arc-spectrum

Now, in many cases the number of lines of definite wavelength observed in such a spectrum is considerable, for example, hundreds of different lines have been observed in the arc-spectrum of iron.

Alchemy: Ancient and Modern 1922

It is also held that until they have explained, without room for doubt, the reasons for the presence of some lines, and the absence of others, of any element in a stellar spectrum; why the arc-spectrum of each element differs from its spark spectrum; what are all the various changes produced in the spectrum of

History of Astronomy George Forbes 1892