.

I have now finished this imperfect account. It is but an apology for not
having brought the process itself before you. I have done the best I could
under the circumstances; and I know your kindness well, for if I were not
aware that I might trust to it, I would not appear here so often as I have
done. The gradual loss of memory and of my other faculties is making
itself painfully evident to me, and requires, every time I appear before
you, the continued remembrance of your kindness to enable me to get
through my task. If I should happen to go on too long, or should fail in
doing what you might desire, remember it is yourselves who are chargeable,
by wishing me to remain. I have desired to retire, as I think every man
ought to do before his faculties become impaired; but I must confess that
the affection I have for this place, and for those who frequent this
place, is such, that I hardly know when the proper time has arrived.

NOTES.

[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 cap