50 INFLUENCE OF A MAGNETIC FIELD UPON THE SPARK SPECTRA OF IRON AND TITANIUM. 



The ease with which the separations of the complex lines both in iron and titanium can be expressed 

 in terms of a affords a confirmation of Runge's law, since failure to give approximation to exact multiples 

 of a appears to occur only in the case of measurements of small weight. It has been necessary only in 

 a very few cases to use multiples of any quantity smaller than a/4, so that errors of measurement are 

 seldom large enough to influence the ratios found. This question will become of more importance when 

 very close components are resolved by a stronger field. 



The presence of "magnetic duphcates," fines exactly similar in structure, with the same intervals 

 between components, furnishes a means of selecting fines which may be connected by series relations. 

 Such dupficates occur for almost every type of separation. Six quintuplets of iron and two of titanium 

 show the same structure and intervals. These are XX 3733.469, 3760.679, 3814.671, 3865.674, 5455.834, 

 5603.186 of iron and 4291. 114, 5720.666 of titanium. Several types of sextuplets appear. The red fines 

 of ironXX62i3.644 and 6337.048 are dupficates, also the titanium fines XX3982.142, 4798.169, and 5491.985. 

 Dupficate septuplets of iron are XX4191.585 and 5079.921. The only titanium septuplet fully resolved, 

 X 4298.828, has the same structure. The four iron octuplets are of the same appearance but have dif- 

 ferent spacing, XX3743.508 and 3788.046 being afike, as are probably also XX4859.928 and 5497-735i 

 though the former was not fully measurable. The blue octuplets of titanium XX 45 2 7. 490 and 4544.864 

 are also dupficates. The iron nine-component fines XX3748.408 and 3840.580 are alike, and X 5405.989 

 has probably the same intervals. Another spacing is shown by the titanium dupficates XX 447 1.408 and 

 4489.262. The fines of iron which probably have ten components are not fuUy resolved, while the three 

 titanium fines show diverse arrangements. Perhaps the finest examples of spacing in multiples of a are 

 the twelve-component fines XX3722.729, 3872.639, 5447.130 of iron, which are exact dupficates, while 

 X4289.237 of titanium is in all respects similar. 



POSSIBLE RELATIONS BETWEEN LINES AS INDICATED BY THE ZEEMAN EFFECT. 



It is hoped that the measurements presented in this paper, especially the summary of complex sepa- 

 rations given on pp. 48 and 49, may eventuaUy aid in finding definite relations among the fines of these 

 spectra. At present, nothing conclusive along this fine is to be offered. Numerous cases of magnetic 

 dupficates have been shown to exist in both spectra. Such fines, especially if they are in the same part 

 of the spectrum, are often affected in the same way as to change of intensity in various fight sources 

 and show a similar magnitude of displacement by pressure. The same vibrating particle probably pro- 

 duces them. 



The differences in wave-number (i/X) have been formed for the various pairs of magnetic dupficates. 

 Only one case was found where two pairs of magnetic dupficates have the same difference of wave-number. 

 The iron octuplets XX3743. 508 and 3788.046 have exactly the same difference in wave-number (314) as 

 the sextuplets XX 6313.644 and 6337.048. No case was found where two pairs of magnetic dupficates 

 of the same t^-pe have the same difference, though this was tried wherever promising, both between known 

 dupficates and as a means of finding new pairs. The differences between duplicates were found to vary 

 greatly for each element and to bear no simple relation to one another; so that as yet no clue has been 

 found which will serv'e in building up series relations. 



