Prof. G. Wiedemann's Magnetic Researches. 57 



§4. 



If the changes of magnetic moment which take place upon 

 torsion enable a conclusion to be drawn as to the rotation of 

 the molecules, it appeared of interest to investigate the pro- 

 cesses connected with the changes still further ; and first to 

 examine a wire subjected to repeated twisting and untwisting 

 within certain limits. 



These experiments were made with the same apparatus, 

 and by the same methods as described above : — Wires, in some 

 cases (temporarily or permanently) longitudinally magnetized 

 by currents led round them, in other cases (temporarily or 

 permanently) transversely-circularly magnetized by currents 

 led through them, were twisted and untwisted through a 

 certain number of degrees, and their moments determined 

 from the deflection of the suspended steel mirror. The devia- 

 tions produced by the magnetizing current were compensated 

 as before. By repeatedly raising and lowering the compen- 

 sating-ring, its constancy during the experiments on tem- 

 porary magnetism could be controlled. 



In the following tables, in order to economize space, the 

 data are given only for the 1st 2nd, 3rd, and nth torsion and 

 detorsion after twisting the ware to and fro so many times 

 that upon repetition of the experiments the same results were 

 obtained, t denotes the angle of torsion, m t the temporary, 

 and ?})p the permanent magnetic moment. 



1. Soft-iron wire 2 millim. thick, temporarily magnetized 

 longitudinally by a current led round it. 



A. 



mt. 



mt. 



t. 



1. 



2. 



3. 



n. 



t. 



1. 



2. 



3. 



n. 



o 

 0... 



362-5 



3545 



354-1 



357-7 



o 



180... 



353 



357-2 



358 



362-5 



30... 



367 



364 



364 



366-3 



150... 



361 



369-5 



3705 



374 



60... 



358-5 



376 



376 



3786 



120... 



376 



379 5 



380 



384 



90... 



346 



381 



383 



384-8 



90... 



375 



378 



378 



381 



120 ... 



343 



374 



375 



3788 



60... 



367-5 



370 



370-5 



372 



150... 



343 



3632 



364 



3681 



30... 



3605 



361 



360-5 



363-6 



180... 



343 



355 



355 



360 



0... 



354 5 



354-5 



355 



358 



210... 



343 



348-5 



348-2 



353 













B. A similar iron wire magnetized by a very weak cui 

 rent. 



