  We report the magnetic susceptibility, specific heat and dielectric constant
on high purity polycrystalline samples of three hexagonal manganites: YMnO_3,
LuMnO_3 and ScMnO_3. These materials can exhibit a ferroelectric transition at
very high temperatures (T_{FE} > 700K). At lower temperatures there is magnetic
ordering of the frustrated Mn^{3+} spins (S=2) on a triangular Mn lattice
(YMnO_3:T_N=71K; LuMnO$_3:T_N=90K and ScMnO_3:T_N=130K). The transition is
characterized by a sharp kink in the magnetic susceptibility at T_N below which
it continues to increase due to the frustration on the triangular lattice. The
specific heat shows one clear continuous phase transition at T_N, which is
independent of external magnetic field up to 9T with an entropy content as
expected for Mn^{3+} ions. The temperature dependent dielectric constant
displays a distinct anomaly at T_N.
