250 M. F. Reich on Diamagnetic Action. 



with the centre of this sphere a magnet of known strength was 

 placed at a certain distance from the mass of bismuth, and the 

 consequent repulsion was observed. The arm of the torsion 

 balance remained during the experiment in a state of oscillation, 

 which at the commencement could be produced at will, either 

 by the attraction of a mass of lead, or by the diamagnetic action 

 itself*. 



From the experiments on the density of the earth, it is known 

 that the oscillating torsion balance never retains for any length 

 of time the same position of equilibrium unchanged, even where 

 all external influences are, as far as we know, preserved constant. 

 These alterations are indeed inconsiderable, but still of a nature 

 calculated to vitiate experiments like the present. Other sources 

 of disturbance the statement of the experiments themselves will 

 reveal. 



Fi7-st experiment. — Three square bar-magnets, 496 millims. 

 long and 8"6 millims. thick, characterized by the numbers 4, 5, 

 and 6, were permitted, for the purpose of ascertaining their in- 

 tensity, to act from a distance of O'^'S upon a compass-needle. 

 The deflection by No. 4 alone was found to be 9° 45'; by Nos. 4 

 and 5 united, 18° 30'; by Nos.4,5, and 6 united,23° 24': the rela- 

 tion of these intensities therefore was as 1 : 1-9472 : 2-5789 ; and 

 the relation of the squares of the intensities as 1:3-7917:6-6508. 



These three magnets were brought in succession as close to 

 the sphere of bismuth as possible, that is to say, into contact 

 with the chamber of the torsion balance, and the following num- 

 bers were observed : — 



Position of equilibrium without magnet . . . 59-200 



Position of equilibrium with magnet No. 4 . . 55-550 



4 & 5 . 48-750 



4,5&6 42-425 



■ ... ... 4 & 5 . 48-075 



4 . . 54-575 



... without magnet . . . 57-500 



It will be observed here that the position of equilibrium of 

 the balance has sensibly changed; this alteration, however, is 

 nearly proportional to the time. Taking, therefore, the mean, 

 we obtain, — 



The position of equilibrium without magnet . . 58-3500 

 The position of equilibrium with magnet No. 4 . 55-0625 



4&5 48-4125 

 4,5&6 42-4250 



* Der Arm der Torsionswaage blieb dabei immer im Schwingen, was zu 

 Anfang beliebig dui-ch die Attraction einer Bleimasse oder durch die dia- 

 magnetische Einwirkung selbst hervorgerufen wurde. 



