DICKINSON AND MUELLER: RESISTANCE THERMOMETER SCALE 177 



form of a U so that the resistance coil could be placed in the re- 

 entrant tube of the gas thermometer, occupying the same position 

 as had the thermocouple in the measurements of Day and Sosman. 

 These two resistance thermometers represent the temperature 

 scale already referred to. The thermometers were compared in 

 the fused salt bath with the gas thermometer, which was operated 

 by Messrs. Day and Sosman 2 . The points at which comparisons 

 were made were approximately 306°, 445°, and 630°. After 

 the observations in the salt bath the constants of the resistance 

 thermometers were verified by recalibration. Two series were 

 made with each thermometer. The results will be seen from the 

 tables below: 



TABLE I 



Calibration of Thermometer D 



Ro 26.6733 



F.I 10. 3171 ±0.0002 



5 1.520 ±0.000 4 



Calibration of Thermometer R 



Ro 4.8321 



F.I 1.8892*0.0001 



8 1.503 ±0.000.3 



Eight determinations of each constant were made. 



The figures indicate an accuracy of about 0?01 in the deter- 

 mination of the fundamental interval and about 0?03 in the 

 determination of the boiling point of sulfur (440.70 in above) 

 from which 8 is computed, and show that either one of the ther- 

 mometers adequately represents the resistance thermometer scale 

 of Waidner and Burgess. 



The results of the comparisons in the salt bath with the gas 

 thermometer are shown in table II. 



The figures in the second column are the serial numbers assigned 

 to the gas thermometer observations. In the fourth column is 

 given the temperature in the salt bath as indicated by the resist- 

 ance thermometer. In the next three columns are the nitrogen 

 thermometer data : p' is the original measured pressure in the 

 nitrogen thermometer bulb in millimeters of mercury at 0°; the 

 application of the correction for the "unheated space" gives the 

 pressures (p) of column six; and in column seven is the tempera- 

 ture. From the differences in the eighth column and the values 



2 This Journal, 2: 171. 1912. 



