1838] 



WRITINGS OF JOSEPH HENRY. 131 



that this exception might possibly be connected with the 

 induced current which takes place in the first coil itself, and 

 which gives rise to the phenomena of the spiral conductor. 

 If this should be found to be minus, we might consider it as 

 existing between the primary and secondary, and the anomaly 

 would thus disappear. Arrangements were therefore made 

 to fully satisfy myself on this point. For this purpose the 

 decomposition of dilute acid and the use of the galvanometer 

 were resorted to, by placing the apparatus between the ends 

 of a cross wire attached to the extremities of the coil, as in 

 the arrangement described by Dr. Faraday (ninth series;) 

 but all the results persisted in giving a direction to this cur- 

 rent the same as stated by Dr. Faraday, namely, that of the 

 primary current. I was therefore obliged to abandon the 

 supposition that the anomaly in the change of the current 

 is connected with the induction of the battery current on itself. 



94. Whatever may be the nature or causes of these changes 

 in the direction, they offer a ready explanation of the neutral- 

 izing action of the plate interposed between two conductors, 

 sinjce a secondary current is induced in the plate; and 

 although the action of this, as has been shown, is in the 

 same direction as the current from the battery, yet it tends 

 to induce a current in the adjacent conducting matter of a 

 contrary direction. The same explanation is also applicable 

 to all the other cases of neutralization, even to those which 

 take place between the conductors of the several orders of 

 currents. 



95. The same principle explains some eflfects noted in 

 reference to the induction of a current on itself. If a flat 

 coil be connected with the battery, of course sparks will be 

 produced by the» induction, at each rupture of the circuit. 

 But if in this condition another flat coil, with its ends joined, 

 be placed on the first coil, the intensity of the shock is much 

 diminished, and when the several spires of the two coils are 

 mutually interposed by winding the two ribbons together 

 into one coil, the sparks entirely disappear in the coil trans- 

 mitting the battery current, when the ends of the other are 

 joined. To understand this, it is only necessary to mention. 



