Bodies are repelled from the Poles of a Magnet. 161 



but feeble. Simple as the problem may appear, it required 

 considerable time and care to obtain the results here recorded. 

 During a first examination of the cubes eight anomalies presented 

 themselves — in eight cases the fibre set either oblique or axial. 

 The whole thirty-five specimens were carefully rescraped with 

 glass and tested once more; still two remained, which, though 

 repelled as masses, persistently set with the fibre axial, and 

 oscillated round this position so steadily as to lead to the sup- 

 position that the real deportment of the substance was thus 

 exhibited. I scraped these cubes ten times successively, and 

 washed them with ail care, but the deportment remained un- 

 changed. The cubes, for the sake of reference, had been stamped 

 with diminutive numbers by the maker of them ; and I noticed 

 at length, that in these two cases a trace of the figures remained : 

 on removing the whole surface which bore the stamp from each, 

 the cubes forsook the axial position, and set, like the others, 

 with the fibre equatorial. 



The influence of the mere form of an impurity was here very 

 prettily exhibited. The cubes in question had been stamped 

 (probably by an iron tool) with the numbers 33 and 37, which 

 lay in the line of the fibre ; the figures, being dumpy little ones, 

 caused an elongation of the magnetic impurity along the said 

 line, and the natural consequence of this elongation was the 

 deportment above described. 



Of the thirty-five specimens examined one proved to be para- 

 magnetic. Now, it may be asked, if the views of molecxxlar 

 action stated in the foregoing pages be correct, how is it that 

 this paramagnetic cube sets its fibre equatorial ? The case is 

 instructive. The substance (bog oak) had been evidently 

 steeped in a liquid containing a small quantity of iron in solu- 

 tion, whence it derives its magnetism ; but here we have no 

 substitution of paramagnetic molecules for diamagnetic ones, as 

 in the cases referred to. The extraneous magnetic constituent 

 is practically indifferent as to the direction of magnetization, 

 and it therefore accommodates itself to the directive action of 

 the wood to which it is attached. 



II. On the Rotation of Bodies between Pointed 

 Magnetic Poles. 



In his experiments on charcoal, wood-bark and other sub- 

 stances, M. Pliicker discovered some very curious phajnomena 

 of rotation, which occurred on removing the substance experi- 

 mented on from one portion of the magnetic field to another. 

 To account for these phicnomena, he assumed, that in the 

 substances which exhibited the rotation, two antagonist forces 

 were perpetually active — a repulsive force, which caused the 



