Titanium, and Vanadium by Thermelectronic Currents. 275 



proved that, in the red fringe, the emission of the carbon 

 bands is primarily governed by electric actions, the tempera- 

 ture serving only to ionize the vapours in the vicinity of the 

 plate. Hence, since both the character and the order of 

 development of the carbon spectrum as given by a tube- 

 furnace are fundamentally identical with those observed in 

 the red fringe, we can only conclude that their emission by 

 the former is due to the same cause — namely, the passage 

 of thermelectronic currents through highly ionized vapours 

 and gases. Thus, if it were possible to exclude therm- 

 electronic currents from the interior of the tube, no carbon 

 bands should be observed, as is the case in the mantles of 

 hydrocarbon names up to 2700° C. 



The arguments brought forward in this discussion lead to 

 the inevitable conclusion that thermelectronic currents, just 

 as in the case of the red fringe, are responsible also for the 

 -emission, in the tube-furnace, of the carbon bands and 

 the red bands of unknown origin. The mere fact that 

 a plate has been rolled up into a tube can therefore not in 

 the least affect the fundamental character of the luminous 

 phenomena observed in its vicinity ; on the contrary, several 

 of the essential conditions for their production are thereby 

 greatly improved. The relatively feeble development of the 

 red bands in the tube-furnace can be most satisfactorily 

 ticcounted for by the feebler electric field existing in the 

 latter ; and this view is entirely corroborated by rny observa- 

 tions with a parallel-plate furnace, in which both the 

 intensity of the acting electric field and the state of develop- 

 ment of the red bands were intermediate between those 

 noted with the single plate and the tube-furnace. 



With regard to the spectrum emission of the luminous 

 vapour, the lines and bands of which are observed to extend 

 below the red fringe spectrum, it has been proved in § 7 

 that it is of the same character as that emitted by these 

 vapours in the tube resistance furnace and in the mantles of 

 flames under the influence of thermo-chemical excitation. 

 The present experiments with the single plate have, there- 

 fore, also furnished an independent confirmation of the 

 -existence of this emission in the tube-furnace. 



§ 12. Probable cause of disagreement between Dr. King's 

 results and mine. 



I have shown * that a tube resistance furnace, worked 

 with continuous current, emits cla>s III. lines of iron only at 



* Hemsalecli, Phil. Mas', vol. xxxvi. p. 214 (1918). 

 T2 



