ELECTRICAL RESISTANCE UNDER PRESSURE. 



121 



descending points were irregular, probably because of slipping of the 

 contacts. At 50° the ascending and descending points agreed more 

 closely, but there were irregularities both ascending and descending, 

 less in magnitude than at 0°, and averaging 2.7% of the maximum 

 pressure effect. 



The results are collected in Table XV and Figure 10; they are 

 seen to be quite normal. The pressure coefficient is negative, and 



TABLE XV. 



Lanthanum. 



Pressure, Kg. / Cm." X 1 

 Lanthanum 



Figure 10. The deviations from linearity of the measured resistance of 

 lanthanum in fractional parts of the resistance at kg. and 0°C. 



increases at the higher temperatures. The relation between pressure 

 and resistance is also normal, the coefficient being smaller at the higher 

 pressures. It is perhaps unusual that the departure from linearity 

 is less at the higher temperatures. The deviations from linearity are 

 so small and so nearly symmetrical about the mean pressure that it 

 is not necessary to reproduce the deviation curve graphically. 



I have been able to find no previous values for the specific resist- 

 ance of this metal. The approximate value for the specimen above. 



