10 AKT. 7. — K. ITOXDA AXD T. TER APA. 



I. SWEDISH IRON and TUNGSTEN STEEL. 



The effect^- of tension or of torsion on the magnetization of 

 iron and steel is so well known that it is superfluous to enter 

 into a detailed description of tlie effect. Only the general features 

 of the change of magnetization will be given here. It will, how- 

 ever, he noticed that our investigation has one characteristics that 

 several effects of the stress on magnetization were studied on tlie 

 same specimen with special attention to tlie order of applying the 

 stress and the field. The specimens were also those on which 

 strains caused by magnetization had been fully studied ; hence 

 the numerical results of the present experiment should be of some 

 use to theoreticians, who have either already obtained, or shall 

 attempt to obtain, some reciprocal relations between magnetization 

 and stress, so that they will be given in their proper places. 



(«) aiiange of mognetizaiion hy tension under constmit 



field: (o/, T)„ 



As will be seen from Figs. 1 and 3, the change of magne- 

 tization oZ,. due to the initial effect of loading increases uj) to a 

 moderate field, and then decreases with it. In Swedish iron, 

 curves (o/„ T),i in weak fields initially bend upward, and after 

 passing through an inflexion point, the curvature changes sign. 

 As the field is increased, the point of inflexion approaches the 

 origin ; in strong fields, o/. is very small, and the curve is nearly 

 straight. In tungsten steel, curve (o/,., T),[ has a slight curvature 

 for all fields. 



In weak fields, the effect of removing the suspended weight 

 is very small and slightly increases the magnetization. Subse- 

 (juent loading causes an, increase of magnetization ; and unloading, 



1) See Wiedemann's ElectricitiU, ."ï, chap. 4; Ewing's IMagnetic Induction, ciiap. 9 ; 

 "Winkolinann, iraiull)iicli der Plivsik, Zweite Anfinge, V.i, p- oCl-üOT, .'îllî-olU, 



