ELECTRICITY. 87 



minute changes, evidence of molecular change will not be 

 detected ; so that, excepting those cases where infinitesimally 

 small quantities of matter are acted on, and our means of de- 

 tection fail, electrical effects are known to us only as changes 

 of ordinary matter. It seems to me as easy to imagine these 

 changes to be effected by a force acting in definite directions, 

 as by a fluid which has no independent or sensible existence, 

 and which, it must be assumed, is associated with, or exerts a 

 force acting upon ordinary matter, or matter of a different 

 order from the supposed fluid. As the idea of the hypothetic 

 fluid is pursued, it gradually vanishes, and resolves itself into 

 the idea of force. The hypothesis of matter without weight 

 presents in itself, as I believe, fatal objections to the theories 

 of electrical fluids, which are entirely removed by viewing 

 electricity as force or motion, and not as matter. 



If it be said that the effects we have been considering may 

 still be produced by a fluid, and that this fluid acts upon ordi- 

 nary matter in certain cases, polarising the matter affected or 

 arranging its particles in a definite direction, whilst in others, 

 by its attractive or repulsive force, it carries with it portions of 

 matter ; then, if the fluid in itself be incapable of recognition 

 by any test, if it be only evidenced by the changes which it 

 operates in ponderable matter, the words fluid and force be- 

 come identical in meaning; we may as well say that the 

 attraction of gravitation or weight is occasioned by a fluid, as 

 that electrical changes are so. 



When, as is constantly done in common parlance, a house 

 is said to be struck, windows broken, metals fused or dissipated 

 by the electrical fluid, are not the expressions used such as, if 

 not sanctioned by habit, would seem absurd ? In all the cases 

 of injury done by lightning there is no fluid perceptible ; the 

 so-called sulphurous odour is either ozone developed by the 

 action of electricity on atmospheric air, or the vapour of some 

 substance dissipated by the discharge ; does it not then seem 

 more consonant with experience to regard these effects as pro- 

 duced by force, as we have analogous effects produced by 

 admitted forces, in cases where no one would invoke the aid 

 of a hypothetic fluid for explanation ? For instance, glasses 

 may be broken by electrical discharges ; so may they by sono- 



