36 



On the Effects of Temperature on Iron. 



the tungsten alloy given in fig. 10 (p. 20), Ave see that the effect 

 of temperature on the first and second stages is very similar 

 in each case ; but in the Cr-Mn-0 alloy the effect is more 

 marked, the first stage entirely disappearing at high tempe- 

 ratures. This is all the more remarkable seeing that in the 

 latter case the value of the magnetic force necessary to bring 

 on the second stage at the ordinary temperature of the room 

 is more than double that required in the case of the tungsten 

 alloy. 



The maximum permeability is obtained with a magnetizing 

 force of about 3*5 c.G.S. at a temperature of 681° C, the 

 value being slightly over 820. As the temperature is raised 

 above 681° C. the initial permeability is increased, as in the 

 case of the tungsten specimen, but the maximum perme- 

 ability obtained in each case decreases. 



At a temperature of 726° C. the alloy is practically non- 

 magnetic. 



On cooling, the magnetic quality does not return until 

 the temperature has fallen to about 650° C. 



The following values of the permeability in terms of mag- 

 netic force were obtained while the temperature fell from 

 645° 0. to 640° C. 



Magnetic Force 018 044 0"88 T76 2-63 4-39 615 7'9 

 Permeability... 324 371 417 487 684 821 688 632 

 It will be noticed that the permeability reaches practically 



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200° 300° 400° 



Temperature. 



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