Hinrichs. on Dark Lines in the Spectra of the Elements. 39 
Group Il, d,=9; 4,=3d,==2°7. 
I. K Dz. 
: i. Cc. E. 
5c 2001°6 2001°6 00 
6 52 AH ; 5-2 ‘0 
6c 72 33°9 38 70 — 2 
6c 413 9 1 41-2 at 
6b 42-2 ie i 421 — 1] 
6c 58-0 a : 583 ++ 3 
Be 66:2 3 ; 664 +2 
5c 67-1 149 17 67°3 + 2 
6a 82:0 826 860+ 6 
The great value of the last E undoubtedly is caused by the 
range of the last interval at the end of a great group; ‘all the 
other values of E are very small. 
The intervals are 
Observed, 4:2:38:1:18:9: — 17 
a 
co 6: 80. 41828: “18 
QA, :18A,:64,:84,:6A, 
and oe pea of pies port ier 
-18 +6: 336 
i —— enemy 
: give further Os ee 
thus pied a symmetric division—here into equal parts—of this 
| great ¢ 
| The catas of A, differs considerably from 4,=4, ; ig it is 
obvious that 24, —54 is almost the same as A.A. = 
These most magnificent groups of the elementary Cobre thus 
fully confirm the ‘four laws deduced from the calcium s 
and extended to the alkaline earths. He nce we may conclude 
. that those laws, in substance, will be found applicable to all ele- 
) mentary spectra. But until much more rich and accurate meas- 
urements, combined with direct determinations of wave-length, 
. have been made, a further prosecution of this investigation will 
useless; we therefore content ourselves with this prelimin 
‘ research, ho ing that future investigations based upon richer 
j material wil a ge tend these laws, and by dividing the larger in- 
tervals, rere that these ronerentet lines are not distributed at 
random but as regular as the stripes produced by diffraction. 
far [ "he observations are now at hand, the above four 
laws seem to point to the following one, including them all: 
The dark lines of any element are oper distributed over 
the spectrum, uidistant groups consisting of _equidis- 
tant lines; but the intensity of these lines regularly increases 
and diminishes, so as to obliterate : number of Prete and even 
of groups, thus producing gaps in t alg aes es, gaps which 
only be hi high eka powers—intense line of light ed great 
seinen ideo —can completed. 
