406 DK. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 



If now the lines 5837'64, 479279 lie taken as D n (2), D 21 (2), their wave numbers are 

 17125 - 54('14), 20858'97('22), giving for the wave number of D 12 (2), or D 21 -i/, the 

 value 17043'43 ('22q '30s). In this '22g is the possible observation error in D 2] (2). 

 The satellite separation of 82'11 must therefore be caused by a denominator difference 

 which is also a multiple of S t . If this be tested, it is found at once that only the first 

 and last of the above set can satisfy this condition, 3.0819 taking 24^ or GS, and 

 29465 taking 28^ or 78. The corresponding values for Cu and Ag are both 23^. 

 The differences between the values calculated from the lines and from the multiples 

 of S 1 are (p between 1 giving the observation error in D n (2)). 



'Oy+14p-22g with 24^ = 8441 



= 9869. 



It is clear that either can easily be made to vanish well within possible errors, 

 more especially the latter. The limit 30819 is higher than that of Ag instead of 

 lower as might be inferred from the fact that the limit of Ag is lower than that of Cu. 

 The limit 29465 is 1179 below that of Ag, which is itself 931 below that of Cu. 

 This seems a probable order of magnitude, especially when it is remembered that there 

 is a gap in the Periodic Table between Ag and Au. But there is further evidence in 

 favour of the latter. If the lines 6278'37, 506475 are collaterals of D (2) as the 

 corresponding lines in Cu and Ag appear to be, 6278'37 should be D n (2)(xS l ). 

 With the limit 30819 this cannot possibly be the case. The oun S l = 351 is so large 

 that there can be no doubt. If however the limit is 29465, the line is D n (2) (A+ 15^). 

 Further, with neither limit is the mantissa of D (2) a multiple of S, and as this is also 

 not the case with Ag or Cu, it may be regarded that in this group either these lines 

 are not of the D type, or possibly like the high melting-point elements of Group II. 

 the first lines correspond to m = 1 and not m = 2. The actual values of the 

 denominators as found are so close to the same value for all three elements as to 

 suggest the existence of a group constant. If the limit 29465 is used the denominators 

 are as given below, and as is seen they differ from such a constant by very small 

 multiples of S. 



Cu. Ag. Au. 



Density. . . 978276(21)' 977162(19) 971409(26) 



146 = S 1263 = 3i 7034 = 53 



978422(21) 978425(19) 978443(26) 



or say a group constant 978430. Whether this apparent equality corresponds 

 to a real relation or not must be left for further evidence. In any case a limit 

 D ( o) = 30819 would throw this relation quite out. 





