﻿406 Displacements in Spectral Lines of Zinc and Titanium. 



is used. The lines X3958, X 3948, A, 3741 show a displace- 

 ment towards the red when compared with the arc spectrum 

 of the pure metal obtained with the same current. None of 

 the other lines give smaller measurements than those obtained 

 from the pure metal under the same conditions. On in- 

 creasing the current to 11^ amperes all the lines appear 

 except X3913, X 3900, and X3641. The lines X 3958, 

 X 3904, X 3741, X 3685, X 3383, and X3372 all show a dis- 

 placement of more than 0'04 A.U. towards the red when 

 compared with the arc measurements of the pure metal with 

 a current of 4 amperes. The line X 3948 is increased in 

 ware-length by 0*034 A.U. 



In the spark spectrum obtained from titanium potassium 

 fluoride all the lines appear when the plate is exposed for 

 3 minutes, and most of them have greater wave-lengths than 

 the corresponding arc lines of the pure metal obtained from 

 a current of 4 amperes. There is a distinct displacement 

 towards the red in the lines X 3948 and X3913. If the 

 exposure is increased to 5 minutes the lines experience very 

 little alteration in wave-length, the differences being within 

 the limits of error in measurement. But when the results 

 of the spark measurements obtained from the titanium salt 

 and those from the pure metal are compared, it is noticed 

 that in some cases the pure metal gives lines the wave-lengths 

 of which are greater than those of the salt. This is the case 

 in the lines X 3900, X 3685, X 3641, X 3505, X 3383, X 3372, 

 X 3349, and X 3341. The same effect is observed with the 

 zinc lines X 4810 and X 4722. 



Conclusion. 



The foregoing measurements prove without doubt that the 

 wave-lengths of the lines in the spectra of the metallic 

 elements are not constant., but that they experience displace- 

 ments tow T ards the red under certain conditions. 



The wave-lengths of lines in the spark spectrum of the 

 pure metal are in general greater than those in the arc 

 spectrum, but the difference alters for the various metals 

 and for the different lines of the metals. 



In the arc spectrum of the pure metal the lines are dis- 

 placed by increasing the current, if the point at which the 

 element vaporises be high enough for the increase in current 

 to produce an increase in the density of the vapour. 



The presence in the arc or spark of atoms of another 

 element appears to have no influence on the wave-lengths of 

 the lines of the substance being examined, the wave-lengths 

 obtained depending on the partial density of the substance 

 itself. 



