I>K. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SEltlES. :; :::: 



|Ks.sil)ility it may be well to determine tin- amount of such error required t<> bring, 

 Kjiy, the valur 'ICi'J't to ;{<>rK, ami :;i;rCi to 3G1'9, as it is prol table the true value of 

 the ratio lies I tetween 361'8 and 3G1''J. The former requires an increase in atomic 

 weight of raW an( l the latter a decrease of ^faf of the accepted values. The 

 following would be the changes in atomic weight required : 



Ca. Sr. Ba. Mg. Zn. CM. Hg. 



-'025 -'036 -'052 +'02; +'04 +'09 +'2 



According to the estimates of accuracy given by BliAUNEK the changes for Mg and 

 Ca are quite impossible, for Zn just possible, and for the others possible. In the case 

 of Mg and Ca, however, small errors in v l -\-v 3 are considerable proportional errors 

 and the deviations may be caused by these. It is necessary to have these estimates 

 before us. Notwithstanding them, the close agreement of the numbers in each set, 

 and the difference between the two sets must produce the conviction that the 

 differences are real, and are not due to errors either in the spectroscopic measure- 

 ments or the atomic weight determinations. 



In the table the multiples given are those which give the oun most closely. An 

 inspection, however, shows that in each element there is some disturbing influence 

 affecting the A, and A 3 in opposite directions. Moreover, the sum of the multiples 

 chosen are in certain cases not the multiple taken for A, + A.,, and this should clearly 

 be so. This happens in Cd, Eu, and Hg. There is apparent a general rule that c, is 

 too small and v a is too large, the deviation increasing with the atomic weight. The 

 discrepancy is equivalent to a transference from the true A, to the true A a . 

 Evidently the transfer in Cd, Eu, and Hg has been so large as to increase A 2 by 

 more than <$,, so that the closest multiple now appears to be too large by unity. If 

 the multiples in A a be diminished by unity, the sum is equal to that for A, + A 3 , and 

 the discrepancy between the ouns from A, to A a increases in a regular order. A 

 similar change has occurred in Sr, only here while the multiple of A, has apparently 

 increased, that of A! has apparently decreased. If the ratio A;, : A, be taken as 

 79 : 171 in place of 80 : 170 the discrepancy again falls into order with the others. 

 With these changed ratios the values become 



Sr 171x90'OG8 79x91*144 



Cd 203x90-252 90x91*351 



Eu ...'.. 246x90*205 87x9T27 



Hg 242x90-446 82x91'17 



This transference must take place in the D a (oo) = S a (o) term. The values are 

 given in the following table in which the first column gives the value of A a : A,, the 

 second the value of the transference, the fourth the transference in v t to v tt the fifth 

 the new value of A 2 , and the third and sixth are as explained later : 



