RELATION OF THE ELECTRIC AND MAGNETIC FORCES. 277 



scribe, would lead to the conclusion that (judging by the amount of effect produced 

 at a distance by forces transverse to the electric current, i. e. magnetic forces,) the in- 

 tervening matter, and therefore the intervening particles, have nothing to do with the 

 phenomena ; or in other words, that though the inductive force of static electricity is 

 transmitted to a distance by the action of the intermediate particles (1164. 1666.), the 

 transverse inductive force of currents, which can also act at a distance, is not trans- 

 mitted by the intermediate particles in a similar way. 



1727. It is however very evident that such a conclusion cannot be considered as 

 proved. Thus when the metal copper is between the pole and the helix (1715. 1719. 

 1725.) or between the two helices (1721.) we know that its particles are affected, 

 and can by proper arrangements make their peculiar state for the time very evident 

 by the production of either electrical or magnetical effects. It seems impossible to 

 consider this effect on the particles of the intervening matter as independent of that 

 produced by the inductric coil or magnet C, on the inducteous coil or core A (1715. 

 1721.); for since the inducteous body is equally affected by the inductric body 

 whether these intervening and affected particles of copper are present or not (1723. 

 1725.), such a supposition would imply that the particles so affected had no reaction 

 back on the original inductric forces. The more reasonable conclusion, as it appears 

 to me, is, to consider these affected particles as efficient in continuing the action 

 onwards from the inductric to the inducteous body, and by this veiy communication 

 producing the effect of no loss of induced power at the latter. 



1728. But then it may be asked what is the relation of the particles of insulating 

 bodies, such as air, sulphur, or lac, when they intervene in the line of magnetic action ? 

 The answer to this is at present merely conjectural. I have long thought there must 

 be a particular condition of such bodies corresponding to the state which causes cur- 

 rents in metals and other conductors (26. 53. 191. 201. 213.) ; and considering that 

 the bodies are insulators one would expect that state to be one of tension. I have by 

 rotating non-conducting bodies near magnetic poles and poles near them, and also 

 by causing powerful electric currents to be suddenly formed and to cease around 

 and about insulators in various directions, endeavoured to make some such state sen- 

 sible, but have not succeeded. Nevertheless, as any such state must be of exceed- 

 ingly low intensity, because of the feeble intensity of the currents which are used to 

 induce it, it may well be that the state may exist, and may be discoverable by some 

 more expert experimentalist, though I have not been able to make it sensible. 



1729. It appears to me possible, therefore, and even probable, that magnetic action 

 may be communicated to a distance by the action of the intervening particles, in a 

 manner having a relation to the way in which the inductive forces of static electricity 

 are transferred to a distance (1677-) ; the intervening particles assuming for the time 

 more or less of a peculiar condition, which (though with a very imperfect idea) I have 

 several times expressed by the term electro-tonic state (60. 242. 1114. 1661.). I hope 

 it will not be understood that I hold the settled opinion that such is the case. I would 



