252 Dr. Wells's Observations on an Influence 
contract. But it appears rather extraordinary, that none of 
those, who contend for the identity of this influence and the 
electric fluid, have ever suspected, that the only very good dry 
conductor of the latter which we know, beside the metals, 
possesses like them the property of exciting the former. I con- 
fess, however, that it was not this consideration, but accident, 
which led me to discover that charcoal is endowed with this 
property, and in such a degree that, along with zinc, it ex- 
cites at least as strongly as gold with zinc, the most power- 
ful combination, I believe, which can in this way be formed 
of the metals. But to prevent disappointments I must men- 
tion, that all charcoal is not equally fit for this purpose, and 
that long keeping seems to diminish its power. 
It being shewn that charcoal is also to be ranked among the 
exciters of this influence, I shall now speak of the circum- 
stances, in which both it and the metals must be placed, to fit 
them for the exercise of their power. With respect to metals, 
Mr. Volta maintains, that to this end it is only necessary, 
that two different species be applied to any other body which 
is a good conductor of electricity, and that a communication be 
established between the two metallic coatings. But charcoal 
is a much better conductor of electricity than water, and yet 
metals in contact with it alone will not excite. Again, Mr. 
Volta says, that the simple application of two metals to two 
parts of an animal disturbs the equilibrium of the electric 
fluid, and disposes it to pass from one of the parts to the 
other, which passage actually takes place, as soon as a con- 
ductor is applied between the metals. But what should pre- 
vent. the passage of the fluid before the application of a new 
conductor, since the metals were already connected by means 
