Periodically intensity modulated optical excitation and magnetical heat dissipation has been used to produce temperature oscillations in three gadolinium samples with differences in the quality of crystallinity. Depending on the circumstances the acoustically detected temperature signal can contain information on specific heat capacity, thermal conductivity or magnetic susceptibility of the material. We have investigated the magnetic field and temperature dependence of these physical properties in the neighbourhood of the critical point (T=Tc and B=0).