HISTORY OF GALVANISM. 



it ought to be considered as identical with elec- 

 tricity. Dr. Wells coincides in opinion with Volta, 

 that the contractions of the muscles depend upon 

 electricity liberated by some cause, independent of 

 the animal body, and that the moisture which is 

 present in all parts is the immediate cause of the 

 facility with which the effect is produced. He 

 discovered the important fact, that charcoal may 

 be employed, together with one of the metals, 

 for exciting the influence; and also that the 

 influence, when excited, may be conducted by 

 charcoal. He argues at length against the hy- 

 pothesis of Volta, respecting the production of 

 the electricity by the contact of the two metals, 

 and urges as a decisive objection to it, that the 

 moisture which is attached to the animal ought to 

 serve as a conductor, and equalize their electrical 

 condition, without their being absolutely brought 

 into contact. 



Dr. Wells made some curious experiments 

 upon the effects that were produced on the power 

 of the metals and on charcoal by friction ; after 

 this operation he found that one of the substances 

 alone was sufficient to produce the contractions. 

 As it appeared that the friction did not immedi- 

 ately communicate electricity to the body that was 

 rubbed, it must be supposed that some change 

 was brought about in its nature, by which its 

 different parts were enabled to act upon each 

 other in the same manner with two distinct 

 substances. He is decidedly of opinion, that 



