UPON GASES AND LIQUIDS. 561 



tvveen the two apices of the poles approximated to 15 milUms., 

 in such a manner that they were situated at the distance of 

 two-thirds of the height of the flame, the latter was depressed 

 and expanded in the equatorial plane. Its form is represented 

 in the equatorial view (taken from the side of one of the poles), 

 figured in PI. IV. fig. 1 : PI. IV. fig. 1 a represents the perpen- 

 dicular axial section of the flame. 



When the flame was moved out of the axial line laterally, it 

 was repelled from that line. When moved from the equatorial 

 plane and approximated to one of the poles, it was repelled 

 towards this plane. 



[6. A tallow candle, burning quietly and not smoking, acted 

 in the same manner. Under the same circumstances, the distance 

 of the poles apart being 15 millims., it exhibited the equatorial 

 view figured in PI. IV. fig. 2. Above, the flame was extended 

 into a sharp wedge with a rectilinear section. 



17. W'hen the apices of the poles are more approximated, the 

 appearance assumes other forms ; in all the experiments which 

 I shall describe hereafter, the constant distance between the 

 apices of the poles, where not expressly stated otherwise, was 

 3*5 millims. 



When the above tallow candle was placed between the poles, 

 80 that the latter were at seven-eighths of the height of the ori- 

 ginal flame, the equatorial view yielded the third figure. PL IV. 

 fig. 3 a represents the corresponding axial section. 



When the apices of the poles were at the middle of the height 

 of the original flame, the equatorial view yielded the fourth 

 figure. PI. IV. fig. 4 a represents the perpendicular axial sec- 

 tion ; and PI. IV. fig. 4 6 is a view from above, in which the 

 flame has the form of an elliptic ring, surrounded by a small 

 faintly-luminous margin, and enclosing a dark space. 



When the tallow candle was elevated as much as possible, 

 hence when the two apices of the poles were at the same height 

 as the upper end of the wick, and the flame cooled by the iron 

 apex of the pole ceased to burn with perfect light, it not only 

 perfectly re-acquired its former luminosity at the moment of 

 closing the circuit, but burned more freely, becoming depressed, 

 and assuming in the equatorial view the form of the fifth figure. 

 A perpendicular axial section is exhibited in PI. IV. fig. 5 a. 



18. As the tallow candle could not be raised higher, a thin 

 loax and a stearine candle were taken ; and instead of the conical 



