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Prof. Norris on Molecular Changes in Iron [Apr. 12, 



It is proposed to consider, in the first place, the phenomena presented 

 by the ordinary steel wire of commerce, when first subjected to the 

 influence of heat. During the heating of such wires, we notice that a 

 first kick occurs at a point varying on the scale from 29° to 33°, and that 

 the wire subsequently proceeds to a high expansion, which may be repre- 

 sented on the scale by the figures 66°, 52^°, 55°, 50|°, and so forth, 

 according to the quality and state of the wire. In the act of cooling a 

 kick commences at points varying from 31 1° to 22°, and terminates at 

 points varying from 33° to 28°, when the finger proceeds on towards zero, 

 but invariably falls short of reaching it by amounts varying from J° to 5 J° 

 {centimetres). [Vide fig. 1.] 



In the next experiment with these wires a much altered state of things 

 is found to obtain. Thus the first kick is lowered a little in position, 

 increased in range ; the expansion of the wire is materially diminished, 

 being now represented by such figures as 58J°, 43^°, 45^°, 50f°, &c. re- 

 spectively. In the cooling the second kick is separated more from the 

 first, being put back in the direction of zero. It will also be seen that in 



