300 POGGENDORFF ON THE PHiENOMENA OF 



Although these results are not free from anomalies, still they 

 plainly show us that the residual lifting power immediately ob- 

 served is greater in the case of unhardened steel than in that of 

 soft iron, but that the case is reversed where, as seems necessary, 

 as it is included in the observation, the permanent lifting power 

 is subtracted from the residual. This subtraction being made, 

 we see that the residual magnetism in the case of soft iron, not- 

 withstanding its small coercive force, is greater than in the case 

 of unhardened steel. The author would regard this experiment 

 as decisive, with regard to the origin of the residual lifting power, 

 were it not that the objection might be started, that the result 

 observed with steel was a mixed one, produced by the residual 

 lifting power of the steel electro-magnet and the iron sub- 

 magnet. 



He would also observe, as may be seen from the foregoing 

 table, that soft steel is in a high degree capable of assuming 

 temporary magnetism, approaching in this respect very near to 

 soft iron ; and that if it is still behind the latter, this is less due 

 to the difference of the direct magnetizability of the particles, 

 than to the difference of what Faraday calls magnetic conducti- 

 bility, or the propagation of the polarity from particle to particle. 



A bar of unhardened steel and a bar of soft iron, both wholly 

 surrounded by equal spirals, exhibit with the same current but 

 slightly different lifting powers ; but the difference at once ex- 

 hibits itself to the disadvantage of the steel, where the ends of 

 the bars protrude even an inch beyond the spirals. 



To residual magnetism is to be referred the fact, that a horse- 

 shoe magnet closed by its keeper is far from producing the same 

 inductive effect on a second magnetization as it produced with 

 the first, as is sufficiently shown by the above values of the 

 currents b and c. Each following magnetization in the same 

 direction produces only the weaker current c. 



If, however, the direction of magnetization be reversed by re- 

 versing the galvanic current, the induced current is obtained, 

 not with the primitive, but with nearly two-fold intensity. A 

 second magnetization in this new direction produces again the 



