368 Intelligence and Miscellaneous Articles. 



naphthaline amounts to 1*4916 at 20°, and decreases 0-0 3 70 for 1° C, 

 The preparation was obtained from Dr. Schuchardt in Grorlitz. — 

 Wiedemann's Annalen, No. 3, 1891. 



ON THE LINE SPECTRA OF THE ELEMENTS OF MENDELEJEFF S 

 SECOND GROUP. BY PROF. KAYSER AND PROF. RUNGE. 



After we had examined the spectra of the elements of Men- 

 delejeff's first group, and had found that they were built up entirely 

 in accordance with law, we passed to the elements of the second 

 group, with the exclusion of beryllium. Here also we have 

 succeeded in finding an entirely homologous structure of the 

 spectra; while for the alkalies, pairs of lines were characteristic 

 which either showed variable difference of vibration (principal series) 

 or constant difference of vibration (secondary series), the elements 

 of the second group are characterized by triplets of lines. Each 

 element has constant differences of vibration i/, and v % both be- 

 tween the first and second and second and third line of all triplets. 

 Of the triplets of each element, one portion is stronger and less 

 sharp ; they form a series of triplets the lines of which can be 

 represented with great accuracy by the equation which we used with 

 the alkalies, 



A-i = A-B- 2 -C- 4 . 



We call those the first secondary series. The other triplets are 

 fainter, but sharper, broadened only on the side of the longer 

 waves. They also form a series, our second secondary series. For 

 Mg r Ca, Zn, Cd, Hg, we have found the first and second series, for 

 Sn only the first, while for Ba we have not been able to find any 

 series. 



According to their spectra the elements fall into two divisions — 

 Mg, Ca, Sr, and Zn, Cd, Hg ; the latter three more especially pre- 

 sent various common phenomena on which this is not the place to 

 enter. In each division, with increase of atomic weight the series 

 move towards the side of the longer waves, as is also the case with 

 the alkalies. In this, however, the second division is displaced to- 

 wards the side of the shorter waves. 



While all lines of the spectrum were taken up by the series iu 

 the case of the alkalies, in the present case this is not so ; about 

 half the lines observed are superfluous in each spectrum. For a 

 number of them we have also found regularities, since they form 

 either pairs with definite distances or triplets ; in any case the number 

 of lines which are apparently distributed over the spectrum without 

 any regularity is a tolerably large one. 



The regular displacement of a spectrum from one element to 

 another finds a natural expression in a regular variation of the 

 constants of our formula. — Berliner Berichte, Feb. 19, 1891. 



