Use of Electricity for Spectral Analysis

It had become clearer that the Hght from a glowing soHd body shows a conHnuous spectrum while a metal that is vaporized emits a characterisHc line spectrum. The yeUow doublet in the sodium spectrum was an example. Charles Wheatstone, well known from the science of electricity, in 1835 invesHgated electrical arcs generated between metal electrodes. The metals he used were mercury, zinc, cadmium, Hn, bismuth and lead. He used a prism for studying the radiaHon from the arcs and observed the disHnct Hnes that consHtuted the spectrum. Further he noted that each metal had its special group of Hnes, which could possibly be used for element idenH-ficaHon. 

Two general techniques for material analysis started to develop. 

We have reached the middle of the century but spectroscopy has not yet been oflfi-ciaUy invented. 

In 1854 he investigated alloys of two metals and showed that when the radiation from an arc discharge was split in a prism, lines typical for each component appeared [10.5]. He also investigated the absorption spectra of hydrogen and other gases [10.6]. 

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