Series System in the Spectrum of (raid. 25 



Several strong lines. appear in positions suitable for P' 2 (2), 

 and they are probably related. The line (4)56911*96, 

 regarded as a P' 2 line, has its mantissa less than that of 

 P'i(2) by 113800 + 389p 1 -333/? 2 . The lines are measured 

 to the nearest unit in the first decimal point — consequently, 

 it' no observation errors are made, they are indefinite to the 

 extent of '05, or in the above p 1 and p 2 are equally probable 

 within ± 5 The mantissse difference is then with great 

 probability exactly A, i. e. the same as for P'(l). We 

 might he tempted, therefore, to allocate it to the real P' 2 (2), 

 were it not that the rule — so far as may be judged from the 

 <3ase in the alkalies — appears to be that this difference is not 

 the same for successive lines, but that it is about -8 to *9A 

 for m^.2, and is an oun multiple also. This condition is 

 satisfied bv (1)56947*61 whose displacement from P\(2) 

 is 110106." As 78JS = A-2fS = 110076, this satisfies the 

 multiple law with no observation error. None oi: the lines 

 in this neighbourhood appear to give observed combination 

 lines with P' 2 (l). The nearest is (2)57191*88 requiring 

 19834*26 as against an observed (In) 19828*64, possibly 

 within error limits, especially as these combination lines 

 •seem susceptible to change by the electric field in the arc. 

 It would seem that the P' 2 lines here are represented by 

 .several associated lines, of which 56947*61 would appear to 

 be the normal line. 



In the following the estimated separations are based on the 

 78| S displacement. 



m = 3. Separation about 394 or Jess. This is satisfied by a 

 v linked line and a combination, viz. : 



(1) 48254-39 r = 63188-44. 



p 2 (l)-^ 2 (3) = (1)25834*32 gives 63191 94 =P',(.-*). 



j)t = ±. Separation about 200. Satisfied bv 

 (2>0 38695*80 . e - 65948*1 1 . 

 p 2 (l)-/? 2 (4) = (2)28595-47 gives 65953*09 = P',(4). 



;n = 5. Separation about 114. 



(5)52476-9 . rf-^j =67424*28. 



(2) 50169-9. e ==67422-2. 



p 2 (l)-jt> 2 (5) = (1)30067*59 gives 67425*21 = P 2 (5). 



»t=6. Separation about 70. 



(2)51051*66.^ = 68303*97. 



p 2 (l)-p 2 (6) = (4n)30944-04 gives 68301*66 =P 2 (6). 



hi -~ 7, 8. Separations about 48, 33*7. 



