Fire

[MariaVerroca]

Is the blue part of the flame the coolest part?

[mibn2cweus]

red less hot / blue more hot

[gen2]

If you are referring to the blue cone of a gas flame (eg Bunsen burner), then the part that is actually emitting the blue light is indeed the hottest as mibn2cweus says; but INSIDE the blue cone is the coldest part of the flame since that is where the gas/air mixture has not yet ignited.

[foolish01]

no its the hottest u fool.

thats why in a chemistry lesson, wen u aint usin the bunse, u leave it on the orange frlame (less hot and burny)

[Gef]

Actually foolish the yellow flame is still very hot and burny (as you describe it). However, it is much more visible which is why it used as the "safety" flame.

[mibn2cweus]

As gen2 says; I suspect the cone is where the explosive nature of the gas (fuel) finds balance with its need for fresh air (oxygen).