in the Motion of the Magnetic Field. 327 



included in the general equations, and can be shown as 

 follows : — 



H = const., ~0-fl\l + AJ + H = O, 



B SC-0' 



(PP)*P* + G>P a + O-a J 2 = g— J 



<}F 



(pp)m + G ^ + °> T2 = §^* 



The new terms introduced in the equations appertaining to 



the coordinates^, p P) ... .; (j>p) p a + G-«p«, {pp) up ? + *&&?, . . . 

 represent the forces of inertia and viscosity respectively. It 

 is clear that in the curve of magnetization showing the de- 

 pendence of magnetization I on the magnetic force H, this 

 process is shown by the straight-lined parts of it parallel to 

 the axis of magnetization.] 



The same equation shows, further, that at the commence- 

 ment of magnetization -jyj must be equal to te, because in 



these conditions , , ^ =0 ; and therefore ^™ =0, if only 



dp. d[o % F . ? J 



-jp is not co , which can happen only in particular cases ; for 



instance, near the temperature of recalescence. This is the 



least value that -^ can have ; it is not great, and if the 

 «ri 



deformations were not existing, the magnetization of iron would 



not differ much from the magnetization of other paramagnetic 



bodies. But that in consequence of these deformations, ^-™ 



dl . ^ J 



increases very rapidly, and ^t increases with it. The 



quantity -j~ exists as long as the deformations change ; when 



the deformations cease to change, the differential coefficient 



-TYj again takes small values. This ceasing of change of 



deformations must be therefore supposed in order to explain 

 so-called magnetic saturation. But if we take into considera- 

 tion that magnetic deformations most likely do not represent 



