6o 



THE ELECTRIC ARC 



This curve represents the voltages with the white arc. 

 Those with the yellow arc were only slightly less than 

 these. This curve differs from those given by Mrs. Ayr ton 

 for the carbon arc in that it shows an increase with the 

 larger currents. This was apparently due to the tendency 

 of the arc with the larger currents to flare out to one side. 

 lit was very difficult with the currents of more than 25 

 amperes to get a steady condition and different readings 



40 



30 



24 



CURRENT 



FIG. 16. 



! varied by 3 or 4 volts. But the voltage with the large cur- 

 rents appeared even with the most steady conditions to be 

 greater than those required for 20 amperes. 



The small voltage required for the flaming arc is largely 

 due to the small drop in potential at the anode. The de- 

 crease in the anode drop caused by putting salts in the arc 

 was shown several years ago by Luggin 1 who found that 

 sprinkling the carbons with soda diminished the anode drop 

 to less than one-half of its former value. 



In the examination of flaming arcs made by myself it 



1 Centralbl. f. Elektrot, 10, 567; 1888. 



