Approximate **data** for the anhysteretic magnetization curve H m (m) = µ −1 (dW m /dm) are derived from the **data** for specific states and compared with the predictions of the analytic formulae in Fig. 5. The agreement is good, particularly near m = 0 and 1. The fields predicted by the two asymptotic formulae differ quite sharply at m = 1/2, where they indicate a step discontinuity in field that matches a similar step in H m (m), the **data** from the series of specific states.