Ok, this may be
but I need to dispel a big myth here. Oxygen is not explosive, and it isn't flammable. Yes, it does enhance a flame, and will make a small fire bigger, but it won't explode or
cause a fire. The person who suggested using a smoldering stick is correct, if the bottle does contain O2, the ember will either glow brighter, or may even reignite, but just having an O2 bottle under pressure near a flame won't cause any damage. Fire needs three things: a heat source, a fuel source, and oxygen. The smoldering stick is the heat and fuel, the oxygen is all around us, so it will smolder for a while. Give it a shot of oxygen from a pressurized tank, and you will able to reignite the stick until the fuel source is used up. The fire won't travel back into the tank and explode, because there is no fuel in there to burn.
Now, I do have to add a disclaimer, since I'm sure someone will try tossing a pressurized oxygen tank into a fire to see what happens, and then try to sue me, but I do not take responsibility for actions like that. Compressed O2 is under a large amount of pressure, and heating a tank beyond it's rated capacity is dangerous, so if you do toss one into a fire and get killed, don't blame me.