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THE ROYAL SOCIETY OF CANADA 



In making the observations the tube was joined to the 110 volt 

 D.C. supply circuit with a varial^le resistance in series which enabled 

 one at will to modify the strength of the current in the arc. 



TABLE in. 

 Calibration Readings. 



Temperature in degrees Centigrade 



Electromftive force of thermocouple in 

 volts. 



(1) Meltmgice 0-°C 



(2) Boiling point of water 100 "C 



(3) Boiling point of naphthalene. 218 -"C 



(4) Melting point of zinc 419 •4°C 



(5) Melting point of silver alloy . . . 935 • °C 



(6) Melting point of potassium 



sulphate 1070-°C 



-2 X 10- 



8-7 

 23-5 

 510 

 123 



145 



Before sealing the wires into the tube the thermo-couple was 

 calibrated by exposing the junction, b, to a series of temperatures 

 given by (1) melting ice (2) water and naphthalene boiling at atmos- 



10 VOI-TJ 



Figure 5 



pheric pressure and (3) zinc, coin silver, and potassium sulphate at 

 their respective melting points. The electromotive forces determined 

 by these temperatures were measured and are given in Table III. A 

 calibration curve drawn from them is shown in Fig. 5. 



