﻿Displacements in Spectral Lines of Zinc and Titanium. 401 



In order to find the effect, if any, on the wave-lengths of 

 the lines caused by the presence of impurities in the arc and 

 spark, brass electrodes were used, which of course caused 

 copper as well as zinc to be present in the glowing vapour. 

 The electrodes had approximately the same dimensions as 

 those of zinc. The arc and spark spectra were obtained 

 under the same conditions as those of pure zinc, with 

 the exception that in the case of brass of course there 

 was no difficulty with regard to the melting of the electrode. 

 The time of exposure was varied between 2 seconds and 

 5 minutes. 



Table I. shows that by using a current of 4 amperes the 

 arc spectrum of zinc gives wave-lengths for three of the 

 chosen lines XX 3345*6, 3345*1, 3282*4, which correspond 

 fairly well with those given by Exner and Haschek when 

 the lines have about the same intensity ; but the wave- 

 lengths for the lines X 3303 and X 3302 are not so great 

 as theirs, and even the greatest values obtained for these 

 lines in the present work are not so large as those of the 

 strongest lines of Exner and Haschek. The wave-lengths 

 here given for these two particular lines when 4 amperes 

 current is used correspond more nearly with the values 

 X 3303*03 and X 3302*67 given by Eder and Valenta. An 

 increase in the strength of the current to 17 or 18 amperes 

 seems to have no effect on the wave-lengths of the lines, 

 within the limits of error, although the intensity of the 

 lines is greatly increased, and they are all reversed. In the 

 spark spectrum obtained from 2 seconds' exposure all these 

 lines except X3282 appear to experience a displacement 

 when compared with the previous arc measurements, and in 

 each case the displacement is towards the less refrangible 

 end of the spectrum. When 30 seconds 5 exposure was used 

 all the lines showed a displacement towards the red when 

 compared with the previous arc measurements. 



In the arc spectrum of brass obtained by using 9 amperes 

 current, the zinc lines show no displacement when compared 

 with those of pure zinc from 4 amperes current, with the 

 exception of X 3282, the wave-length of which is smaller than 

 with pure zinc. With a current of 14 amperes all the lines 

 are reversed and the lines X3302 and X 3282 are displaced 

 towards the red, and with 18 amperes there is a considerable 

 increase in the wave-lengths of all the lines. The fact that 

 these reversed lines experience a displacement is in agree- 

 ment with the results of Duffield, Jewell, and Exner and 

 Haschek. The spark spectrum of brass obtained bv giving 



Phil. Mag. S. 6. Yol. 29. No. 171. March 1915. 2 D 



