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PROCEEDINGS OF THE AMERICAN ACADEMY. 



second or subsequent applications ; there is a gradual settling down 

 to a steady state. In the case of mercury, this was due to the equal- 

 ization of strains in the containing capillary of glass. In the case of 

 the manganin, some such process of accommodation must be going on 

 within the mass of the metal. This is shown principally by drift of the 



TABLE IV. 

 Pressure Coefficient op Resistance of Manganin. 



zero, but the pressure coefficient may change slightly. The seasoning 

 process occupies more time for the manganin than for the glass; it 

 may extend over as much as a month after the first application. It 

 is hastened by frequent applications of pressure, but may apparently 

 run to completion in sufficient time after only one application. To 

 effect the seasoning, it does not seem to be necessary to subject the 

 coil to the maximum pressure under which it is contemplated using it. 

 The coil used to the highest pressure reached in this work, 20,500 kgm., 

 had been seasoned by the application of not more than 12,000 kgm., yet 

 it showed no farther change after the application of a pressure 8500 

 kgm. in excess of the seasoning pressure. 



The results obtained with one such well-seasoned coil at 0° 

 are shown in the table. In making the comparison with the 

 absolute gauge all the precautions described in the first part of ths 

 paper were observed. It is seen that within the limits of error of 

 the pressure readings, the change of resistance is proportional to 

 pressure. 



