We can consider the solis as "materilas" having a great variability of their properties. In practical geotechnics is usual to use the results of various tests to get, starting from easier to obtain properties, information of greater importance in the applications. It's usual to use, for this aim, empirical relations derived from statistical elaborations. Among the relations which are most in use, are pointed out the ones that links togheter the compression index with a basic property (e.g. liquid limit, natural water content, void index, etc.). A well know empiracal relation which allows to obtain the overconsolidation ratio starting from the seharing resistance angle, the undrained cohesion and the effective vertical stress, shows a great range of variability. Are also pointed out some relations of quite good reliability which allows to evaluate the shearing resistance angle by means of the plasticity index. At last these investigations, althought based on a limited data sample takene from literature (and hence not really quantitatively exhaustive) gives quite interesting results both regarding the practical use of the already existing relations and in theoretical study. In particular the verification of these laws by means of experimental data can allow the improvement of the reliability of these relations.