DR. W. M. HICKS: A CRITICAL STUDY OF 8PFXTTRAL SERIffi. 



381 



Group II. The Alkaline Ea/rths. The series are most fully and regularly developed 

 in Ca and Sr. In Ba and Ra the configurations which give rise to the nonnal type 

 seem to be so modified that displaced lines become common, and in cases the normal 

 line has disappeared. On the other hand, Mg seems to range itself with the Zn 

 sub-group. It will be best therefore to deal with Ca and Sr first, and as they are 

 built on a precisely similar plan to consider them together. 



The following table gives the wave numbers of the series together with certain 

 others which are clearly similarly related in the different elements. The separations 

 are indicated by thick figures. The wave-lengths are given in Appendix II. 



Ca. 



16203-40 21-75 16225-15 

 16204-72 



21799-02 21-13 21820-15 13'58 21833-73 



24391-49 21-50 24412-99 13'66 24426-65 



25793-67 21-64 25815-31 13 "55 25828-86 



26634-00 22-43 26656-43 14-29 26670-72 



27177-76 21-58 27199-34 15-09 27214-43 



Sr. 

 14801-57 101-73 14903-30 



15046-98 61-70 15108-68 



20530-76 69-78 20590-54 

 20432-18 100-64 20532-82 

 20435-10 



23045-78 99-26 23145-04 58'54 23203-58 



24457-06 100-05 24557-11 59 25 24616-36 



25303-32 100-47 25403-79 58 '61 25462-40 

 25850-61 



Analogous Sets in Ca and Sr. 

 17847-46 21-94 17869-40 13'86 17883-26 



17887-55 21-81 17909-34 



18968-53 21-58 18990-10 14'01 19004-11 



Ba. 



13089-79 260-60 13350-39 



13471-69 259-76 13731-45 157'55 13889-00 

 13477-44 



18686-80255-17 18941-97 



21308-19 252-51 21560-70 148'32 21709-02 



18061-87 100-20 18162-07 56-61 18218-68 



18239-35 100-62 18339-97 



19016-64 100-34 19116-98 59'75 19176-73 



Ra. 



17793-09 

 17300-80 699-93 18000-73 



22037-41 456 64 22494-05 

 21350-92 701-89 22052 -1 



22706- 84'" 

 23667-07 



22979-57 



23919-27" 23995-83 



"> F 12 (5)(A. 2 ). *F,(6)(9A,). 



