254 ® r - Wells’s Observations on an Influence 
placed in the same water, and found that the muscles, which 
depended upon it, were from this procedure thrown into 
contractions. Now, in this experiment, there was surely room 
enough for the influence to pass through both metals, and the 
moisture immediately touching them, without going near to 
the nerve. I think it, therefore, probable, that motions are in 
no case produced by any thing passing from the dry exciters 
through the muscles and nerve, but that they are occasioned 
by some influence, naturally contained in those bodies as moist 
substances, being suddenly put in motion when the two dry 
exciters are made to touch both them, and each other ; in like 
manner as persons, it is said, have been killed by the motion 
of their proper quantity of the electric fluid. But to return 
from conjecture to facts, I shall now examine, whether it be 
always necessary to employ two dry exciters, that is, two 
metals, or one metal and charcoal, in order to occasion con- 
tractions. 
Gold and zinc, the first the most perfect of the metals, the 
other an imperfect one, operate together very powerfully in pro- 
ducing contractions ; while gold, and the next most perfect me- 
tal, silver, operate very feebly. It would seem, therefore, that 
the more similar the metals are, which are thus used, the less is 
the pov/er arising from their combination. Two pieces of the 
same metal, but with different portions of alloy, are still more 
feeble than gold and silver ; and the power of such pieces be- 
comes less and less, in proportion as they approach each other 
in point of purity. From these facts it has been inferred, that, 
if any two pieces of the same metal were to possess precisely 
the same degree of purity, they would if used together be en- 
tirely inert, in regard to the excitement of muscular contrac- 
