52 DR. FARADAY*S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 



tive action, occurring at the moment when the principal current is stopped. I at one 

 time thought they were due to an action continued during the continuance of the 

 current, and expected that a steel magnet would have an influence according to its 

 position in the helix, comparable to that of a soft iron bar, in assisting the effect. 

 This, however, is not the case ; for hard steel, or a magnet in the helix, is not so ef- 

 fectual as soft iron ; nor does it make any difference how the magnet is placed in the 

 helix, and for very simple reasons, namely, that the effect does not depend upon a 

 permanent state of the core, but a change of state, and that the magnet or hard steel 

 cannot sink through such a difference of state as soft iron, at the moment contact 

 ceases, and therefore cannot produce an equal effect in generating a current of elec- 

 tricity by induction (34. 37.). 



1101. As an electric current acts by induction with equal energy at the moment 

 of its commencement as at the moment of its cessation (10. 26.), but in a contrary 

 direction, the reference of the effects under examination to an inductive action, would 

 lead to the conclusion that corresponding effects of an opposite nature must occur 

 in a long wire, a helix, or an electro-magnet, every time that contact is made with the 

 electromotor. These effects will tend to establish a resistance for the first moment 

 in the long conductor, producing a result equivalent to the reverse of a shock or a 

 spark. Now it is very difficult to devise means fit for the recognition of such nega- 

 tive results ; but as it is probable that some positive effect is produced at the time, 

 if we knew what to expect, I think the few facts bearing upon this subject with which 

 I am acquainted are worth recording. 



1102. The electro-magnet was arranged with an electrolyzing apparatus at x, as 

 before described (1084.), except that the intensity of the chemical action at the elec- 

 tromotor was increased until the electric current was just able to produce the feeblest 

 signs of decomposition whilst contact was continued at G and E (1079.) ; (the iodine 

 of course appearing against the end of the cross wire P;) the wire N was also sepa- 

 rated from A at r, so that contact there could be made or broken at pleasure. Under 

 these circumstances the following set of actions was repeated several times : contact 

 was broken at r, then broken at G, next made at r, and lastly renewed at G ; thus 

 any current from N to P due to breahing of contact was avoided, but any additional 

 force to the current from P to N due to making contact could be observed. In this 

 way it was found, that' a much greater decomposing effect (causing the evolution of 

 iodine against P) could be obtained by a few completions of contact than by the cur- 

 rent which could pass in a much longer time if the contact was contifiued. This 1 

 attribute to the act of induction in the wire A B D at the moment of contact render- 

 mg that wire a worse conductor, or rather retarding the passage of the electricity 

 through it for the instant, and so throwing a greater quantity of the electricity which 

 the electromotor could produce, through the cross wire passage N P. The instant 

 the induction ceased, AB D resumed its full power of carrying a constant current of 



