342 
DR. W. M HICKS : A CRITICAL STUDY OF SPECTRAL SERIES. 
Suppose the atomic weight is W and the number of electrons involved is xW. 
Then the oun is given by 
4 = s(W+xW/ 1850)* = J„(l+ 
If another value depends on y electrons 
whence 
x-y = 925 = 925 
0 0 
which gives the transference. At present these considerations are only of speculative 
interest, but a numerical illustration is given below (p. 381) in connection with Kr. 
The resnlts obtained in this investigation have given the oun with much greater 
exactness than any value obtained in [III.], even than that of Ag. The value of 
q = has been determined [III., p. 404] as near 361'75 with Ag = 107’88. I now 
believe from later work that the true value is closer to this than I thought at that 
time, but in any case it is far less accurate than the ouns themselves. While, 
therefore, we can use the ouns to give extremely accurate values of the ratios of the 
atomic weight of the gases, the actual values in terms of Ag are not so exact, 
although more accurate than those obtained by chemical means. This statement of 
course depends on the supposition of the exact proportionality of oun and square of 
atomic weight. 
The values of ^ as obtained later are here collected and the atomic weight deduced 
from them by taking q = 36175. 
Ne. A. Kr. X. RaEm. 
S . . . 14•4708±-0006; 57-9209±-002; 249•536± •004 ; 611‘0100±'0017 ; 1787*024±-05 
W. . . 20■0005±-0004; 40-0141±-0006; 83*0543±0006 ; 129•963± •00018 ; 222*259±-003 
Chemical. 20*2 39*88 82*92 130*2 222 to 222*4 
It will be seen that in all cases the spectral determinations are much closer to 
integral values than the chemical, except in the case of RaEm as estimated from 
Honigschmidt’s value for Ra. In this case, however, the spectral material is 
defective. It is shown from one of the criteria that a value of the oun = 1785’23 is 
just possible but improbable, or = 1783'38 almost impossible. These would give 
respectively iv — 222T48± and 222*033 ±. It is curious also that from the defective 
observational work for Ra [III., p. 327] the value of S from vi + v^ = 254096 = 137^, 
whence tv = 226*43 is also greater than Honigschmidt’s and more in accordance with 
the value obtained by Mme. CuRlE. The value for the Emanation is, however, much 
more reliable than the above for Ra. If, regarded as a whole, the deviations from the 
chemical values (RaEm excepted) are greater than chemists will allow possible, it 
