84 NOMOS. 



that there are these chemical changes in metallic 

 conductors during the current; for they show that 

 such changes are necessary to magnetism,, which is 

 another name for electricity. 



Again, if " magnetism" be electricity, we see a 



way of solving that greatest of all magnetical riddles 



permanency. In order to this, indeed, all that is 



necessary is to apply the theory of the 



stone and" Leyden jar. In this jar the charge is 



retain"their preserved by the mechanical interposition 



magnetic o f the glass between the excited coatings. 



power. 



It is preserved because the glass presents 

 a barrier to the reunion of those polar elements in 

 the metallic coatings and elsewhere, which have 

 been separated by the current, and whose separation 

 and reunion is the current. In the loadstone and 

 in steel the oxygen and carbon act (we may suppose) 

 the part of the glass in the Leyden jar; and the 

 " magnetism " is rendered permanent simply because 

 these substances present a mechanical barrier to the 

 reunion of the polar molecules of the iron. Iron 

 very readily enters into the electric state, and as 

 readily passes out of it. The elements of its mole- 

 cules are peculiarly mobile. But if carbon be 

 combined with iron, as in steel, the affinities of the 

 molecules are occupied, and their ready decomposi- 

 tion and recombination is interfered with. Hence 

 steel is an infinitely worse "conductor" than iron. 

 But if the electric current be sufficiently strong to 

 produce the necessary decompositions in the steel, 

 the carbon still interferes with the recombinations. 

 Like the glass of the Leyden jar, it mechanically 



