1902.] Longitudinal Magnetic Field on Internal Viscosity. 301 



about 400 C.G.S., but the curves obtained showed only a very slight 

 tendency to move to the right, so slight that if they had been drawn 

 they could not have been distinguished in the diagram from Curves 5 

 and 6. The same vibrator was used for the iron wire as had been used 

 in the case of nickel, and the period of vibration was 5*27 seconds. 

 For iron, then, we have the remarkable result that the effect of a 

 magnetic field on the rate of subsidence of torsional oscillations is to 

 diminish that rate, and by an amount diminishing with increasing field 

 until a field of about 160 or 170 C.G.S. is reached, after which the effect 

 of the field, however great, is practically constant. This is, of course, 

 what one would expect in consequence of saturation of the iron, but it 

 is a result very remarkably different from that obtained for nickel. 

 The totally different behaviours in the two cases seem to point to an 

 entirely different collocation of elementary magnets in the nickel and 

 the iron, i.e., perfectly distinct molecular constitution, consistent, how- 

 ever, in each case with magnetisability. 



Results for Steel. — Diagram V shows three curves obtained for piano- 

 forte steel wire. The same vibrator was employed as in the former 



10.8 



126" 



AmpLibude. 



162 



180 



20 



I 



j 



60 



o 



30 



100 



D I AGE AM V. 



Curve 

 1 



Field. 

 C.GKS. 



2 110 



3 230 



cases, and it gave with this wire a period of 16*81 seconds. The fields 

 were respectively 0, 110, and 230 C.G.S. , and it will be noticed that the 

 results are very similar to those obtained for iron, except that the 



