Oil...
Please think about new element ideas. Don't just go "Ooo, I think we should add Deoxyribonucleuic acids because then would make something that recognisees the ID of the stickman". If you can mix elements to make-do then please do that. I'm getting incredibly annoyed with poeple posting the first thing that comes to mind. One thing im glad about though is that you have thought of everything that the element could do. Just apply with a good element idea and you might be in.

I'm working on something similar at the moment... What I've got at the moment is OIL can be pressurised into plastic which melts back into oil. Plastic acts the same as goo when under a lot of pressure but doesn't disappear. To get that working right I had to remove the OIL<->GAS relationships so to maintain some functionality I'm working on Diesel (Fuel Oil)


Diesel (DESL) Characteristics (What I've got coded):
Ignites at 143f (from what I can figure about 61 in game)
Heavier than oil but lighter than water (would be heavier than water based on atomic weight but BP has recently proven otherwise)
Ignites under high pressure (60 at the moment, will probably change it later)
Becomes GAS under negative pressure
GAS has to be under high pressure to become diesel

I'll post the git location when I'm done...

UPDATE:
there is a bug where you end up with STONE after burning it... I ain't gotta clue where it come from but I shall be working on where/why in a bit and figuring out what should be left behind. Ignore the "new version" notice.. I don't know how to disable it ^^' Heres the GIT repo anyway...

My Git Fork: git://github.com/antb/The-Powder-Toy.git