A program has been developed for the semiquantitative evaluation of photographically recorded spark source mass spectra. The densitometer readings are transformed into relative intensities, considering the mass dependence of the photographic response and the instrumental transmission characteristics. Line assignments are made, accurate within 5 to 30 millimass units, depending on the mas. Most interference problems are quantitatively evaluated. Many notations are used to aid the analyst in the interpretation of the data. Finally the concentraiion for each element is calculated in parts per million. © 1973, American Chemical Society. All rights reserved.