[mclennan] 



TEMPERATURE OF THE MERCURY ARC 



67 



The results obtained in one particular set of observations with 

 the arc established in the tube are given in Table IV. In making 

 this set the fall of potential between the two terminals of the tube 

 was measured simultaneously with the strength of the cm-rent pass'ng 

 through it. At the same time the corresponding electromotive forces 

 were read off from the compensation apparatus. Column I in Table 

 IV gives the energy, expressed in watts, consumed by the arc, and 

 column II the corresponding electromotive forces given by the junction. 



Column III gives the temperatures corresponding to these as 

 deduced from the calibration curve in Fig. 5. 



TABLE IV. 

 Temperature of Mercury Arc. 



Energy supplied to mercury 

 arc in watts. 



Electromotive force of ther- 

 mo couple in volts. 



II 



63 



71 



80 



91 



92 



97 



102 



109 



114 



121 



126 



134 



141 



147 



152 



158 



165 



170 



174 



182 



189 



191 



196 



X 10-^ 



Temperature in degrees 

 Centigrade. 



Ill 



From the numbers given in this column it will be seen'^that a 

 temperature of 1400° C. was reached. This was obtainedf'when a 

 current of 10 '6 amperes was passing through the tube and it was 



