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



observation errors and also possible error due to incorrectness of D(<), i.e., 

 These give the denominator as 291 (2932'27'130-'364). Now 2932'27 is very 

 close to 2939, which is given as the approximate value of A in Table I. The 

 denominator is then written 291 A, and with this new value of A the corresponding 

 value of the oun is calculated as 361'944w a instead of the old value 362'68w 2 , which 

 for comparison is entered next to it. 



Notes on the Tables. 



Na. A is so small that several multiples of it might be taken for D within limits. 



Eb. DI does not give a multiple of A although close to it. If, however, Rb has 

 satellites, the denominator for D 12 will be a few multiples of S less than that of D n . 

 That for Cs is 1 l^S less in the corresponding case. The values in the table are given 

 for 8(5 and 10<1 Judging from the value of the oun it is probably near 8<J. In any 

 case the multiple would be 59A. This is a very strong argument that lib does 

 possess satellites. 



Cs. Neither D n or D 12 give multiples of A. 



Mg. As in Na, A 2 is too small, and- the denominator too large to give anything 

 definite. 



Sr. Dj 3 gives the oun clearly too small, although better than in the original table. 

 D 12> however, gives a value 361738 quite close to the probable value. A similar 

 result is shown also by Cd which occupies an analogous position in the next 

 sub-group. If D 13 behaves in what appears to be the normal manner, it would 

 appear necessary to take the atomic weight to be '10 less than BBAUNER'S value, viz., 

 87 '56 in place of 87 '66, which is probably too large a change to be acceptable. 



Ba. In Barium the first set is doubtful. That taken above shows no satellites. 

 The denominator is therefore that for D 13 , and this is a multiple which gives a value 

 of the oun much nearer the probable value than that in Table I. Evidence will be 

 given later however under BaF that there is a normal satellite triplet, outside the 

 region of observation, where D 13 has the denominator 2 '04 19 54, which, from analogy 

 with the other elements of this group, has a " mantissa" 1 '04 1954, and this is again a 

 multiple of A 2 . This, therefore, is probably the correct value, and the other set will 

 be collaterally displaced from this by 18A 2 . 



Ra. The first line should be far in the ultra red, and has not been observed. The 

 multiple 31A 2 is determined indirectly (see BaF below). 



Cd. This element shows the same irregularity as in Sr, in that D J3 does not give 

 an exact multiple of A 2 , although one close to it. Here, however, we have to go 

 back to D n before finding the exact multiple, and D n gives almost the precise value 

 of the oun as in Table I., which was itself very exact. 



Eu. D 13 is '917794, which is 50A 2 +1344, A 2 having the value 18329 of Table I. 

 If it is 50A 2 exactly, A 2 would be 18355'88-2'28 making the oun (361'46-'04) in 

 place of 360 '93 of Table I., a great improvement. 



