6o 



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



Trials with other limits for the small, medium and large classes have shown that the group percentages 

 are not materially altered, as this results in a transfer back and forth of lines near the limits chosen. An 

 attempt to reduce Group 2 was made by taking all those Hnes which had one or both values so near the 

 hmit of the class that the error of measurement, if in the favorable direction, might have put the two 

 values into the same class and so have brought the line into Group i. Lines of complex Zeeman separa- 

 tion were also treated in this way; 35 iron lines were thus selected, which when added to Group i as given 

 in Table 13 raised its total to 64 per cent of the whole. This number, then, may be in fair agreement as 

 to order of magnitude, while the remaining 36 per cent are divergent beyond the errors of measurement 

 and in some distances widely different. This last device is of course not a fair treatment of the data, 

 since the error of measurement is as likely to move the values wider apart as closer together, and if the 

 same treatment had been applied to the lines of Group i, some of them would have moved into Group 2. 

 However, giving the agreement hypothesis the benefit of the doubt, the proportions of 64 and 36 per 

 cent appear to be the most favorable that can be gotten out of the list of iron lines. 



Table 13. Summary of Classes. 



In Group 3 we have those lines for which either separation or displacement is small and the other 

 large, and in addition 4 lines of iron and 2 of titanium which appear to be unaffected by the magnetic 

 field, while they show a variety of displacements, in some cases large. These offer examples of ability to 

 respond to one displacing agency and not to the other. 



A closer quantitative comparison is afforded by taking the average separations and displacements for 

 large groups of lines. This is done in Tables 14 and 15. The method in forming Table 14 was to make 

 a list of all pressure displacements classified as small, place opposite them the Zeeman separations for 

 the same lines, and take the mean of each list for comparison of the magnitude of the two effects. Means 

 were formed in the same way for lines of medium and large displacement. The ratios of mean separa- 

 tion to mean displacement can then be compared. In obtaining the results for each class, means were 

 formed for the lines in three groups according to wave-length. The whole table thus gives a comparison 

 of the means for the several groups, and also an indication as to how the means for both separation and 

 displacement change with the wave-length. 



Table 15 was made in the same way as Table 14, except that here the class of Zeeman separation, 

 small, medium, or large, was taken as the basis, and the corresponding pressure displacements used for 

 a comparison of means. 



