Observations at the- Poles of the Electric Arc. 959 



variation of pressure with time from the moment of starting 

 the arc was studied. The results are shown in curves 

 (1A, B, (\ D) for cathode, (2 A, B, C, D) for anode. 

 Curves 1 A and 2 A definitely show th t evolution of gas 



Curves I. and II. 



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■ KOI.*. . 



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B - 



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, 10-5 - 



C • 



■ 00 - ■• 



-10.5 - 



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= 105 - 



o 







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120 



Anode, Jhessvrl . 



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12.5cm*. 





HOLE-, 



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C • - so • . - n o 



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is at first the main cause of the pressure. The rate of 

 evolution rises as the carbon warms and falls afterwards 

 as the supply of absorbed gas is exhausted. Curves B, C, 

 and D are observations taken with the same carbons 

 untouched. There was an interval of 5 minutes between 

 the end of A and the beginning of B, of 30 minutes 

 between C and B, and a whole night between C and D. 

 It is clearly seen that while a little re-absorption of gas 

 took place in the 5 minutes' interval, it is mere obvious 

 after a 30 minutes' interval. From the form of curves ID 

 and 2D the recovery of gay, except in the deeper- sealed 

 part of the carbon, would appear to be practically completed 

 over night. » 



