Hartley and Ramage — Banded Flame-Spectra of Metals. 341 



principal lines in tlieir spark- spectra, and merge into bands in the flame-spectra, 

 or broaden when the quantity of substance is large. This is a feature which has 

 already been observed in tliese and other spectra.* 



Copper lines, wave-lengths, . . . 3274 and 3248. 



Silver lines, wave-lengths, . . . 3383 and 3281. 



There are no lines of gold corresponding to these in the same region, but one 

 line of still higher refrangibility has been photographed, at wave-length 2675. 

 The bands in tlie spectrum of gold are distinguished by being more refrangible 

 than those which apparently corres^^ond to them in the spectrum of copper ; and we 

 should, from this fact, and from the apparent homology of the spectra, expect the 

 doublet of gold to lie in the same region of more refrangible rays. The line photo- 

 graphed is much weaker than the corresponding lines of silver and copper. We 

 attribute this fact to the insufficiency of the energy of the flame to produce these 

 more rapid vibrations with the same amplitude as in the less rapid vibrations of the 

 copper and silver lines. The same want of energy is apparent in the spark- 

 spectrum of gold.f 



All of these five lines have an intensity of ten in the arc-spectra of the metals, 

 and the second line of the gold doublet, wave-length 2428, not yet observed in the 

 flame-spectrum, has also the maximum intensity. 



The flame-spectrum of gold chloride, investigated by Mitscherlich, Lecocq de 

 Boisbaudran, and Damar9ay, does not appear to be related to the spectrum of the 

 metal. 



Spectra of the Metals of the Alkaline Earths. 



Many bands are present in the oxyhydrogen flame-spectra of these metals. 

 These bands, which differ entirely in character from those just described, have 

 always been attributed to the oxides or to other compounds of the metals. They 

 are diffuse and not degraded ; neither are they composed of lines. We have no 

 direct evidence of the compounds from which they are produced being dissociated 

 in the flame, as is the case with the alkali metals, and we know that different 

 compounds, when care is exercised that they shall not be converted into oxides or 

 undergo dissociation, yield different band-spectra, though the metal be the same in 

 each compound. The spectra obtained from oxides have already been examined. J 



Spectra of Magnesium, Zinc, Cadmium, and Mercury. 



There are points of great interest in the flame-spectra of these metals. 

 Lines and bands are present in the spectrum of magnesium burning in air, and 

 in the spectra of compounds of this metal heated in the oxyhydrogen flame. The 



* " Flame-Spectra at High Temperatures," Phil. Trans., vol. 185 (A.), 1894, p. 1029. 

 I Journ. Chem. See, vol. 41, 1882, p. 84. 

 \ " Flame-Spectra at High Temperatures." Loc. cit. 



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