INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 747 



in the scale hanging from the other end of the beam was requisite 

 to separate the watch-glass from the two halves of the keeper ; 

 but after it had been withdrawn, the watch-glass, at a certain 

 distance (about 50 millim.) from the electro-magnet, ivas held fast 

 by the latter in such a manner, that when further removed from 

 the magnet it was attracted, and when more approximated to it, 

 it was repelled. On opening the circuit, the watch-glass con- 

 taining the phosphorus separated further from the electro- 

 magnet. 



When only two cells were used, the phaenomenon described 

 above was still better observed ; even a less excess of weight 

 separated the watch-glass ; and the latter, when in greater proxi- 

 mity to the electro-magnet, assumed the repose of stable equili- 

 brium. When this had ensued, and the magnetism was then 

 withdrawn, the watch-glass separated completely from the elec- 

 tro-magnet. 



The same phcenomenon was very well seen with ten cells, when 

 the phosphorus was removed from the watch-glass and placed 

 immediately in the brass ring. The position of equilibrium in 

 this case existed at a distance of 4 millim. to 5 millim. from the 

 two halves of the keeper. 



51. Finally, when mercury was placed in the watch-glass 

 instead of the phosphorus, its withdrawal then ensuing with the 

 slight excess of weight 0*05 grm., the watch-glass assumed a 

 stable position of equilibrium at a very small distance (about 

 1 millim.) from the halves of the keeper, so that at a little distance 

 it appeared still to adhere to the halves of the keeper. A con- 

 siderable excess of weight was requisite to remove the watch- 

 glass further from the halves of the keeper ; this separation oc- 

 curred immediately when the magnetism was withdrawn. In 

 another experiment, 120 grms. of mercury were poured into a 

 porcelain cup, spherically rounded at the bottom, and this was 

 suspended in a brass ring. As the attraction of the empty cup 

 M'ith the ring was too feeble, an iron rod (arranged axially) was 

 fixed by means of wax to the corresponding beam ; on using ten 

 cells the attraction then rose to 1*20 grm. The cup with mer- 

 cury was then withdrawn by a load of 0*80 grm., so that we get 

 0*40 grm. as the diamagnetic repulsion of the mercury. The 

 stable position of equilibrium occurred at an elevation of I mil- 

 lim. to 2 millims. ; on opening the circuit, the cup was raised 

 more than 100 millims. 



