iSO THE INSUFFlCIEI^Cr OF PHYSICAL LAW. 



however great, and affects those beyond as if nothing 

 intervened. Unlike all other forces, it is incapable of 

 saturation. A magnet quickly gets its load, beyond 

 which it can carry no more. If it spends energy on one 

 object, it has that much less for any other. But the 

 earth acts on an apple, on a planet, on the sun, and on 

 each star in space, and affects each one as if it alone was 

 the object of its attraction. Neither the presence, the 

 absence, nor the intervention of one body, or of any num- 

 ber of bodies, has any effect on its influence on another. 



The attraction of cohesion acts only at insensiljle dis- 

 tances, has no relation whatever to mass, and varies in 

 intensity in some inverse power of the distance of a 

 higher order than the square. 



Then there are the Laws of Chemistry. Running 

 through them all, and giving them use and vitality, is 

 the law of chemical affinity. Unlike the law of gravita- 

 tion, and like the law of cohesion, it acts only at insensi- 

 ble distances. Its most striking peculiarity is that there 

 always results from its action a change of properties, the 

 old disappearing and new ones taking their place. Un- 

 like the organic world, the child is always unlike its 

 parents. The only properties never affected by chemical 

 action are mass and weight. 



In electricity as in chemistry the number of observed 

 ' ' invariable orders of sequence ' ' is very great. It attracts 

 and repels not merely at insensible distances, but at dis- 

 tances whose limits are yet unknown. It travels from 

 place to place, through solid wires, and refuses to go 

 through a vacuum, while it all the time sends off waves of 

 energy that most easily go through that which is im- 

 passable to the electricity itself. It pulls apart chemical 

 compounds, and causes others to form. Nor can I detect 

 any one principle that runs thiough and connects all its 

 phenomena, unless it be the lew of polarity, that appar- 

 ently impossible, but yet actual condition by which two 



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