Calorimetric Investigation of Spin-Glass Ordering in CuMn

New measurements near $T_{\mathrm{sg}}$ characterize the heat-capacity anomaly associated with spin-glass ordering. There are no discontinuities in the heat capacity or its temperature or field derivatives but there is a relatively sharp anomaly in the field derivative and a broad anomaly in the temperature derivative. A failure of thermodynamics to predict correctly the relation between heat capacity and magnetic susceptibility may be a manifestation of the "nonergodic" behavior of disordered systems.