The great deal of information on the structure of electrolyte solutions, available from the analysis of the X-ray radial distribution functions, has been widely illustrated in the previous chapter. However, it must be always kept in mind that in X-ray diffraction (XRD) studies deconvolution of radial distribution data into the pair interaction peaks is always difficult, often ambiguous, and never unique. In Figure 1 an example taken from a FeCl3 solution shows how complicated the deconvolution can be. Here, the single contributions to the total radial curve have been, of course, derived from the model and could not correspond to the real ones. Nevertheless, whatever the real situation is, the figure gives a precise idea of how many partial contributions participate in the total radial curve calculated from the experimental data. Experimental (solid strong line) and calculated (dashed line) distribution curves for a FeCl<sub>3</sub> solution. The individual contributions to the calculated curve are shown for the main interactions reported in Table 16, <xref ref-type="book-part" rid="chapter3">Chapter 3</xref>. https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351077774/7ec6b4e0-f9ea-4e6b-bf1b-2efb3c83e801/content/fig4_1.tif"/> (From Magini, M. and Radnai, T., J. Chem. Phys., 71, 4255, 1979. With permission.)