184 PROCEEDINGS OP THE AMERICAN ACADEMY 



surfaces induced by rolling, two bars from the same steel, one rolled 

 and the other pressed, were magnetized and then measured. The 

 ratio of the specific magnetism of pressed to rolled was as 9 to 5, the 

 rolled having the smaller amount. The existing difference, in this 

 case, is probably owing to a difference in hardness, rather than to any 

 molecular condition of the surfaces. 



The specific magnetisms of all the bars are small when compared 

 with good steel magnets. Kohlrausch says that good magnets, of 

 common fprra, should have S = 40. The bar of ordinary tool steel, 

 however, retained but 7.46. Still it was soft, and by tempering would 

 doubtless have doubled this value. 



If forged nickel and tungsten can be made to maintain a specific 

 magnetism of 10, it will form a useful addition to the resources of 

 physical laboratories. From the high polish of which it is suscepti- 

 ble and its freedom from damaging atmospheric influences, it will be 

 most happily suited for the manufacture of mirror magnets where 

 magnetic damping is to be employed. 



Jefferson Physical Labokatoky. 



