyway, they're very cool. The potential applications for pipeline transport are amazing -- high speed transport without concerns for things like slug flow, liquid holdup, and the link -- but trying to build a pipeline that can maintain supercritical conditions is pretty hard, even if it's designed only for a fluid with relatively low critical properties.

Don "I wonder if anyone here has the experience to fill in the gaps in my knowledge for me?" Monkey