Michael Faraday founded a series of Christmas lectures for young people at the Royal Institution, London, UK, in 1825. The lectures are still given there. In 1848, six lectures covered the chemistry and physics of flames.

Faraday called these lectures, which were first printed as a book in 1861, The Chemical History of a Candle. One of the experiments shows that the temperature in a candle flame is not homogeneous. The heat is generated by the chemical reaction that takes place in the outer parts of the flame, where the dark ring appears in the video.

Faraday describes in lecture two: “In the middle of the flame, where the wick is, there is combustible vapor. On the outside of the flame is the air which is necessary for the burning of the candle. Between the two, intense chemical action takes place, whereby the air and the fuel act upon each other, and at the very same time that we obtain light the vapor itself is consumed. … The heat of the flame is not in the inside. It is in a ring, exactly in the place where the chemical action takes place.”

• Michael Faraday, A Course of Six Lectures on the Chemical History of a Candle, Griffin, Bohn & Co. 1861. Full text from Project Gutenberg
• Chemistry of the Christmas Candle,
  Klaus Roth
  ChemViews Magazine 2011.
  DOI: 10.1002/chemv.201000133
  When we light a candle, the chemistry we are pursuing is not only especially beautiful, but also especially complex
• Clever Picture: What Makes a Candle Flame?,
  ChemViews Magazine 2011.
  DOI: 10.1002/chemv.201000145
  The different reaction zones of a candle flame and its heat and mass transfer pathways
• Quiz: Candle Flame,
  ChemViews Magazine 2015.
  Do intact wax molecules come in contact with oxygen?
• Five-video series on Michael Faraday’s lectures by Bill Hammack (YouTube) 

This video is part of:

• Chemistry Advent Calendar 2016,
  ChemViews Mag. 2016.
  DOI: 10.1002/chemv.201600101