"Mike M" <nospam@nospam.com> wrote in message 
news:eb8r7u01d0i@enews2.newsguy.com...
|  A friend thinks that water is the only thing that can exist in all 3 states,
|  solid, liquid and gas.
|  (He doesn't realize there are more than 3).
|
|  I'm trying to convince him that ANYTHING can exist in those 3 states given
|  the right
|  temperature and pressure. How can I prove it to him?



You can't.  What is the liquid phase of dry ice called?  Wet CO2 ?
 http://www.dryiceinfo.com/

Androcles

Extract from the provided link:

   HOW DRY ICE IS MADE
   The first step in making dry ice is to compress carbon
   dioxide gas until it liquefies, at the same time removing
   the excess heat. The C02 gas will liquefy at a pressure of
   approximately 870 pounds per square inch at room
   temperature. Next, the pressure is reduced over the liquid
   carbon dioxide by sending it through an expansion valve into
   an empty chamber. The liquid will flash, with some turning
   into gas causing the remainder to cool. As the temperature
   drops to -109.3°F, the temperature of frozen CO2, some of it
   will freeze into snow. This dry ice snow is then compressed
   together under a large press to form blocks or extruded into
   various sized pellets. Dry Ice is much heavier than
   traditional ice, weighing about double.