Sananaaineeee 
see BE ey eat Oe See On ee ee See eee ee 
G. Hinrichs on Spectral Lines. 359 
or the first to the last nearly as 8:4, Also 544+8=57 to 78 
nearly as 7:9. The reductions were performed by means of 
the known grade, no one of the above strontium lines coincid- 
ing with Ditscheiner’s lines 
he alkaline earths give as the difference of wave-lengths 
characterizing their spectrum, magnesium pos calcium 16:0, 
strontium 16°1, and barium 16° 3, or in millimete 
Atomic Wii ato 
weight. m. 
Magnesium, - - - - 12 000000157 
Caloium, «+2... 2° 0 000000160 
Btrontiam,. a:.hu.0 6 eee 0:00000161 
Barium, - - - - 68°5 000000163 
Mean value, 0-011000160 
This coincidence is very remarkable, though the absolute 
identity can hardly be pla Fs admissible. We -shall come 
back to this point in our theoretical remar 
§ Sodium spectrum.—Professor Cooke ‘of Cambridge has 
ecently given * four drawings of the three sodium lines forming 
F raunhofer's D. From — figures I find by measurement 
=12 mm., «D,=8 mm., or the distances are as 
t am very sorry that I aye not the detariiiatiang! ‘of Wolf 
and Diacon in regard to the spectra of the alkalies. Interesting 
and zaluable results might no doubt be derived from these ob- 
Me 
Ben n spectrum.—We will now review the three large and 
Raat groups of the iron spectrum as given in our first article. 
Grour I. d,—3-29-—-0""-000000329. 
I K WwW a Ww’ E 
46 12006 5623-25 562158  -—+1°67 
6c 1242: 5569°40 556899 + °41 
o 42 12456 5565°65 556570 2 = “05 
The intervals are inthe i oem Only the first value of E may 
be considered important—may disappear =e the observation 
of a line between the first two given a 
The intervals give the following series: 
2 4 5 + 1 1 
Necieieinnipescmemniaad? 
or 1+5 § 5 1 
showing that the following may be considered as intervals of 
higher order: 
DD, edd 1916, DS setd = 1645 
* This Journal, 1866, xl, 179. * This Journal, 1863, xxv, 414. 
* 
