the Spectrum of Copper. 463 



atomic weight of copper in terms of that of Ag comes to 

 63'5569 + '006. Brauner's value of the chemical atomic 

 weight is 63-56 ±-01. 



With this approximate value of A it is now possible to test 

 for D lines corresponding to the order m = l, in which the 

 D satellite sequence or d 2 (V) has its mantissa a multiple 

 of A. The actual values will depend on the true value of N 

 but the deviation from the truth on this account will not 

 amount to more than 7 or 8 units in the sequent, and will be 

 passed over for the present. The extrapolated mantissa of 

 rfj(l) is 967250. The actual value for d 2 (2) is 977297. 

 That of d 2 (l) must be less than the latter, and the multiple 

 therefore be in the neighbourhood of 132. Any evidence 

 of the real existence of D(l) lines must be based on com- 

 bination lines with the inverse D' set, and on the presence of 

 summation lines. It may be said at once that no such, 

 evidence can be found for 131 A. With the values above 

 132 A = 964535-43-6 f-14y. The d 2 (l) is N/(1 + 132A) 2 

 = 28417-66 + 1-26 f 4 "41y. Consequently 



D 12 (l) = 3105-82 -'26 f, 

 D 12 (l)=59941-14 + 2'26f. 



There is a line at (1) 59916" 12-36 dX of Handke's but no 

 other in this region. If it is the surviving strongest D n line 

 the D set should be 



D 12 = 59941-14 + 2*26 f, 

 Du= 59916-12-36^, 

 B 22 = 60189-62 + 2-26%. 



£ is probably not greater than a few decimals so that the 

 satellite separation is o-=25 + 36 dX, but this may be modified 

 up to + 7 by the unknown error in N. As it stands how- 

 ever, the separation of 25 would be due to 2i8 1 — 6 8, as. 

 usual slightly larger than for the m = 2 set (23 6\). 



The inverse D' lines are in wave numbers in R.A. 



D 12 '= -(8)17537-66, 

 D n ' = -(1)17439-40, 

 D 22 ' = -(8)17289-22. 



It should be noted that the D n line instead of being the 

 strongest of the set is extremely weak, and seems to indicate 

 that very few of the d 2 configurations have split up to form 



