In The Name of the Wind, Kvothe encounters a chemical (or alchemical substance) called Regim Ignaul Neratum, or "bone-tar". From the safety lecture that accompanies it, we know that it:
- It's highly caustic ("Spill it on your arm and it'll eat through to the bone in about ten seconds")
- It boils at room temperature.
- "The liquid is extremely volatile. As a gas it exhibits surface tension and viscosity, like mercury."
- "It is heavier than air and does not dissipate."
- The cloud of gas it evaporates into at room temperature and pressure will spontaneously ignite and burn a "bright sodium-red"
Obviously, this is a fantasy book. If this is an alchemical substance, we can expect it to have behaviors which no-real world chemical has (witness Wil's later demonstration about alchemy breaking "obvious" rules). But that doesn't mean it isn't real.