522 On the Nature of the so-called Coercive Force. 



In the fourth and fifth series, the greater numbers which 

 stand forward denote the weight not yet sufficient to effect sepa- 

 ration, and the smaller numbers behind the brackets denote the 

 weight of shot which was added. 



9. Taking the mean values of the single determinations of 

 each series we obtain the following result : — 



Glass hard steel. Yellow steel. Blue steel. Soft iron, 



grins, grms. grins, grins. 



I. 01225 0-268 0340 0-405 



II. 1-1000 1725 2-210 2-625 



III 



/18-4 J25-0 T29-9 /36-0 



124-3 V 



\18-2 1J24-3 \29-7 \34-6 



IV. 233 261 298 331 



V. 1149 1245 1438 1572 



Setting the attraction of the button of glass hard steel equal 

 unity, we obtain for the attraction of the three other buttons the 

 following proportionate numbers : — 



10. This tabular statement shows, as was to be expected, in a 

 striking manner, that the harder the steel is, the more feebly it 

 is magnetized; but that with increasing force, its magnetism 

 increases in a so much quicker ratio. We see that when high 

 power is applied, the yellow steel is not much mox-e strongly 

 attracted than the glass hard, but is more than twice as strongly 

 attracted when the force is feeble ; and that the magnetic de- 

 portment of the blue steel forms the transition to the attraction 

 of the soft iron. By the feeblest of the forces applied this is 

 attracted 3§ times, by the highest power only 1^ time more 

 strongly than the glass hard steel*. 



* This result seems to be an important contribution towards a physical 

 theory of magnetism. The word " resistance " appears to us unhappily 

 chosen by M. Pliicker ; in the case of iron it is an exhaustion of the quality 

 on which its attraction depends, rather than a resistance to further mag- 

 netization, which seems to be indicated by the experiments. — J. T. 



