Titanium, and Vanadium by Thermelectromc Currents. 273 



the emission of red radiations. Now, a re-examination of 

 my old spectrograms referring to the tube-furnace has 

 revealed the presence of the characteristic bands of the red 

 fringe; but although they coincide in position, their character 

 is markedly different from that observed with the plate, for 

 they are much less intense and, what is more noteworthy, 

 nothing like as hazy. To give an idea of their relative 

 unimportance in the case of the tube-furnace, it may suffice 

 to mention that the more sharply defined calcium bands at 

 6185 and 6211, which are completely masked by them in the 

 spectrum of the red fringe as obtained with the single plate, 

 are distinctly brought out. It will be shown in a subsequent 

 paper that, when two parallel plates are used, the red bands 

 of the fringe spectrum, although much more intense and 

 prominent than in the tube-furnace, are nevertheless appre- 

 ciably reduced in haziness and extent as compared with 

 their development in the case of the single plate. Now, the 

 only vital factor which changes appreciably on passing from 

 the single plate to the two-plate arrangement and the tube- 

 furnace, is the intensity of the electric field. Thus, with 

 the single plate, the red bands begin to show only with an 



electric field of about 7 — -; with the two-plate arrangement 



cm. * a 



they come out with only about 4 -^-, and in the tube-furnace 



already with less than 1 — ; the diminishing values for the 



intensities of the electric fields are, of course, in keeping 

 with the higher degrees of ionization which prevail in the 

 case of the two parallel plates and in that of the tube-furnace. 

 These facts and considerations seem to indicate that the red 

 bands, being as they are stimulated by electric actions, will 

 be susceptible also to variations of the acting electric force, 

 and it may, therefore, reasonably be conceived that the 

 extraordinary haziness and intensity which characterize 

 them in the red fringe are caused by the relatively strong- 

 electric field which is created by forcing a heavy current 

 through the graphite plate. I hope to show in a subsequent 

 paper that the lines of the doublet series of sodium are simi- 

 larly affected when acted upon by strong electric fields. 

 Hence the weakness and the relatively low degree of hazi- 

 ness of the red bands in the tube-furnace are quite consistent 

 with the feeble electric field prevailing therein. 



The lines of titanium and vanadium have not been ob- 

 served by me in the tube-furnace ; it is possible that these 

 elements are not contained as impurities in the carbon tubes 



Phil. Mag. S. 6. Yol. 39. No. 231. March 1920. T 



