350 Hartley and Ramage — Banded Flame-Sjoectra of Metals. 



Band Spectra: Arsenic, vanadium, yttrium, cerium, praseodymium, neodymium. 

 The compounds of the last four elements under examination in all probability 

 yield oxides, and the spectra are those of the oxides. 



Band and Line Spectra: Nickel, cobalt, rhodium, and iridium. — Most probably 

 the spectra are those of the metals. 



It must be understood that the flame-si^ectra in these cases give lines in 

 addition to bands, or bands in addition to line-spectra, sometimes as if they 

 were components of different spectra, and in some cases as if the lines arose out 

 of the edges of the bands by some change in the conditions of the flame. 



Germanium. — Very faint indications of bands have been obtained also in the 

 flame-sjDectrum of germanium. 



There can now be no doubt that band or channelled spectra are given alike by 

 metals as well as by metalloids such as tellurium and arsenic, or non-metallic 

 elements such as sulphur and phosphorus. It is equally true that these bands are 

 entirely due to the metals in many cases, though there are instances of bands or 

 broad lines being undoubtedly rendered by compounds, as for example, under 

 certain conditions, by the haloid salts of the alkaline-earth metals, also by haloid 

 salts of gold and of copper. 



Conclusions. 



(1). Metals of very different characters belonging to different groups in the 

 periodic system of classification yield banded spectra or spectra composed of both 

 bands and distinct lines. As examples, we have magnesium, zinc, and cadmium ; 

 copper, silver, and gold ; aluminium, indium, and thallium ; palladium and iridium ; 

 bismuth, tin, and lead. 



(2). Metals which are combustible and which evolve a large amount of heat upon 

 combustion, forming oxides which are but slightly volatile, yield banded spectra ; 

 so also do those metals the oxides of which are easily volatilised, and furthermore, 

 those metals that do not form oxides at the temperature of the flame. 



(3). Certain groups of elements yield banded spectra which are degraded 

 towards the less refrangible rays, as, for instance, the metals coj^per, silver, and 

 gold ; aluminium and indium ; beryllium and lanthanum ; others exhibit spectra the 

 bands of which are degraded on the more refrangible side, as magnesium, zinc, and 

 cadmium. 



(4). Many lines, independent of those bands which are composed of fine lines, 

 are present in the flame-spectra of palladium and iridium. Both of these metals 

 are difficult to volatilise in the oxyhydrogen flame ; hence only small quantities of 

 the vapour are jjresent in the flame. The same feature belongs to the spectra of 

 some of the metals which are easily volatilised, when only small quantities are 

 present. 



