Harriry anp 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- 
graphed 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 the 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,{ or Exner and Haschek,§ are distinguished by the 
initials EK. & V. or E. & H. in the following tables of wave-lengths. 
Tue Frame-Spucrrum of Macyesium, 
Between wave-lengths 5900 and 3530. 
Lines and bands degraded towards the violet. 
ee Description. 
5209 A strong line. Degraded on the more refrangible side. It corresponds with 
one of the magnesium-hydrogen bands. (Liveing & Dewar.) 
5184 A strong line. 
5174 Line. A triplet common to flame, are, and spark. (L. & D.) 
5168 Line. 
5154 A weak line. Magnesium oxide according to Watts and Lecocq de Boisbaudran. 
5004 1st band. 
4993 2nd ,, Not observed in the magnesium-hydrogen spectrum by Liveing 
3 3rd_,, & Dewar. 
71 4th 5; A similar group assigned to magnesium oxide contains apparently 
60 BUN op these bands, or bands similar to them. 
44 6th ,, 
4572 A line according to Liveing & Dewar, common to flame, are, and spark—(4571:3, 
Exner & Haschek.) 
4100 
; Me An exceedingly strong continuous spectrum. 
00 
* Denkschr. d. kais. Akad. d. Wiss., Wien., Bd. 1x1., 1894. 
} Astrophys. Journ., vol. x1z., 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 ultravioletten Funkenspectra der Elemente.” 
Ag., and Cu., Bd. cv., Abt. ii., (1896). Zn., Cd., Mg., Al., Bd. cyr., Abt. i1., (1897). 
Strong lines of Ag., Cu., Pd., and Ir., Bd. cvz., Abt. ii., (1897). 
Au., Bd. cy, Abt. ii., (1898). Be., In., La., Bd. cvm., Abt. ii., (1899). 
