During a lecture on his newly
discovered alkali metals, Humphry Davy gave a dramatic
demonstration as to the possible origin of the force of a volcanic eruption. Knighted just the day before,
Sir Humphry gave his lecture to a packed audience right here
in the lecture theatre of the Royal Institution, where a young Michael Faraday
was sat at the back taking notes. Faraday’s notebook, which he
presented to Davy, is an important record since Davy himself did not leave accurate
details of his demonstration lectures. This is Faradays’ account of the lecture
given by Davy on Friday 10th April 1812, where he describes Davy’s experiment
to simulate the volcanic eruption. It consisted of a miniature volcano. He had built upon a square board
a pile of earth and stones in the form of a mountain crater. Openings and fissures were left
in the top and the sides of this mountain in which was put
pieces of the metal potassium. Sir Humphry Davy took a bottle of water and poured some of its
contents into the fissures. The beauty and violence
of this demonstration depends on the incredibly
reactive metal potassium that Davy had discovered
just a few years before. Its reaction with water produces
the flammable gas hydrogen and it also burns in the air
with this beautiful purple flame. Although Davy suggested this might be a possible explanation
for volcanic activity and earthquakes, we now know that this isn’t
due to such chemical reactions. Nevertheless, Davy’s spectacular demonstrations,
illustrating natural phenomena which very few members of the audience
would have seen at the time, would have been extremely impressive
and it’s little wonder that they contributed to his reputation as one of the
most brilliant lecturers of the day.