25B Dr. Wells's Observations on an Influence 
to have been produced by insulating the metal completely ; 
which is contrary to fact. 
4. I placed a limb of a frog, properly prepared, upon the 
floor of my chamber ; if a severe frost had not prevailed when 
I made this experiment, I should have laid it upon the moistened 
surface of the earth. I then raised from the muscles, by means 
of an electric, the loose end of the nerve, and touched it with 
the rubbed part of a piece of metal ; but no contractions fol- 
lowed. To be convinced that this was not owing to any want 
of virtue in the metal, I kept the same part of it still in con- 
tact with the nerve, while I applied another part to the muscles ; 
immediately upon which contractions were excited. 
5. Admitting now the limb of an animal to be in such an 
experiment completely insulated, and that the metal actually 
becomes electrical from the friction it undergoes, surely a very 
few applications can only be required to place them both in 
the same state with respect to the electric fluid ; and when this 
happens, all motions depending on the transflux of that fluid 
must necessarily cease. I have found, however, that a piece 
of metal which has been rubbed will excite contractions, after 
it has been many times applied to the limb. In one instance, 
vigorous contractions were occasioned by the 200th applica- 
tion ; and if I had chosen to push the experiment further, I 
might certainly have produced many more. I may mention 
also, as connected with this fact, that I have frequently ob- 
served a piece of metal to excite motions, an entire day after it 
had been rubbed. 
What I have said will, probably, be thought more than suf- 
ficient to prove, that metals, after being rubbed, do not produce 
