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



In each case a measurement was made of the magnetic suscepti- 

 bility in air of the ball used, by weighing it in a known magnetic 

 field and observing the loss or gain in weight. 



In this manner the following determinations were made : 



The Magnetic Susceptibility of the Silver Ball. 



Weight of silver ball in air at 15 C. = 132-010 grams. 

 Weight of silver ball in water at 2 C. = 119-235 grams. 

 Yolume of silver ball at 15 C. = 12" 775 c.c. 



The absolute 'magnetic susceptibility of air is 0'024 X 10 6 . 



The mean apparent susceptibility of silver in air is therefore from 



