noun
inner cone of a flame; reducing flame
Technical term in chemistry for the inner, cooler part of a flame where incomplete combustion occurs, often used in flame tests and reducing reactions. Contrasts with 外炎 (outer oxidizing flame).
See also: 外炎
ブンゼンバーナーの内炎は還元性がある。
The inner cone of a Bunsen burner flame is reducing.
内炎と外炎の温度差を利用して実験を行う。
We conduct the experiment using the temperature difference between the inner and outer flames.
外炎 is the outer, oxidizing part of a flame, hotter and blue, while 内炎 is the inner, reducing cone.
Compound of 内 (inner) and 炎 (flame). The term is a direct calque from Western chemistry terminology.