I see and use the ‼‼ descriptor on Science a lot where it really doesn't apply, but I think this is one of the times it's appropriate to do so.
So a few seasons ago, I encountered Sosmil, a towering humanoid composed of fire. Beware its thirst for warm blood!(or something, doesn't matter now anyway). Sent one dwarf down to kill it, he did so, and died when the beast exploded, as creatures made of flame are wont to do. All of his flammable stuff burns, and generates smoke for quite some time.
Now things get interesting. Sick of having this cloud of smoke down in the third level access tunnel, I order some walls built around the pile of burning stuff. One of the guys standing in the smoke cloud suddenly develops a severe case of being on fire and promptly melts. This same thing starts happening to everyone who hangs out in the area(only the masons, really).
I take a look, and the walls next to the pile are warm, same as if magma were behind them. Okay.
I space the walls away from the pile and finish them up. In the process, someone sets a rock on the pile, and the smoke abruptly stops. This is likely coincidence, as I checked the pile and there were no more burning items in it. I decide to pour some water on it, to see what happens. Nothing. I drop an alpaca on it. The alpaca is sadly not on fire. I deconstruct everything. Sosmil's flames and body parts are still there, the alpaca is unharmed.
So, what's going on here? Was the smoke itself superheated? Did I somehow "put out" the FB's body parts? Has anyone else done testing with flame FB body parts?
tl;dr: Effing flame body parts, how do they work?