Note

204
tongue, are, I say, differently affected according as this current goes against
and strikes the tip, so that the fluid enters into it; or, as it moves in a contrary
direction, so as to go out of it. Now since, when the tin is applied to this most
sensible part of the tongue, and the silver to the back part, the acid taste is
perceived, and by inverting the position of the metals, the alkaline one, the
following questions naturally arise; When does the Electric fluid enter, when
does it go out? Which of the two metals gives it to the tongue, which re-
ceives it?

In order to discover this I returned to the artificial Electricity of the Ma-
chine, and I found that the acid taste is excited when the electric current comes
against the point of the tongue (when the fluid enters it); and that when the
current moves in a contrary direction (when it goes out), either no taste is
excited, or it is alkaline. Make trial by presenting the tip of the tongue to the
extremity of an Electrified Conductor with a blunt point, at such a distance
as that no spark sufficient to strike the tongue sharply may be produced, but
only so that the tip of the tongue may be stimulated by the electric air. If the
Electricity of the Conductor should be positive, you will perceive a weak
acid taste; if negative, either no taste at all, or one a little alkaline. The expe-
riment will succeed better if, to the blunt metallic point, you substitute a
small cone of wood, which spits out the fire without giving sparks, even to
a body very near it. Also by bringing the tongue immediately into contact
with the conductor, or with the cone of wood, or other body annexed to it,
(particularly if the tongue be wet) and keeping it firmly applied to it while
the machine is made to act, the same acidulous taste is perceived from posi-
tive Electricity, and from negative, either none at all, or, when the machine
acts very strongly, a trifling alkaline sensation.

Tin then, which, when applied to the tip of the tongue acts like a con-
ductor positively electrified, that is excites upon it the same acid taste, and
even a stronger one; Tin I say, (and also Zinc and Lead) causes the Electric
fluid to enter into the Tongue. Silver, (and also Gold, Platina and Mercury)
which acts like a conductor negatively electrified, either exciting no taste
or an alkaline one, draws out the fluid. This fluid, returning afterwards from
the Silver to the Tin, which for that purpose, must communicate together,
either immediately, or by the interposition of other metals, continues in that
manner to circulate, and, for the same reason, the Taste continues to be per-
ceived on the tongue; neither do the spasmodic convulsions, or tetanus cease,
in a frog prepared and submitted to such experiments, till, by removing one
or other of the communications, the circle is interrupted.

Such is the Theory of this new principle of Electricity, for which, however,
the name of Animal Electricity is by no means proper, in the sense intended
by Galvani, and by others; namely, that the Electric fluid becomes unbalanced