Abstract
The field dependence of the susceptibility of some spin glass materials is interpreted in terms of Neel's model of superparamagnetism, leading to a universal plot for the following substances: (La,Gd)Al2, MnO.Al2O3.SiO2, Cu-Mn, Co-Ga, Eu-Sr-S. Values of the mean zero field blocking temperature and the mean anisotropy field HK are deduced, the latter also by an independent method. The origins of HK are discussed.