Applications of filters are routine and useful techniques in X-ray diffraction and.can also be useful in X-ray spectrography to improve analytical results with very simple procedures. Fankuchen demonstrated the use of filters over the window of the X-ray tube to minimize background from the target element and/or elements in other components of the X-ray tube in research programs at the X-ray- Laboratory, Metallurgy Division, Denver Research Institute during the summer of 1952. This general procedure has been adapted to routine analyses by modification of the spectrograph to provide for movement of filters in and out of position between the window of the X-ray tube and the sample while the instrument is in operation. Placement of filters in the X-ray beam path of the spectrograph between the sample and the analyzing crystal is also a useful procedure to reduce interferences by elements exhibiting lines at closely adjacent wavelengths.