Richard Melson
September 2006
Michael Faraday
Chemical History of a candle

Michael Faraday

Michael Faraday, FRS (September 22, 1791August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. He established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena.

Some historians of science refer to him as the best experimentalist in the history of science. It was largely due to his efforts that electricity became viable for use in technology. The SI unit of capacitance, the farad, is named after him, as is the Faraday constant, the charge on a mole of electrons (about 96,485 coulombs). Faraday's law of induction states that a magnetic field changing in time creates a proportional electromotive force.

He held the post of Fullerian Professor of Chemistry at the Royal Institution of Great Britain. Faraday was the first, and most famous, holder of this position to which he was appointed for life


Published Works by Michael Faraday

[Footnote 1: Page 16. The Royal George sunk at Spithead on The 29th of
August, 1782. Colonel Pasley commenced operations for the removal of the
wreck by the explosion of gunpowder, in August, 1839. The candle which
Professor Faraday exhibited must therefore have been exposed to the action
of salt water for upwards of fifty-seven years.]

[Footnote 2: Page 17. The fat or tallow consists of a chemical combination
of fatty acids with glycerine. The lime unites with the palmitic, oleic,
and stearic acids, and separates the glycerine. After washing, the
insoluble lime soap is decomposed with hot dilute sulphuric acid. The
melted fatty acids thus rise as an oil to the surface, when they are
decanted. They are again washed and cast into thin plates, which, when
cold, are placed between layers of cocoa-nut matting, and submitted to
intense hydraulic pressure. In this way the soft oleic acid is squeezed
out, whilst the hard palmitic and stearic acids remain. These are further
purified by pressure at a higher temperature, and washing in warm dilute
sulphuric acid, when they are ready to be made into candles. These acids
are harder and whiter than the fats from which they were obtained, whilst
at the same time they are cleaner and more combustible.]

[Footnote 3: Page 19. A little borax or phosphorus salt is sometimes
added, in order to make the ash fusible.]

[Footnote 4: Page 27. Capillary attraction or repulsion is the cause which
determines the ascent or descent of a fluid in a capillary tube. If a
piece of thermometer tubing, open at each end, be plunged into water, the
latter will instantly rise in the tube considerably above its external
level. If, on the other hand, the tube be plunged into mercury, a
repulsion instead of attraction will be exhibited, and the level of the
mercury will be lower in the tube than it is outside.]

[Footnote 5: Page 29. The late Duke of Sussex was, we believe, the first
to shew that a prawn might be washed upon this principle. If the tail,
after pulling off the fan part, be placed in a tumbler of water, and the
head be allowed to hang over the outside, the water will be sucked up the
tail by capillary attraction, and will continue to run out through the
head until the water in the glass has sunk so low that the tail ceases to
dip into it.]

[Footnote 6: Page 37. The alcohol had chloride of copper dissolved in it:
this produces a beautiful green flame.]

[Footnote 7: Page 54. Lycopodium is a yellowish powder found in the fruit
of the club moss (_Lycopodium clavatum_). It is used in fireworks.]

[Footnote 8: Page 58. Bunsen has calculated that the temperature of the
oxyhydrogen blowpipe is 8061? Centigrade. Hydrogen burning in air has a
temperature of 3259? C., and coal-gas in air, 2350? C.]

[Footnote 9: Page 60. The following is the action of the sulphuric acid in
inflaming the mixture of sulphuret of antimony and chlorate of potassa. A
portion of the latter is decomposed by the sulphuric acid into oxide of
chlorine, bisulphate of potassa, and perchlorate of potassa. The oxide of
chlorine inflames the sulphuret of antimony, which is a combustible body,
and the whole mass instantly bursts into flame.]

[Footnote 10: Page 63. The "air-burner," which is of such value in the
laboratory, owes its advantage to this principle. It consists of a
cylindrical metal chimney, covered at the top with a piece of rather
coarse iron-wire gauze. This is supported over an argand burner, in such a
manner that the gas may mix in the chimney with an amount of air
sufficient to burn the carbon and hydrogen simultaneously, so that there
may be no separation of carbon in the flame with consequent deposition of
soot. The flame, being unable to pass through the wire gauze, burns in a
steady, nearly invisible manner above.]

[Footnote 11: Page 74. Water is in its densest state at a temperature of
39.1? Fahrenheit]

[Footnote 12: Page 74. A mixture of salt and pounded ice reduces the
temperature from 32? F. to zero--the ice at the same time becoming fluid.]

[Footnote 13: Page 82. Potassium, the metallic basis of potash, was
discovered by Sir Humphrey Davy in 1807, who succeeded in separating it
from potash by means of a powerful voltaic battery. Its great affinity for
oxygen causes it to decompose water with evolution of hydrogen, which
takes fire with the heat produced.]

[Footnote 14: Page 98. Professor Faraday has calculated that there is as
much electricity required to decompose one grain of water as there is in a
very powerful flash of lightning.]

[Footnote 15: Page 101. A solution of acetate of lead submitted to the
action of the voltaic current, yields lead at the negative pole, and brown
peroxide of lead at the positive pole. A solution of nitrate of silver,
under the same circumstances, yields silver at the negative pole, and
peroxide of silver at the positive pole.]

[Footnote 16: Page 129. The gas which is thus employed as a test for the
presence of oxygen, is the binoxide of nitrogen, or nitrous oxide. It is a
colourless gas, which, when brought in contact with oxygen, unites with
it, forming hyponitric acid, the red gas referred to.]

[Footnote 17: Page 152. _Marble_ is a compound of carbonic acid and lime.
The muriatic acid being the stronger of the two, takes the place of the
carbonic acid, which escapes as a gas, the residue forming muriate of lime
or chloride of calcium.]

[Footnote 18: Page 186. _Lead pyrophorus_ is made by heating dry tartrate
of lead in a glass tube (closed at one end, and drawn out to a fine point
at the other) until no more vapours are evolved. The open end of the tube
is then to be sealed before the blowpipe. When the tube is broken and the
contents shaken out into the air, they burn with a red flash.]

[Footnote 19: Page 216. _Water-gas_ is formed by passing vapour of water
over red-hot charcoal or coke. It is a mixture of hydrogen and carbonic
oxide; each of which is an inflammable gas.]

Poster's note: "combustion that makes!" was corrected from a misprint
"combusion that makes!" in the original.

End of The Chemical History Of A Candle
by Michael Faraday