18.8" Messrs. Maclean and Makita Goto on 



degree of failure of justice which may be expected — amounts to 

 8 per cent, of the successful ; or rather 8-5- V^2, say 6, per cent., 

 if we define the just verdict as that which would be found by taking 

 the average of the results obtained by a variety of competent 

 examiners. 



XXI. Some Electrical Properties of Flames. By Magnus 

 Maclean, M.A., F.R.S.E., and Makita Goto (Japan)*. 



[Plate V.] 



JN connexion with our experiments on the " Electrification 

 of Air by Combustion," we were led to make some ex- 

 periments on the electricity of different parts of the flame 

 itself. A Bunsen burner was used, and the potentials at 

 different points, both inside and outside of the flame, were 

 examined. In fig. 1, Plate V., is shown the arrangement 

 for examining the inside of the flame. AA and BB are pla- 

 tinum wires insulated from the burner and projecting into 

 the flame 5 millim. above the upper end of the burner. These 

 wires can be adjusted by bending so as to lie in various 

 positions from the middle line of the flame to its boundary. 

 In our experiments one of them was left insulated (with its 

 end free in air), while the other was connected to a terminal 

 of a Thomson Quadrant Electrometer. Or, again, one wire 

 was connected to one terminal of the electrometer, and the 

 other to the other terminal. The Bunsen burner itself was 

 always connected to earth. The sensitiveness of the electro- 

 meter was generally such that a difference of potential of 

 2Qo volt between the terminals could be observed. 



In fig. 2 is shown the arrangement for examining the 

 outside of the flame. C is a platinum wire fused into a glass 

 tube which covers the wire except a very small portion of its 

 end. D is the scale for measuring the distance of the point 

 of the platinum wire from the boundary of the flame. E is 

 the index. 



By these arrangements it was found that the flame is 

 negatively electrified, while the film of air surrounding the 

 flame is positively electrified. These results were already 

 obtained by Elster and Geitel. Our results agree with what 

 they found, though our method of examining the different 

 parts of the flame is different from their method. (See an 

 abstract of their experiments by S. P. Thompson in ' Nature,' 



* Communicated by the Authors. 



