380 DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 



denominator 3'007542 and the latter 2'987479, the one apparently too large and the 

 other too small to fit in with the progression of the lines for m = 3, 4. But the 

 mantissa for the latter is within limits 2(5 below that for m = 3 [see Note 3 at end]. 



In Rb there is a line at wave number 2129'0 which would require a denominator 

 2'997805, well in step with the other two. PASCHEN identifies it as Di 2 (3) P 2 (4), 

 assuming the existence of satellites in RbD. It would seem to be more probably the 

 F(2) sought for. There is another line given as 2156'! or 2164'4. If the former is 

 the more correct it gives denominator = 3 '00 11 38. In Cs no line appears with wave 

 number near 4450. There are two lines, however, with wave numbers 3409 '93 and 

 3321 '37 which differ by 88'56'6, and certainly suggest the doublet series depending 

 on the D(2) satellite. This requires a separation of 97 '96, and if they belong to the 

 F series there must be a satellite with a separation 9 '40 '6 which we should not 

 expect to observe as being too faint. The lines give a mantissa 2 '8 5 1708 with a 

 satellite difference 1003. The latter may be, within limits, 2<5, a value which in the 

 alkaline earths seems to be closely associated with F satellites. But the mantissa is 

 less than that for m = 3, when a larger value should be expected. Even if not F (2) 

 itself it may be related to the F cycle in a similar way to certain displacements found 

 in the alkaline earths (see pp. 383, 413), and it should be noted that if so there 

 seem to be lines in corresponding positions in K and Rb. They are (in wave numbers) 

 the 1182'9 referred to above for K and 1911 '05 in Rb. The latter requires a 

 denominator 2'971391. In this connection it is interesting to note that PASCHEN 

 makes the remark that this line at times shows itself double. The separation 

 calculated from his numbers is 1'12, giving a denominator difference of 107 for 

 F](oo) and F 3 (>), i.e., for VD n (2) and VD ]2 (2). This would indicate a sort of 

 incipient satellite in RbD. These considerations seem to show that there is some 

 likelihood that m = 3 does not give the first line of the F series, and they will be felt 

 to have greater weight when the curious irregularity in the F(2) of the alkaline 

 earths to be noticed immediately is taken into account. The question is further 

 discussed on p. 397 in connection with the other elements. 



The next question is, is there any indication of F satellites in the accepted lines ? 

 If so we should only expect to find it in Cs. Now RANDALL gives weak lines 8080'9 

 close to 8083'!, Fj (4), and 8018'9 close to 8020'6, F 2 (4). They look like satellites 

 only on the wrong side. The first changes the denominator by 2000, which is within 

 easy limits of 1914 = 3^. It will be shown that this is a common satellite difference 

 in the alkaline earths. Further, it makes the denominator 4'9718, thus bringing the 

 values for m = 3, 4, 5, 6 in order, which is not the case in the table above. There is, 

 therefore, something to be said in favour of taking the normal F (4) doublet to be at 

 8080'9, 8018'9, and that that is then collaterally displaced by 3<5 to the stronger lines 

 8083'!, 8020'6. It is also quite in keeping with analogy in the alkaline earths that a 

 similar displacement is not shown in the case of the first lines F(3) (if F(3) are the 

 first lines). 



