Question

Why do goldsmiths blow the outer surface of the flame with a metallic blow pipe for melting gold ?

Answer 1

Thanks for asking the question.
Goldsmiths blows the outer surface because it is the hottest part of the flame and undergoes complete combustion. It is also called as Luminous Zone. It is used for melting of metal. It produces carbon dioxide.
Combustion means burning or any chemical change that produces heat and light.During this process hydrocarbon reacts with oxygen to produce carbon dioxide and water.
Hope it helps.

Answer 2

Goldsmiths blow the outer most zone of a flame in order to melt gold or silver because the outermost zone is a zone of complete combustion, also known as luminous zone. The ignition temperature of this zone is the highest and thus helps in melting the metal the best in order to creat desired designs or patterns.

Thank you!!