Metallic toxics such as mercury, lead, cadmium, manganese, and other species are now of particular importance in relationship to coal‐based utilities, waste‐to‐energy plants, medical waste incinerators, and other industrial sources of atmospheric emissions or residues deposited in landfills. These metals are strong emitters or absorbers of middle ultraviolet light in the same general spectral region where important molecular pollutants are active. The furnace system of a commercial atomic absorption spectrometer, a continuum ultraviolet light source (a deuterium arc), and an oscillating entrance slit (adapted from second derivative spectroscopy) are applied to the measurement of toxic metals. The second‐harmonic ripple in the output of the photomultiplier tube is amplified by use of a tuned amplifier. A large signal‐to‐noise improvement is achieved when this system is calibrated and optimized with the metallic species of interest. This approximately compensates for the selectivity loss in using a continuum source in place of special lamps. Employment of this system is described in detail for the detection of mercury and the results are given for eight metals (Hg, Cd, Mn, Zn, Pb, Ni, Cu, and Cr). Data scatter when using this second‐harmonic spectrometer system is roughly 1/10 that of standard procedures.