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Flame with out the Burn?

 
 
Reply Wed 24 Feb, 2010 03:35 pm
I was wondering, is there a substance on this earth that can produce a flame (particularly blue, but any color is fine) But does not have the burning affect a normal flame would?
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Type: Question • Score: 4 • Views: 723 • Replies: 11
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rosborne979
 
  1  
Reply Thu 25 Feb, 2010 08:01 am
@LadySnips,
LadySnips wrote:

I was wondering, is there a substance on this earth that can produce a flame (particularly blue, but any color is fine) But does not have the burning affect a normal flame would?

The lowest flame temperature I could find was for Propane (like your Bunsen Burner). But that's still pretty hot (hot enough to hurt you if you let it).
Robert Gentel
 
  1  
Reply Thu 25 Feb, 2010 11:47 am
@rosborne979,
Is that lower than alcohol? Alcohol isn't too bad, I used to soak my arm in it and set it on fire as a stunt and it didn't hurt as much as any other thing I burned myself with. It actually didn't hurt at all for the first few seconds.
Francis
 
  1  
Reply Thu 25 Feb, 2010 12:20 pm
Read about (google it) "Smithell's cold flame"...
Walter Hinteler
 
  2  
Reply Thu 25 Feb, 2010 01:21 pm
@Francis,
And then there's the "flamme de trompette" ... Wink
(Nor sure if I would use that to déclarer ma flamme - which certainly is quite hot. Very Happy )
Francis
 
  2  
Reply Thu 25 Feb, 2010 02:11 pm
@Walter Hinteler,
Indeed, and you may burn your wings..

One should not declare his flame out of the blue..
DrewDad
 
  1  
Reply Thu 25 Feb, 2010 02:27 pm
@Robert Gentel,
The temperature of the flame is different from how much heat is transferred.

With your alcohol trick, you're getting a cooling effect from the liquid evaporating into vapor. The vapor also (briefly) insulates your arm from the flames. Think of testing an iron: if you lick your finger, the water vaporizes on contact and keeps you from getting a burn.

Edit: http://en.wikipedia.org/wiki/Leidenfrost_effect

Quote:
The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than the liquid's boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly. This is most commonly seen when cooking; one sprinkles drops of water in a skillet to gauge its temperature"if the skillet's temperature is at or above the Leidenfrost point, the water skitters across the metal and takes longer to evaporate than it would in a skillet that is above boiling temperature, but below the temperature of the Leidenfrost point. It has also been used in some potentially dangerous demonstrations, such as dipping a wet finger in molten lead[1] or blowing out a mouthful of liquid nitrogen, both enacted without injury to the demonstrator.[2] The effect is also responsible for the ability of liquid nitrogen to skitter across lab floors, collecting dust in the process.

It is named after Johann Gottlob Leidenfrost, who discussed it in A Tract About Some Qualities of Common Water in 1756.
farmerman
 
  1  
Reply Thu 25 Feb, 2010 02:31 pm
I have a beautiful new bridge over the EVerglades for sale, any serious offers ?
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Walter Hinteler
 
  2  
Reply Thu 25 Feb, 2010 02:34 pm
@Francis,
Francis wrote:

One should not declare his flame out of the blue..


Well, that's why I use a flamme pilote ...
Francis
 
  1  
Reply Thu 25 Feb, 2010 02:36 pm
@Walter Hinteler,
Pfftt! Mr. Green
0 Replies
 
Robert Gentel
 
  1  
Reply Thu 25 Feb, 2010 03:25 pm
@DrewDad,
DrewDad wrote:
The temperature of the flame is different from how much heat is transferred.

With your alcohol trick, you're getting a cooling effect from the liquid evaporating into vapor.


Yes, that is why it is initially actually cold. But there is more to it than that, alcohol really doesn't burn as hot as other stuff (doesn't hurt as much after the effect wears off) and other stuff (gasoline) would have stuck to the skin more than it does.
DrewDad
 
  1  
Reply Thu 25 Feb, 2010 03:37 pm
@Robert Gentel,
http://chemistry.about.com/b/2008/01/12/how-to-make-fireballs.htm
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