DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 335 



international atomic weights wen- used, ami {'or Mg it is 24'32 in place of BRAUNER'S 

 24-362. This clearly gave A, = 160J, and A. + A, = 237<J, with S = (362'09'65) w* 

 the uncertainty '65 not including that of atomic weight and being chiefly due to 

 uncertainty in vi + v a . The transference required now is 270, and the fraction of <J, is 

 '502, again clearly not that of the Ca group, but when account is taken of the 

 uncertainty in vi + v a quite possibly agreeing with that of the Zn group. The 

 assumption that the international value of w is more correct than BRAUNER'S certainly 

 gets over the difficulties mentioned above. But we are not justified in choosing the 

 values from the particular systems which best suit our theories. The discrepancy 

 between the international and BRAUNER'S is very great from 10 to 15 times 

 BRAUNER'S indication of his possible error. 



Another suggestion as to a. possible explanation may be given. There have been 

 various indications in [I. and II.] that small variations in N may occur. If so it is 

 possible to produce the changes observed by a small change SN in the middle line of 

 the triplet. The necessary changes to do this are given in the sixth column. The 

 changes clearly depend on the squares of the atomic weight, for if they are expressed 

 in the form xw* they are 



Sr . . . 5'20 = 6767t^ = 4x l'564i^ Cd . . . 11'86 = 



Ba . . . 3'34 = 1777W 2 Eu . . . 2176 = 9'426w* 



Ha ... 8'13 = 1-58610* Hg. . . 38'50 = 9'596w* 



in which it may be noticed that 9 '426 = 6x 1'571. Again multiples of a quantity 

 depending on the square of the atomic weight enter, and it is especially interesting 

 to note that the Zn group are affected with the multiple 6. If Ca and Zn show 

 similar displacements, Ca would require <5N = '25 in place of '16 and Zn 4'03. Zn 

 is clearly 0, i.e., is unaffected, but considering the small numbers involved in Ca and 

 conseqtiently large proportional errors, Ca might well show '25 instead of '16. The 

 question naturally arises, do these quantities depend in any way on the oun ? Now 

 any change in N may be supposed to arise either as a real change in N itself or an 

 apparent change due to the introduction of a factor in connection with the 1/D*. In 

 other words, the quantity VD is 



(l+/)a 



N or N 



- 



Looked at from this point of view, 9'426tp a requires N (l + '000859^) or 

 N (1 + '000429 iv*y. Now 55j would give < 000452r l , but if the present explanation 

 is the true one, this is not a likely value since it will not include the alkaline earths. 

 A value 6<$i = < 0005428w a would be expected. The Ba value 1777 would give 

 (T000088J0 2 ), or practically (!+<$,)". It rather looks as if this explanation is a part 

 of the truth. If more exact measures were at disposal it might be well to assume 



