RESEARCHES OX MAGNETOSTRICTION. 



359 



The following' table gives Cantone's determination of the 

 intensity of magnetization : — 



It will be seen from the above table that on account of the 

 great demagnetizing factor, the magnetizing force was less than 

 8 C.G.S. units, although the field in the coil was nearly GO. 



Cantone did not observe any alteration of volume in the iron, 

 ovoid even with a magnetizing current of 12 ampères ; but it is 

 quite probable that the intensity of the magnetizing force as well as- 

 that of magnetization was insufficient to produce appreciable change- 

 On account of the small susceptibility of nickel, the effect of 

 the demagnetizing- factor in Cantone's nickel ovoid was not so 

 marked as in the iron ovoid. So far as we are aware, he was the 

 first to notice the diminution of volume in nickel by magnetization.. 

 Although his measurements with dilatoineter filled with water and! 

 with alcohol are widely discordant, it is beyond doubt that the 

 readings with alcohol are the more reliable for reasons which will 

 be afterwards given. His calculation of Kirchhofes coefficients 

 h' and k" based on the measurement of the change of length and 

 of volume in nickel by magnetization throw much light on the 

 theory of magnetostriction. 



Our knowledge of the change of internal capacity of tubes of 

 iron, steel, and nickel in the magnetic field has been largely ex- 



