548 



The nickel was first placed between the flat poles of the electro- 

 magnet, with its length across the lines of force, and, one galvano- 

 meter electrode being kept soldered to the junction of the nickel and 

 the copper reference-conductor, the other galvanometer electrode was 

 applied to the testing conductor till the point (equipoteritial with 

 that point of junction) which could be touched without giving any 

 deflection of the needle, was found. A multiplying branch, 3 feet 

 of No. 18 wire, was then soldered with its ends fths of an inch on 

 each side of this point, and, as soon as the solderings were cool, the 

 corresponding point on this multiplying branch was found. The 

 magnetizing current was after that sent in either direction through 

 the coils of the electro-magnet, and it was found that the moveable 

 galvanometer electrode had to be shifted over about 4-g- inches on the 

 multiplying branch towards the end of the testing conductor con- 

 nected with the nickel, that is to say, in such a direction as to indi- 

 cate a diminished resistance in the nickel. When the same opera- 

 tions were gone through with the nickel placed longitudinally be- 

 tween the poles of the electro-magnet, the zero- point on the multi- 

 plying branch was shifted about 6 inches in the direction which 

 indicated an increased resistance in the nickel. 



The piece of iron similarly tested, gave effects in the same direc- 

 tion in each case, and the results originally obtained for iron ( 146, 

 155, 161-177) were thus verified. 



No effect whatever could be discovered when the piece of brass 

 was similarly tried. It is much to be desired that experiments with 

 highly increased power, and with a better kind of galvanometer, 

 should be made, to discover whatever very small influence is really 

 produced by magnetic force on the comparatively non-magnetic 

 metals. 



The shifting of the neutral point on the multiplying branch re- 

 quired to balance the effect produced by the longitudinal magnetiza- 

 tion in the iron, was only from 1^ to 2 inches. Three inches were 

 required to balance the opposite effect of the transverse magneti- 

 zation. 



Hence, with the same magnetic force, the effect of longitudinal 

 magnetization in increasing the resistance, is from three to four times 

 as great in nickel as in iron ; but the contrary effect of transverse 

 magnetization is nearly the same in the two metals with the same 



