Bodies are repelled from the Poles of a Magnet. 289 



pair pai'allel to ft/. The consequence is, that a cube of crystal- 

 lized bismuth suspended in the manner described, in a sufficiently 

 uniform field of magnetic force, will move in the same direction 

 as the cross in fig. 4 : its centre of gravity will therefore apjjroach 

 the pole N, which was to be demonstrated. 



This deduction is perfectly illustrated by experiment. It is 

 manifest that the effect of the pole S upon the cube adjacent to 

 it is to increase the moment of rotation of the rectangular box : 

 the same reasoning applies to it as to the pole N. 



Referring to fig. 27a, page 278, it will be seen that we have 

 here dealt with the second and gravest objection of M. Matteucci, 

 and converted the facts upon which the objection is based into a 

 proof of diamagnetic polarity, so cogent that it alone would seem 

 to be sufficient to decide this important question. Holding the 

 opinion entertained by M. Matteucci regarding the natu^re of 

 diamagnetic force*, his objection must have appeared to him to 

 be absolutely unanswerable : I should be glad to believe that the 

 remarks contained in this Appendix furnish, in the estimation 

 of the distinguished philosopher referred to, a satisfactory expla- 

 nation of the difficulty which he has disclosed. 



Let me, in conclusion, briefly direct the reader's attention to 

 the body of evidence laid before him in the foregoing pages. It 

 has been proved that matter is repelled by the pole of a magnet 

 in virtue of an induced condition into which the matter is thrown 

 by such a pole. It is shown that the condition evoked by one 

 pole is not that which is evoked by a pole of an opposite quality 

 — that each pole excites a condition peculiar to itself. A perfect 

 antithesis has been shown to exist between the deportment of 

 paramagnetic and diamagnetic bodies when acted on by a mag- 

 net alone, by an electric current alone, or by a magnet and an 

 electric current combined. The perplexing phsenomena resulting 

 from molecular structure have been laid open, and the antithesis 

 between paramagnetic and diamagnetic action traced throughout. 

 It is further shown, that whatever title to polarity the deportment 

 of a bar of soft iron, surrounded by an electric current, and acted 

 on by other magnets, gives to this substance, a bar of bismuth 

 possesses precisely the same title : the disposition of forces, which 

 in the former case produces attraction, produces in the latter case 

 repulsion, while the repulsion of the iron finds its exact comple- 

 ment in the attraction of the bismuth. Finally, we have a case 

 adduced by M. ]\Iatteucci which suggests a crucial experiment 

 to which all our previous reasoning has been submitted, by which 

 its accuj-acy has been proved, and the insufficiency of the assump- 



* " II nc i)eut exister dans Ics coq)s diamagnctiques une polaiite telle 

 qu'on la concoit dans le fer doux."— Cowrs Special, p. 201. 



