To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectroscopic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.
U.S. Patent No. 4,692,875, Sept. 8, 1987; Chem. Abstr. Not Found