the Electricity of Flame. 1 6 7 



A series of very carefully made experiments have most de- 

 cisively confirmed both these conclusions. 



§ 6. Dependence of the Electromotive Force upon the Nature 



of the Metals. 

 If a platinum electrode is brought into the base of the flame 

 or into the sensitive stratum of air while the apex is, as exactly 

 as possible, at the same place conducted to earth, considerably 

 different values are obtained, according to the nature of the 

 conducting metal. In the series of experiments recorded in 

 the following table the position of the electrodes was that 

 represented in fig. 2 a. B, as well as the flame itself, remained 

 unmoved during the whole time of a series of experiments, 

 while the apex-electrode S consisted successively of wires of 

 platinum, iron, copper, and aluminium. The experiments 

 were made with the non-luminous flame of the small Bunsen 

 burner described at the commencement. 



Table I. 







The flame-apex electricity Electromotive 



force for D = 



= 100. 



conducted awav by Series of 



experiments. 





I. II. 



in. 



IV. 



Platinum . . 49-6 116-0 



157-2 



188-4 



Iron .... 64-3 139-0 



173-8 



232-0 



Copper 153-2 



208-8 



2(34-0 



Aluminium . . 171-0 237-0 



■268-8 



364-0 



In all four series the flame shows itself very highly electric 

 when conducted away by aluminium, less so with conduction 

 by copper, still more feebly on the employment of iron ; and 

 the smallest values are obtained with conduction by platinum. 

 When both electrodes dip into the flame the result is com- 

 pletely analogous; and it is just the same when, instead of the 

 non-luminous gas-flame, a luminous gas-flame or a spirit- 

 flame is employed. The peculiar position of aluminium also 

 with such an arrangement of the electrodes and the employ- 

 ment of such flames follows from Table II. 



Table II. 



~ , c a Apes of flame conducted-from by Electrodes 



Kind of flame. ^ Platilium- Aluminium. " as in 



Ordinary Bunsen burner 74-2 149*2 Fig. 2 L 



Luminous gas-flame . . 49-6 112-2 Fig. 2 b 



Spirit-flame .... 16O0 278-0 Fig. 2 a 



The base-electrode, in all the series of experiments, consisted 

 of a platinum wire. As the wires employed were not of equal 

 thickness, we made another series of experiments with three 

 plates, of exactly equal thickness, of aluminium, copper, and 



