i think he can. a common misconception is that roy's alchemy is "flame alchemy" but it's not. as you said, roy can adjust the concentration of oxygen in the air, and in the manga at least, his skills are quite versetile.

for example, in an omake kinda thing, he uses his alchemy to loewr the oxygen concentration around a woman's head so he could catch her when she swooned and invite her for tea. (the oxygen de-gentleman strategy)

so, yes, i think he COULD put out a fire with his alchemy, almost definately.

i'd never thought about it though. that's so cool.

Well if he could somehow remove the oxygen from directly around the fire, he could.

He could also do it just because he's awesome. :D

totally random, but you know where i might be able to find a bigger/full version of your icon? :)

Technically, that's not possible because it's one of the few "unreversable reactions" that you'll learn in chemistry.
It can't be reversed because of the fact that the end products aren't what the reactants are.
The tree would be charred, and there's no way that he could remove the things caught in there...

But then agian... it's their special world.. ANYTHING could happen. .___.

eh, sort of. It's my understanding from my family of firefighters that there's something that happens when a fire runs out of oxygen . . . I forget what it's called, but basically:

Sometime a fire in a house will go "out" because all the oxygen has been used up. Typically, the firefighters will go up on the roof of the house and cut a hole in the roof. Now, they have to be very careful when doing so, because as soon as the heat that's left in whatever's been burned caches some fresh air, it will flare up (think like grease drips on a BBQ grill- as soon as the grease drops on the hot coals, you get a flame that shoots up). If they were looking down into the hole they'd created in the roof, they'd get their face burned off when the oxygen hit the embers.

So, I would say that he could put the fire out by starving it of oxygen (the same thing that happens when one snuffs a candle) HOWEVER the size and heat of that fire would affect his ability to put out the fire. Could he suffocate a large fire for long enough to have all the embers die out? I doubt it. Could he walk into a candle light room and put every candle out? Probably.

i should add that that's my default icon . . . i've recently become aware that some people use icons to be snarky . . . i'm not one of them . . . i just always thought that ed beaing the piss outta ling with his arm was funny as hell :)

i love this thread, it's giving me all kinds of ideas...

thank you for bringing this topic up. :)

Well, before giving Roy extra powers, one has to consider that his alchemic ability wouldn't work as it is described. Oxygen is not, itself, combustible; if it were, when you lit a match the entire world would go up in flames. The oxygen has to react with something, and the proportion of combustible gasses naturally in the atmosphere (I can't remember the exact number) is somewhere around 2%. If his alchemy allows him to concentrate those sufficiently, then he could make a small flame, from which he could then siphon energy to break apart carbon dioxide and water and use the carbon and hydrogen to continue the burn.

Of course, one must add a bit of "it's FMA" to the above, since the amount of energy needed to split carbon dioxide and water apart is the same amount of energy released when they are fused together, meaning that the reaction would a) not be self-sustaining and b) would produce no heat.

But I ramble. I see no reason why Roy wouldn't be able to put out a fire, and drawing from the above comment, he would probably be able to put out the embers by condensing the water in the atmosphere. After all, if his alchemy allows him to manipulate oxygen, why not water vapor too?

He should have been able to put out the fire... however... I don't see how he'd need the SPARK GLOVES for this.

Uh... I think this is a case of teh pretty overruling logic.