DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 405 



quantities involved. For instance, it has enabled UB to obtain a value of * correct 

 to about a unit in the sixth significant figure. In the case of Au, the knowledge 

 is still more fragmentary than in Ag and the value of A has not been determined. 

 By the application of our new laws, however, it is possible to obtain a good deal 

 of information based on evidence of weight, and it will be intM-sting to consider 

 it shortly here. Although the spectrum of Au shows many analogies with those of 

 Cu and Ag, no lines have been assigned to the S or D series. Tin-re is a strong 

 doublet in the ultra-violet 2676*05, 2428'06 (v = 3815*28) analogous to the linen 

 allocated to the P series in Cu and Ag. There is only one other doublet in K.H.'s 

 list with the same separation, viz., 6278'37, 506475 ( = 3815'54). This is clearly 

 analogous to the doublets 5782*30, 5700*39 in Cu and 5545*86, 5276*4 in Ag, which 

 have the respective doublet separations but which do not belong to the S or D series. 

 E and H however give an arc line at 4811*81, which gives a separation of 3815*57 

 with K.K.'s line at 4065'22. This has the appearance of a D set, D,, being at 

 4792*79 with a satellite separation of 82*47. But if so it is quite out of step with 

 the progression of the D ia lines for Cu and Ag, viz., 5220 (Cu), 547l(Ag). But 

 5837'64 gives with the above 479279 a separation 3733*43 the same as that between 

 4792 and 4065, and they are in step with Cu and Ag as D,, (2) and D(2), the 

 fainter satellite D 12 being unobserved. This would seem the more probable allocation. 

 In any case, the curious doubling of a D type would have to be explained. There is, 

 however, here not sufficient data to determine the limits, or the other formulas 

 constants or the value of A. But it is possible to arrive at a probable estimate by 

 the following considerations. The limit D ( ) will probably be in step with those of 

 Cu and Ag, viz., 31515, 30644, i.e., will l>e in the neighbourhood of 30000. Now A 

 must give v = 3815*54 and must itself be a multiple of the oun, in fact if it is similar 

 to Cu and Ag of <5 4 . Now W == l'J7'20 with an uncertainty of a few units in the 

 second decimal place. The ratio q = 361'80* + y, where y is probably not greater 

 than 1 in the first decimal place and it will be regarded as a correction on the *l 

 From this it follows that S = 1406'930*097 + '38y. The uncertainty *097 due to 

 the uncertainty in W produces so small an effect that it may be neglected here. 

 Now A must tie a multiple of S and must give with the proper value of D(oo), 

 v= 3815*54 + *30s, '30 being the maximum error of v and therefore s between 1. 

 This condition gives the following sets of possible limits in the neighbourhood of 

 D(co) = 30,000:- 30819-15 + r57*-6y with A = 76<* 



about 30542 ,. 77f5 



30266 ,, 785 



29994 7: ' 



29724 



29465*18 + l'45.<r-57y 8lJ 



* The actual calculations were made before the last most probable 361-890 was obtained, but nothing 

 is to lie gained by recalculating to it. 



