Art X-ray spectrographic technique requiring no calibration curves is used to determine chlorine, bromine, and lead in automotive combustion deposits. Other elements, such as zinc and barium, can probably be determined by the same X-ray technique. The inert dilution method, described by Sherman in 1957, is employed. Improvements in sample preparation have been made to make the procedure more reliable. Results are calculated by the use of a formula, which is shown to be valid even though sample and standard have composition differences which cause interelement-effect errors if calibration-curve techniques are used. Adequate agreement is obtained between the inert dilution X-ray method and chemical procedures.