Abstract: A method of measuring the content of a given element in a sample by means of X-ray radiation. The sample is first irradiated with primary radiation of a given wave length, to excite first composite fluorescent radiation from the sample whose content of said element is to be determined. Subsequent hereto the sample is then irradiated with primary radiation having a shorter wave length than the first mentioned radiation, to excite a second fluorescent radiation from said sample. The magnitude of the first fluorescent radiation is then subtracted from the magnitude of the second fluorescent radiation, whereat the difference therebetween constitutes the intensity of fluorescence radiation of the shortest wave length which can be excited by the primary radiation having the shorter wave length.

Abstract: A method and apparatus for measuring the content of an element by means of X-ray-radiation. Electrons from the cathode of a low-power X-ray tube are directed onto one side of the anode of said tube, said anode comprising a thin layer of anode material on a beryllium plate. The electrons excite primary X-ray-radiation in the anode material, including the characteristic X-ray lines. The radiation passes out through the opposite side of the anode as transmission radiation and is directed onto the element to be measured, whereupon fluorescense occurs, said fluorescense being caused by the characteristic lines. The fluorescense lines of the substance are then isolated by means of a balanced filter.