Electrical Conductivity of Flames. 



477 



was supported near one end of the flame and the other was 

 fixed to a stand sliding in grooves parallel to the flame, so 

 that it could be moved along horizontally in the flame and 

 so placed at any desired distance from the fixed electrode. 

 Since the quartz tube was a good insulator, a current could 

 be passed horizontally from one end of the flame to the other 

 without fear of any of it going through the tube instead 

 of the flame. This arrangement of apparatus is shown 

 diagrammatically in fig. 1. 



Fig. 1. 



F FF.F Flame 

 1.1. Quartz Tube: 



B. Buns en Bor'mer. 



E.E. PlAT/AJUM ELECTRODES. 



The current through the flame between the electrodes was 

 measured by means of a moving-coil galvanometer, and the 

 potential-difference between the electrodes by means of an 

 electrostatic voltmeter. The electrodes were bright red hot. 

 The variation of the current with the distance between the 

 electrodes for different potential-differences will be first con- 

 sidered. The following table gives the observed galvanometer 

 deflexions. Each number is the mean of several observations 

 (1 = 8-8 xlO- 9 ampere). 



Potential 

 difference. 



■ 



Distance between Electrodes. 





600 volts 



1 cm. 



4 - 5 cms. 



9 cms, 



13 5 cms. 



18 cms. 



310 



255 



175 



130 



67 



42 



22 



9 



5 



304 



9Qn 



280 



230 



155 



104 



53 



32 



14 



6 



3-5 



270 

 215 

 143 



90 

 48 

 29 



13 i 

 53 



3 



400 „ 



247 240 



200 „ 



170 

 125 



64 

 39 

 20 



8 



4*7 



165 

 115 



57 



35 



16 



7 



4 



120 „ 



40 „ 



20 „ 



10 „ 



4 „ 



2 „ 









