friction, the metals hold a mid-position. They are all essentially
mercurial substances. (In quicksilver, which for this reason was given
the name 'mercury' by the alchemists, this fact comes to an
ur-phenomenal appearance.) Among the many facts proving the mercurial
nature of the metals, there is one of particular interest to us. This
is their peculiar relationship to the processes of oxidation and
reduction.

Metals, in their metallic state, are bearers of latent levity, which
can be set free either through combustion or through corrosion. They
differ from one another by their relative degree of eagerness to enter
into and remain in the metallic, that is, the reduced state, or to
assume and keep the state of the oxide (in which form they are found in
the various metallic oxides and salts). There are metals such as gold,
silver, etc., for which the reduced state is more or less natural;
others, such as potassium, sodium, etc., find the oxidized state
natural and can be brought into and kept in the reduced state only by
artificial means. Between these extremes there are all possible degrees
of transition, some metals more nearly resembling the 'noble', others
more nearly the 'corrosive', metals.

We remember that it was the different relationship of sulphur and
phosphorus to reduction and oxidation which led us to envisage them as
ur-phenomenal representatives of the alchemic polarity. We may
therefore say that there are metals which from the alchemic point of
view more nearly resemble sulphur, others more nearly phosphorus,
whilst others again hold an intermediary position between the extremes.
It is on these differences among the various metals that their galvanic
properties are based.