= Solution
For Co, the full field-polarized ionic value is
$$
\boxed{M_{\rm sat}=N_AgS\mu_B\simeq4.25\ \mu_B\text{ per Co}\simeq2.37\times10^4\ \mathrm{G\,cm^3\,mol^{-1}}.}
$$
This is distinct from the much smaller weak-ferromagnetic domain moment, approximately 450 G cm$^3$ mol$^{-1}$ at low field. A low-temperature isothermal loop should have a \b[small hysteretic central component superposed on the antiferromagnetic field response]. Reversal changes the selected weak-ferromagnetic domain and produces remanence and coercivity. At larger fields the <magnetization> continues to increase as the opposed sublattice moments rotate; a spin-flop or spin-reorientation feature may occur depending on field direction and anisotropy. Only sufficiently strong fields approach the full ionic saturation value, so the small low-field loop must not be labelled as saturation at 4.25 $\mu_B$.
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