208

I have made some trials upon the senses of smelling and hearing, but
could not succeed; perhaps because the Electric current cannot be directed
so as to pass by a narrow passage through the olfactory and auditory nerves;
perhaps because these nerves are not sufficiently sensible. I have discovered
that charcoal (but only some chosen pieces) is equal to metals with respect
to the power of putt ting in motion the Electric fluid by connexion with wet
substances; indeed, it rather surpasses gold and silver, so that by making
use of tin and charcoal for the two coatings, a greater effect is produced than
with Tin and Silver.

I am etc.

A. VOLTA

Pavia, 22 May, 1793.