Susceptibility of Iron in Colloidal Solution. 



263 



As wood is itself slightly diamagnetic the field will exert a 

 force on the block even with no current through the foil — an 

 effect which must be taken into consideration. Table I gives the 

 weights which were necessary to counterbalance the block of 

 wood, with no current passing through the tin-foil, when different 

 currents were sent through the coils of the electromagnet. In 

 column III are recorded the pulls exerted by the fields of different 

 strengths on the block of wood. 



Table I. 



Susceptibility of Wooden Block ; no current in foil. 



Current for 



Counterbalancing 



Pull due to the 



Electromagnet 



weight 



Magnetic Field 



amperes 



39-053 grams 





8 





39-023 „ 

 39-054 „ 



— -031 grams 



9-9 , 

 , , 





39-016 „ 

 39-053 „ 



- -037 „ 



11-8 , 





39-012 „ 

 39-054 „ 



- -042 „ 



15 , 



o 





39-001 „ 

 39-052 „ 



- -051 „ 



17 



o 





38-996 ,, 

 39-052 „ 



- -056 „ 



In Curve I the numbers given in columns I and III are plotted, 

 the abscissae being currents and the ordinates the weights in 

 milligrams. From this curve we may deduce the pull when any 

 intermediate current is sent through the magnet. 



60 













































































&U 



























40 













































































8 10 12 14 16 18 



Ampere* 



Curve I. 



