Volta reaches a similar conclusion after repeating some of
Bennett's experiments. In referring to this decision of Volta
as to the origin of the electric charge in contact
electrification, Ostwald says:

'We stand here at a point where the most prolific error of
Electrochemistry begins, the combating of which has from that
time on occupied almost the greater part of the scientific work
in this field.'

The error, from Ostwald's point of view, lies in the assumption
that the transference of electricity from the one metal to the
other is a primary phenomenon of metallic contact. He, with
many others, including some of the most distinguished
physicists and chemists of the past century, regard the
electrical transference as a secondary phenomenon resulting
from the previous oxidation of one of the metals. Thus Lodge,
in discussing the opposite electrification of plates of zinc
and copper when brought into contact says:

'The effective cause of the whole phenomenon in either case is
the greater affinity of oxygen for zinc rather than copper.'

The apparent conflict of opinion between those who hold that
the different affinities of the metals for oxygen is the cause
of the rearrangement of their electrical charges when brought
into contact and those who hold with Bennett and Cavallo that
the metals in their natural state have different affinities for
the electrical fluid must disappear when we recognize that all