Prof. Norton on Molecular Physics. 281 



cles, in the substance, within which circular currents can be 

 established. 



To the action of the current upon each compound molecule, 

 with its own proper atmosphere (p. 99), as a whole, are to be as- 

 cribed the remarkable phenomena of Induced Currents, especially 

 so called. Experiment has hitherto failed to detect the exist- 

 ence of any current, from one such molecule to another, or 

 through the mass of a body, produced by the uniform action of 

 an established current. All such induced currents result from 

 either an increase or a decrease in the effective action of the in- 

 ducing current, and are wholly due to the indirect mode of ope- 

 ration of this current. This fact indicates, in accordance with 

 the views that have been advanced upon electric polarization 

 (p. 100), that the current developes a polarization in the com- 

 pound molecules of bodies which increases or decreases as the 

 external impulsive action of the current increases or decreases, 

 but remains constant so long as this action continues the same. 

 This polarization is Faraday's " electrotonic state ". of bodies. 



Magnetism. — The general nature of the magnetic currents, as 

 distinguished from other electric currents, has just been indicated. 

 The existence of such currents in the surface of a compound 

 molecule seems to imply that there is a virtual chain of particles 

 extending circularly around it, which there should be if the num- 

 ber of particles in each group be large. Ampere's researches 

 have completely established that the idea of circular molecular 

 currents is the key to all magnetic phenomena. It suffices there- 

 fore, for our present purpose, to show, as has been done, that 

 such currents are legitimately deducible from the fundamental 

 conceptions laid down at the outset, and that the mutually attrac- 

 tive and repulsive actions of currents may also be derived from 

 the same mechanical ideas (p. 278). We adopt, then, definitively, 

 Ampere's theory of the constitution of a magnet. 



The immediate cause of the development of magnetic currents 

 is the direct impulsive action of an established current taking 

 effect upon the particles in the surface of compound molecules. 



In respect to magnetic properties, we have specially to distin- 

 guish soft iron and steel. The cause of their difference of pro- 

 perty seems to lie simply in a difference in the conducting-power 

 of the groups of particles into which they are aggregated. If 

 in soft iron these groups are good conductors, the electric aether 

 set in motion should pass freely around them, unattended with 

 any material polarization of the particles, and unresisted by the 

 force that results from such polarization (p. 103). When the 

 exciting cause ceases to operate, there is no force remaining to 

 counteract the resistance of the universal aether to the flow of 

 the electricity and the retarding operation of contiguous oppo- 



