1904.] in Relation to the Fluted Spectrum of Titanium. 225 



able doubt that titanium is the main factor in the production of the 

 dark flutings which characterise the Antarian group of stars. 



This explanation of the dark flutings suggests that the appearance 

 of bright flutings in the Antarian spectrum arises chiefly from effects 

 of contrast. It does not, of course, exclude the possibility of the 

 presence of bright flutings, such as might be indicated by local 

 brightenings which are not exactly in coincidence with the edges of 

 dark flutings. 



Whether the absorption flutings are produced by the vapour of 

 titanium or by that of the oxide has not yet been completely 

 determined. As already pointed out, the flutings may be obtained 

 either from the oxide or the chloride, but as the latter so readily 

 unites with oxygen on exposure to air, it furnishes no evidence against 

 the supposition that the flutings are due to the oxide. 



The author has pleasure in acknowledging the very able assistance 

 which has been rendered in the experimental work involved in this 

 investigation by Mr. F. W. Jordan, B.Sc, Teacher in Training in the 

 Department of Astronomical Physics, Royal College of Science. 



DESCRIPTION OF PLATE 6. 



1. Yisible spectrum of o Herculis, as drawn by Duner. 



2. Flutings of titanium, as they appear in the spectrum of the " flame of the arc," 



when charged with titanium oxide. 



3. Photographic spectrum of o Ceti, from a photograph taken at the Stonyhurst 



College Observatory, November 29, 1897. 



4. Flutings of titanium, as they appear when a spark, without jar, is passed through 



the fumes which rise from titanium chloride on exposure to air. 



{Note. — The coincidences cannot be very exactly shown in this manner, on 

 account of the differences of dispersion of the three instruments with which 

 the spectra were recorded.) 



