CONCLUDING REMARKS. 169 



may be ; so the other affections are only matter moved or 

 molecularly agitated in certain definite directions. I have 

 already considered the hypothesis that the passage of electri- 

 city and magnetism causes vibrations in an ether permeating 

 the bodies through which the current is transmitted, i.e. the 

 application of the same ethereal hypothesis to these impon- 

 derables which had previously been applied to light ; many, 

 in speaking of some of their effects, admit that electricity and 

 magnetism cause or produce by their passage vibrations in the 

 particles of matter, but regard the vibrations produced as an 

 occasional, though not always a necessary, effect of the pas- 

 sage of electricity, or of the increment or decrement of mag- 

 netism. The view which I have taken is, that such vibrations, 

 molecular polarisations, or motions of some sort from particle 

 to particle, are themselves electricity or magnetism ; or, to 

 express it in the converse, that dynamic electricity and mag- 

 netism are themselves motion, and that permanent magnetism, 

 and static electricity, are conditions of force bearing a similar 

 relation to motion which tension or gravitation do. The so- 

 called imponderables affect matter in all its states. Gases 

 which have transmitted light are altered, e.g. chlorine is ren- 

 dered capable of combining with hydrogen, liquids are altered, 

 peroxalate of iron is chemically changed and gives off carbonic 

 acid, and the light which has produced these effects is less able 

 to produce them a second time. Solids are altered, as shown 

 in the extensive range of photographic effects. So with elec- 

 tricity, compound gases are changed chemically, e.g. ammonia 

 or carbonic acid ; elementary gases are changed allotropically, 

 e.g. phosphorus vapour or oxygen ; liquids are changed, as in 

 the electrolysis of water, &c.; and solids are changed, as in the 

 projection of particles of the terminals, and molecular impres- 

 sions on polished surfaces. Chemical affinity is only known 

 to us by its affecting matter in the three states, and magnetism 

 is proved to affect liquids and solids, though as yet gases are 

 not shown to be altered by it. 



This theory might well be discussed in greater detail than 

 has been used in this work ; but to do this and to anticipate 

 objections would lead into specialties foreign to my present 

 object, in the course of this Essay my principal aim having 



