What is the hottest and coolest portion of non-luminous flame?

Question

I need your help!

Answer 1

look @ jpg photo #4 @

http://commons.wikimedia.org/wiki/Common...

what you see is the bright blue cone, which is the hottest part of the flame. it is were combustion just begins. it surrounds a a cone of cold not yet burning air/fuel

away form the bright blue cone to the side & especially above it , you see the  colder region of the flame, it is less lluminous.  Here  later combustion takes place of fuel that was not ignited @ the bright cone