316 



Profs. J. A. Fleming and J. Dewar. 



(3) The apparent weight of the ball in water, magnet not excited. 



(4) The apparent weight of the ball in the solution used, magnet 



not excited. 



(5) The apparent weight of the ball in the liquid, the magnet 



being excited with a known current, and the position of the 

 ball in the field accurately known. 



From these weighings we obtain all the required information. For 

 from (1) and (3) we obtain the volume of the ball, and from (1), 

 (2), and (3) the magnetic susceptibility of the ball, and from (4) and 

 (5) the magnetic susceptibility of the liquid. 



The sphere used as a testing substance was suspended by a long 

 fine platinum or gold wire from one pan of the balance. A small 

 beaker filled with water or the salts solution under test was placed 

 over the pole of this magnet and the sphere suspended in it. 



In some cases when using strong exciting currents we found it 



Table II. Induction Densities (H) of Field of Tubular Electro- 

 magnet at various distances x along the Axial Line. 



