326 FKAGMENTS OF SCIENCE. 



equilibrium was 526 : the movement being from a large* 

 to a smaller number. We thus observe a manifest polar 

 action of the bismuth cylinders upon the magnet ; one. 

 pair of ends deflecting it in one direction, and the other 

 pair deflecting it in the opposite direction. 



Substituting for the cylinders of bismuth thin 

 cylinders of iron, of magnetic slate, of sulphate of iron, 

 carbonate of iron, protochloride of iron, red ferrocyanide 

 of potassium, and other magnetic bodies, it was found 

 that when the position of the magnetic cylinders was 

 the same as that of the cylinders of bismuth, the deflec- 

 tion produced by the former was always opposed in 

 direction to that produced by the latter ; and hence the 

 disposition of the force in the diamagnetic body must 

 have been precisely antithetical to its disposition in the 

 magnetic ones. 



But it will be urged, and indeed has been urged 

 against this inference, that the deflection produced by 

 the bismuth cylinders may be due to induced currents 

 excited in the metal by its motion within the helices. 

 In reply to this objection, it may be stated, in the 

 first place, that the deflection is permanent, and can- 

 not therefore be due to induced currents, which are only 

 of momentary duration. It has also been urged that 

 such experiments ought to be made with other metals, 

 and with better conductors than bismuth ; for if due 

 to currents of induction, the better the conductor, the 

 more exalted will be the effect. This requirement was 

 complied with. 



Cylinders of antimony were substituted for those of 

 bismuth. This metal is a better conductor of elec- 

 tricity, but less strongly diamagnetic than bismuth. 

 If therefore the action referred to be due to induced 

 currents we ought to have it greater in the case of anti- 

 mony than with bismuth ; but if it springs from a true 



