reducing flame

A reducing flame is a flame, or part of a flame, that contains partially burned gas and can extract oxygen from metallic oxides placed within it. This occurs in the inner cone of a gas flame, where different chemical reactions take place compared to the outer cone.12

Combustion itself is a chemical reaction, usually involving oxygen, that generates heat and light in the form of flame. This reaction is rapid because the generated energy raises the temperature, accelerating the process further. Flames emit light through thermoluminescence (from thermal energy) and chemiluminescence (from chemical energy released in exothermic reactions). Many flames also contain ions and electrons, making them electrically conductive. Soot formation is common in hydrocarbon flames, making them luminous.34