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



PASCHEN allots the following for Zn and Cd, viz., in wave numbers : 



6059-50 



6065'51 



ZnF(3) 6062-55 



3'05 



2-43 



6064-98 



CdF(3) 6083-37 



6095-35 



CdF 3 (4) 8595-57 



17-86 



11-98 



The line 8595 must be allotted to F 3 because it makes the difference 266 with 

 8872, so that the two are F lines connected with D J3 (2) and iiie companion to the D 13 

 line 267 above it. This relation has already been discussed under the D series above. 

 For Hg he assigns 5814 to Fj (3), 5843 to F 2 (3), 5908'68 to F 4 (3), 8316'40 to F, (4), 

 8409'85 to F 3 (4). Now 5843 is double with dn =4"8, corresponding to a displace- 

 ment S, and may well be F 21 . F 22 , whilst 5908 is F 3 (3). Again, 8316'40 and 8409'85 

 are separated by 93"45, which is so close to 34'68 + 62'04 as to indicate that they are 

 Fj (4) and F 3 (4) and that F 2 (4) has not been observed. 



With these allocations VF(3)* = 6939'07 and VF(4) = 4436'66 and the denomi- 

 nators for the lines calculated from the first lines (except CdF 3 (4)) are 



Zn. 



3'978529-287'lf 



Cd. 



3'970387-285'3^ 



4-960809-556'4^ 



Hg. 



3'975605-286'5^ 



4-971938-560-3^ 



The differences of the mantissae of the two orders in Cd and Hg are 



Cd. 

 9578 + 271 213 = 9561 ; 



Hg. 



3667 + 274 



= 3629; 



in which the probable variations of are small fractions. In fact, the greatest 

 uncertainties are due to observation errors. 



There is not much material to throw light on the origin of the F term here, nor in 

 fact is there evidence that the fundamental lines, or the first lines, of the series are 



* On the basis of RITZ'S combining theory PASCHEN gives the following allocations (lines in wave- 

 lengths) : 



3011-17 = S 1 (oo) -VF (3) 2799-76 = Si (oc)-VF (4) 



2642-70 = S 2 (oo)-VF(3) 2478-09 = S 2 ( a,) - VF (4) 



2524-80 = S 3 ( 00) - VF (3) 2374-11 = S 3 (oo)-VF(4) 



There can be little doubt about the correctness of this allocation. Using the value of Si ( oo) in [II.] 

 40139-55 and the wave numbers -33200-19, 35707-02 of the first lines of each set there results 

 VF (3) = 6939-36, 4432-53, which are practically the same as those found direct. 



