The Chemical History Of A Candle

Six lectures on the chemistry and physics of flames that Michael Faraday delivered at the Royal Institution in 1848 under the heading The Chemical History of a Candle were part of the series of Christmas lectures for young people that Faraday established in 1825 and which are still presented there each year. The several zones of combustion in a candle flame and the presence of carbon particles in the luminous zone were discussed in the lectures. The creation and evaluation of hydrogen, oxygen, nitrogen, and carbon dioxide gas characteristics were demonstrated. In order to show an electrolysis cell, platinum conductors are first electroplated by dissolved copper, followed by the generation of hydrogen and oxygen gases and their subsequent recombination to produce water. Studies are done on the characteristics of water, such as how much it expands when it freezes (causing iron containers to explode) and how much steam is produced when it vaporizes. There are demonstrations of methods for weighing gases on a balance. The effects of atmospheric pressure are illustrated and described. Faraday makes several remarks regarding adequate attention to safety and notes that several of the demonstrations and experiments carried out in the lectures may be undertaken by youngsters "at home."

Sdílet