94 



BRIDGMAN. 



The temperature coefficient of resistance of Calcium at atmospheric 

 pressure has been preA'iously measured by Northrup,^^ who found 

 between 0° and 100° the value 0.00246, and by Swisher, i° who found 

 the relation between temperature and resistance to be linear between 

 0° and 600°, and the coefficient to be 0.00364 of the value at 0°. An 

 examination of Swisher's results shows that there were considerable 

 irregularities, and that Within his limits of error it is not possible to 

 say whether his coefficient between 0° and 100° is greater or less than 

 my value above. The low value of Northrup is probably due to 

 impurity in his sample. 



In smoothing the experimental results for the most probable final 

 values, the usual procedure was followed. The results at each temper- 

 ature were first smoothed independently, and then readjusted so as to 

 give smooth temperature differences. The effect of insufficient 

 seasoning in the runs at 25° and 75° was shown by the greater read- 

 justments necessary at these temperatures. The maximum read- 

 justment necessary was 0.0% at 0°, 4.6% at 25°, 1.4%o at 50°, 1.8% at 

 75°, and 0.4%^ at 96°. 



TABLE VII. 



Calcium. 



