The principal susceptibilities of praseodymium salts have been
measured from room temperature down to liquid air temperature, The results are discussed in terms of the crystalline electric field theory. It is found that (1) on the basis of a single Suitable cubic field the observed magnetic moment at all temperatures in the range studied can be explained satisfactorily. (2) The observed large anisotropies of the crystals point to the existence 0f strongly asymmetric rhombic field. (3) a rough
estimate of the rhombic part of the field shows that the splitting by it is by no means small and compares favorably with the cubic splitting. (4) The X1-axis of praseodymium sulphate rotates by about 63 degrees in the range studied