  It is found that in a wide range of temperatures and magnetic fields even a
small concentration of magnetic impurities in a sample leads to a $T^{-1}$
temperature dependence of the nuclear heat capacity. This effect is related to
a nuclear-spin polarization by the magnetic impurities. The parameter that
controls the theory turns out not to be the impurity concentration $C_{imp}$
but instead the quantity $c_{imp} \mu_e / \mu_n$, where $\mu_e$ and $\mu_n$ are
the magnetic moments of an electron and a nucleus, respectively. The ratio of
$\mu_e$ and $\mu_n$ is of order of $10^3$.
