39 



Hunter's opinion, that irritability is the 

 effect of some subtile, mobile, invisible 

 substance, superadded to the evident struc- 

 ture of muscles, or other forms of vege- 

 table and animal matter, as magnetism 

 is to iron, and as electricity is to various 

 substances with which it may be connect- 

 ed. Mr. Hunter doubtless thought, an<J 

 I believe most persons do think, that in 

 magnetic and electric motions, a subtile 

 invisible substance, of a very quickly and 

 powerfully mobile nature, puts in motion 

 other bodies which are evident to the 

 senses, and are of a nature more gross 

 and inert. To be as convinced as I am 

 of the probability of Mr. Hunter's Theory 

 as a cause of irritability, it is, I am aware, 

 necessary to be as convinced as I am 

 that electricity is what I have now sup- 

 posed it to be, and that it pervades all 

 nature. To obtain this conviction it is 

 necessary that the facts connected with this 



