﻿certain Spectral Lines of Zinc and Titanium. 405 



The first column in Table III. gives the wave-lengths of the 

 thirteen titanium lines in the arc spectrum obtained by using 

 a current of 4 amperes and metallic electrodes. As may- 

 be seen the intensities of these lines are small, but they 

 are well defined and sharp. The lines X 3^58*3, X 3948*8, 

 X 3904*9, X 3641-4, X 3372*9, X 3341*9 correspond fairly well 

 with the wave-lengths given by Exner and Haschek when 

 the lines have about the same intensity, but the other lines 

 show a smaller wave-length than theirs, this being especially 

 the case with X 3913*6, X 3900*6, X 3685*3, and X 3383*9. 

 The wave-lengths given here for X 3900*6 and X 36853 

 correspond with the measurements of Eder and Valenta which 

 are X 3900*68 and X 3685*30, those of Exner and Haschek 

 being X 3900*72 and X 3685*37 respectively. The other 

 lines X3913 and X3383 are not given at all by Eder and 

 Valenta. When the strength of the current is increased to 

 9 amperes, most of the lines show an inclination towards the 

 side of greater wave-length when compared with those ob- 

 tained from a current of 4 amperes, but a decided displace- 

 ment is seen in the lines X3958, X 3913, X 3904, X 3383, 

 X3372, and X3341, and in each case towards the red end of 

 the spectrum. On further increasing the current to 18 

 amperes, all the lines are displaced more than 0*04 A.U. from 

 the previous measurements with a current of 4 amperes, 

 except X 3948 and X 3349, although the wave-lengths of each 

 of these is greater than with 4 amperes. The lines X 3372, 

 X 3349, and X 3341 are reversed. 



In the spark spectrum obtained by an exposure of three 

 seconds, nine of the chosen titanium lines appear on the 

 plate, and all show a displacement towards the red when 

 compared with the corresponding lines obtained from the 

 arc using a current of 4 arnperes, although the intensities 

 are almost the same in each case. The line X 3913 was 

 difficult to measure owing to the proximity of a line in the 

 iron spectrum, but the alteration in the relative positions of 

 the two lines can be seen even on examination of the plates 

 with the naked eye. When the time of exposure is increased 

 to 1 minute all the thirteen lines are seen on the plate, and 

 all show a displacement of more than 0*04 A.U. when com- 

 pared with the arc spectrum from a current of 4 amperes. 

 The lines X 3383, X 3372, and X 3341 are not sharp except 

 at the ends, which part was measured in each case. The 

 line X 3349 is broad, and owing to the proximity of another 

 titanium line equally broad, was difficult to measure. 



Only seven of the chosen lines appear in the arc spectrum 

 of titanium potassium fluoride when a current of 4 amperes 



