[SCOTT] ELECTRICAL RESISTANCE THERMOMETERS 159 



No. 4 Pure 608 8-28 



No. 4 Annealed 2521 2-75 



No. 5 844 5-80 



No. 5 Annealed 1374 4-20 



No. 6 697 7-25 



Steel 501 13-47 



Kahlbaum's (hard) 365 13-98 



It is apparent from these figures that when a specimen is annealed, 

 the permeability is increased, while the Steinmetz coefficient is dimin- 

 ished. These quantities change with the purity of the iron in the same 

 way as the temperature coefficient. 



Pure iron when used at temperatures in the neighbourhood of 

 0° C, and in measurements involving small differences of tempera- 

 ture, is in our experience superior to platinum in showing smaller 

 changes of zero. 



