CAPACITY FOR HEAT OF METALS AT DIFFERENT TEMPERATURES. 



133 



RESISTANCE OF REFERENCE COIL. 

 National Physical laboratory Report. 

 ( 'OIL Immersed in Unstirred Paraffin Oil cooled to C. 



Hence, the factor to convert our box readings to international ohms = 0'99G78. 

 As the same ratio arms and plugs in the thousand and hundred dials were used in 

 the determination of both coils, any change in the relative values of the dial box 



20-65 



20-64 



20-65 



Temjo 



10 20 50 40 50 5 60* 10^ So 3 so 5 wcT uo 

 Fig. 4. Variation of resistance of heating coil with temperature and time. 



Curve ABC, July 18 to October 26, 1912. 

 EF, December 4 December 30, 1912. 

 GHK, January 19 February 10, 1913. 



LM, February 17 19, 1913. 



NO, 23 March 2, 1913. 



i.v 





since calibration (' Phil. Trans.,' vol. 184, p. 409) would not appreciably affect OUF 

 results. Fig. 4 shows the variation with temperature of the heating coil and the 

 permanent change by use and exposure to temperatures of about 100 C. 



" Probable error of resistance values is not greater than 2 parts in 100,000." 



