Critical Points of Nickel and Iron. 

 Fig:. 4. — Iron. 



399 



. +i 

























permeabi 



o 















































o 

 .2 +20 



1 































WA 

















"3 



& +10 



a 















































2 

 ** 

























the load 16 kilos, cuts the curve. Both the loading and un- 

 loading curves lie entirely above the load-line, and there is no 

 point of cutting this line. 



Fig. 5 deals with a nickel wire of the same degree of 

 purity as the first but \\ millim. in diameter. The stress 



Fig. 5. — Nickel. 

 Kilos on lever. 



4 fi 8 



10 



-20 



•30 



-50 



-60 



■70 





1 kilo on the lever represents a stress of 2 # (58 kilos per sq. millim. 

 was carried by the aid of a lever to very nearly the breaking- 

 point of the wire. There is in this case no perceptible lagging 

 of mechanical strain behind stress, the curve on loading being 



