Bodies are repelled from the Poles of a Magnet. 267 



column, that of the normal diamagnctic bar; the third shows 

 the deportment of the abnormal paramagnetic bar, and the fourth 

 that of the abnormal diamagnetic bar. 



A comparison of the first two columns shows us that the de- 

 portment of the normal magnetic bar is perfectly antithetical to 

 that of the normal diamagnetic one. When, on the application 

 of the second force, an end of the former is deflected to the right, 

 the same end of the latter is deflected to the left. When the 

 position of equilibrium of the magnetic bar, under the joint action 

 of the two forces, is from N.E. to S.W., then the position of 

 equilibrium for the diamagnetic bar is invariably from N.W. to 

 S.E. There is no exception to this antithesis, and I have been 

 thus careful to vary the conditions of experiment in all possible 

 ways, on account of the divergent results obtained by other 

 inquirers. In his recent memoirs upon this subject, M. v. Fei- 

 litsch states that he has found the deflection of diamagnetic 

 bodies, under the cix'cum stances here described, to be precisely 

 the same as that of paramagnetic bodies : this result is of course 

 opposed to mine ; but when it is remembered that the learned 

 German worked confessedly with the " i-oughest apparatus," and 

 possessed no means of eliminating the effects of structure, there 

 seems little difficulty in referring the discrepancy between us to 

 its proper cause. 



The same perfect antithesis will be observed in the case of the 

 abnormal bars, on a comparison of the third and fourth columns. 

 In all cases then, whether we apply the magnet singly, or the cur- 

 rent singly, or the magnet and current combined, the deportment 

 of the normal diamagnetic bar is opposed to that of the normal 

 paramagnetic one, and the deportment of the abnormal paramag- 

 netic bar is opposed to that of the abnormal diamagnetic one. 

 But if we compare the normal ])aramagnetic with the abnormal 

 diamagnetic bar, we see that the deportment of the one is identical 

 with that of the other*. The same identity of action is observed 

 when the normal diamagnetic bar is compared with the abnormal 

 paramagnetic one. The necessity of taking molecular structure 

 into account in experiments of this nature could not, I think, be 

 more strikingly exhibited. 



For each of the bars, under the operation of the two forces, 

 there is an oblique position of equilibrium : on the application 



* Identical to the e}'e, but not to the mind. The notion aj)pears to be 

 entertained by some, that, by changing molecular stnicture, I had actually 

 converted paramagnetic substances into diamagnetic ones, and vice versa. 

 No such change, liowever, can cause the mass of a diamagnetic body sus- 

 pended by its centre of gravity to be attracted, or the mass of a ])aramag- 

 netic body to be repelled. But by a change of molecular structure, one of 

 the forces may be so caused to apply itself that it shall present to the eye 

 all the directive phtenomena exhibited by the other. — J. T., May 5, 186>, 



T2" 



