Nitrogen Thermometer from Zinc to Palladium. 149 



1550°, a somewhat startling surprise awaits us. Although the 

 curve below the copper point is a practically perfect reproduc- 

 tion of the observations, it diverges from the gas thermometer 

 scale at the melting point of palladium by 245 microvolts, 

 which represents a temperature error of nearly 20°. This 

 comparison is made in the table below : 



Observed — 



Observed Calculated Calculated 



Temperature Microvolts Microvolts Microvolts 



Zinc 418-2° 3429 3429 



Antimony ... 629'2 5530 5530 



Silver 960-0 9113 9115 —2 



Gold 1062-4 10295 10298 —3 



Copper 1082-6 10534 10534 



Extrapolation. 



1207-1 12000 12027 —27 



12988 13100 13161 —61 



Diopside 1391 -2 14228 14338 —110 



Nickel 1452-3 14945 15112 —167 



Cobalt 1489-8 15439 15608 —169 



Palladium ... 1549-2 16143 16388 —245 



If, on the other hand, we follow Day and Clement, and 

 represent t as a function of E, using the same data as before, 

 the equation will take the form 



t = 47-2 + -11297E — 1-3946(10)- 6 E 2 



This curve passes through the fixed points below 1100° nearly 

 as accurately as the previous one, and is also quite competent 

 to interpolate temperatures throughout the range of the old 

 standard scale. Extrapolating this in turn up to the palladium 

 point and comparing it with our gas thermometer measure- 

 ments in the higher region leads to temperatures about 40° too 

 low. 



Observed — 

 Observed Calculated Calculated 



Zinc 418-2° 418-2° 0° 



Antimony ._. 629-2 629*3 —0-1 



Silver __"_ 960-0 960-9 -0-9 



Gold 1062-4 1062-4 



Copper 1082-6 1082-5 +0-1 



Extrapolation 



1207-1 . 1202-0 -1-5-1 



1298-8 1287-8 +11-0 



Diopside 1391-2 1372-0 -j-19'2 



Nickel 1452-3 1424-0 +28-3 



Cobalt 1489-8 1459*0 +30-8 



Palladium... 1549-2 1507*0 +42*2 



