THE MOLECULAR PROCESS IN MAGNETIC INDUCTION. 265 



the magnetism to the load (Fig. 14). This is because some of the molec- 

 ular groups are every time being broken up during the loading, and 

 re-established during the unloading, and that, as we saw already, in- 

 volves hysteresis. Consequently, too, each loading and unloading re- 

 quires the expenditure of a small (juantity of energy, which goes to 

 heat the metal. 



S260 



S 260 



r Inailini: :iii<l iiiili>:i(linir- 



Moreover, a remarkably interesting conclusion ibllows. This hys- 

 teresis, and conse(juent dissii)ation of energy, will also hai)pen though 

 there be no magnetization of the piece as a whole; it depends on the 

 fact that the molecules are magnets. Accordingly, we should expect 

 to find, and experiment conflrins this (see Phil. Tram.^ 188;"), j). 014), 

 that if tlie wire is loaded and unloaded, even when no magnetic field 

 acts and there is no magnetism, its i)hysical qualities which are changed 

 by the load will change in a manner involving hysteresis. In i>artic- 

 ular, the length will be less for the same load during loading than dur- 

 ing unloading, so that woik may be wasted in every cycle of loads. 

 There can be no sucli thing as i)erfect elasticity in a magnetizable 

 metal, unless, indeed, the raiige of the strain is so very narrow that 

 none of the molecules tumble through unstable states. This nuiy have 



