TX: Your example of a substance with a much
lower melting point is good, but I guess what
I can't make clear is the negligible nature of
variations of less than 100 degrees when compared
to a flame well over 10 times the melting
point, no matter how much you want to de-rate it.
As you mentioned, different wick sizes would
make a difference, more difference than the
minor variations in melting points and ignition
temperatures. The wick would control the
amount of fuel fed, and thereby make a larger
flame, burning more wax.
If you don't want to do the math, that's OK,
but please don't think that a minor change
in just the melting point is going to make
the candle burn longer, given the very
large delta between any possible melting point
and the minimum possible flame temp.
Melting is going to happen "for free", and
the rate of consumption is going to be
a property of the basic material, not subject
to much modification, as ignition temperatures
of anything that can be burned will be,
by definition, slightly less than the usual
temperature of the flame. (I'm ignoring
purely chemical reactions like magnesium flares
here, as discussion of super-high temperature
combustion won't help us to better understand
candles.)
Scratchy? No way. Just trying to point out
that the heat required to create the
"liquid/solid interface is much higher than
the resulting temperature of the interface
itself. Also, if the flame generated only
slightly more heat than the mass of the candle
could absorb, then one would be unable to burn
one's finger by placing it in the air near
the base of the flame. If you try it, you
quickly find that there is lots of excess
heat not being absorbed by the mass of the
candle available to give you a 3rd degree
burn.
Dick is strongly advised to not try the above,
as he would ignore the evidence of the painful
burn as mere "scientific thought", and would
continue to hold his finger there until he
required medical treatment, which he would
reject as even more "scientific thought", but
he'd be unable to dial 911 or drive himself
to the emergency room due to the rejection of
the "scientific thought" that went into both
the internal combustion engine, and the
telephone system.