358 G. Hinrichs on Spectral Lines. 
I K D Grade. De 
Qe = 2081°1 : igh SS 
eet 8 833 = 2X1665 
le 1287.5 : ; 
oe eee ee. Fas 76-6 1X 16°6 
s.  iseta. Ott. 18? 060 = a K1606 
1b spe, oe ae 665 = 41664 
4} Gers 180 18 302 = : its 
3a 719°6 : ao ee 
2 718-7 9 2°5 23: <= 7 
On account of our method here used, only such lines could 
be considered as are sufficiently close to admit of our reduction 
of the difference in K by simple multiplication with the grade. 
All lines accessible give the interval 16-6—the mean of the six 
determinations is 16°3. It is also seen that the actual intervals 
are very simple multiples hereof. 
§ 20. Magnesium spectrum. 
I K WwW 
Ww E 
6e 1655°6 5165°8 1 5166-07 —27 
6f 1648°8 5171°3 5171°3 0 
4c 1634-7 5181-0 
4g 1634°1 5181°5 5181-76 +26 
where d—5-23. 
The line 6/ is Fraunhofer’s }. The reduction was here effected 
arithmetically by means of the grade ‘8; affecting only the last 
given number. 
These three or four lines forming a natural group, the total 
range or 3d, i. e., 15°69, becomes characteristic of this element. 
$21. Strontium spectrum. It will be noticed that this differ- 
ence is very nearly the same as the one previously found for 
barium and calcium. It thus becomes of great interest to ascer- 
tain whether or not strontium also herein agrees with the other 
praia of the group of alkaline earths. We have for stron- 
am 
I K Ww ; w E 
36 753°8 5400-0 4 5400-0 0-0 
3a 1274-7 = 5532-0 . 55306 + 1-4 
4¢ 1820 = 54800, 54823 28 
3 { 28579 4806-0 43070 ~—1:0 
4a 2858°5 
2 gs 8:9) 
2859-4) 
where d=16-1, 
The intervals give 
: 54 3 73 
OF eRe sd oma 
