io4 Traces of Unity in the Various 



force, this latter force would be got from nothing, and 

 perpetual motion be obtained." The whole history of 

 static magnetism, moreover, can be scarcely said to point 

 beyond matter. This force becomes an initiating force 

 when associated with motion, that is, when it is rising or 

 falling, or when a magnetized body is moved in the 

 neighbourhood : but not otherwise. It does not differ 

 from the other physical forces in this respect, for each of 

 these has to be initiated in some way : and it certainly 

 agrees with them in having a title to membership in the 

 same brotherhood, and this the same title, for as is 

 shewn in so many different magneto-electric con- 

 trivances, when magnetism is associated with motion, 

 electricity is at once developed, with /teat and light and 

 chemical affinity and motion in its train. 



It is difficult not to look upon chemical affinity as a 

 mere mode of molecular attraction between dissimilar 

 substances. There is nothing about it to make it 

 necessary to call in the aid of any mysterious imponder- 

 able entity : there is much about it to make it certain 

 that it agrees with the other physical forces which have 

 been under consideration in being subject to the same 

 rule of correlation. What is called voltaic electricity 

 might, perhaps more appropriately, be called voltaic 

 chemistry. A proportionate and equivalent electrical 

 effect is always produced by a given amount of chemical 

 action : and if this action be only turned in a given 

 direction, as in the voltaic battery, the idea of chemical 

 affinity merges in that of electricity, and, once 

 developed, this electricity in turn becomes magnetism, 

 and heat and light and motion and chemical affinity 

 again. The correlation is as comprehensive as it can 

 be, no one single force being left out in the cold. The 

 case is merely a repetition of the other cases, in each of 



