174 



DAY AND SOSMANI NITROGEN THERMOMETER SCALE 



TABLE III 



Gas Thermometer Determinations of the Boiling Point of Sulfur 



since 1890 



1 Phil. Trans., A 181 : 119-157. 1891. 

 2 Trav. Mem. Bur. Int., 12. 1902. 



3 Ibid., p. 90. 



4 Proc. Roy. Soc, A 81 : 339-362. 1908. 

 6 Ibid., A 83: 106-108. 1910. 



6 Ann. Physik, 35 : 761-774. 1911. The value given for N 2 is calculated from the 

 authors' table of experimental results. They give in their paper only the final 

 mean value on the thermodynamic scale. 



7 This determination, often quoted as direct, is in reality indirect. In his first 

 investigation (Phil. Trans. 1887) Callendar showed that his parabolic formula 

 represented within 1° the variation of resistance with temperature as determined 

 by the constant pressure air thermometer to 600°. In his later work (Phil. Trans. 

 1891) he showed by a comparison of two resistance thermometers with the air 

 thermometer, using sulfur merely as a constant temperature bath, that his original 

 value of 8 = 1.57 would still represent the results for these thermometers within 

 the limits of error (about ± 0?3). This value of 8 was then used to calculate the 

 sulfur boiling point determined with several platinum thermometers in the usual 

 form of sulfur boiling tube. 



