Hartley and Ramage — Banded Flame-Spectra of Metals. 



343 



mercury heated in the cyanogen flame. More recently, Eder and Valenta* have 

 described a band-spectrum of mercury. They obtained it by passing electric 

 sparks from a coil, without a Leyden jar, through mercury vapour as it distilled 

 through a capillary tube. The band-spectrum of mercury has also been photo- 

 grajDhed by Huff,t who carefully exhausted the gases (air, &c.) from the tubes 

 employed, and proved also that the band-spectrum was not due to the constituents 

 of the glass. It is most probable that these bands will be observed in the flame- 

 spectrum of mercury when tlie temperature of the flame is higher than that of the 

 oxyhydrogen flame ; as, for instance, in the oxy-acetylene flame. The bands of 

 mercury obtained by other observers, generally by means of the spark, are similar 

 in character to those of zinc and cadmium. They are degraded towards the ultra- 

 violet, and the four metals of this group are alike, and peculiar in this respect. 



References to the measurements of lines in the spark-spectra of elements, photo- 

 graphed by Eder and Valenta,J or Exner and Haschek,§ are distinguished by the 

 initials E. & V. or E. & H. in the following tables of wave-lengths. 



The Flame-Spectkum of Magnesium, 



Between loave-lengths 5900 and 3530. 



Lines and bands degraded towards the violet. 



*Denkschr. d. kais. Akad. d. "Wiss., Wien.,Bd. lxi., 1894. 



f Astrophys. Journ., vol. xii., Sept., 1900, p. 111. 



\ Eder & Valenta. Denkschr. d. kais. Akad. d. Wiss., "Wien. 



Cu., Ag., and Au., Bd. 63, (1896). Cd., Bd. 61. (1894). Cd., Mg., Al., &c., Bd. 60, (_1893). 

 § Exner & Haschek. Sitzungsberichte d. kais. Akad. d. Wiss., "Wien. 

 " Uber die ultravioletton Funkenspectra der Elcmente." 



Ag., and Cu., Bd. cv., Abt. ii., (1896). Zn., Cd., Mg., AL, Bd. cvi., Abt. ii., (1897). 

 Strong lines of Ag., Cu., Pd., and Ir., Bd. cti.,. Abt. ii., (1897V 



Au., Bd. era., Abt. ii., (1898). Be., In., La., Bd. cvm., Abt. ii., (1899). 



