Electrical Conductivity of Flames. 



479 



nearly proportional to the current through the flame. The 

 following are some of the results obtained : — 



Current. 

 (0). 



P.D. 



PJD.-rC. 



270 

 54 

 18 



4-0 volts. 

 0-25 „ 



0-0148 

 0-0148 

 00139 



The P.D. between the two small electrodes varied to some 

 extent as they were moved along the flame together, owing 

 to the non-uniformity of the name, but at any one point not 

 very near either electrode it was always proportional to the 

 current. Near the negative electrode the P.D. became too 

 large io be measured on the quadrant electrometer, and very 

 close to the positive electrode it also became large. 



The fall of potential (V) between the disk electrodes may 

 be regarded as made up of three parts — the sudden fall near 

 the negative electrode, say Y 2 ; the fall near the positive 

 electrode, say "V"i ; and the fall in the uniform gradient, which 

 is proportional to the current and to the distance between 

 the electrodes. Hence approximately 



V=V 1 +Y 2 +A(V, 

 where A is a constant, the current, and d the distance 

 between the electrodes. 



The following table gives the values of {Y l 4- V2) g°t by 

 subtracting ACd from V, using the results given above. 

 The value of A was got from the measurements of the electric 

 intensity between the electrodes by means of the equation 



ACrf = Xrf. 



X 



We have -p = A = 0'03, the current being expressed as 

 before in terms of the corresponding galvanometer deflexion. 

 Hence Y^Y^Y-O'OSGd. 



P.D. 



1 



1 cm. 



4-5 cms. 



9 cms. 



13*5 cms. 



18 cms. 



600volts ;. 



..: 591 



..! 392 



.. 195 



116 



38 



19 



9 



4 



-,> 



559 

 367 

 177 

 103 

 31-4 

 14-7 

 73 

 29 

 1-4 



520 

 335 

 155 

 89 

 24-6 

 10-6 

 5-7 

 21 

 09 



487 

 307 

 137 

 78 

 186 

 7-0 

 4-3 

 1-6 

 06 



454 

 284 

 123 

 71-4 

 14-0 

 4-3 

 2-8 

 11 

 0-4 



400 , 



200 „ 



120 „ 



40 „ 



20 „ 



10 „ 



4 „ 



2 





